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Urogenital
The document discusses the human urogenital system and kidney anatomy and function. It provides details on: - The location and external anatomy of the kidneys in the body. - The internal anatomy of the kidneys including nephrons, renal corpuscles, tubules, and collecting ducts. - How the kidneys filter blood to remove wastes and regulate fluid and electrolyte balance through processes like filtration, reabsorption, and secretion in the nephrons. - Hormonal control of kidney functions including ADH and aldosterone.
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Urogenital
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- 2. 26-2 Urogenital System Functions •Filtering of blood, Removal of wastes and metabolites • Regulation of – blood volume and composition – concentration of blood solutes – pH of extracellular fluid – blood cell synthesis • Synthesis of Vitamin D • Reproduction and sexual function
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- 4. 26-4 Location and ExternalAnatomy of Kidneys • Location – Lie behind peritoneum on posterior abdominal wall on either side of vertebral column – Lumbar vertebrae and rib cage partially protect – Right kidney slightly lower than left • External Anatomy – Renal capsule • Surrounds each kidney – Perirenal fat • Engulfs renal capsule and acts as cushioning and source of energy – Renal fascia • Anchors kidneys to abdominal wall, separates from abdomen – Hilum • Renal artery and nerves enter and renal vein and ureter exit kidneys
- 5. 26-5 Internal Anatomy ofKidneys • Cortex: Outer area – Renal columns • Medulla: Inner area – Renal pyramids • Calyces – Major: Converge to form pelvis – Minor: Papillae extend • Nephron: Functional unit of kidney – Juxtamedullary – Cortical
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- 7. 26-7 Histology of theNephron
- 8. 26-8 Internal Anatomy ofKidneys • Renal corpuscle – Bowman’s or Renal capsule • Parietal layer • Visceral layer – Glomerulus • Network of capillaries goes into another capillary bed called the peritubular Capillaries - Arterioles – Afferent • Blood to glomerulus – Efferent • Drains not into veinule but another arteriole • Tubules – Proximal (convoluted) tubule – Loops of Henle • Descending limb • Ascending limb – Distal (convoluted) tubules • Collecting ducts
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- 11. 26-11 Ureters and UrinaryBladder • Ureters – Tubes through which urine flows from kidneys to urinary bladder • Urinary bladder – Stores urine • Urethra – Transports urine from bladder to outside of body – Difference in length between males and females – Sphincters • Internal urinary • External urinary
- 12. 26-12 Ureters and UrinaryBladder
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- 14. 26-14 Filtration • Filtration – Renalfiltrate • Plasma minus blood cells and blood proteins • Most (99%) reabsorbed • Filtration membrane – Fenestrated endothelium, basement membrane and pores formed by podocytes • Filtration pressure – Responsible for filtrate formation – Glomerular capillary pressure (GCP) minus capsule pressure (CP) minus colloid osmotic pressure (COP) – Changes caused by glomerular capillary pressure EFP = GCP – CP – COP Where Effective filtration pressure = EFP
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- 16. 26-16 Tubular Reabsorption • Reabsorptionalmost 90% takes place in Proximal tubule via – Passive transport – Active transport – Cotransport • Specialization of tubule segments • Distal tubule and collecting duct affected by hormones like ADH & Aldosterone • Substances transported – Active transport moves Na+ across nephron wall – Other ions and molecules moved by cotransport – Passive transport moves water, urea, lipid-soluble, nonpolar compounds
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- 18. 26-18 Reabsorption in Loopof Henle
- 19. 26-19 Reabsorption in Loopof Henle
- 20. 26-20 Tubular Secretion • Substancesenter proximal or distal tubules and collecting ducts • H+ , K+ and some substances not produced in body are secreted by countertransport mechanisms
- 21. 26-21 Secretion of Hydrogenand Potassium
- 22. 26-22 Urine Production • InProximal tubules – Na+ and other substances removed – Water follows passively – Filtrate volume reduced • In descending limb of loop of Henle – Water exits passively, solute enters – Filtrate volume reduced 15% • In ascending limb of loop of Henle – Na+ , Cl- , K+ transported out of filtrate – Water remains • In distal tubules and collecting ducts – Water movement out regulated by ADH • If absent, water not reabsorbed and dilute urine produced • If ADH present, water moves out, concentrated urine produced
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- 25. 26-25 Urine Concentration Mechanism •When large volume of water consumed – Eliminate excess without losing large amounts of electrolytes – Response is kidneys produce large volume of dilute urine • When drinking water not available – Kidneys produce small volume of concentrated urine – Removes waste and prevents rapid dehydration
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- 27. 26-27 Hormonal Mechanisms • ADH –Secreted by posterior pituitary – Increases water permeability in distal tubules and collecting ducts • Aldosterone – Produced in adrenal cortex – Affects Na+ and Cl- transport in nephron and collecting ducts • Renin – Produced by kidneys, causes production of angiotensin II • Atrial natriuretic hormone – Produced by heart when blood pressure increases • Inhibits ADH production • Reduces ability of kidney to concentrate urine
- 28. 26-28 Effect of ADHon Nephron
- 29. 26-29 Aldosterone Effect onDistal Tubule
- 30. 26-30 Autoregulation and Sympathetic Stimulation •Autoregulation – Involves changes in degree of constriction in afferent arterioles – As systemic BP increased, afferent arterioles constrict and prevent increase in renal blood flow • Sympathetic stimulation – Constricts small arteries and afferent arterioles – Decreases renal blood flow
- 31. 26-31 Clearance and TubularLoad • Plasma clearance – Volume of plasma cleared of a specific substance each minute – Used to estimate GFR – Used to calculate renal plasma flow – Used to determine which drugs or other substances excreted by kidney • Tubular load – Total amount of substance that passes through filtration membrane into nephrons each minute – Normally glucose is almost completed reabsorbed
- 32. 26-32 Tubular Maximum • Tubularmaximum – Maximum rate at which a substance can be actively absorbed – Each substance has its own tubular maximum
- 33. 26-33 Urine Flow and MicturitionReflex • Urine flow – Hydrostatic pressure forces urine through nephron – Peristalsis moves urine through ureters • Micturition reflex – Stretch of urinary bladder stimulates reflex causing bladder to contract, inhibiting urinary sphincters – Higher brain centers can stimulate or inhibit reflex
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- 35. 26-35 Effects of Agingon Kidneys • Gradual decrease in size of kidney – Decrease in kidney size leads to decrease in renal blood flow • Decrease in number of functional nephrons • Decrease in renin secretion and vitamin D synthesis • Decline in ability of nephron to secrete and absorb
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