{"id":395,"date":"2023-12-04T10:24:49","date_gmt":"2023-12-04T15:24:49","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/chapter\/gross-anatomy-of-the-kidney\/"},"modified":"2023-12-04T10:48:17","modified_gmt":"2023-12-04T15:48:17","slug":"gross-anatomy-of-the-kidney","status":"web-only","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/chapter\/gross-anatomy-of-the-kidney\/","title":{"raw":"Gross Anatomy of the Kidney","rendered":"Gross Anatomy of the Kidney"},"content":{"raw":"\n<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\n<p class=\"textbox__title\">Learning Objectives<\/p>\n\n<\/header>\n<div class=\"textbox__content\">\n\nBy the end of this section, you will be able to:\n<ul>\n \t<li>Describe the external structure of the kidney, including its location, support structures, and covering<\/li>\n \t<li>Identify the major internal divisions and structures of the kidney<\/li>\n \t<li>Identify the major blood vessels associated with the kidney and trace the path of blood through the kidney<\/li>\n \t<li>Name structures found in the cortex and medulla<\/li>\n \t<li>Describe the physiological characteristics of the cortex and medulla<\/li>\n \t<li>Identify the ureters, urinary bladder, and urethra, as well as their location, structure, histology, and function<\/li>\n \t<li>Compare and contrast male and female urethras<\/li>\n<\/ul>\n<\/div>\n<\/div>\n&nbsp;\n<p id=\"fs-id1542887\">The kidneys lie on either side of the spine against the back of the abdominal wall, well protected by muscle, fat, and ribs. They are roughly the size of your fist. The kidneys require a lot of blood flow, receiving about 25 percent of the blood pumped by the heart at rest.<\/p>\n&nbsp;\n<div id=\"fs-id2967956\" class=\"anatomy interactive\" data-type=\"note\" data-has-label=\"true\" data-label=\"\">\n\n<span style=\"font-family: 'Cormorant Garamond', serif;font-size: 1.602em\">External Anatomy<\/span>\n\n<\/div>\n<div id=\"fs-id2434228\" class=\"bc-section section\" data-depth=\"1\">\n<p id=\"fs-id1592078\">The right kidney is located slightly lower than the left, due to displacement by the liver. Upper portions of the kidneys are somewhat protected by the eleventh and twelfth ribs&nbsp;<span style=\"font-size: 1em\">(<\/span><a class=\"autogenerated-content\" style=\"font-size: 1em\" href=\"#fig-ch26_03_01\">Figure 9.1<\/a><span style=\"font-size: 1em\">) <\/span><span style=\"text-align: initial;font-size: 1em\">and are also surrounded and protected by a connective tissue capsule and surrounding fat<\/span><span style=\"text-align: initial;font-size: 1em\">.<\/span><\/p>\n\n<div id=\"fig-ch26_03_01\" class=\"bc-figure figure\">\n<div data-type=\"title\"><\/div>\n<div class=\"bc-figcaption figcaption\"><\/div>\n\n[caption id=\"\" align=\"aligncenter\" width=\"425\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/2608_Kidney_Position_in_Abdomen-1.jpg\" alt=\"This image shows a human torso and shows the location of the kidneys within the torso.\" width=\"425\" height=\"1204\" data-media-type=\"image\/jpg\"> <strong>Figure 9.1<\/strong> <em>&nbsp;The kidneys are slightly protected by the ribs and are surrounded by fat for protection (not shown).<\/em>[\/caption]\n\n<\/div>\n<p id=\"fs-id2488605\">Atop each kidney is an adrenal gland. The adrenal cortex, or outer layer of the adrenal gland, influences renal function by producing the hormone aldosterone to stimulate sodium reabsorption.<\/p>\n\n<\/div>\n<div id=\"fs-id2519880\" class=\"bc-section section\" data-depth=\"1\">\n<h3 data-type=\"title\">Internal Anatomy<\/h3>\n<p id=\"fs-id2303293\">Inside the kidney there is an outer region called the <span data-type=\"term\">[pb_glossary id=\"1107\"]renal cortex[\/pb_glossary]<\/span> and an inner region called the <span data-type=\"term\">[pb_glossary id=\"1103\"]medulla[\/pb_glossary]<\/span> (<a class=\"autogenerated-content\" href=\"#fig-ch26_03_02\">Figure 9.2<\/a>). The <span data-type=\"term\">[pb_glossary id=\"1105\"]renal columns[\/pb_glossary]<\/span> are connective tissue extensions that pass from the cortex through the medulla to separate the <span data-type=\"term\">[pb_glossary id=\"1110\"]renal pyramids[\/pb_glossary]<\/span> (triangular segments formed of tissue from the medulla) and <span data-type=\"term\">[pb_glossary id=\"1109\"]renal papillae[\/pb_glossary]<\/span>. The papillae are bundles of collecting ducts that transport urine made by the functional tissue of the kidney to the <span data-type=\"term\">[pb_glossary id=\"1099\"]calyces[\/pb_glossary]<\/span> of the kidney for excretion.