Glossary
- β-oxidation
-
Fatty acid oxidation to form acetyl CoA.
- abdominal aorta
-
Portion of the aorta inferior to the aortic hiatus and superior to the common iliac arteries.
- abdominal cavity
-
Division of the anterior (ventral) cavity that houses the abdominal viscera.
- accessory digestive organ
-
Digestive organ that food doesn't pass directly through. Includes teeth, tongue, salivary glands, gallbladder, liver, and pancreas.
- acetyl coenzyme A (acetyl CoA)
-
Starting molecule of the Krebs cycle and end product of β-oxidation.
- acid
-
A substance that releases hydrogen ions (H+) in solution.
- acidosis
-
Condition caused by buildup of acids in body fluids, resulting in blood with pH<7.35.
- acinus
-
Cluster of glandular epithelial cells in the pancreas that secretes pancreatic juice in the pancreas.
- acrosomal reaction
-
Release of digestive enzymes by sperm that enables them to burrow through the corona radiata and penetrate the zona pellucida of an oocyte prior to fertilization.
- acrosome
-
A sac-like organelle forming a cap over the anterior portion of the head of a sperm cell, derived from Golgi.
- action potential
-
Change in voltage of a cell membrane in response to a stimulus that results in transmission of an electrical signal; unique to neurons and muscle fibres.
- active transport
-
Movement across a membrane against the concentration gradient, requiring a transport protein and energy in some form.
- adaptive immune response
-
Relatively slow but very specific and effective immune response controlled by lymphocytes.
- adenosine diphosphate (ADP)
-
Lower energy form of ATP, containing two phosphate groups after the third phosphate group phosphorylated another molecule and transferring energy to it.
- adenosine triphosphate (ATP)
-
Nucleotide containing ribose and an adenine base that is essential in energy transfer.
- adrenal gland
-
Endocrine gland located at the top of each kidney that is important for the regulation of the stress response, blood pressure and blood volume, water homeostasis, and electrolyte levels.
- adrenocorticotropic hormone (ACTH)
-
(Also, corticotropin) anterior pituitary hormone that stimulates the adrenal cortex to secrete corticosteroid hormones.
- Adrenocorticotropic hormone releasing hormone
-
(Also corticotropin releasing hormone, CRH) hormone from the hypothalamus that stimulates adrenocorticotropic hormone release from the anterior pituitary.
- agglutination
-
Clump together.
- alanine
-
An amino acid.
- albumin
-
Most abundant plasma protein, accounting for most of the osmotic pressure of plasma.
- aldosterone
-
Hormone produced and secreted by the adrenal cortex that stimulates sodium and fluid retention and increases blood volume and blood pressure.
- alimentary canal
-
Continuous muscular digestive tube that extends from the mouth to the anus.
- alkaline
-
An ionic solution with basic properties (pH >7).
- alkalosis
-
Condition where the blood is more alkaline (basic) than usual (pH >7.35).
- allantois
-
Finger-like outpocketing of yolk sac forms the primitive excretory duct of the embryo; precursor to the urinary bladder.
- allele
-
Alternative forms of a gene that occupy a specific locus on a specific gene.
- alveolar dead space
-
Air space within alveoli that are unable to participate in gas exchange.
- alveolus
-
Small, grape-like sac that performs gas exchange in the lungs (pl.= alveoli).
- amino acid
-
Building block of proteins; characterized by an amino and carboxyl functional groups and a variable side-chain.
- amnion
-
Transparent membranous sac that encloses the developing fetus and fills with amniotic fluid.
- ampulla
-
General anatomical term for the dilated end part of certain ducts of canals.
- ampulla of Vater
-
See hepatopancreatic ampulla
- anabolic reactions
-
Reactions that build smaller molecules into larger molecules.
- anaphase
-
Third phase of mitosis, during which sister chromatids separate toward opposite poles, and spindle fibres begin to elongate the cell.
- Anaphase I
-
Third phase of meiosis I, during which homologous chromosomes are separated to opposite poles.
- anaphase II
-
The third phase of meiosis II, during which sister chromatids are separated to opposite poles of the cell.
- anatomical dead space
-
Air space present in the airway that never reaches the alveoli and therefore never participates in gas exchange.
- androgen
-
Steroid hormone (the most well-known of which is testosterone) that regulates development of male characteristics.
- anemia
-
Deficiency of red blood cells or hemoglobin, often linked to iron deficiency.
- anterior cavity
-
Larger body cavity located anterior to the posterior (dorsal) body cavity; includes the serous membrane-lined pleural cavities for the lungs, pericardial cavity for the heart, and peritoneal cavity for the abdominal and pelvic organs; also referred to as ventral cavity.
- antibody
-
(Also, immunoglobulin) antigen-specific protein secreted by plasma cells.
- anticoagulant
-
Substance such as heparin that opposes coagulation.
- antidiuretic hormone (ADH)
-
(Also, vasopressin) hypothalamic hormone that is stored by the posterior pituitary and that signals the kidneys to reabsorb water.
- antigen
-
Molecule recognized by the receptors of B and T lymphocytes.
- antigen-presenting cell (APC)
-
Various lymphocytes capable of displaying (presenting) antigens from engulfed pathogens to T-cells to facilitate the cell-mediated immune response.
- antral follicle
-
See tertiary follicle
- antrum
-
Fluid-filled chamber that characterizes a mature tertiary (antral) follicle.
- anuria
-
Absence of urine produced; production of 50 mL or less per day.
- aorta
-
Largest artery in the body, originating from the left ventricle and descending to the abdominal region where it bifurcates into the common iliac arteries at the level of the fourth lumbar vertebra; arteries originating from the aorta distribute blood to virtually all tissues of the body.
- aortic arch
-
Arc that connects the ascending aorta to the descending aorta; ends at the intervertebral disk between the fourth and fifth thoracic vertebrae.
- aortic sinus
-
Small pocket in the ascending aorta near the aortic valve that are the locations of the baroreceptors (stretch receptors) and chemoreceptors that trigger a reflex that aids in the regulation of vascular homeostasis.
- apical
-
That part of a cell or tissue which, in general, faces an open space.
- apneustic centre
-
Network of neurons within the pons that stimulate the neurons in the dorsal respiratory group; controls the depth of inspiration.
- appendix
-
(Also, vermiform appendix) coiled tube attached to the cecum.
- areola
-
Highly pigmented, circular area surrounding the raised nipple and containing areolar glands that secrete fluid important for lubrication during suckling.
- areolar connective tissue
-
A type of loose connective tissue proper that shows little specialization with cells dispersed in the matrix.
- arteriole
-
Very small artery that leads to a capillary.
- artery
-
Blood vessel that conducts blood away from the heart; may be a conducting or distributing vessel.
- ascending aorta
-
Portion of the aorta that continues downward past the end of the aortic arch; subdivided into the thoracic aorta and the abdominal aorta.
- ATP synthase
-
Protein pore complex on the inner membrane of the mitochondrion that creates ATP.
- atresia
-
Death of ovarian follicles.
- atrioventricular bundle
-
(also, bundle of His) group of specialized myocardial conductile cells that transmit the impulse from the AV node through the interventricular septum; form the left and right atrioventricular bundle branches
- atrioventricular bundle branches
-
(Also, left or right bundle branches) specialized myocardial conductile cells that arise from the bifurcation of the atrioventricular bundle and pass through the interventricular septum; lead to the Purkinje fibers and also to the right papillary muscle via the moderator band.
- atrioventricular node
-
Clump of myocardial cells located in the inferior portion of the right atrium within the atrioventricular septum; receives the impulse from the SA node, pauses, and then transmits it into specialized conducting cells within the interventricular septum.
- atrioventricular valve
-
One-way valves located between the atria and ventricles; the valve on the right is called the tricuspid valve, and the one on the left is the mitral or bicuspid valve.
- autonomic nervous system
-
Branch of the efferent (impulses travelling away from the brain) peripheral nervous system dealing with involuntary actions; consists of the sympathetic and parasympathetic branches.
- autonomic tone
-
Contractile state during resting cardiac activity produced by mild sympathetic and parasympathetic stimulation.
- autorhythmicity
-
Ability of cardiac muscle to initiate its own electrical impulse that triggers the mechanical contraction that pumps blood at a fixed pace without nervous or endocrine control.
- autosomal chromosomes
-
Chromosomes excluding the sex chromosomes.
- autosomal dominant
-
Pattern of dominant inheritance that corresponds to a gene on one of the 22 autosomal chromosomes.
- autosomal recessive
-
Pattern of recessive inheritance that corresponds to a gene on one of the 22 autosomal chromosomes.
- axillary artery
-
Continuation of the subclavian artery as it penetrates the body wall and enters the axillary region; supplies blood to the region near the head of the humerus (humeral circumflex arteries); the majority of the vessel continues into the brachium and becomes the brachial artery.
- axillary region
-
Area inferior to the shoulder joint (armpit, or underarm).
- axillary vein
-
Major vein in the axillary region; drains the upper limb and becomes the subclavian vein.
- B cells
-
Lymphocytes that act by differentiating into an antibody-secreting plasma cell.
- baroreceptor
-
Sensory receptor (stretch receptor) sensitive to changes in pressure.
- Bartholin’s glands
-
(Also, greater vestibular glands) glands that produce a thick mucus that maintains moisture in the vulva area.
- base
-
A substance that accepts hydrogen ions (H+) in solution, thereby releasing hydroxide ions (OH-)
- bicarbonate
-
HCO3-, an ion produced as a byproduct of metabolism and crucial to regulating pH as part of a chemical buffer system in blood.
- biconcave
-
Concave (dipping in) on both sides.
- bicuspid
-
See premolar
- bicuspid valve
-
See mitral valve
- bile
-
Alkaline solution produced by the liver and important for the emulsification of lipids.
- bile duct
-
Tube through which bile travels from the liver and gall bladder to the hepatopancreatic ampulla.
- bile salts
-
Salts that are released from the liver in response to lipid ingestion and surround the insoluble triglycerides to aid in their conversion to monoglycerides and free fatty acids.
- bilirubin
-
Main bile pigment, which is responsible for the brown color of feces.
- blastocyst
-
Term for the conceptus at the developmental stage that consists of about 100 cells shaped into an inner cell mass that is fated to become the embryo and an outer trophoblast that is fated to become the associated fetal membranes and placenta.
- blastomere
-
Daughter cell of a cleavage.
- body (of the stomach)
-
Mid-portion of the stomach.
