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The Urinary System Part 1
Honors Anatomy & Physiology
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Kidney Functions Regulating total water volume and total solute concentration in water Regulating ECF ion concentrations Ensuring long-term acid-base balance Removal of metabolic wastes, toxins, drugs © 2013 Pearson Education, Inc.
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Kidney Functions Endocrine functions Activation of vitamin D
Renin - regulation of blood pressure Erythropoietin - regulation of RBC production Activation of vitamin D Gluconeogenesis during prolonged fasting © 2013 Pearson Education, Inc.
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Urinary System Organs Kidneys - major excretory organs
Ureters - transport urine from kidneys to urinary bladder Urinary bladder - temporary storage reservoir for urine Urethra transports urine out of body © 2013 Pearson Education, Inc.
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Figure 25.1 The urinary system.
Hepatic veins (cut) Esophagus (cut) Inferior vena cava Renal artery Adrenal gland Renal hilum Aorta Renal vein Kidney Iliac crest Ureter Rectum (cut) Uterus (part of female reproductive system) Urinary bladder Urethra © 2013 Pearson Education, Inc.
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Kidney Anatomy Retroperitoneal, in the superior lumbar region; ~ T12 to L5 Right kidney crowded by liver lower than left Adrenal (suprarenal) gland atop each kidney Convex lateral surface, concave medial surface; vertical renal hilum leads to renal sinus Ureters, renal blood vessels, lymphatics, and nerves enter and exit at hilum © 2013 Pearson Education, Inc.
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Figure 25.2b Position of the kidneys against the posterior body wall.
12th rib © 2013 Pearson Education, Inc.
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Figure 25.2a Position of the kidneys against the posterior body wall.
Anterior Inferior vena cava Aorta Peritoneum Peritoneal cavity (organs removed) Supportive tissue layers Renal vein • Renal fascia anterior posterior Renal artery • Perirenal fat capsule • Fibrous capsule Body of vertebra L2 Body wall Posterior © 2013 Pearson Education, Inc.
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Kidney Anatomy Layers of surrounding supportive tissue
Renal fascia Anchoring outer layer of dense fibrous connective tissue Perirenal fat capsule Fatty cushion Fibrous capsule Prevents spread of infection to kidney © 2013 Pearson Education, Inc.
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© 2013 Pearson Education, Inc.
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Nephroptosis “floating kidney” inferior displacement of a kidney
develops mostly in very thin people adipose capsule or renal fascia deficient females 10x > males dangerous: ureter may get blocked or kinked
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Internal Anatomy Renal cortex Granular-appearing superficial region
Renal medulla Composed of cone-shaped medullary (renal) pyramids Pyramids separated by renal columns Inward extensions of cortical tissue © 2013 Pearson Education, Inc.
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Internal Anatomy Papilla
Tip of pyramid; releases urine into minor calyx Lobe Medullary pyramid and its surrounding cortical tissue; ~ 8/kidney Renal pelvis Funnel-shaped tube continuous with ureter © 2013 Pearson Education, Inc.
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More renal vocabulary Parenchyma: renal cortex + pyramids
Papillary Ducts: collecting ducts for urine formed in nephrons Minor Calyces: cuplike structure papillary ducts drain into Major Calyces: receive drainage from minor calyces
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© 2013 Pearson Education, Inc.
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Figure 25.3 Internal anatomy of the kidney.
Renal hilum Renal cortex Renal medulla Major calyx Papilla of pyramid Renal pelvis Minor calyx Ureter Renal pyramid in renal medulla Renal column Fibrous capsule Photograph of right kidney, frontal section Diagrammatic view © 2013 Pearson Education, Inc.
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Homeostatic Imbalance
Pyelitis Infection of renal pelvis and calyces Pyelonephritis Infection/inflammation of entire kidney Normally - successfully treated with antibiotics © 2013 Pearson Education, Inc.
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Blood and Nerve Supply Kidneys cleanse blood; adjust its composition rich blood supply Renal arteries deliver ~ ¼ (1200 ml) of cardiac output to kidneys each minute Arterial flow into and venous flow out of kidneys follow similar paths Nerve supply via sympathetic fibers from renal plexus © 2013 Pearson Education, Inc.
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Blood supply of the kidneys
kidneys receive 20 – 25% of resting cardiac output right & left renal arteries (branches of abdominal aorta/drain into IVC)
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Figure 25.4a Blood vessels of the kidney.