<\/p>\n\n<div id=\"fig-ch26_03_02\" class=\"bc-figure figure\">\n<div data-type=\"title\"><\/div>\n\n[caption id=\"\" align=\"aligncenter\" width=\"475\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/2610_The_Kidney-1.jpg\" alt=\"The left panel of this figure shows the location of the kidneys in the abdomen. The right panel shows the cross section of the kidney.\" width=\"475\" height=\"1129\" data-media-type=\"image\/jpg\"> <strong>Figure 9.2<\/strong> <em>The left kidney with renal hilum<\/em>[\/caption]\n\n<\/div>\n<\/div>\n<div id=\"fs-id2433958\" class=\"bc-section section\" data-depth=\"1\">\n<h3 data-type=\"title\">Renal Hilum<\/h3>\n<p id=\"fs-id1764618\">The <span data-type=\"term\">[pb_glossary id=\"1108\"]renal hilum[\/pb_glossary]<\/span> is the entry and exit site for structures servicing the kidneys: blood vessels (artery and vein), nerves, lymphatics, and ureters (<a class=\"autogenerated-content\" href=\"#fig-ch26_03_02\">Figure 9.2<\/a>).<\/p>\n\n<div id=\"fs-id2198084\" class=\"bc-section section\" data-depth=\"2\">\n<h4 data-type=\"title\">Nephrons and Vessels<\/h4>\n<p id=\"fs-id2718604\">The renal arteries branch into smaller and smaller vessels,&nbsp;eventually forming afferent arterioles (<a class=\"autogenerated-content\" href=\"#fig-ch26_03_03\">Figure 9.3<\/a>). The afferent arterioles feed the capillaries in the glomeruli that are vital to the function of the kidney.<\/p>\n\n<div id=\"fig-ch26_03_03\" class=\"bc-figure figure\">\n<div data-type=\"title\"><\/div>\n\n[caption id=\"\" align=\"aligncenter\" width=\"475\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/2612_Blood_Flow_in_the_Kidneys.jpg\" alt=\"This figure shows the network of blood vessels and the blood flow in the kidneys.\" width=\"475\" height=\"1581\" data-media-type=\"image\/jpg\"> <strong>Figure 9.3<\/strong> <em>Blood Flow in the Kidney<\/em>[\/caption]\n\n<\/div>\n<p id=\"fs-id2532837\">[pb_glossary id=\"1102\"]Nephrons[\/pb_glossary] are the \u201cfunctional units\u201d of the kidney; they cleanse the blood and balance water and electrolytes, like sodium and potassium. &nbsp;The afferent arterioles form the capillaries of the glomeruli (sing. [pb_glossary id=\"1101\"]glomerulus[\/pb_glossary]). The glomerulus is surrounded by [pb_glossary id=\"1098\"]Bowman\u2019s capsule[\/pb_glossary], which forms a space around the glomerulus called Bowman\u2019s space. The nephron is composed of tubules that are continuous with Bowman\u2019s space. The glomerulus and Bowman\u2019s capsule together form the [pb_glossary id=\"1106\"]renal corpuscle[\/pb_glossary]. These glomerular capillaries filter the blood based on particle size. After passing through the renal corpuscle, the capillaries form a second arteriole, the [pb_glossary id=\"1100\"]efferent arteriole[\/pb_glossary] (<a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/25-3-gross-anatomy-of-the-kidney#fig-ch26_03_04\">Figure 9.4<\/a>). These will next form the [pb_glossary id=\"1104\"]peritubular capillary[\/pb_glossary] network around the more distal portions of the nephron tubule before returning to the venous system. As the glomerular filtrate passes through the nephron, these peritubular capillary networks recover most of the solutes, nutrients, and water, and return them to the circulation.<\/p>\n\n<div id=\"fig-ch26_03_04\" class=\"bc-figure figure\">\n<div data-type=\"title\"><\/div>\n\n[caption id=\"\" align=\"aligncenter\" width=\"380\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/2611_Blood_Flow_in_the_Nephron.jpg\" alt=\"This image shows the blood vessels and the direction of blood flow in the nephron.\" width=\"380\" height=\"1946\" data-media-type=\"image\/jpeg\"> <strong>Figure 9.4<\/strong> <em>Blood Flow in the Nephron<\/em>[\/caption]\n\n<\/div>\n<\/div>\n<div id=\"fs-id2753827\" class=\"bc-section section\" data-depth=\"2\">\n<p id=\"fs-id2419964\">Urine requires specialized structures to remove it from the body safely and efficiently, and to store it until a convenient time for excretion. All structures involved in the transport and storage of the urine are large enough to be visible to the naked eye.