- body of uterus
-
Middle section of the uterus.
- Bowman’s capsule
-
(Also, glomerular capsule) cup-shaped sack lined by a simple squamous epithelium (parietal surface) and specialized cells called podocytes (visceral surface) that participate in the filtration process; receives the filtrate which then passes on to the PCTs.
- Boyle’s law
-
relationship between volume and pressure as described by the formula: P1V1 = P2V2. Basically, pressure increases and volume decreases.
- brachial artery
-
continuation of the axillary artery in the brachium; supplies blood to much of the brachial region; gives off several smaller branches that provide blood to the posterior surface of the arm in the region of the elbow; bifurcates into the radial and ulnar arteries at the coronoid fossa
- brachiocephalic artery
-
Single vessel located on the right side of the body; the first vessel branching from the aortic arch; gives rise to the right subclavian artery and the right common carotid artery; supplies blood to the head, neck, upper limb, and wall of the thoracic region.
- brachiocephalic vein
-
One of a pair of veins that form from a fusion of the external and internal jugular veins and the subclavian vein; subclavian, external and internal jugulars, vertebral, and internal thoracic veins lead to it; drains the upper thoracic region and flows into the superior vena cava.
- bradycardia
-
Abnormally low heart rate (<60 beats per minute).
- bronchiole
-
Branch of bronchi that are 1 mm or less in diameter and terminate at alveolar sacs.
- bronchus
-
Tube connected to the trachea that branches into many subsidiaries and provides a passageway for air to enter and leave the lungs (pl.= bronchi)
- Brunner's glands
-
See duodenal glands
- brush border
-
Fuzzy appearance of the small intestinal mucosa created by microvilli.
- buccal cavity
-
See oral cavity
- buffer
-
A chemical system that resists change in pH of a solution by either accepting or releasing hydrogen ions in response to acids or bases, respectively.
- bulbourethral gland
-
(Also, Cowper’s glands) glands that secrete a lubricating mucus that cleans and lubricates the urethra prior to and during ejaculation.
- calyx
-
Cup-like structure receiving urine from the collecting ducts where it passes on to the renal pelvis and ureter. (plural= calyces)
- Cancellous bone
-
See spongy bone
- canine
-
See cuspid
- capacitation
-
Process that occurs in the female reproductive tract in which sperm are prepared for fertilization; leads to increased motility and changes in their outer membrane that improve their ability to release enzymes capable of digesting an oocyte’s outer layers.
- capillary
-
Smallest of the blood vessels where physical exchange occurs between the blood and tissue cells surrounded by interstitial fluid.
- carbaminohemoglobin
-
bound form of hemoglobin and carbon dioxide.
- carbohydrate
-
Class of organic compounds built from sugars, molecules containing carbon, hydrogen, and oxygen in a 1-2-1 ratio.
- cardia
-
(Also, cardiac region) part of the stomach surrounding the cardiac orifice (esophageal hiatus).
- cardiac cycle
-
Period of time between the onset of atrial contraction (atrial systole) and ventricular relaxation (ventricular diastole).
- cardiac region
-
See cardia
- cardiac skeleton
-
Reinforced connective tissue located within the atrioventricular septum; includes four rings that surround the openings between the atria and ventricles, and the openings to the pulmonary trunk and aorta; the point of attachment for the heart valves.
- carotid sinus
-
Small pocket near the base of the internal carotid arteries that are the locations of the baroreceptors and chemoreceptors that trigger a reflex that aids in the regulation of vascular homeostasis.
- carrier
-
(In genetics) heterozygous individual who does not display symptoms of a recessive genetic disorder but can transmit the disorder to his or her offspring.
- catabolic reaction
-
Chemical reaction that breaks down more complex organic molecules.
- cation
-
Ion with a positive charge.
- cecum
-
Pouch forming the beginning of the large intestine.
- cell cycle
-
The life cycle of a cell, including interphase and mitotic phases.
- cellular respiration
-
Production of ATP from glucose oxidation via glycolysis, the Krebs cycle, and oxidative phosphorylation.
- centriole
-
Small, self-replicating organelle that provides the origin for microtubule growth and moves DNA during cell division.
- centromere
-
A structure on a chromosome, where sister chromatids are attached, and where the mitotic spindle attaches.
- centrosome
-
Cellular structure that organizes microtubules during cell division.
- cerebrospinal fluid (CSF)
-
Circulatory medium within the CNS that is produced by ependymal cells in the choroid plexus filtering the blood.
- cervix
-
Elongate inferior end of the uterus where it connects to the vagina.
- chemical digestion
-
Enzymatic breakdown of food.
- chemiosmosis
-
The diffusion of ions across a semipermeable membrane, down their electrochemical gradient.
- chemoreceptors
-
Sensory receptor that senses chemical concentrations.
- chemotaxis
-
Cell movement in response to a chemical gradient.
- chief cell
-
Gastric gland cell that secretes pepsinogen.
- cholecystokinin (CCK)
-
A hormone secreted by enteroendocrine cells of the duodenum in response amino acids, fatty acids and HCl. Stimulate gall bladder contraction (release of stored bile).
- chordae tendineae
-
String-like extensions of tough connective tissue that extend from the flaps of the atrioventricular valves to the papillary muscles.
- chorion
-
Membrane that develops from the syncytiotrophoblast, cytotrophoblast, and mesoderm; surrounds the embryo and forms the fetal portion of the placenta through the chorionic villi.
- chorionic cavity
-
Precursor to the chorion; forms from extra-embryonic mesoderm cells.
- chorionic membrane
-
Precursor to the chorion; forms from extra-embryonic mesoderm cells.
- chorionic villi
-
Projections of the chorionic membrane that burrow into the endometrium and develop into the placenta.
- chromatin
-
Substance consisting of DNA and associated proteins.
- chromosome
-
A long DNA molecule, combined with proteins that contains a number of genes. The normal chromosome compliment is 23 pairs of homologous chromosomes, one each from mother and father.
- chyme
-
Soupy liquid created (first in the stomach) when food is mixed with digestive juices.
- cilia
-
Small appendage on certain cells formed by microtubules and modified for movement of materials across the cellular surface (singular = cilium).
- circular fold
-
(Also, plica circulare) deep fold in the mucosa and submucosa of the small intestine.
- citric acid cycle
-
See Krebs cycle
- cleavage
-
Form of mitotic cell division in which the cell divides but the total volume remains unchanged; this process serves to produce smaller and smaller cells.
- cleavage furrow
-
Contractile ring that forms around a cell during cytokinesis that pinches the cell into two halves.
- clitoris
-
(Also, glans clitoris) nerve-rich area of the vulva that contributes to sexual sensation during intercourse.
- clonal expansion
-
Growth of a clone of selected lymphocytes.
- clonal selection
-
Stimulating growth of lymphocytes that have specific receptors.
- clotting factor
-
(Also, coagulation factors) group of 12 identified substances active in coagulation.
- coagulation
-
Formation of a blood clot; part of the process of hemostasis.
- coagulation factors
-
See clotting factors
- coccyx
-
Small bone located at inferior end of the adult vertebral column that is formed by the fusion of four coccygeal vertebrae; also referred to as the “tailbone”.
- codominance
-
Pattern of inheritance that corresponds to the equal, distinct, and simultaneous expression of two different alleles.
- collagen fibre
-
The most abundant of three protein fibres found in the extracellular matrix of connective tissues.
- collecting duct
-
Tubule that connects multiple nephrons to the minor calyx in the renal pelvis.
- colon
-
Part of the large intestine between the cecum and the rectum.
- colostrum
-
Thick, yellowish substance secreted from a mother’s breasts in the first postpartum days; rich in antibodies.
- common bile duct
-
Structure formed by the union of the common hepatic duct and the gallbladder’s cystic duct.
- common carotid artery
-
Right common carotid artery arises from the brachiocephalic artery, and the left common carotid arises from the aortic arch; gives rise to the external and internal carotid arteries; supplies the respective sides of the head and neck.
- common hepatic duct
-
Duct formed by the merger of the two hepatic ducts.
- common iliac arteries
-
Branch of the aorta that leads to the internal and external iliac arteries.
- common iliac vein
-
One of a pair of veins that flows into the inferior vena cava at the level of L5; the left common iliac vein drains the sacral region; divides into external and internal iliac veins near the inferior portion of the sacroiliac joint.
- conceptus
-
Pre-implantation stage of a fertilized egg and its associated membranes.
- conducting zone
-
Region of the respiratory system that includes the organs and structures that provide passageways for air and are not directly involved in gas exchange.
- cornea
-
Fibrous covering of the anterior region of the eye that is transparent so that light can pass through it.
- corona radiata
-
In an oocyte, a layer of granulosa cells that surrounds the oocyte and that must be penetrated by sperm before fertilization can occur.
- coronary arteries
-
Branches of the ascending aorta that supply blood to the heart; the left coronary artery feeds the left side of the heart, the left atrium and ventricle, and the interventricular septum; the right coronary artery feeds the right atrium, portions of both ventricles, and the heart conduction system.
- coronary sinus
-
Large, thin-walled vein on the posterior surface of the heart that lies within the atrioventricular sulcus and drains the heart myocardium directly into the right atrium.
- coronary sulcus
-
Sulcus (groove) that marks the boundary between the atria and ventricles
- corpus albicans
-
Nonfunctional structure remaining in the ovarian stroma following structural and functional regression of the corpus luteum.
- corpus cavernosus
-
Either of two columns of erectile tissue in the penis that fill with blood during an erection (plural = corpora cavernosa).
- corpus luteum
-
Transformed follicle after ovulation that secretes progesterone.
- cortical nephron
-
Nephron with loop of Henle that does not extend into the renal medulla.
- cortical reaction
-
Following fertilization, the release of cortical granules from the oocyte’s plasma membrane into the zona pellucida creating a fertilization membrane that prevents any further attachment or penetration of sperm; part of the slow block to polyspermy.
- corticotropin
-
See adrenocorticotropic hormone
- corticotropin releasing hormone
-
See adrenocorticotropic hormone releasing hormone
- cortisol
-
Hormone produced by the adrenal gland in response to stress, stimulates gluconeogenesis, the catabolism of glycogen, and downregulation of the immune system and glucose levels.
- costal cartilage
-
Hyaline cartilage structure attached to the anterior end of each rib that provides for either direct or indirect attachment of most ribs to the sternum.
