Figure 26-1 An Introduction to the Urinary System. Organs of the Urinary System Kidney Produces urine Ureter Transports urine toward the urinary bladder Urinary bladder Temporarily stores urine prior to urination Urethra Conducts urine to exterior; in males, it also transports semen p. 973 Anterior view

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Figure 26-2a The Position of the Kidneys. Adrenal gland Diaphragm 11th and 12th ribs Left kidney L1 vertebra Right kidney Ureter Renal artery and vein Inferior vena cava Iliac crest Aorta Urinary bladder Urethra p. 974 a A posterior view of the trunk

Figure 26-4a The Structure of the Kidney. Renal cortex Renal medulla Inner layer of fibrous capsule Renal pyramid Renal sinus Connection to minor calyx Adipose tissue in renal sinus Minor calyx Major calyx Renal pelvis Hilum Kidney lobe Renal papilla Renal columns Ureter Fibrous capsule p. 976 a A diagrammatic view of a frontal section through the left kidney

Figure 26-5a The Blood Supply to the Kidneys. Cortical radiate veins Cortical radiate arteries Interlobar arteries Cortex Segmental artery Adrenal artery Renal artery Renal vein Interlobar veins Arcuate veins Medulla Arcuate arteries p. 977 a A sectional view, showing major arteries and veins

Figure 26-5b The Blood Supply to the Kidneys. Glomerulus Cortical radiate vein Afferent arterioles Cortical radiate artery Arcuate artery Arcuate vein Cortical nephron Juxtamedullary nephron Renal pyramid Interlobar vein Interlobar artery Minor calyx p. 977 b Circulation in a single kidney lobe

Figure 26-5c The Blood Supply to the Kidneys. Renal vein Renal artery Segmental arteries Interlobar veins Interlobar arteries Arcuate veins Arcuate arteries Cortical radiate veins Cortical radiate arteries Venules Afferent arterioles NEPHRONS Peritubular capillaries Glomerulus Efferent arteriole p. 977 c A flowchart of renal circulation

p. 979 The general appearance and location of nephrons in the kidneys Figure 26-7a The Locations and Structures of Cortical and Juxtamedullary Nephrons. Cortical nephron Juxtamedullary nephron Cortex Medulla Collecting duct Papillary duct Renal papilla Minor calyx p. 979 a The general appearance and location of nephrons in the kidneys

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Figure 26-6 The Functional Anatomy of a Representative Nephron and the Collecting System (Part 1 of 2). NEPHRON Proximal convoluted tubule Distal convoluted tubule • Reabsorption of water, ions, and all organic nutrients • Secretion of ions, acids, drugs, toxins • Variable reabsorption of water, sodium ions, and calcium ions (under hormonal control) Cuboidal cells with abundant microvilli Cuboidal cells with few microvilli Mitochondria Renal tubule Renal corpuscle • Production of filtrate Squamous cells Efferent arteriole Afferent arteriole Glomerulus Glomerular capsule Descending limb of loop begins Ascending limb of loop ends Capsular space Nephron loop Descending limb Further reabsorption of water Thick ascending limb Squamous cells Ascending limb Reabsorption of sodium and chloride ions Thin descending limb Low cuboidal cells KEY Filtrate Solute reabsorption or secretion p. 978 Water reabsorption Variable solute reabsorption or secretion Variable water reabsorption

p. 978 COLLECTING SYSTEM Collecting duct Figure 26-6 The Functional Anatomy of a Representative Nephron and the Collecting System (Part 2 of 2). COLLECTING SYSTEM Collecting duct • Variable reabsorption of water and reabsorption or secretion of sodium, potassium, hydrogen, and bicarbonate ions Intercalated cell Principal cell KEY Filtrate Papillary duct Water reabsorption • Delivery of urine to minor calyx Variable water reabsorption Solute reabsorption or secretion Minor calyx Columnar cells p. 978 Variable solute reabsorption or secretion

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Figure 26-8a The Renal Corpuscle. Glomerular capsule Capsular epithelium Visceral epithelium (podocyte) Glomerular capillary Capsular space Efferent arteriole Proximal convoluted tubule Distal convoluted tubule Juxtaglomerular complex Macula densa Juxtaglomerular cells Afferent arteriole p. 981 a Important structural features of a renal corpuscle.