<\/p>\n\n<h3>Ureters<\/h3>\n<p id=\"fs-id2338701\">As urine is formed, it drains into the calyces of the kidney, which merge to form the funnel-shaped renal pelvis in the hilum of each kidney. The renal pelvis narrows to become the ureter of each kidney. As the ureters approach the bladder, they turn and enter the bladder at an angle. This creates a one-way valve that allows urine into the bladder but prevents reflux of urine from the bladder back into the ureter.<\/p>\n\n<h3><span style=\"font-family: 'Cormorant Garamond', serif;font-size: 1.602em\">Bladder<\/span><\/h3>\n<div id=\"fs-id2447210\" class=\"bc-section section\" data-depth=\"1\">\n<div id=\"fs-id1616433\" class=\"bc-section section\" data-depth=\"1\">\n<p id=\"fs-id1616696\">The urinary bladder collects urine from the ureters (<a class=\"autogenerated-content\" href=\"#fig-ch26_02_02\">Figure 9.5<\/a>) and lies in front of the uterus in females, behind the pubic bone and in front of the rectum. In males, the anatomy is similar, minus the uterus, and with the addition of the prostate below the bladder, surrounding the [pb_glossary id=\"1111\"]urethra[\/pb_glossary].<\/p>\n\n\n[caption id=\"\" align=\"aligncenter\" width=\"1962\"]<img src=\"https:\/\/openstax.org\/apps\/archive\/20220509.174553\/resources\/25f1d6b7a9fc77ce5f74cd7574878a2b92845715\" alt=\"The left panel of this figure shows the cross section of the bladder and the major parts are labeled. The right panel shows a micrograph of the bladder.\" width=\"1962\" height=\"1202\"> <strong>Figure 9.5<\/strong> <em>(a) Anterior cross section of the bladder. (b) The detrusor muscle of the bladder (source: monkey tissue) LM \u00d7 448. (Micrograph provided by the Regents of the University of Michigan Medical School \u00a9 2012)<\/em>[\/caption]\n\n<\/div>\n<div id=\"fs-id2339546\" class=\"bc-section section\" data-depth=\"1\">\n<div id=\"fig-ch26_02_04\" class=\"bc-figure figure\">\n<h3><span style=\"font-family: 'Cormorant Garamond', serif;font-size: 1.602em\">Urethra<\/span><\/h3>\n<\/div>\n<\/div>\n<p id=\"fs-id2569293\">The <span data-type=\"term\">urethra<\/span> transports urine from the bladder to the outside of the body for disposal. The urethra is the only part of the urinary system that shows any significant anatomic difference between males and females; all other urine transport structures are identical <a class=\"autogenerated-content\" href=\"#fig-ch26_02_01\">(Figure 9.6<\/a>).<\/p>\n\n<div id=\"fig-ch26_02_01\" class=\"bc-figure figure\" data-orient=\"vertical\">\n<div class=\"bc-figcaption figcaption\"><\/div>\n\n[caption id=\"\" align=\"aligncenter\" width=\"560\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/Female_and_Male_Urethra-1.jpg\" alt=\"The left panel of this figure shows the organs in the female urinary system and the right panel is the male.\" width=\"560\" height=\"714\" data-media-type=\"image\/jpg\"> <strong>Figure 9.6<\/strong> <em>Female and Male Urethras The urethra transports urine from the bladder to the outside of the body. (a) a female urethra and (b) a male urethra.<\/em>[\/caption]\n\n<\/div>\n<p id=\"fs-id2108795\">The urethra in both males and females begins inferior and central to the two ureteral openings.<\/p>\n\n<div id=\"fs-id2042066\" class=\"bc-section section\" data-depth=\"2\">\n<h4 data-type=\"title\">Female Urethra<\/h4>\n<p id=\"fs-id1910316\">The main difference between the from the male urethra is the female urethra's short length of about 4 cm. This makes it less of a barrier to fecal bacteria than the longer male urethra and the best explanation for the greater incidence of urinary tract infections (UTIs) in women.<\/p>\n\n<\/div>\n<div id=\"fs-id2252307\" class=\"bc-section section\" data-depth=\"2\">\n<h4 data-type=\"title\">Male Urethra<\/h4>\n<p id=\"fs-id2071647\">The male urethra passes through the prostate gland immediately inferior to the bladder before passing below the pubic symphysis. The length of the male urethra varies but averages 20 cm in length.