- Cowper's glands
-
See bulbourethral glands
- crossing over
-
process by which genetic information of homologou, non-sister chromatids, is exchanged during prophase I, thereby increasing genetic variability of gametes.
- crypt of Lieberkühn
-
See intestinal gland
- cuspid
-
(Also, canine) pointed tooth used for tearing and shredding food.
- cystic duct
-
Duct through which bile drains and enters the gallbladder.
- cytokine
-
Soluble, short-range, cell-to-cell communication molecule.
- cytokinesis
-
Division of the cytoplasm to form two separate cells.
- cytoplasm
-
Internal material between the cell membrane and nucleus of a cell, mainly consisting of a water-based fluid called cytosol, within which are all the other organelles and cellular solute and suspended materials.
- cytosol
-
Clear, semi-fluid medium of the cytoplasm, made up mostly of water.
- cytotoxic T cell
-
T lymphocyte with the ability to induce apoptosis in target cells.
- Dalton’s law
-
Statement of the principle that a specific gas type in a mixture exerts its own pressure, as if that specific gas type was not part of a mixture of gases.
- defensins
-
Antimicrobial proteins released from neutrophils and macrophages that create openings in the plasma membranes to kill cells.
- dendritic cell
-
A monocyte-derived phagocytic cell, function as antigen-presenting cells (APC).
- depolarization
-
Change in a cell membrane potential from rest toward or above zero (as during an action potential).
- dermis
-
Layer of skin between the epidermis and hypodermis, composed mainly of connective tissue and containing blood vessels, hair follicles, sweat glands, and other structures.
- descending aorta
-
Portion of the aorta that continues downward past the end of the aortic arch; subdivided into the thoracic aorta and the abdominal aorta.
- descending colon
-
Part of the colon between the transverse colon and the sigmoid colon.
- detrusor muscle
-
Smooth muscle in the bladder wall; fibres run in all directions to reduce the size of the organ when emptying it of urine.
- diapedesis
-
(Also, emigration) process by which leukocytes squeeze through adjacent cells in a blood vessel wall to enter tissues.
- diastole
-
Period of time when the heart muscle is relaxed and the chambers fill with blood.
- diastolic pressure
-
Lower number recorded when measuring arterial blood pressure; represents the minimal value corresponding to the pressure that remains during ventricular relaxation.
- diploid
-
Having two copies of genetic material.
- distal
-
Describes a position farther from the point of attachment or the trunk of the body.
- distal convoluted tubule
-
Portion of the nephron distal to the loop of Henle that receive hyposmotic filtrate from the loop of Henle and empty into collecting ducts
- distensible
-
Able to stretch and expand.
- diuretics
-
Compound that increases urine output, leading to decreased water conservation.
- dominant
-
(In genetics) describes a trait that is expressed both in homozygous and heterozygous form.
- dorsal
-
Describes the back or direction toward the back of the body; also referred to as posterior.
- dorsal respiratory group (DRG)
-
Region of the medulla oblongata that stimulates the contraction of the diaphragm and intercostal muscles to induce inspiration.
- dorsalis pedis artery
-
Forms from the anterior tibial artery; branches repeatedly to supply blood to the tarsal and dorsal regions of the foot.
- ductus arteriosus
-
Shunt in the pulmonary trunk that diverts oxygenated blood back to the aorta.
- ductus deferens
-
(Also, vas deferens) duct that transports sperm from the epididymis through the spermatic cord and into the ejaculatory duct.
- ductus venosus
-
Shunt that causes oxygenated blood to bypass the fetal liver on its way to the inferior vena cava.
- duodenal glands
-
(Also, Brunner’s gland) mucous-secreting gland in the duodenal submucosa.
- duodenum
-
First part of the small intestine, which starts at the pyloric sphincter and ends at the jejunum.
- ectoderm
-
Primary germ layer that develops into the central and peripheral nervous systems, sensory organs, epidermis, hair, and nails.
- edema
-
Swelling due to excess body fluid.
- effector cell
-
Immune cell with a direct, adverse effect on a pathogen.
- ejaculatory duct
-
Duct that connects the ampulla of the ductus deferens with the duct of the seminal vesicle at the prostatic urethra.
- electrocardiogram
-
Surface recording of the electrical activity of the heart that can be used for diagnosis of irregular heart function; also abbreviated as EKG.
- electrolyte
-
A solution containing ions.
- electron
-
Subatomic particle having a negative charge and nearly no mass; found orbiting the atom’s nucleus.
- electron transport chain
-
ATP production pathway in which electrons are passed through a series of oxidation-reduction reactions that forms water and produces a proton gradient.
- embryo
-
Developing human during weeks 3–8.
- emigration (of leukocytes)
-
See diapedesis
- emulsification
-
Process of mixing liquids that don't normally mix.
- endocrine gland
-
Tissue or organ that secretes hormones into the blood and lymph without ducts such that they may be transported to organs distant from the site of secretion.
- endocytosis
-
Import of material into the cell by formation of a membrane-bound vesicle.
- endoderm
-
Primary germ layer that goes on to form the gastrointestinal tract, liver, pancreas, and lungs.
- endometrium
-
Inner lining of the uterus, part of which builds up during the secretory phase of the menstrual cycle and then sheds with menses.
- endothelin
-
Hormones that cause vasoconstriction or release of NO.
- endothelium
-
Layer of smooth, simple squamous epithelium that lines the endocardium and blood vessels.
- enteric
-
Relating to or found in the intestines.
- enteroendocrine cell
-
Specialized hormone-secreting cell found in the gastrointestinal tract and pancreas.
- enterohepatic circulation
-
Recycling mechanism that conserves bile salts.
- enteropeptidase
-
Intestinal brush-border enzyme that activates trypsinogen to trypsin.
- enzyme
-
Molecule (usually a protein) that catalyzes chemical reactions.
- epididymis
-
A coiled tube attached to the testis where newly formed sperm continue to mature.
- epiglottis
-
Leaf-shaped piece of elastic cartilage that is a portion of the larynx that swings to close the trachea during swallowing.
- epinephrine
-
Primary and most potent catecholamine hormone secreted by the adrenal medulla in response to short-term stress; also called adrenaline.
- epiphysis
-
Wide section at each end of a long bone; filled with spongy bone and red marrow (plural = epiphyses).
- epithelial tissue
-
Type of tissue that serves primarily as a covering or lining of body parts, protecting the body; it also functions in absorption, transport, and secretion.
- erythrocyte
-
(Also, red blood cell) mature myeloid blood cell that is composed mostly of hemoglobin and functions primarily in the transportation of oxygen and carbon dioxide.
- erythropoiesis
-
Process of producing red blood cells.
- erythropoietin
-
Glycoprotein that triggers the bone marrow to produce RBCs; secreted by the kidney in response to low oxygen levels.
- esophageal hiatus
-
Opening in the diaphragm through which the esophagus passes.
- esophagus
-
Muscular tube that runs from the pharynx to the stomach.
- essential
-
A nutrient that cannot be produced by the body (or, at least, in sufficient quantities).
- estradiol
-
One of the hormones collectively referred to as estrogens.
- estrogens
-
Class of predominantly female sex hormones important for the development and growth of the female reproductive tract, secondary sex characteristics, the female reproductive cycle, and the maintenance of pregnancy. Estradiol is the most common active estrogen.
- exocrine gland
-
Gland that secretes substance directly to target tissues or outside of body via glandular ducts (e.g. sweat glands, digestive glands).
- exocytosis
-
Export of a substance out of a cell by formation of a membrane-bound vesicle.
- external anal sphincter
-
Voluntary skeletal muscle sphincter in the anal canal.
- external intercostal muscles
-
Skeletal muscles between ribs, originating on the lower margin of the upper rib, inserting on the upper margin of the rib below, and serving to elevate the rib cage.
- external respiration
-
Gas exchange that occurs in the alveoli.
- external urinary sphincter
-
Skeletal muscle; must be relaxed consciously to void urine.
- extracellular fluid (ECF)
-
Fluid exterior to cells; includes the interstitial fluid, blood plasma, and fluids found in other reservoirs in the body.
- facilitated diffusion
-
Passive diffusion of a substance with the aid of a membrane protein.
- falciform ligament
-
Ligament connecting the liver to the anterior body wall.
- fallopian tube
-
See uterine tube
- fatty acid
-
Consisting of a carboxyl group (COOH) and an unbranched hydrocarbon chain. A non-polar component of all lipids.
- fauces
-
Opening between the oral cavity and the oropharynx.
- femoral arteries
-
Continuation of the external iliac artery after it passes through the body cavity; divides into several smaller branches, the lateral deep femoral artery, and the genicular artery; becomes the popliteal artery as it passes posterior to the knee.
- femoral artery
-
Continuation of the external iliac artery after it passes through the body cavity; divides into several smaller branches, the lateral deep femoral artery, and the genicular artery; becomes the popliteal artery as it passes posterior to the knee.
- femoral vein
-
Drains the upper leg; receives blood from the great saphenous vein, the deep femoral vein, and the femoral circumflex vein; becomes the external iliac vein when it crosses the body wall.
- femur
-
Bone in the upper leg.
- fenestrated capillary
-
Type of capillary with pores or fenestrations in the endothelium that allow for rapid passage of certain small materials.
- fermentation
-
Anaerobic pathway by which smaller amounts of ATP can be produced when oxygen is limited or absent. Lactic acid is a byproduct.
- fertilization
-
Unification of genetic material from male and female haploid gametes.
- fertilization membrane
-
Impenetrable barrier that coats a nascent zygote; part of the slow block to polyspermy.
- fetus
-
Developing human during the time from the end of the embryonic period (week 9) to birth.
- fibrin
-
Insoluble, filamentous protein that forms the structure of a blood clot.
- fibrinogen
-
Plasma protein produced in the liver and involved in blood clotting.
- fibrinolysis
-
Gradual degradation of a blood clot.
- filtrate
-
A liquid that has passed through a filter; in nephrons, the liquid in the lumen after passing though the glomerulus.
- flagellum
-
Appendage on certain cells formed by microtubules and modified for movement (plural = flagella)
- flatus
-
Gas in the intestine.
- flavin adenine dinucleotide (FAD)
-
Electron acceptor similar to NAD+, carrying electrons from the Kreb's cycle to the electron transport chain. FADH2 is the reduced, higher energy form with additional electrons.
- follicle
-
Ovarian structure of one oocyte and surrounding granulosa (and later theca) cells.
- follicle-stimulating hormone (FSH)
-
Anterior pituitary hormone that stimulates the production and maturation of sex cells.