Figure 26-8b The Renal Corpuscle. Podocyte nucleus Filtration membrane Fenestrated endothelium Dense layer Filtration slits Mesangial cell Capillary endothelial cell Pores RBC Pedicels Podocyte Capsular space Capsular epithelium b This cross section through a portion of the glomerulus shows the components of the filtration membrane of the nephron. p. 981

Figure 26-6 The Functional Anatomy of a Representative Nephron and the Collecting System (Part 1 of 2). NEPHRON Proximal convoluted tubule Distal convoluted tubule • Reabsorption of water, ions, and all organic nutrients • Secretion of ions, acids, drugs, toxins • Variable reabsorption of water, sodium ions, and calcium ions (under hormonal control) Cuboidal cells with abundant microvilli Cuboidal cells with few microvilli Mitochondria Renal tubule Renal corpuscle • Production of filtrate Squamous cells Efferent arteriole Afferent arteriole Glomerulus Glomerular capsule Descending limb of loop begins Ascending limb of loop ends Capsular space Nephron loop Descending limb Further reabsorption of water Thick ascending limb Squamous cells Ascending limb Reabsorption of sodium and chloride ions Thin descending limb Low cuboidal cells KEY Filtrate Solute reabsorption or secretion p. 978 Water reabsorption Variable solute reabsorption or secretion Variable water reabsorption

Figure 26-10a Glomerular Filtration. Glomerulus Dense layer Efferent arteriole Capillary lumen Afferent arteriole Filtration slit Podocyte Pedicels Pore Capsular space Filtration membrane p. 988 a The glomerular filtration membrane

Figure 26-10b Glomerular Filtration. Factors Controlling Glomerular Filtration The glomerular hydrostatic pressure (GHP) is the blood pressure in the glomerular capillaries. This pressure tends to push water and solute molecules out of the plasma and into the filtrate. The GHP, which averages 50 mm Hg, is significantly higher than capillary pressures elsewhere in the systemic circuit, because the efferent arteriole is smaller in diameter than the afferent arteriole. The blood colloid osmotic pressure (BCOP) tends to draw water out of the filtrate and into the plasma; it thus opposes filtration. Over the entire length of the glomerular capillary bed, the BCOP averages about 25 mm Hg. Filtrate in capsular space Plasma proteins The net filtration pressure (NFP) is the net pressure acting across the glomerular capillaries. It represents the sum of the hydrostatic pressures and the colloid osmotic pressures. Under normal circumstances, the net filtration pressure is approximately 10 mm Hg. This is the average pressure forcing water and dissolved substances out of the glomerular capillaries and into the capsular space. 50 10 mm Hg 25 15 Solutes Capsular hydrostatic pressure (CsHP) opposes GHP. CsHP, which tends to push water and solutes out of the filtrate and into the plasma, results from the resistance of filtrate already present in the nephron that must be pushed toward the renal pelvis. The difference between GHP and CsHP is the net hydrostatic pressure (NHP). The capsular colloid osmotic pressure is usually zero because few, if any, plasma proteins enter the capsular space. p. 988 b Net filtration pressure

Figure 26-10b Glomerular Filtration Factors Controlling Glomerular Filtration Glomerular hydrostatic pressure (GHP) Blood colloid osmotic pressure (BCOP) Filtrate in capsular space Plasma proteins 50 10 mm Hg Net filtration pressure (NFP) 25 15 Solutes Capsular hydrostatic pressure (CsHP) Capsular colloid osmotic pressure p. 988 Net filtration pressure © 2015 Pearson Education, Inc. 19

