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.

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Douglas College Human Anatomy & Physiology II (4th ed.) Copyright © 2021 by Douglas College is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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