- follicular phase
-
Days 1-14 of the ovarian cycle, during which tertiary follicles grow and secrete estrogens.
- folliculogenesis
-
Development of ovarian follicles from primordial to tertiary under the stimulation of gonadotropins.
- foramen ovale
-
Opening in the fetal heart that allows blood to flow directly from the right atrium to the left atrium, bypassing the fetal pulmonary circuit.
- foreskin
-
See prepuce
- fossa ovalis
-
Oval-shaped depression in the interatrial septum that marks the former location of the foramen ovale.
- functional residual capacity (FRC)
-
Sum of ERV and RV, which is the amount of air that remains in the lungs after a tidal expiration.
- fundus
-
General anatomical term for the part of a hollow organ furthest from its mouth. In the stomach: the uppermost portion, above and to the left of the cardia. In the uterus: domed portion superior to the uterine tubes.
- gallbladder
-
Accessory digestive organ that stores and concentrates bile. Located beneath the right lobe of the liver.
- gamete
-
Haploid reproductive cell (egg or sperm in humans) that contributes genetic material to form an offspring.
- gastrin
-
Peptide hormone that stimulates secretion of hydrochloric acid and gut motility.
- gastrocolic reflex
-
Propulsive movement in the colon activated by the presence of food in the stomach.
- gastrulation
-
Process of cell migration and differentiation into three primary germ layers following cleavage and implantation.
- general adaptation syndrome
-
The human body’s three-stage response pattern to short- and long-term stress.
- genes
-
Portion of a chromosome that codes for the assembly of a particular protein or RNA.
- genotype
-
The genetic makeup of an individual. Also referring to the alleles an individual has for a particular gene (e.g. homozygous or heterozygous).
- genotypic ratio
-
Predicted ratio of genotypes among offspring.
- germ cell
-
Cell that gives rise to a gamete.
- gestation
-
In human development, the period required for embryonic and fetal development in utero; pregnancy.
- glans clitoris
-
See clitoris
- glans penis
-
Bulbous end of the penis that contains a large number of nerve endings.
- globulin
-
Heterogeneous group of plasma proteins that includes transport proteins, clotting factors, immune proteins, and others.
- glomerular capsule
-
See Bowman's capsule
- glomerular filtration rate (GFR)
-
Rate of renal filtration.
- glomerulus
-
Tuft of capillaries surrounded by Bowman’s capsule; filters the blood based on size.
- glottis
-
Opening between the vocal folds through which air passes when producing speech.
- glucagon
-
Pancreatic hormone that stimulates the catabolism of glycogen to glucose, thereby increasing blood glucose levels.
- glucocorticoid
-
Hormones produced by the zona fasciculata of the adrenal cortex that influence glucose metabolism.
- gluconeogenesis
-
Process of glucose synthesis from pyruvate or other molecules.
- glucose
-
Monosaccharide commonly used as energy in the body (substrate for glycolysis).
- glycerol
-
Molecule that forms the 'backbone' of many lipids, including triglycerides.
- glycogen
-
Polysaccharide used as a storage form of glucose in the liver.
- glycogenesis
-
Metabolic process that builds glycogen molecules from glucose.
- glycogenolysis
-
Metabolic process that breaks down glycogen into glucose molecules.
- glycolysis
-
Series of metabolic reactions that breaks down glucose into pyruvate and produces ATP.
- glycoprotein
-
Proteins with short polysaccharide chains attached.
- goblet cell
-
Mucous producing cell (a unicellular gland).
- goiter
-
Enlargement of the thyroid gland either as a result of iodine deficiency or hyperthyroidism.
- gonadotropin
-
Hormones that regulate the function of the gonads.
- gonadotropin releasing hormone (GnRH)
-
Hormone released by the hypothalamus that stimulates the release of hormones known as gonadotropins from the anterior pituitary: follicle stimulating hormone (FSH) and luteinizing hormone (LH)
- gonadotropins
-
Hormones that regulate the function of the gonads.
- granulosa cells
-
Supportive cells in the ovarian follicle that produce estrogens.
- growth hormone (GH)
-
(Also, somatotropin) anterior pituitary hormone that promotes tissue building and influences nutrient metabolism.
- growth hormone releasing hormone (GHRH)
-
Hormone from the hypothalamus that stimulates release of growth hormone (GH) from the anterior pituitary.
- haematocrit
-
See hematocrit
- haploid
-
One copy of each homologous chromosomes, (half the normal genetic complement), as in gametes.
- haustral contraction
-
Slow segmentation in the large intestine.
- heart sounds
-
Sounds heard with a stethoscope of the closing of the atrioventricular valves (“lub”) and semilunar valves (“dub”).
- helper T cell
-
T cells that secrete cytokines to enhance other immune responses, involved in activation of both B and T cell lymphocytes.
- hematocrit
-
(also, packed cell volume) volume percentage of erythrocytes in a sample of centrifuged blood.
- hemoglobin
-
Oxygen-carrying compound in erythrocytes.
- hemolysis
-
Breakdown of blood cells.
- hemophilia
-
Genetic disorder characterized by inadequate synthesis of clotting factors.
- hemopoiesis
-
(Also, hematopoiesis) production of the formed elements of blood.
- hemostasis
-
Physiological process by which bleeding ceases.
- hepatic artery
-
Artery that supplies oxygenated blood to the liver.
- hepatic flexure
-
See right colic flexure
- hepatic portal vein
-
Vein that supplies deoxygenated nutrient-rich blood to the liver.
- hepatocytes
-
Liver cells.
- hepatopancreatic ampulla
-
(Also, ampulla of Vater) bulb-like point in the wall of the duodenum where the bile duct and main pancreatic duct unite.
- heterozygous
-
Having two different alleles for a given gene.
- histamine
-
Vasoactive (active on blood vessels) mediator in granules of mast cells and is the primary cause of allergies and anaphylactic shock.
- homeostasis
-
Steady, dynamic state of body systems (specifically of extracellular fluid) that living organisms maintain.
- homologous chromosomes
-
Pair of similar (but not identical) chromosomes in a diploid cell, containing the same genes but possibly differing in alleles, one inherited from each parent.
- homozygous
-
Having two identical alleles for a given gene.
- hormone
-
Secretion of an endocrine organ that travels via the bloodstream or lymphatics to induce a response in target cells or tissues in another part of the body.
- hormone receptor
-
Protein within a cell or on the cell membrane that binds a hormone, initiating the target cell response.
- human chorionic gonadotropin (hCG)
-
Hormone that directs the corpus luteum to survive, enlarge, and continue producing progesterone and estrogen to suppress menses and secure an environment suitable for the developing embryo.
- humerus
-
Bone in the upper arm.
- hydrolysis
-
Chemical reaction in which water is used to break one or more chemical bonds.
- hydrophilic
-
Describes a substance or structure attracted to water.
- hydrophobic
-
Describes a substance or structure repelled by water.
- hymen
-
Membrane that covers part of the opening of the vagina.
- hyoid
-
Small, U-shaped bone located in upper neck that does not contact any other bone.
- hyperpnea
-
Increased rate and depth of ventilation due to an increase in oxygen demand that does not significantly alter blood oxygen or carbon dioxide levels.
- hyperthyroidism
-
Clinically abnormal, elevated level of thyroid hormone in the blood; characterized by an increased metabolic rate, excess body heat, sweating, diarrhea, weight loss, and increased heart rate.
- hypertonic
-
Describes a solution concentration that is higher than a reference concentration.
- hyperventilation
-
Increased ventilation rate that leads to abnormally low blood carbon dioxide levels and high (alkaline) blood pH.
- hypoosmotic
-
See hypotonic
- hypothalamus
-
Region of the diencephalon inferior to the thalamus that functions in neural and endocrine signaling.
- hypotonic
-
Describes a solution concentration that is lower than a reference concentration
- hypoxia
-
Lack of oxygen supply to the tissues.
- ileocecal sphincter
-
Sphincter located where the small intestine joins with the large intestine.
- ileum
-
End of the small intestine between the jejunum and the large intestine.
- immunological memory
-
Ability of the adaptive immune response to mount a stronger and faster immune response upon re-exposure to a pathogen.
- implantation
-
Process by which a blastocyst embeds itself in the uterine endometrium.
- incisor
-
Midline, chisel-shaped tooth used for cutting into food.
- independent assortment
-
Mendelian principle that states that alleles from one parent will sort independently from those of the other parent. This occurs during metaphase I when maternal and paternal homologous chromosomes align themselves independently to maternal and paternal chromosomes of any other pair.
- inferior
-
Describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column); also referred to as caudal.
- inferior vena cava
-
Large systemic vein that returns blood to the heart from the inferior portion of the body.
- infundibulum
-
A general anatomical term for a funnel-shaped structure; in the hypothalamus, the stalk containing vasculature and neural tissue that connects the pituitary gland to the hypothalamus (also called the pituitary stalk).
- ingestion
-
Taking food into the GI tract through the mouth.
- inguinal canal
-
Opening in abdominal wall that connects the testes to the abdominal cavity.
- innate immune response
-
Rapid but relatively nonspecific immune response.
- inner cell mass
-
Cluster of cells within the blastocyst that is fated to become the embryo.
- inner mitochondrial membrane
-
Innermost of the double membrane, this is highly folded into cristae, providing a large surface area for chemical reactions such as the electron transport chain.
- inorganic
-
Chemical substance lacking carbon-hydrogen bonds.
- inspiratory capacity (IC)
-
Sum of the TV and IRV, which is the amount of air that can maximally be inhaled past a tidal expiration.
- inspiratory reserve volume (IRV)
-
Amount of air that enters the lungs due to deep inhalation past the tidal volume.
- insulin
-
Pancreatic hormone that enhances the cellular uptake and utilization of glucose, thereby decreasing blood glucose levels.
- internal anal sphincter
-
Involuntary smooth muscle sphincter in the anal canal.
- internal carotid artery
-
Arises from the common carotid artery and begins with the carotid sinus; goes through the carotid canal of the temporal bone to the base of the brain; combines with branches of the vertebral artery forming the arterial circle; supplies blood to the brain.
- internal intercostals
-
Skeletal muscles between ribs, originating on the upper margin of a rib, inserting on lower margin of the rib above and serving to depress the rib cage.
- internal respiration
-
Gas exchange that occurs at the level of body tissues.
- internal urinary sphincter
-
Smooth muscle at the juncture of the bladder and urethra; relaxes as the bladder fills to allow urine into the urethra.