<\/p>\n\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"fs-id2593288\" class=\"summary\" data-depth=\"1\">\n<h1>Chapter Review<\/h1>\n<p id=\"fs-id2388415\">The structure of the kidney is divided into two main regions\u2014the peripheral rim of cortex and the central medulla. The two kidneys receive about 25 percent of cardiac output (amount of blood pumped by the heart). They are protected by fat and overlying ribs and muscle. Ureters, blood vessels, lymph vessels, and nerves enter and leave at the renal hilum. There are about 1.3 million nephrons per kidney and these are the \u201cfunctional units\u201d that perform the important physiologic functions. The glomerulus (a specialized capillary bed) filters blood and the filtrate is captured by Bowman\u2019s capsule. Most water and solutes are recovered by a second capillary bed that surrounds the tubules of the nephron. This filtrate is processed into urine by the renal tubules and finally flows into collecting ducts that drain into the minor calyces, which merge to form major calyces. The urine then proceeds to the renal pelvis and finally the ureters to the bladder. Urine is stored in the bladder until urination. The male and female urethras differ in their length and the presence of a prostate in males.<\/p>\n\n<\/div>\n<h1>Review Questions<\/h1>\n[h5p id=\"92\"]\n<h1>Adaption<\/h1>\n<p style=\"text-align: start\">This chapter is adapted from the following text:<\/p>\n<p style=\"text-align: start\"><a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/25-3-gross-anatomy-of-the-kidney\" target=\"_blank\" rel=\"noopener\">Gross Anatomy of the Kidney<\/a>&nbsp;<strong>in&nbsp;<\/strong><a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/25-3-gross-anatomy-of-the-kidney\">Anatomy and Physiology<\/a>&nbsp;by&nbsp;OSCRiceUniversity&nbsp;is licensed under a&nbsp;<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">Creative Commons Attribution 4.0 International License<\/a><\/p>\n","rendered":"<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\">Learning Objectives<\/p>\n<\/header>\n<div class=\"textbox__content\">\n<p>By the end of this section, you will be able to:<\/p>\n<ul>\n<li>Describe the external structure of the kidney, including its location, support structures, and covering<\/li>\n<li>Identify the major internal divisions and structures of the kidney<\/li>\n<li>Identify the major blood vessels associated with the kidney and trace the path of blood through the kidney<\/li>\n<li>Name structures found in the cortex and medulla<\/li>\n<li>Describe the physiological characteristics of the cortex and medulla<\/li>\n<li>Identify the ureters, urinary bladder, and urethra, as well as their location, structure, histology, and function<\/li>\n<li>Compare and contrast male and female urethras<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<p id=\"fs-id1542887\">The kidneys lie on either side of the spine against the back of the abdominal wall, well protected by muscle, fat, and ribs. They are roughly the size of your fist. The kidneys require a lot of blood flow, receiving about 25 percent of the blood pumped by the heart at rest.<\/p>\n<p>&nbsp;<\/p>\n<div id=\"fs-id2967956\" class=\"anatomy interactive\" data-type=\"note\" data-has-label=\"true\" data-label=\"\">\n<p><span style=\"font-family: 'Cormorant Garamond', serif;font-size: 1.602em\">External Anatomy<\/span><\/p>\n<\/div>\n<div id=\"fs-id2434228\" class=\"bc-section section\" data-depth=\"1\">\n<p id=\"fs-id1592078\">The right kidney is located slightly lower than the left, due to displacement by the liver. Upper portions of the kidneys are somewhat protected by the eleventh and twelfth ribs&nbsp;<span style=\"font-size: 1em\">(<\/span><a class=\"autogenerated-content\" style=\"font-size: 1em\" href=\"#fig-ch26_03_01\">Figure 9.1<\/a><span style=\"font-size: 1em\">) <\/span><span style=\"text-align: initial;font-size: 1em\">and are also surrounded and protected by a connective tissue capsule and surrounding fat<\/span><span style=\"text-align: initial;font-size: 1em\">.<\/span><\/p>\n<div id=\"fig-ch26_03_01\" class=\"bc-figure figure\">\n<div data-type=\"title\"><\/div>\n<div class=\"bc-figcaption figcaption\"><\/div>\n<figure style=\"width: 425px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/2608_Kidney_Position_in_Abdomen-1.jpg\" alt=\"This image shows a human torso and shows the location of the kidneys within the torso.