Figure 26-12 Transport Activities at the PCT (Part 1 of 2). Lumen containing tubular fluid Cuboidal epithelial cells Proximal convoluted tubule Distal convoluted tubule Glomerulus Glomerular capsule Collecting duct KEY Nephron loop Water reabsorption Solute reabsorption p. 993 Variable solute reabsorption or secretion Urine storage and elimination

Figure 26-12 Transport Activities at the PCT (Part 2 of 2). Tubular fluid Cells of proximal convoluted tubule Glucose and other organic solutes Osmotic water flow p. 988 Peritubular fluid KEY Peritubular capillary Leak channel Diffusion Countertransport Reabsorption Exchange pump Cotransport Secretion

Figure 26-13a Countercurrent Multiplication and Urine Concentration (Part 2 of 2). Tubular fluid Urea Cells of thick ascending limb This plasma membrane is impermeable to water p. 995 Loop of Henle KEY Cotransport Exchange pump Reabsorption Peritubular fluid Secretion Diffusion a The mechanism of sodium and chloride ion transport involves the Na+–K+/2 Cl– carrier at the apical surface and two carriers at the basal surface of the tubular cell: a potassium–chloride cotransport pump and a sodium–potassium exchange pump. The net result is the transport of sodium and chloride ions into the peritubular fluid.

Figure 26-13b Countercurrent Multiplication and Urine Concentration. Thin descending limb (permeable to water; impermeable to solutes) Thick ascending limb (impermeable to water; active solute transport) KEY Impermeable to water Impermeable to solutes Impermeable to urea; variable permeability to water Permeable to urea Renal medulla p. 995 b Transport of NaCl along the ascending thick limb results in the movement of water from the descending limb.

Figure 26-13c Countercurrent Multiplication and Urine Concentration. Renal cortex DCT and collecting ducts (impermeable to urea; variable permeability to water) Thin descending limb (permeable to water; Impermeable to urea) KEY Impermeable to water Papillary duct (permeable to urea) Impermeable to solutes Impermeable to urea; variable permeability to water Permeable to urea Na+ Cl– Renal medulla Urea c The permeability characteristics of both the loop and the collecting duct tend to concentrate urea in the tubular fluid and in the medulla. The nephron loop, DCT, and collecting duct are impermeable to urea. As water reabsorption occurs, the urea concentration increases. Papillary duct permeability to urea makes up nearly one-third of the solutes in the deepest portions of the medulla. p. 995

Figure 26-8a The Renal Corpuscle. Glomerular capsule Capsular epithelium Visceral epithelium (podocyte) Glomerular capillary Capsular space Efferent arteriole Proximal convoluted tubule Distal convoluted tubule Juxtaglomerular complex Macula densa Juxtaglomerular cells Afferent arteriole p. 988 a Important structural features of a renal corpuscle.

Figure 26-14ab Tubular Secretion and Solute Reabsorption by the DCT. Sodium and chloride reabsorption along entire length of DCT Sodium–potassium exchange in aldosterone-sensitive portion of DCT and collecting duct Distal convoluted tubule Tubular fluid Tubular fluid Glomerulus Glomerular capsule Cells of distal convoluted tubule Collecting duct Proximal convoluted tubule Sodium ions are reabsorbed in exchange for potassium ions when these ion pumps are stimulated by aldosterone (A). Nephron loop Urine storage and elimination Peritubular fluid Peritubular capillary KEY Leak channel Cotransport Countertransport Diffusion Exchange pump Reabsorption Aldosterone- regulated pump Secretion p. 998 DCT a The basic pattern of the reabsorption of sodium and chloride ions and the secretion of potassium ions. b Aldosterone-regulated reabsorption of sodium ions, linked to the passive loss of potassium ions.