- Interphase
-
Portions of the cell cycle that are not part of mitosis.
- interstitial fluid
-
Extracellular fluid in the small spaces between cells not contained within blood vessels.
- intestinal gland
-
(Also, crypt of Lieberkühn) gland in the small intestinal mucosa that secretes intestinal juice.
- intestinal juice
-
Mixture of water and mucus that helps absorb nutrients from chyme.
- intra-alveolar pressure
-
(Also, intrapulmonary pressure) pressure of the air within the alveoli.
- intracellular fluid (ICF)
-
Fluid inside cells.
- intrapleural pressure
-
Pressure of the air within the pleural cavity.
- intrapulmonary pressure
-
See intra-alveolar pressure
- intrinsic factor
-
Glycoprotein required for vitamin B12 absorption in the small intestine.
- involuntary
-
Referring to nervous control of functions without conscious thought,
- ion
-
Atom with an overall positive or negative charge. Many function as electrolytes.
- ischemia
-
Insufficient blood flow to the tissues.
- isosmotic
-
Having equal solute concentrations.
- jejunum
-
Middle part of the small intestine between the duodenum and the ileum.
- juxtaglomerular apparatus
-
Located at the juncture of the distal convoluted tubule and the afferent and efferent arterioles of the glomerulus; plays a role in the regulation of renal blood flow and glomerular filtration rate.
- juxtamedullary nephron
-
Nephron adjacent to the border of the cortex and medulla with loops of Henle that extend into the renal medulla.
- karyotype
-
Systematic arrangement of images of chromosomes into homologous pairs.
- ketoacidosis
-
Complication of diabetes wherein the blood becomes acidic because of increased levels of ketones.
- ketogenesis
-
Formation of ketone bodies during periods of glucose starvation.
- ketone bodies
-
Alternative source of energy when glucose is limited, created when too much acetyl CoA is created during fatty acid oxidation. Consist of acetone, acetoacetic acid and β-hydroxybutyric acid.
- kinetochore
-
Part of the chromosome's centromere to which the mitotic spindle attaches.
- Korotkoff sounds
-
Noises created by turbulent blood flow through the vessels.
- Krebs cycle
-
(Also, citric acid cycle or tricarboxylic (TCA) cycle) converts pyruvate into CO2 and high-energy FADH2, NADH, and ATP molecules.
- labia majora
-
Hair-covered folds of skin located behind the mons pubis.
- labia minora
-
Thin, pigmented, hairless flaps of skin located medial and deep to the labia majora.
- labial frenulum
-
Midline mucous membrane fold that attaches the inner surface of the lips to the gums.
- labium
-
Lip (plural = labia)
- lactate
-
(Also, lactic acid) a three-carbon acid formed as a product of lactic acid fermentation, and used as a substrate in gluconeogenesis.
- lacteal
-
Lymphatic capillary in the villi of the intestine.
- lacteals
-
Lymphatic capillary in the villi.
- lamina propria
-
Part of a mucous membrane (composed of loose connective tissue) that supports an epithelium.
- laryngopharynx
-
Portion of the pharynx bordered by the oropharynx superiorly and esophagus and trachea inferiorly; serves as a route for both air and food.
- larynx
-
Cartilaginous structure that produces the voice, prevents food and beverages from entering the trachea, and regulates the volume of air that enters and leaves the lungs.
- left atrioventricular valve
-
See mitral valve
- left bundle branch
-
See atrioventricular bundle branches
- left colic flexure
-
(Also, splenic flexure) point where the transverse colon curves below the inferior end of the spleen.
- lesser omentum
-
Double layer of peritoneum extending from the stomach and duodenum to the liver.
- leukocyte
-
(also, white blood cell) colorless, nucleated blood cell, the chief function of which is to protect the body from disease.
- Leydig cells
-
Cells between the seminiferous tubules of the testes that produce testosterone; a type of interstitial cell.
- ligament
-
Strong band of dense connective tissue spanning between bones.
- ligamentum arteriosum
-
Scar tissue formed as the ductus arteriosus contracts during the neonatal period.
- ligamentum venosum
-
Scar tissue formed as the ductus venosus closes.
- lingual lipase
-
Digestive enzyme from glands in the tongue that acts on triglycerides.
- lipid
-
Class of nonpolar organic compounds built from hydrocarbons and distinguished by the fact that they are not soluble in water.
- lipogenesis
-
Synthesis of lipids that occurs in the liver or adipose tissues.
- lipolysis
-
Breakdown of triglycerides into glycerol and fatty acids.
- liver
-
Largest gland in the body, overlying the stomach, whose functions include bile production and a number of metabolic and regulatory functions.
- loop of Henle
-
Descending and ascending portions between the proximal and distal convoluted tubules; those of cortical nephrons do not extend into the medulla, whereas those of juxtamedullary nephrons do extend into the medulla.
- lumen
-
Space inside of a tube, hollow organ or blood vessel.
- luteal phase
-
The phase of the ovarian cycle that occurs after ovulation (days 14-28) during which the corpus luteum secretes high levels of progesterone, and new dominant follicles develop (in time for the next cycle). if pregnancy does not occur, the corpus luteum begins to disintegrate after 1-12 days (meaning that the luteal phase is relatively fixed in duration, whereas the follicular phase can vary).
- luteinization
-
Process of transforming a follicle post-ovulation to the corpus luteum.
- luteinizing hormone (LH)
-
Anterior pituitary hormone that triggers ovulation and the production of ovarian hormones in females, and the production of testosterone in males.
- lymph
-
Fluid contained within the lymphatic system.
- lymph node
-
One of the bean-shaped organs found associated with the lymphatic vessels.
- lymphocyte
-
White blood cell characterized by a large nucleus and small rim of cytoplasm.
- lysozyme
-
Digestive enzyme with bactericidal properties.
- macrophage
-
Ameboid (irregular outline with peripheral projections) phagocyte found in several tissues throughout the body.
- major histocompatibility complex (MHC)
-
Gene cluster whose proteins present antigens to T cells.
- mammary glands
-
Glands in the breast that secrete milk.
- mandible
-
Bone that forms the lower jaw bone; the only moveable bone of the skull.
- mass movement
-
Long, slow, peristaltic wave in the large intestine.
- mast cell
-
Cell found in the skin and the lining of body cells that contains cytoplasmic granules with vasoactive mediators such as histamine.
- mean arterial pressure (MAP)
-
Average driving force of blood to the tissues; approximated by taking diastolic pressure and adding 1/3 of pulse pressure.
- mechanical digestion
-
Chewing, mixing, and segmentation that prepares food for chemical digestion.
- mediastinum
-
A central compartment in the thoracic cavity located intermediate to the left and right pleural cavities.
- medulla
-
Inner region of kidney containing the renal pyramids.
- medulla oblongata
-
Lowest (most inferior) part of the brain, controlling many autonomic functions including heart rate, breathing, and digestion.
- meiosis
-
Process by which germ cells form four genetically distinct daughter cells (gametes) for sexual reproduction.
- memory cell
-
Long-lived immune cell reserved for future exposure to a pathogen, allowing a rapid secondary adaptive response.
- menses
-
Shedding of the inner portion of the endometrium out though the vagina; also referred to as menstruation.
- menses phase
-
Phase of the menstrual cycle in which the endometrial lining is shed.
- menstrual cycle
-
Approximately 28-day cycle of changes in the uterus consisting of a menses phase, a proliferative phase, and a secretory phase.
- mesenchyme
-
Embryonic tissue from which connective tissue cells derive.
- mesentery
-
Double-layered extension of the peritoneum that supports most abdominal organs.
- mesoderm
-
Primary germ layer that becomes the skeleton, muscles, connective tissue, heart, blood vessels, and kidneys.
- metabolism
-
Sum of all catabolic and anabolic reactions that take place in the body.
- metaphase
-
The second phase of mitosis, during which replicated chromosomes align on the metaphase plate and the mitotic spindle completes.
- Metaphase I
-
second phase of meiosis I during which homologous chromosomes align on the metaphase plate.
- Metaphase II
-
The second stage of meiosis II, during which replicated chromosomes (consisting of a pair of sister chromatids) align along the metaphase plate.
- metaphase plate
-
Imaginary medial plane in a mitotic cell, along which replicated chromosomes align during metaphase.
- MHC class I
-
Major histocompatibility complex found on most cells of the body, it binds to the CD8 molecule on T cells.
- MHC class II
-
Major histocompatibility complex found on macrophages, dendritic cells, and B cells, it binds to CD4 molecules on T cells.
- microfilament
-
The thinnest of the cytoskeletal filaments; composed of actin subunits that function in muscle contraction and cellular structural support.
- microvillus
-
Small projection of the plasma membrane of the absorptive cells of the small intestinal mucosa (plural= microvilli)
- micturition
-
Also called urination or voiding.
- mineral
-
Inorganic ions or compounds that work with other nutrients to carry out important body functions.
- mineralocorticoids
-
Hormones produced by the zona glomerulosa cells of the adrenal cortex that influence fluid and electrolyte balance.
- mitochondrial matrix
-
Space within the inner mitochondrial membrane, containing a viscous fluid where the Krebs cycle takes place.
- mitochondrion
-
One of the cellular organelles bound by a double lipid bilayer that function primarily in the production of cellular energy (ATP).
- mitosis
-
Division of genetic material, during which the cell nucleus breaks down and two new, fully functional, nuclei are formed. Usually immediately followed by cytokinesis (cell division).
- mitotic
-
Referring to mitosis, often indicating cell division though mitosis and cell division (cytokinesis) are separate, usually linked, processes.
- mitotic spindle
-
Structure composed of centrosomes and microtubules, responsible for aligning and separating replicated chromosomes and elongating and dividing the cell during mitosis and cytokinesis.
- mitral valve
-
(Also, left atrioventricular valve or bicuspid valve) valve located between the left atrium and ventricle; consists of two flaps of tissue.
- monocyte
-
Precursor to macrophages and dendritic cells seen in the blood.
- monomers
-
A "building block" of complex organic molecules. Complex organic molecules are usually composed of a number of similar monomers (e.g. amino acids in protein).
- monosaccharides
-
Simple carbohydrate consisting of a single carbon-oxygen ring.
- morula
-
Tightly packed sphere of blastomeres that has reached the uterus but has not yet implanted itself.
- motilin
-
Hormone that initiates migrating motility complexes.