\" width=\"425\" height=\"1204\" data-media-type=\"image\/jpg\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 9.1<\/strong> <em>&nbsp;The kidneys are slightly protected by the ribs and are surrounded by fat for protection (not shown).<\/em><\/figcaption><\/figure>\n<\/div>\n<p id=\"fs-id2488605\">Atop each kidney is an adrenal gland. The adrenal cortex, or outer layer of the adrenal gland, influences renal function by producing the hormone aldosterone to stimulate sodium reabsorption.<\/p>\n<\/div>\n<div id=\"fs-id2519880\" class=\"bc-section section\" data-depth=\"1\">\n<h3 data-type=\"title\">Internal Anatomy<\/h3>\n<p id=\"fs-id2303293\">Inside the kidney there is an outer region called the <span data-type=\"term\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1107\">renal cortex<\/a><\/span> and an inner region called the <span data-type=\"term\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1103\">medulla<\/a><\/span> (<a class=\"autogenerated-content\" href=\"#fig-ch26_03_02\">Figure 9.2<\/a>). The <span data-type=\"term\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1105\">renal columns<\/a><\/span> are connective tissue extensions that pass from the cortex through the medulla to separate the <span data-type=\"term\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1110\">renal pyramids<\/a><\/span> (triangular segments formed of tissue from the medulla) and <span data-type=\"term\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1109\">renal papillae<\/a><\/span>. The papillae are bundles of collecting ducts that transport urine made by the functional tissue of the kidney to the <span data-type=\"term\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1099\">calyces<\/a><\/span> of the kidney for excretion.<\/p>\n<div id=\"fig-ch26_03_02\" class=\"bc-figure figure\">\n<div data-type=\"title\"><\/div>\n<figure style=\"width: 475px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/2610_The_Kidney-1.jpg\" alt=\"The left panel of this figure shows the location of the kidneys in the abdomen. The right panel shows the cross section of the kidney.\" width=\"475\" height=\"1129\" data-media-type=\"image\/jpg\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 9.2<\/strong> <em>The left kidney with renal hilum<\/em><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div id=\"fs-id2433958\" class=\"bc-section section\" data-depth=\"1\">\n<h3 data-type=\"title\">Renal Hilum<\/h3>\n<p id=\"fs-id1764618\">The <span data-type=\"term\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1108\">renal hilum<\/a><\/span> is the entry and exit site for structures servicing the kidneys: blood vessels (artery and vein), nerves, lymphatics, and ureters (<a class=\"autogenerated-content\" href=\"#fig-ch26_03_02\">Figure 9.2<\/a>).<\/p>\n<div id=\"fs-id2198084\" class=\"bc-section section\" data-depth=\"2\">\n<h4 data-type=\"title\">Nephrons and Vessels<\/h4>\n<p id=\"fs-id2718604\">The renal arteries branch into smaller and smaller vessels,&nbsp;eventually forming afferent arterioles (<a class=\"autogenerated-content\" href=\"#fig-ch26_03_03\">Figure 9.3<\/a>). The afferent arterioles feed the capillaries in the glomeruli that are vital to the function of the kidney.<\/p>\n<div id=\"fig-ch26_03_03\" class=\"bc-figure figure\">\n<div data-type=\"title\"><\/div>\n<figure style=\"width: 475px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/2612_Blood_Flow_in_the_Kidneys.jpg\" alt=\"This figure shows the network of blood vessels and the blood flow in the kidneys.\" width=\"475\" height=\"1581\" data-media-type=\"image\/jpg\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 9.3<\/strong> <em>Blood Flow in the Kidney<\/em><\/figcaption><\/figure>\n<\/div>\n<p id=\"fs-id2532837\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1102\">Nephrons<\/a> are the \u201cfunctional units\u201d of the kidney; they cleanse the blood and balance water and electrolytes, like sodium and potassium. &nbsp;The afferent arterioles form the capillaries of the glomeruli (sing. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1101\">glomerulus<\/a>). The glomerulus is surrounded by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1098\">Bowman\u2019s capsule<\/a>, which forms a space around the glomerulus called Bowman\u2019s space. The nephron is composed of tubules that are continuous with Bowman\u2019s space. The glomerulus and Bowman\u2019s capsule together form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1106\">renal corpuscle<\/a>. These glomerular capillaries filter the blood based on particle size. After passing through the renal corpuscle, the capillaries form a second arteriole, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1100\">efferent arteriole<\/a> (<a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/25-3-gross-anatomy-of-the-kidney#fig-ch26_03_04\">Figure 9.4<\/a>). These will next form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1104\">peritubular capillary<\/a> network around the more distal portions of the nephron tubule before returning to the venous system. As the glomerular filtrate passes through the nephron, these peritubular capillary networks recover most of the solutes, nutrients, and water, and return them to the circulation.<\/p>\n<div id=\"fig-ch26_03_04\" class=\"bc-figure figure\">\n<div data-type=\"title\"><\/div>\n<figure style=\"width: 380px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/2611_Blood_Flow_in_the_Nephron.jpg\" alt=\"This image shows the blood vessels and the direction of blood flow in the nephron.\" width=\"380\" height=\"1946\" data-media-type=\"image\/jpeg\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 9.4<\/strong> <em>Blood Flow in the Nephron<\/em><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div id=\"fs-id2753827\" class=\"bc-section section\" data-depth=\"2\">\n<p id=\"fs-id2419964\">Urine requires specialized structures to remove it from the body safely and efficiently, and to store it until a convenient time for excretion. All structures involved in the transport and storage of the urine are large enough to be visible to the naked eye.<\/p>\n<h3>Ureters<\/h3>\n<p id=\"fs-id2338701\">As urine is formed, it drains into the calyces of the kidney, which merge to form the funnel-shaped renal pelvis in the hilum of each kidney. The renal pelvis narrows to become the ureter of each kidney. As the ureters approach the bladder, they turn and enter the bladder at an angle. This creates a one-way valve that allows urine into the bladder but prevents reflux of urine from the bladder back into the ureter.<\/p>\n<h3><span style=\"font-family: 'Cormorant Garamond', serif;font-size: 1.602em\">Bladder<\/span><\/h3>\n<div id=\"fs-id2447210\" class=\"bc-section section\" data-depth=\"1\">\n<div id=\"fs-id1616433\" class=\"bc-section section\" data-depth=\"1\">\n<p id=\"fs-id1616696\">The urinary bladder collects urine from the ureters (<a class=\"autogenerated-content\" href=\"#fig-ch26_02_02\">Figure 9.5<\/a>) and lies in front of the uterus in females, behind the pubic bone and in front of the rectum. In males, the anatomy is similar, minus the uterus, and with the addition of the prostate below the bladder, surrounding the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_395_1111\">urethra<\/a>.<\/p>\n<figure style=\"width: 1962px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/openstax.org\/apps\/archive\/20220509.174553\/resources\/25f1d6b7a9fc77ce5f74cd7574878a2b92845715\" alt=\"The left panel of this figure shows the cross section of the bladder and the major parts are labeled. The right panel shows a micrograph of the bladder.\" width=\"1962\" height=\"1202\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 9.5<\/strong> <em>(a) Anterior cross section of the bladder. (b) The detrusor muscle of the bladder (source: monkey tissue) LM \u00d7 448. (Micrograph provided by the Regents of the University of Michigan Medical School \u00a9 2012)<\/em><\/figcaption><\/figure>\n<\/div>\n<div id=\"fs-id2339546\" class=\"bc-section section\" data-depth=\"1\">\n<div id=\"fig-ch26_02_04\" class=\"bc-figure figure\">\n<h3><span style=\"font-family: 'Cormorant Garamond', serif;font-size: 1.602em\">Urethra<\/span><\/h3>\n<\/div>\n<\/div>\n<p id=\"fs-id2569293\">The <span data-type=\"term\">urethra<\/span> transports urine from the bladder to the outside of the body for disposal. The urethra is the only part of the urinary system that shows any significant anatomic difference between males and females; all other urine transport structures are identical <a class=\"autogenerated-content\" href=\"#fig-ch26_02_01\">(Figure 9.6<\/a>).