Cortical radiate vein Cortical radiate artery Arcuate vein Arcuate artery Interlobar vein Interlobar artery Segmental arteries Renal vein Renal artery Renal pelvis Ureter Renal medulla Renal cortex Frontal section illustrating major blood vessels © 2013 Pearson Education, Inc.
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Figure 25.4b Blood vessels of the kidney.
Aorta Inferior vena cava Renal artery Renal vein Segmental artery Interlobar vein Interlobar artery Arcuate vein Arcuate artery Cortical radiate vein Peritubular capillaries or vasa recta Cortical radiate artery Afferent arteriole Efferent arteriole Glomerulus (capillaries) Nephron-associated blood vessels (see Figure 25.7) (b) Path of blood flow through renal blood vessels © 2013 Pearson Education, Inc.
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Kidney transplant donor kidney is placed in pelvis of recipient thru abd wall incision renal artery & vein attached Ureter of transplanted kidney attached to urinary bladder normally. nonfunctioning kidney left in place
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Nephrons Structural and functional units that form urine
> 1 million per kidney Two main parts Renal corpuscle Renal tubule © 2013 Pearson Education, Inc.
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Nephrons 80 85% are cortical nephrons 15 – 20% are medullary nephrons
short LoH: blood supply from efferent arterioles 15 – 20% are medullary nephrons long LoH: blood supply from vasa recta (from efferent arterioles) thin ascending followed by thick ascending limb
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Renal Corpuscle Two parts of renal corpuscle Glomerulus
Tuft of capillaries; fenestrated endothelium highly porous allows filtrate formation Glomerular capsule (Bowman's capsule) Cup-shaped, hollow structure surrounding glomerulus © 2013 Pearson Education, Inc.
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Renal Corpuscle Glomerular capsule
Parietal layer - simple squamous epithelium Visceral layer - branching epithelial podocytes Extensions terminate in foot processes that cling to basement membrane Filtration slits between foot processes allow filtrate to pass into capsular space © 2013 Pearson Education, Inc.
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Bowman’s Capsule parietal layer forms wall of capsule
fluid filtered from glomerular capillaries enter capsular space
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Histology of a Nephron
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Bowman’s Capsule 2 layers: visceral & parietal
visceral: modified simple squamous cells called podocytes have foot-like projections called pedicels that wrap around endothelial cells of glomerular capillaries
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Figure 25.5 Location and structure of nephrons.
Renal cortex Renal medulla Renal pelvis Glomerular capsule: parietal layer Basement membrane Ureter Podocyte Kidney Fenestrated endothelium of the glomerulus Renal corpuscle • Glomerular capsule Glomerular capsule: visceral layer • Glomerulus Distal convoluted tubule Apical microvilli Mitochondria Highly infolded basolateral membrane Proximal convoluted tubule Proximal convoluted tubule cells Cortex Apical side Medulla Basolateral side Thick segment Thin segment Distal convoluted tubule cells Nephron loop • Descending limb • Ascending limb Nephron loop (thin-segment) cells Collecting duct Principal cell Intercalated cell Collecting duct cells © 2013 Pearson Education, Inc.
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Figure 25.5 Location and structure of nephrons. (2 of 7)
Glomerular capsule: parietal layer © 2013 Pearson Education, Inc.
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Figure 25.5 Location and structure of nephrons. (3 of 7)
Basement membrane Podocyte Fenestrated endothelium of the glomerulus Glomerular capsule: visceral layer © 2013 Pearson Education, Inc.
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Renal Tubule 3 parts Proximal convoluted tubule
Proximal closest to renal corpuscle Nephron loop Distal convoluted tubule Distal farthest from renal corpuscle © 2013 Pearson Education, Inc.
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Renal Tubule Proximal convoluted tubule (PCT)
Cuboidal cells with dense microvilli (brush border surface area); Functions in reabsorption and secretion confined to cortex © 2013 Pearson Education, Inc.
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Figure 25.5 Location and structure of nephrons. (4 of 7)
Apical microvilli Mitochondria Highly infolded basolateral membrane Proximal convoluted tubule cells © 2013 Pearson Education, Inc.
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Renal tubule & collecting duct
PCT: cells have microvilli: increase surface area for reabsorption & secretion
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Renal Tubule Nephron loop Descending and ascending limbs
Proximal descending limb continuous with proximal tubule Distal descending limb = descending thin limb; simple squamous epithelium Thick ascending limb Cuboidal to columnar cells; thin in some nephrons Function: urine concentration by managing amount of water reabsorbed © 2013 Pearson Education, Inc.