- mucosa
-
Innermost lining of the alimentary canal.
- muscularis
-
Muscle (skeletal or smooth) layer of the alimentary canal wall.
- mutation
-
Change in the nucleotide sequence of DNA.
- myometrium
-
Smooth muscle layer of uterus that allows for uterine contractions during labor and expulsion of menstrual blood.
- naïve lymphocyte
-
Mature B or T cell that has not yet encountered antigen for the first time.
- nascent
-
Beginning to grow and develop.
- natural killer cell
-
Cytotoxic lymphocyte of innate immune response.
- nephrons
-
Functional unit of the kidney that carry out all filtration and modification to produce urine; consist of renal corpuscles, proximal and distal convoluted tubules, and descending and ascending loops of Henle; drain into collecting ducts.
- neuromuscular junction (NMJ)
-
Synapse between the axon terminal of a motor neuron and the section of the membrane of a muscle fiber with receptors for the acetylcholine released by the terminal.
- neurotransmitter
-
Chemical signal that is released from the synaptic end bulb of a neuron to cause a change in the target cell.
- neutralization
-
Inactivation of a virus by the binding of specific antibody.
- neutrophil
-
Phagocytic white blood cell recruited from the bloodstream to the site of infection via the bloodstream.
- nicotinamide adenine dinucleotide (NAD+)
-
Electron acceptor that carries electrons from glycolysis and citric acid cycle to the electron transport chain (or supplies electrons during lactic acid fermentation). NADH is the higher energy form, carrying two electrons.
- nitric oxide (NO)
-
Gas produced by the blood vessel endothelium that acts as a powerful vasodilator, active over short distances (between nearby cells) for very short times (seconds).Not to be confused with the anesthetic nitrous oxide (N2O).
- nondisjunction
-
A chromosomal disorder in which chromosomes fail to disjoin and move to opposite poles during either Meiosis I or Meiosis II.
- norepinephrine
-
Secondary catecholamine hormone secreted by the adrenal medulla in response to short-term stress; also called noradrenaline.
- nucleic acid
-
Class or organic molecules consisting of a chain of nucleotides (including DNA and RNA).
- nucleolus
-
Small region of the nucleus that functions in ribosome synthesis.
- nucleus
-
(In nervous system) a localized collection of neuron cell bodies that are functionally related; a “center” of neural function (plural= nuclei).
- O
- oliguria
-
Underproduction of urine (<400–500 mL/day).
- oocyte
-
Cell that results from the division of the oogonium and undergoes meiosis I at the LH surge and meiosis II at fertilization to become a haploid ovum.
- oogenesis
-
Process by which oogonia divide by mitosis to primary oocytes, which undergo meiosis to produce the secondary oocyte and, upon fertilization, the ovum.
- oogonia
-
Ovarian stem cells that undergo mitosis during female fetal development to form primary oocytes.
- oral cavity
-
(Also, buccal cavity) mouth.
- oral vestibule
-
Part of the mouth bounded externally by the cheeks and lips, and internally by the gums and teeth.
- organic compound
-
Substance that contains both carbon and hydrogen.
- oropharynx
-
Portion of the pharynx flanked by the nasopharynx, oral cavity, and laryngopharynx that is a passageway for both air and food.
- osmolarity
-
The solute concentration of a solution.
- osmoreceptor
-
Sensory receptor that is stimulated by changes in solute concentration (osmotic pressure) in the blood.
- osmosis
-
Diffusion of water molecules down their concentration gradient across a selectively permeable membrane.
- osmotic
-
Referring to solute concentration.
- ovarian cycle
-
Approximately 28-day cycle of changes in the ovary consisting of a follicular phase and a luteal phase.
- ovaries
-
Female gonads that produce oocytes and sex steroid hormones (notably estrogen and progesterone).
- oviduct
-
See uterine tube
- ovulation
-
Release of a secondary oocyte and associated granulosa cells from an ovary.
- oxidative phosphorylation
-
Process that converts high-energy NADH and FADH2 into ATP.
- oxyhemoglobin
-
(Hb–O2) bound form of hemoglobin and oxygen.
- oxytocin
-
Hypothalamic hormone stored in the posterior pituitary gland and important in stimulating uterine contractions in labor, milk ejection during breastfeeding, and feelings of attachment (also produced in males).
- P wave
-
Component of the electrocardiogram that represents the depolarization of the atria.
- packed cell volume
-
See hematocrit
- pancreas
-
Accessory digestive organ that secretes pancreatic juice, and hormones (glucagon and insulin). Located between the stomach and duodenum in the epigastric and left hypochondriac regions of the abdomen.
- pancreatic amylase
-
Carbohydrate-digesting enzyme secreted by the pancreas and active in the small intestine.
- papillae
-
For gustation (taste), a bump-like projection on the surface of the tongue that contains taste buds.
- papillary muscle
-
Extension of the myocardium in the ventricles to which the chordae tendineae attach.
- parasympathetic
-
Branch of the autonomic nervous system associated with resting systems ("rest and digest").
- parietal cell
-
Gastric gland cell that secretes hydrochloric acid and intrinsic factor.
- parietal pleura
-
Outermost layer of the pleura that connects to the thoracic wall, mediastinum, and diaphragm.
- parotid gland
-
One of a pair of major salivary glands located inferior and anterior to the ears.
- Partial pressure
-
Force exerted by each gas in a mixture of gases.
- parturition
-
Childbirth
- pathogen
-
An infectious agent that causes disease, typically a bacterium, virus, fungus, or microscopic parasite.
- pepsin
-
Digestive enzyme the digests protein into peptides and amino acids. Secreted by the chief cells in the stomach, pepsin is the active form of pepsinogen (after it comes in contact with HCl).
- pepsinogen
-
Inactive form of pepsin.
- perfusion
-
Delivery of blood through a capillary bed.
- pericardial cavity
-
Cavity surrounding the heart filled with a lubricating serous fluid that reduces friction as the heart contracts.
- perimetrium
-
Outer epithelial layer of uterine wall.
- peristalsis
-
Muscular contractions and relaxations that propel food through the GI tract.
- peritoneum
-
Serous membrane that lines the abdominopelvic cavity and covers the organs found there.
- peritubular capillaries
-
Second capillary bed of the renal portal system; surround the proximal and distal convoluted tubules; associated with the vasa recta.
- pH
-
A measure of the acidity or alkalinity or a solution, measured as the negative logarithm of the hydrogen ion (H+) concentration of a solution.
- phagocyte
-
Large immune cells capable of phagocytosis to ingest pathogens.
- phagocytosis
-
Cell process (a form of endocytosis) in which a cell engulfs and ingests another large particle or cell.
- pharynx
-
Region of the conducting zone that forms a tube of skeletal muscle lined with respiratory epithelium; located between the nasal conchae and the esophagus and trachea.
- phenotype
-
Physical or biochemical manifestation of the genotype; expression of the alleles.
- phenotypic ratio
-
Predicted ratio of phenotypes among offspring; this may differ from the genotypic ratio for the same cross where certain genotypes (e.g. homozygous dominant and heterozygous) have the same phenotype.
- phosphate
-
PO4-, an ion that is an important component of bone, plasma membranes (phospholipids) and ATP. Regulated by parathyroid hormone (PTH).
- phospholipids
-
An amphipathic lipid molecule containing a phosphate head (polar) and two fatty acid tails (non-polar). The major molecule comprising plasma membranes.
- phosphorylation
-
Process by which a high-energy phosphate is added to a molecule. That molecule is said to be phosphorylated.
- physiology
-
Science that studies the chemistry, biochemistry, and physics of the body’s functions.
- pituitary gland
-
Bean-sized organ suspended from the hypothalamus that produces, stores, and secretes hormones in response to hypothalamic stimulation (also called hypophysis).
- placenta
-
Organ that forms during pregnancy to nourish the developing fetus; also regulates waste and gas exchange between mother and fetus.
- placentation
-
Formation of the placenta; complete by weeks 14–16 of pregnancy.
- plasma
-
In blood, the liquid extracellular matrix composed mostly of water that circulates the formed elements and dissolved materials throughout the cardiovascular system.
- plasma cell
-
Differentiated B cell that is actively secreting antibody.
- platelet
-
(Also, thrombocytes) one of the formed elements of blood that consists of cell fragments broken off from megakaryocytes.
- platelet plug
-
Accumulation and adhesion of platelets at the site of blood vessel injury.
- pleura
-
Membrane surrounding the lungs (plural= pleurae)
- pleural cavity
-
Space between the visceral and parietal pleurae.
- pleural fluid
-
Substance that acts as a lubricant for the visceral and parietal layers of the pleura during the movement of breathing.
- plica circulare
-
See circular fold
- pneumotaxic centre
-
Network of neurons within the pons that inhibit the activity of the neurons in the dorsal respiratory group; controls rate of breathing.
- polycythemia
-
Elevated level of hemoglobin, whether adaptive or pathological.
- polyspermy
-
Penetration of an oocyte by more than one sperm.
- polyuria
-
Urine production in excess of 2.5 L/day; may be caused by diabetes insipidus, diabetes mellitus, or excessive use of diuretics.
- pons
-
Portion of the brainstem connecting the medulla oblongata with the midbrain. Serves as a connection to cerebellum, as well as functions including sleep cycles and the origin of some cranial nerves.
- pontine respiratory group
-
Group of neurons controlling both inspiration and expiration, found in the dorsal lateral pons (a region of the brain); includes the apneustic and pneumotaxic centres.
- popliteal artery
-
Continuation of the femoral artery posterior to the knee; branches into the anterior and posterior tibial arteries.
- porta hepatis
-
“Gateway to the liver” where the hepatic artery and hepatic portal vein enter the liver.
- posterior
-
Describes the back or direction toward the back of the body; also referred to as dorsal.
- posterior tibial artery
-
Branch from the popliteal artery that gives rise to the fibular or peroneal artery; supplies blood to the posterior tibial region.
- precipitate
-
(Verb, in chemistry) moving a substance out of solution by forming a solid.
- premolar
-
(Also, bicuspid) transitional tooth used for mastication, crushing, and grinding food.
- prepuce
-
(Also, foreskin) flap of skin that forms a collar around, and thus protects and lubricates, the glans penis.
- primary adaptive response
-
Immune system’s response to the first exposure to a pathogen.
- primary follicles
-
Ovarian follicles with a primary oocyte and one layer of cuboidal granulosa cells.
- primary oocyte
-
Immature oocyte, produced during fetal development where meiosis is 'paused' after prophase I.