<\/p>\n<div id=\"fig-ch26_02_01\" class=\"bc-figure figure\" data-orient=\"vertical\">\n<div class=\"bc-figcaption figcaption\"><\/div>\n<figure style=\"width: 560px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-content\/uploads\/sites\/2131\/2023\/12\/Female_and_Male_Urethra-1.jpg\" alt=\"The left panel of this figure shows the organs in the female urinary system and the right panel is the male.\" width=\"560\" height=\"714\" data-media-type=\"image\/jpg\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 9.6<\/strong> <em>Female and Male Urethras The urethra transports urine from the bladder to the outside of the body. (a) a female urethra and (b) a male urethra.<\/em><\/figcaption><\/figure>\n<\/div>\n<p id=\"fs-id2108795\">The urethra in both males and females begins inferior and central to the two ureteral openings.<\/p>\n<div id=\"fs-id2042066\" class=\"bc-section section\" data-depth=\"2\">\n<h4 data-type=\"title\">Female Urethra<\/h4>\n<p id=\"fs-id1910316\">The main difference between the from the male urethra is the female urethra&#8217;s short length of about 4 cm. This makes it less of a barrier to fecal bacteria than the longer male urethra and the best explanation for the greater incidence of urinary tract infections (UTIs) in women.<\/p>\n<\/div>\n<div id=\"fs-id2252307\" class=\"bc-section section\" data-depth=\"2\">\n<h4 data-type=\"title\">Male Urethra<\/h4>\n<p id=\"fs-id2071647\">The male urethra passes through the prostate gland immediately inferior to the bladder before passing below the pubic symphysis. The length of the male urethra varies but averages 20 cm in length.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"fs-id2593288\" class=\"summary\" data-depth=\"1\">\n<h1>Chapter Review<\/h1>\n<p id=\"fs-id2388415\">The structure of the kidney is divided into two main regions\u2014the peripheral rim of cortex and the central medulla. The two kidneys receive about 25 percent of cardiac output (amount of blood pumped by the heart). They are protected by fat and overlying ribs and muscle. Ureters, blood vessels, lymph vessels, and nerves enter and leave at the renal hilum. There are about 1.3 million nephrons per kidney and these are the \u201cfunctional units\u201d that perform the important physiologic functions. The glomerulus (a specialized capillary bed) filters blood and the filtrate is captured by Bowman\u2019s capsule. Most water and solutes are recovered by a second capillary bed that surrounds the tubules of the nephron. This filtrate is processed into urine by the renal tubules and finally flows into collecting ducts that drain into the minor calyces, which merge to form major calyces. The urine then proceeds to the renal pelvis and finally the ureters to the bladder. Urine is stored in the bladder until urination. The male and female urethras differ in their length and the presence of a prostate in males.<\/p>\n<\/div>\n<h1>Review Questions<\/h1>\n<h1>Adaption<\/h1>\n<p style=\"text-align: start\">This chapter is adapted from the following text:<\/p>\n<p style=\"text-align: start\"><a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/25-3-gross-anatomy-of-the-kidney\" target=\"_blank\" rel=\"noopener\">Gross Anatomy of the Kidney<\/a>&nbsp;<strong>in&nbsp;<\/strong><a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/25-3-gross-anatomy-of-the-kidney\">Anatomy and Physiology<\/a>&nbsp;by&nbsp;OSCRiceUniversity&nbsp;is licensed under a&nbsp;<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">Creative Commons Attribution 4.0 International License<\/a><\/p>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_395_1107\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1107\"><div tabindex=\"-1\"><p>outer part of kidney containing all of the nephrons; some nephrons have loops of Henle extending into the medulla<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1103\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1103\"><div tabindex=\"-1\"><p>inner region of kidney containing the renal pyramids<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1105\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1105\"><div tabindex=\"-1\"><p>extensions of the renal cortex into the renal medulla; separates the renal pyramids; contains blood vessels