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Figure 26-14c Tubular Secretion and Solute Reabsorption by the DCT. H+ secretion and HCO3– reabsorption along entire DCT and collecting duct Distal convoluted tubule Tubular fluid Hydrochloric acid Ammonium chloride Glomerulus Glomerular capsule Collecting duct Proximal convoluted tubule Amino acid deamination Nephron loop Urine storage and elimination KEY Leak channel Cotransport Countertransport Diffusion Sodium bicarbonate Exchange pump Reabsorption Aldosterone- regulated pump Secretion p. 999 DCT & CD c Hydrogen ion secretion and the acidification of urine occur by two routes. The central theme is the exchange of hydrogen ions in the cytosol for sodium ions in the tubular fluid, and the reabsorption of the bicarbonate ions generated in the process.

p. 1000 Tubule permeabilities and the osmotic concentration of urine Figure 26-15a The Effects of ADH on the DCT and Collecting Duct (Part 2 of 2). Renal cortex PCT DCT Glomerulus KEY = Na+/Cl– transport = Antidiuretic hormone = Water reabsorption = Variable water reabsorption Solutes = Impermeable to solutes = Impermeable to water Renal medulla Collecting duct = Variable permeability to water a Tubule permeabilities and the osmotic concentration of urine without ADH Large volume of dilute urine p. 1000

p. 1000 Tubule permeabilities and the osmotic Figure 26-15b The Effects of ADH on the DCT and Collecting Duct (Part 2 of 2). Renal cortex KEY = Na+/Cl– transport = Antidiuretic hormone = Water reabsorption = Variable water reabsorption = Impermeable to solutes = Impermeable to water Renal medulla = Variable permeability to water b Tubule permeabilities and the osmotic concentration of urine with ADH Small volume of concentrated urine p. 1000

Figure 26-13c Countercurrent Multiplication and Urine Concentration. Renal cortex DCT and collecting ducts (impermeable to urea; variable permeability to water) Thin descending limb (permeable to water; Impermeable to urea) KEY Impermeable to water Papillary duct (permeable to urea) Impermeable to solutes Impermeable to urea; variable permeability to water Permeable to urea Na+ Cl– Renal medulla Urea c The permeability characteristics of both the loop and the collecting duct tend to concentrate urea in the tubular fluid and in the medulla. The nephron loop, DCT, and collecting duct are impermeable to urea. As water reabsorption occurs, the urea concentration increases. Papillary duct permeability to urea makes up nearly one-third of the solutes in the deepest portions of the medulla. p. 995 CD

Figure 26-11 The Response to a Reduction in the GFR (Part 2 of 2). Autoregulation Immediate local response in the kidney HOMEOSTASIS RESTORED Increased glomerular blood pressure if sufficient Normal GFR Dilation of afferent arterioles HOMEOSTASIS DISTURBED HOMEOSTASIS Normal glomerular filtration rate Contraction of mesangial cells Decreased GFR resulting in decreased filtrate and urine production Start Constriction of efferent arterioles p. 991

Figure 26-11 The Response to a Reduction in the GFR (Part 1 of 2). Renin–Angiotensin-Aldosterone System Integrated endocrine and neural mechanisms activated Renin in the bloodstream triggers formation of angiotensin I, which is then activated to angiotensin II by angiotensin converting enzyme (ACE) in the capillaries of the lungs Endocrine response Juxtaglomerular complex increases production of renin Angiotensin II triggers increased aldosterone secretion by the adrenal glands Angiotensin II triggers neural responses Angiotensin II constricts peripheral arterioles and further constricts the efferent arterioles Aldosterone increases Na+ retention HOMEOSTASIS RESTORED Increased stimulation of thirst centers Increased systemic blood pressure Increased fluid consumption Increased glomerular pressure Increased blood volume Increased fluid retention Increased ADH production Constriction of venous reservoirs Increased cardiac output Increased sympathetic motor tone Together, angiotensin II and sympathetic activation stimulate peripheral vasoconstriction HOMEOSTASIS Normal glomerular filtration rate p. 991

Figure 26-16 Summary of Renal Function (Part 1 of 6).

Figure 26-16 Summary of Renal Function (Part 2 of 6).