- primordial follicles
-
Least developed ovarian follicles that consist of a single oocyte and a single layer of flat (squamous) granulosa cells.
- progesterone
-
Predominantly female sex hormone important in regulating the female reproductive cycle and the maintenance of pregnancy.
- prolactin
-
Anterior pituitary hormone that promotes development of the mammary glands and the production of breast milk. Often abbreviated PRL
- proliferative phase
-
Phase of the menstrual cycle in which the endometrium proliferates.
- prometaphase
-
Late prophase of mitosis, during which the mitotic spindle has attached to the kinetochore of each replicated chromosome.
- prophase
-
The first phase of mitosis, during which the nucleolus disappears, the nuclear envelope disintegrates, mitotic spindle begins to form, and chromosomes condense.
- prophase I
-
First phase of meiosis I during which chromatin condenses to form chromosomes, nuclear envelope disintegrates, mitotic spindle forms, and homologous chromosomes pair together and crossing over occurs.
- Prophase II
-
The first phase of meiosis II, during which chromatin condenses and the mitotic spindle forms.
- prophylaxis
-
Action taken to prevent disease.
- proprioreceptor
-
Sensory receptors providing information about location and movement of body parts; the “sense of the self”.
- prostaglandin
-
Similar to hormones, lipids produced by various cells (not glands), usually at the site of an injury or other issue, that are active over a short distance (targeting other cells in the same tissue).
- prostate
-
Doughnut-shaped gland at the base of the bladder surrounding the urethra and contributing fluid to semen during ejaculation.
- protein
-
Class of organic compounds that are composed of many amino acids linked together by peptide bonds.
- proton
-
Heavy subatomic particle having a positive charge and found in the atom’s nucleus.
- proximal convoluted tubule
-
Tortuous tubule receiving filtrate from Bowman’s capsule; most active part of the nephron in reabsorption and secretion.
- pulmonary artery
-
Single large vessel exiting the right ventricle that divides to form the right and left pulmonary arteries.
- pulmonary circuit
-
Parts of the circulatory system involving blood flow to and from the lungs.
- pulmonary trunk
-
The single large vessel exiting the right ventricle that divides to form the right and left pulmonary arteries.
- pulmonary veins
-
Two sets of paired vessels, one pair on each side, that are formed from the small venules leading away from the pulmonary capillaries that flow into the left atrium.
- Punnett square
-
Grid used to display all possible combinations of alleles transmitted by parents to offspring and predict the mathematical probability of offspring inheriting a given genotype.
- Purkinje fibres
-
Specialized myocardial conduction fibres that arise from the bundle branches and spread the impulse to the myocardial contraction fibers of the ventricles.
- pyloric antrum
-
Wider, more superior part of the pylorus.
- pyloric sphincter
-
Sphincter that controls stomach emptying.
- pylorus
-
Lower, funnel-shaped part of the stomach that is continuous with the duodenum.
- pyruvic acid
-
(Also, pyruvate) Three-carbon end product of glycolysis and starting material that is converted into acetyl CoA that enters the citric acid cycle.
- QRS complex
-
Component of the electrocardiogram that represents the depolarization of the ventricles and includes, as a component, the repolarization of the atria.
- reabsorption
-
Movement of substances from forming urine (in nephron or collecting ducts) back into body cells and bloodstream.
- recessive
-
Describes a trait that is only expressed in homozygous form and is masked in heterozygous form.
- rectal valve
-
One of three transverse folds in the rectum where feces is separated from flatus.
- rectum
-
Part of the large intestine between the sigmoid colon and anal canal.
- red blood cell
-
See erythrocyte
- red bone marrow
-
Connective tissue in the interior cavity of a bone where hematopoiesis takes place.
- renal
-
Referring to the kidneys.
- renal column
-
Extension of the renal cortex into the renal medulla; separates the renal pyramids; contains blood vessels and connective tissues.
- renal cortex
-
Outer part of kidney containing all of the nephrons; some nephrons have loops of Henle extending into the medulla.
- renal hilum
-
Recessed medial area of the kidney through which the renal artery, renal vein, ureters, lymphatics, and nerves pass.
- renal papilla
-
Medullary area of the renal pyramids where collecting ducts empty urine into the minor calyces.
- renal pyramid
-
Cone-shaped tissue in the medulla of the kidney containing collecting ducts and the loops of Henle of juxtamedullary nephrons.
- repolarization
-
Return of the membrane potential to its normally negative voltage at the end of the action potential.
- residual volume (RV)
-
Varying amounts of air within the lung at a given time.
- respiratory zone
-
Includes structures of the respiratory system that are directly involved in gas exchange.
- right bundle branch
-
See atrioventricular bundle branches
- right colic flexure
-
(Also, hepatic flexure) point, at the inferior surface of the liver, where the ascending colon turns abruptly to the left.
- ruga
-
Series of ridges formed by the folding of an organ wall (in stomach for example)(plural= rugae).
- saccharolytic fermentation
-
Anaerobic decomposition of carbohydrates.
- sacral
-
Referring to the sacrum (bone).
- sacrum
-
Single bone located near the inferior end of the adult vertebral column that is formed by the fusion of five sacral vertebrae; forms the posterior portion of the pelvis.
- sagittal plane
-
Two-dimensional, vertical plane that divides the body or organ into right and left sides.
- salivary amylase
-
Digestive enzyme in saliva that acts on starch (a polysaccharide carbohydrate).
- salivary gland
-
An exocrine gland that secretes a digestive fluid called saliva.
- salt
-
An ionically bonded chemical compound. This is more general than the common culinary definition; table salt (NaCl) is one of many chemical salts.
- scalenes
-
Group of three skeletal muscles on either side of the neck. Originate on cervical vertebrae, insert on first and second ribs, serving to flex and medially rotate the neck.
- scrotum
-
Skin-covered muscular sac containing the testes.
- secondary active transport
-
Form active transport where the energy comes from the concentration gradient of a secondary substance (often Na+ or H+).
- secondary adaptive response
-
Immune response observed upon re-exposure to a pathogen, which is stronger and faster than a primary response.
- secondary follicle
-
Ovarian follicle with a primary oocyte and multiple layers of granulosa cells.
- secondary oocyte
-
Immature oocyte after the first meiotic division (which occurs in the tertiary follicle); oocytes are ovulated at this stage.
- secretin
-
A hormone produced by enteroendocrine cells of the duodenum in response to acidity. Stimulates liver and pancreatic digestive secretions.
- secretion
-
In the nephron, solutes that pass from capillaries (blood) to lumen (urine) after glomerular filtration.
- secretory phase
-
Phase of the menstrual cycle in which the endometrium secretes a nutrient-rich fluid in preparation for implantation of an embryo.
- segmentation
-
Alternating contractions and relaxations of non-adjacent segments of the intestine that move food forward and backward, breaking it apart and mixing it with digestive juices.
- semen
-
Ejaculatory fluid composed of sperm and secretions from the seminal vesicles, prostate, and bulbourethral glands.
- semi-permeable
-
Feature of any barrier that allows certain substances to cross but excludes others.
- semilunar valve
-
Valves located at the base of the pulmonary trunk and at the base of the aorta.
- seminal vesicle
-
Gland that produces seminal fluid, which contributes to semen.
- seminiferous tubule
-
Location of meiosis in the male, and production of sperm.
- septum
-
A wall or divider. In heart, specifically: the wall or partitions that divides the heart into chambers (plural= septa).
- serosa
-
Outermost layer of the alimentary canal wall present in regions within the abdominal cavity.
- Sertoli cells
-
Cells that support germ cells through the process of spermatogenesis.
- serum
-
Blood plasma that does not contain clotting factors.
- sex chromosomes
-
The X and Y chromosomes.
- shunt
-
Circulatory shortcut that diverts the flow of blood from one region to another.
- sigmoid colon
-
End portion of the colon, which terminates at the rectum.
- simple diffusion
-
Passive movement of a substance from an area of high concentration to an area of lower concentration (across a cell membrane for instance).
- sinoatrial node
-
Known as the pacemaker, a specialized clump of myocardial conducting cells located in the superior portion of the right atrium that has the highest inherent rate of depolarization that then spreads throughout the heart.
- sinus rhythm
-
Normal contractile pattern of the heart.
- sinusoid capillaries
-
Rarest type of capillary, which has extremely large intercellular gaps in the basement membrane in addition to clefts and fenestrations; found in areas such as the bone marrow and liver where passage of large molecules occurs.
- sister chromatid
-
An identical copy of a chromosome, formed during S phase in preparation for mitosis, attached at the centromere to another sister chromatid.
- small intestine
-
Section of the alimentary canal where most digestion and absorption occurs.
- smooth muscle
-
Type of muscle tissue found primarily in the walls of hollow organs.
- solute
-
Substances dissolved in a solution.
- somatic cell
-
A body cell, excluding germ cells. Normally diploid, each cell containing a complete set of genes.
- somatotropin
-
See growth hormone
- spermatogenesis
-
Process of producing sperm.
- sphincter
-
A ring-shaped smooth muscle that can open or close a passage in the body.
- spleen
-
Secondary lymphoid organ that filters pathogens from the blood (white pulp) and removes degenerating or damaged blood cells (red pulp).
- splenic flexure
-
See left colic flexure
- spongy bone
-
(Also, cancellous bone) trabeculated osseous tissue that supports shifts in weight distribution.
- stem cell
-
Cell that is oligo-, multi-, or pleuripotent that has the ability to produce additional stem cells rather than becoming further specialized.
- sternum
-
Flattened bone located at the center of the anterior chest.
- steroid
-
A type of lipid containing four rings and a fatty acid tail. Examples include testosterone and cholesterol.
- stomach
-
Alimentary canal organ that contributes to chemical and mechanical digestion of food from the esophagus before releasing it, as chyme, to the small intestine.
- stratum basalis
-
Basal layer of the uterine epithelium that remains relatively unchanged during the menstrual cycle.
- stratum functionalis
-
The thicker of the two uterine epithelial layers, that thickens and is shed during the menstrual cycle in response to estrogens and progesterone.
- strong acid
-
Acid that completely dissociates (releasing all of it's H+) in solution.
- strong base
-
Base that completely dissociates (releasing all of it's H+) in solution.
- styloid process
-
Downward projecting, elongated bony process located on the inferior aspect of the skull.