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Figure 25.5 Location and structure of nephrons. (6 of 7)
Nephron loop (thin-segment) cells © 2013 Pearson Education, Inc.
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Collecting Ducts Two cell types Principal cells
Sparse, short microvilli Maintain water and Na+ balance Intercalated cells Cuboidal cells; abundant microvilli; two types A and B; both help maintain acid-base balance of blood © 2013 Pearson Education, Inc.
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Figure 25.5 Location and structure of nephrons. (7 of 7)
Principal cell Intercalated cell Collecting duct cells © 2013 Pearson Education, Inc.
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Collecting Ducts Receive filtrate from many nephrons
Run through medullary pyramids striped appearance Fuse together to deliver urine through papillae into minor calyces © 2013 Pearson Education, Inc.
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Figure 25.5 Location and structure of nephrons.
Renal cortex Renal medulla Renal pelvis Glomerular capsule: parietal layer Basement membrane Ureter Podocyte Kidney Fenestrated endothelium of the glomerulus Renal corpuscle • Glomerular capsule Glomerular capsule: visceral layer • Glomerulus Distal convoluted tubule Apical microvilli Mitochondria Highly infolded basolateral membrane Proximal convoluted tubule Proximal convoluted tubule cells Cortex Apical side Medulla Basolateral side Thick segment Thin segment Distal convoluted tubule cells Nephron loop • Descending limb • Ascending limb Nephron loop (thin-segment) cells Collecting duct Principal cell Intercalated cell Collecting duct cells © 2013 Pearson Education, Inc.
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Classes of Nephrons Cortical nephrons—85% of nephrons; almost entirely in cortex Juxtamedullary nephrons Long nephron loops deeply invade medulla Ascending limbs have thick and thin segments Important in production of concentrated urine © 2013 Pearson Education, Inc.
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Figure 25.7a Blood vessels of cortical and juxtamedullary nephrons.
Cortical nephron Juxtamedullary nephron • Short nephron loop • Glomerulus further from the cortex-medulla junction • Efferent arteriole supplies peritubular capillaries • Long nephron loop • Glomerulus closer to the cortex-medulla junction • Efferent arteriole supplies vasa recta Renal corpuscle Glomerulus (capillaries) Efferent arteriole Cortical radiate vein Cortical radiate artery Glomerular capsule Afferent arteriole Collecting duct Proximal convoluted tubule Distal convoluted tubule Afferent arteriole Efferent arteriole Peritubular capillaries Ascending limb of nephron loop Cortex-medulla junction Arcuate vein Kidney Arcuate artery Vasa recta Nephron loop Descending limb of nephron loop © 2013 Pearson Education, Inc.
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Nephron Capillary Beds
Renal tubules associated with two capillary beds Glomerulus Peritubular capillaries Juxtamedullary nephrons also associated with Vasa recta © 2013 Pearson Education, Inc.
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Nephron Capillary Beds
Glomerulus - specialized for filtration Different from other capillary beds – fed and drained by arteriole Afferent arteriole glomerulus efferent arteriole Blood pressure in glomerulus high because Afferent arterioles larger in diameter than efferent arterioles Arterioles are high-resistance vessels © 2013 Pearson Education, Inc.
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Juxtaglomerular Complex (JGC)
One per nephron Involves modified portions of Distal portion of ascending limb of nephron loop Afferent (sometimes efferent) arteriole Important in regulation of rate of filtrate formation and blood pressure © 2013 Pearson Education, Inc.
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Juxtaglomerular Apparatus (JGA)
Three cell populations Macula densa granular cells extraglomerular mesangial cells Tall, closely packed cells of ascending limb Chemoreceptors; sense NaCl content of filtrate © 2013 Pearson Education, Inc.
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Juxtaglomerular Apparatus (JGA)
source of Renin: regulation of blood pressure
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Juxtaglomerular Apparatus (JGA)
Granular cells (juxtaglomerular, or JG cells) Enlarged, smooth muscle cells of arteriole Secretory granules contain enzyme renin Mechanoreceptors; sense blood pressure in afferent arteriole © 2013 Pearson Education, Inc.
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Juxtaglomerular Apparatus (JGA)
Extraglomerular mesangial cells Between arteriole and tubule cells Interconnected with gap junctions May pass signals between macula densa and granular cells © 2013 Pearson Education, Inc.
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End of Urinary System Part 1
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QUIZ Next Class!
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