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Renal system

Renal system. Learning objectives. To outline the renal system; To describe the structure and function of nephron,processes of urine formation; To describe briefly the processes of urine formation; To describe the renin-angiotensin system;

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Renal system

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  1. Renal system

  2. Learning objectives • To outline the renal system; • To describe the structure and function of nephron,processes of urine formation; • To describe briefly the processes of urine formation; • To describe the renin-angiotensin system; • To describe the regulationofpotassium, calcium and pH.

  3. RENAL SYSTEM EXCRETION ~ removal of toxic waste productions of metabolism from the body WASTE ~ nitrogenous waste (urea & ammonia), CO2, bile pigment

  4. RENAL SYSTEM OSMOREGULATION ~ the process maintaining constant osmotic equilibrium between the internal & external environment of an organism

  5. Mammalian renal system I KIDNEY  paired organs in abdominal cavity  held firmly by peritoneum  embedded in fat  solid, dark red & bean shape  below stomach  renal artery vs renal vein

  6. Structure of kidney

  7. Mammalian renal system II URETERS  narrow tubes  passing urine from kidneys to bladder  valves  prevent back flow of urine  stop bacteria from going into kidney

  8. Diaphragm Kidney Ureter Bladder Urethra

  9. Mammalian renal system III URINARY BLADDER  muscular bag  stores urine temporarily  300 cm3 of urine  sensation of urination  contraction of bladder + relaxation of sphincter muscle forces urine out

  10. Ureter Ureteral opening Urethra Urethral orifice

  11. Mammalian renal system IV URETHRA  muscular tube  carries ONLY URINE in female  carries URINE & SEMEN in male

  12. A nephron unit

  13. FLOW OF GLOMERULAR FILTRATE Glomerulus Bowman’s space in Bowman’s capsule Descending limb of Henle’s loop Proximal convoluted tubule Ascending limb of Henle’s loop Distal convoluted tubule Renal pelvis Collecting duct

  14. NEPHRON  1,000,000 nephrons / kidney  structural & functional units Cortical nephron ~ in cortex, short Loop of Henle, osmoregulation under NORMAL condition  Juxtamedullary nephron ~ at junction of cortex & medulla, long Loop of Henle, osmoregulation when SHORT OF WATER

  15. Nephron • Renal corouscle  Glomerulus: knot of blood capillaries  Bowman’s capsule • Proximal convoluted tubule • Descending limb of loop of Henle • Ascending limb of loop of Henle • Distal convoluted tubule • Collecting duct

  16. Functions of kidney • Excretion ~ remove nitrogenous waste i.e. urea, salts, water, heat, toxic substance • Osmoregulation ~ controlling amount of water in body ~ maintain osmotic potential

  17. Urine Formation • Pressure filtration (ultrafiltration) • Reabsorption • Tubular secretion

  18. Ultrafiltration • Occur at Malpighian body • Glomerular filtrate: all substances in blood except RBCs & plasma protein  Blood pressure: Diameter of afferent arteriole > Diameter of efferent arteriole  Glomerular filtrate rate 180l/ day  Adaptation large area, great pressure, thin ,membrane

  19. Reabsorption • 99% of the glomerular filtrate are reabsorbed • matter reabsorbed:  all glucose, amino acid  mineral salts  other useful substances  SELECTIVE REABSORPTION • Method of reabsorption diffusion  active transport

  20. Sites of reabsorption  Proximal convoluted tubule ~ major site of reabsorption (80%) ~ microvilli  surface area ~ numerous mitochondria ~ surrounded by pertubular capillaries

  21. Sites of reabsorption  Loop of Henle ~ conserve water in terrestrial mammal ~ creates & maintain an increasing osmotic gradient in the medulla ~ Na+ in medulla vigorous osmotic extraction of water from collecting ducts  hypertonic urine

  22. Formation of hypertonic urine

  23. Sites of reabsorption  Vasa recta ~ narrow capillaries situated close to loop of Henle ~ freely permeable to ions, urea & water ~ Counter current exchanger system

  24. Counter current exchange system

  25. Sites of reabsorption  Distal convoluted tubule ~ fine control of salt, water & pH balance of the blood  Collecting duct ~ water is extracted by osmosis   conc.  hypertonic urine

  26. Tubular secretion • Takes place in distal convoluted tubule • absorption of unnecessary: ammonia, potassium & drug from capillary network & secrete them into lumen of tubule

  27. Regulation of urine composition • Anti-diuretic hormone(ADH) • Aldosterone • Renin-angiotensin system

  28. ADH

  29. ADH ADH

  30. Aldosterone

  31. Renin angiotensin system

  32. Potassium content • most abundant intracellular ion • reabsorbed by proximal convoluted tubule & loop of Henle, secreted by collecting ducts •  K  secretion • aldosterone  secretion of K

  33. Calcium content •  Ca   excitability of nerve & muscle cell membranes  hypocalcemic tetany •  Ca  cardiac arrthythmias • most reabsorbed, no secretion

  34. pH level • Metabolic reactions are highly sensitive to H+ • Sources of H+ gain or loss Gain ~ from CO2, metabolism of protein etc, loss of CO32- in diarrhea & urine Loss ~ in vomitus & urine

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