- subclavian artery
-
Right subclavian arises from the brachiocephalic artery, whereas the left subclavian artery arises from the aortic arch; gives rise to the internal thoracic, vertebral, and thyrocervical arteries; supplies blood to the arms, chest, shoulders, back, and central nervous system.
- subclavian vein
-
(Left and right) located deep in the thoracic cavity; becomes the axillary vein as it enters the axillary region; drains the axillary and smaller local veins near the scapular region; leads to the brachiocephalic vein.
- sublingual gland
-
One of a pair of major salivary glands located beneath the tongue.
- submandibular gland
-
One of a pair of major salivary glands located in the floor of the mouth.
- submucosa
-
Connective tissue underlying a mucosa.
- submucosal plexus
-
(Also, plexus of Meissner) nerve supply that regulates activity of glands and smooth muscle.
- substrate
-
Reactant in an enzymatic reaction.
- substrate-level phosphorylation
-
Phosphorylation of ATP during glycolysis and the Kreb's Cycle.
- superficial
-
Describes a position nearer to the surface of the body.
- superior
-
The direction towards the head.
- superior vena cava
-
Large systemic vein that returns blood to the heart from the superior portion of the body.
- surfactant
-
A substance that reduces surface tension of a liquid.
- sympathetic
-
Branch of the autonomic nervous system associated with emergency systems ("fight of flight").
- syncytiotrophoblast
-
Superficial cells of the trophoblast that fuse to form a multinucleated body that digests endometrial cells to firmly secure the blastocyst to the uterine wall.
- systemic circuit
-
Parts of the circulatory system involving blood flow to and from almost all the tissues in the body (other than the pulmonary circuit)
- systole
-
Period of time when the heart muscle is contracting.
- systolic pressure
-
Larger number recorded when measuring arterial blood pressure; represents the maximum value following ventricular contraction.
- T cells
-
Lymphocyte that acts by secreting molecules that regulate the immune system or by causing the destruction of foreign cells, viruses, and cancer cells.
- T wave
-
Component of the electrocardiogram that represents the repolarization of the ventricles.
- tachycardia
-
Abnormally high heart rate (>100 beats per minute).
- tarsal
-
One of the seven bones that make up the posterior foot; includes the calcaneus, talus, navicular, cuboid, medial cuneiform, intermediate cuneiform, and lateral cuneiform bones.
- TCA cycle
-
See Krebs cycle
- telophase
-
Final phase of telophase, during which chromosomes (now separated at opposite poles) decondense and nuclear envelope re-forms.
- telophase I
-
The final phase of meiosis I, during which replicated chromosomes (consisting of paired sister chromatids) form new nuclei at either end of the dividing cell.
- telophase II
-
The final phase of meiosis II, resulting in four (from two separate cells each undergoing meiosis II) daughter cells that each genetically unique (from each other and from the parent cell).
- temporal bone
-
Paired bones that form the lateral, inferior portions of the skull, with squamous, mastoid, and petrous portions.
- tenia coli
-
One of three smooth muscle bands that make up the longitudinal muscle layer of the muscularis in all of the large intestine except the terminal end.
- tertiary follicle
-
(Also, antral follicle) ovarian follicle with a primary or secondary oocyte, multiple layers of granulosa cells, and a fully formed antrum.
- testis
-
Male gonad (plural = testes).
- testosterone
-
Steroid hormone secreted by the male testes and important in the maturation of sperm cells, growth and development of the male reproductive system, and the development of male secondary sex characteristics.
- theca cells
-
Estrogen-producing cells in a maturing ovarian follicle.
- thoracic aorta
-
Portion of the descending aorta superior to the aortic hiatus.
- thoracic cavity
-
Division of the anterior (ventral) cavity that houses the heart, lungs, esophagus, and trachea.
- thorax
-
The chest area, containing the thoracic cavity.
- thrombin
-
Enzyme essential for the final steps in formation of a fibrin clot.
- thymus
-
Organ that is involved in the development and maturation of T-cells and is particularly active during infancy and childhood.
- thyroid
-
Large butterfly-shaped endocrine gland responsible for the synthesis of thyroid hormones. Located anterior to the trachea, just inferior to the larynx.
- thyroid hormones
-
Collection of hormones secreted by the thyroid gland with wide-ranging metabolic affects.
- Thyroid stimulating hormone releasing hormone (TSHRH)
-
Hormone from the hypothalamus that stimulates release of thyroid stimulating hormone from the anterior pituitary.
- thyroid-stimulating hormone
-
Anterior pituitary hormone that triggers secretion of thyroid hormones by the thyroid gland (often abbreviated TSH, also called thyrotropin)
- thyrotropin
-
See thyroid stimulating hormone
- tidal volume (TV)
-
Amount of air that normally enters the lungs during quiet breathing.
- tissue
-
Group of similar or closely related cells that act together to perform a specific function.
- tissue factor
-
Protein thromboplastin, which initiates the extrinsic pathway when released in response to tissue damage.
- tonsil
-
Lymphoid nodule associated with the nasopharynx.
- total dead space
-
Sum of the anatomical dead space and alveolar dead space.
- total lung capacity (TLC)
-
Total amount of air that can be held in the lungs; sum of TV, ERV, IRV, and RV.
- totipotent
-
Embryonic cells that have the ability to differentiate into any type of cell and organ in the body.
- trachea
-
Tube composed of cartilaginous rings and supporting tissue that connects the lung bronchi and the larynx; provides a route for air to enter and exit the lung.
- trait
-
Variation of an expressed characteristic.
- transverse colon
-
Part of the colon between the ascending colon and the descending colon.
- transverse plane
-
Two-dimensional, horizontal plane that divides the body or organ into superior and inferior portions.
- tricarboxylic acid (TCA) cycle
-
See citric acid cycle.
- triglyceride
-
Lipid compound composed of a glycerol molecule bonded with three fatty acid chains.
- trophoblast
-
Fluid-filled shell of squamous cells destined to become the chorionic villi, placenta, and associated fetal membranes.
- tropic
-
Hormones that affect the secretion of other hormones.
- trypsin
-
Enzyme that digests proteins in the small intestine. Activated form of trypsinogen (Activated by enteropeptidase).
- trypsinogen
-
Precursor of the digestive enzyme trypsin.
- tunica adventitia
-
See tunica externa
- tunica externa
-
(Also, tunica adventitia) outermost layer or tunic of a vessel (except capillaries).
- tunica intima
-
(Also, tunica interna) innermost lining or tunic of a vessel.
- tunica media
-
Middle layer or tunic of a vessel (except capillaries).
- tunice interna
-
See tunica intima
- umbilical cord
-
Connection between the developing conceptus and the placenta; carries deoxygenated blood and wastes from the fetus and returns nutrients and oxygen from the mother.
- urea
-
Nitrogenous compound formed in the liver from ammonium (which is toxic), a product of protein metabolism.
- urea cycle
-
Process that converts potentially toxic nitrogen waste into urea that can be eliminated through the kidneys.
- ureter
-
One of two tubes carrying urine from kidney to bladder.
- urethra
-
Transports urine from the bladder to the outside environment.
- uterine tube
-
(Also, fallopian tube or oviduct) duct that facilitates transport of an ovulated oocyte to the uterus.
- uterus
-
Muscular hollow organ in which a fertilized egg develops into a fetus.
- vagina
-
Tunnel-like organ that provides access to the uterus for the insertion of semen and from the uterus for the birth of a baby.
- vagus nerve
-
Tenth cranial nerve; responsible for the autonomic control of organs in the thoracic and upper abdominal cavities.
- Valsalva’s maneuver
-
Voluntary contraction of the diaphragm and abdominal wall muscles and closing of the glottis, which increases intra-abdominal pressure and facilitates defecation.
- vas deferens
-
See ductus deferens
- vasa recta
-
Branches of the efferent arterioles that parallel the course of the loops of Henle and are continuous with the peritubular capillaries; with the glomerulus, form a portal system.
- vascular spasm
-
Initial step in hemostasis, in which the smooth muscle in the walls of the ruptured or damaged blood vessel contracts.
- vasoconstriction
-
Constriction of blood vessels
- vasodilation
-
Dilation (increased internal diameter) of blood vessels.
- vasopressin
-
See antidiuretic hormone
- vein
-
Blood vessel that conducts blood toward the heart.
- ventral
-
Group of similar or closely related cells that act together to perform a specific function.
- ventral cavity
-
Larger body cavity located anterior to the posterior (dorsal) body cavity; includes the serous membrane-lined pleural cavities for the lungs, pericardial cavity for the heart, and peritoneal cavity for the abdominal and pelvic organs; also referred to as anterior body cavity.
- ventral respiratory group (VRG)
-
Region of the medulla oblongata that stimulates the contraction of the accessory muscles involved in respiration to induce forced inspiration and expiration.
- venule
-
Small vessel leading from the capillaries to veins.
- vermiform appendix
-
see appendix
- vestigial
-
A structure that, through the course of evolution, no longer has a function.
- villus
-
Projection of the mucosa of the small intestine (plural= villi).
- visceral pleura
-
Innermost layer of the pleura that is superficial to the lungs and extends into the lung fissures.
- vital capacity (VC)
-
Sum of TV, ERV, and IRV, which is all the volumes that participate in gas exchange.
- vitamin
-
Organic compound required by the body to perform biochemical reactions like metabolism and bone, cell, and tissue growth.
- vitamin B12
-
Vitamin found in meat, fish, dairy and eggs that is necessary for neuron function, hematopoiesis and fatty acid oxidation.
- weak acid
-
Acid that partially dissociates in water. In solution, a chemicial equilibrium exists, with some acid, and some dissociated constituents present simultaneously.
- weak base
-
Base that partially dissociates in water. In solution, a chemicial equilibrium exists, with some base, and some dissociated constituents present simultaneously.
- white blood cell
-
See leukocyte
- X-linked dominant
-
Pattern of dominant inheritance that corresponds to a gene on the X chromosome of the 23rd pair.
- X-linked recessive
-
Pattern of recessive inheritance that corresponds to a gene on the X chromosome of the 23rd pair.
- yellow bone marrow
-
Connective tissue in the interior cavity of a bone where fat is stored.
- yolk sac
-
Membrane associated with primitive circulation to the developing embryo; source of the first blood cells and germ cells and contributes to the umbilical cord structure.
- zona pellucida
-
Glycoprotein layer surrounding the cell membrane of an oocyte.
- zygote
-
Fertilized egg; a diploid cell resulting from the fertilization of haploid gametes from the male and female lines.