and connective tissues<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1110\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1110\"><div tabindex=\"-1\"><p>six to eight cone-shaped tissues in the medulla of the kidney containing collecting ducts and the loops of Henle of some nephrons<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1109\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1109\"><div tabindex=\"-1\"><p>medullary area of the renal pyramids where collecting ducts empty urine into the minor calyces<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1099\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1099\"><div tabindex=\"-1\"><p>cup-like structures receiving urine from the collecting ducts where it passes on to the renal pelvis and ureter<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1108\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1108\"><div tabindex=\"-1\"><p>medial area of the kidney through which the renal artery, renal vein, ureters, lymphatics, and nerves pass<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1102\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1102\"><div tabindex=\"-1\"><p>functional units of the kidney that carry out 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<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1101\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1101\"><div tabindex=\"-1\"><p>tuft or cluster of capillaries surrounded by Bowman\u2019s capsule; filters the blood based on molecular size<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1098\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1098\"><div tabindex=\"-1\"><p>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<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1106\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1106\"><div tabindex=\"-1\"><p>consists of the glomerulus and Bowman\u2019s capsule<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1100\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1100\"><div tabindex=\"-1\"><p>arteriole carrying blood from the glomerulus to the capillary beds around the convoluted tubules and loop of Henle; portion of the portal system<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1104\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1104\"><div tabindex=\"-1\"><p>second capillary bed of the renal portal system; surround the proximal and distal convoluted tubules; associated with the vasa recta<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_395_1111\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_395_1111\"><div tabindex=\"-1\"><p>transports urine from the bladder to the outside environment<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":103,"menu_order":4,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":["j-gordon-betts-d9kmjwz62y","kelly-a-young-ebcqggfbjy","james-a-wise-qr37sjotpp","eddie-johnson-spzb6fnj8w","brandon-poe-fjzinvjayf","dean-h-kruse-tnf4evhepq","oksana-korol-uhzmfvuyzq","jody-e-johnson-povh9ndei8","mark-womble-oqasblbzan","peter-desaix-cgobjrlxm6"],"pb_section_license":"cc-by"},"chapter-type":[],"contributor":[161],"license":[53],"class_list":["post-395","chapter","type-chapter","status-web-only","hentry","contributor-peter-desaix-cgobjrlxm6","license-cc-by"],"part":386,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/pressbooks\/v2\/chapters\/395","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/wp\/v2\/users\/103"}],"version-history":[{"count":1,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/pressbooks\/v2\/chapters\/395\/revisions"}],"predecessor-version":[{"id":1290,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/pressbooks\/v2\/chapters\/395\/revisions\/1290"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/pressbooks\/v2\/parts\/386"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/pressbooks\/v2\/chapters\/395\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/wp\/v2\/media?parent=395"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/pressbooks\/v2\/chapter-type?post=395"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/wp\/v2\/contributor?post=395"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol2200\/wp-json\/wp\/v2\/license?post=395"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}