The document summarizes the kidney's role in controlling urine volume and concentration. It describes how the nephron filters blood to form an ultrafiltrate, reabsorbs necessary solutes and water along different regions of the nephron, and secretes wastes. The second convoluted tubule and collecting duct reabsorb additional water under control of antidiuretic hormone (ADH), which increases their permeability. When blood concentration rises, ADH release increases water reabsorption to concentrate urine, and when it falls ADH decreases to produce dilute urine.

1. The Kidney Control of urine volume and concentration

2. Region of nephron Activity Bowman’s capsule

3. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood

4. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule

5. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis

6. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes

7. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes Loop of Henle

8. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes Loop of Henle Active secretion of chloride ions from ultrafiltrate inascending limb

9. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes Loop of Henle Active secretion of chloride ions from ultrafiltrate inascending limb Second convoluted tubule

10. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes Loop of Henle Active secretion of chloride ions from ultrafiltrate inascending limb Second convoluted tubule Reabsorption of Na +

11. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes Loop of Henle Active secretion of chloride ions from ultrafiltrate inascending limb Second convoluted tubule Reabsorption of Na +

12. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes Loop of Henle Active secretion of chloride ions from ultrafiltrate inascending limb Second convoluted tubule Reabsorption of Na + Faculative reabsorbtion of water under control of ADH

13. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes Loop of Henle Active secretion of chloride ions from ultrafiltrate inascending limb Second convoluted tubule Reabsorption of Na + Faculative reabsorbtion of water under control of ADH Secretion of H + , NH4 + , urea,creatinine and some drugs

14. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes Loop of Henle Active secretion of chloride ions from ultrafiltrate inascending limb Second convoluted tubule Reabsorption of Na + Faculative reabsorbtion of water under control of ADH Secretion of H + , NH4 + , urea,creatinine and some drugs Collecting duct

15. Region of nephron Activity Bowman’s capsule Ultrafiltration of blood in the glomerulus under hydrostatic pressure produces an ultrfiltrate free of plama proteins and cellular elements of the blood First convoluted tubule reabsorbtion of water by osmosis Reabsorbtion of solutes such as Na + , K + , Cl - , HCO3 - , aa and glucose by a mixture of active and passive processes Loop of Henle Active secretion of chloride ions from ultrafiltrate inascending limb Second convoluted tubule Reabsorption of Na + Faculative reabsorbtion of water under control of ADH Secretion of H + , NH4 + , urea,creatinine and some drugs Collecting duct Faculative reabsorbtion of water under control of ADH

16. Control of water reabsorbtion by ADH The permeability of the walls of the second convoluted tubule and collecting duct is increased by antidiuretic hormone (ADH) ADH is produced by the hypothalamus but secreted by the pituitary. A rise in blood concentration (i.e. its water potential becomes more negative) is detected by osmoreceptors in the hypothalamus

17. normal water potential of blood

18. normal water potential of blood receptors in hypothalamus becomes less negative

19. normal water potential of blood receptors in hypothalamus second convoluted tubule and collecting ducts becomes less negative less ADH produced

20. normal water potential of blood receptors in hypothalamus second convoluted tubule and collecting ducts less water reabsorbed becomes less negative less ADH produced

21. normal water potential of blood receptors in hypothalamus second convoluted tubule and collecting ducts less water reabsorbed becomes less negative less ADH produced

22. normal water potential of blood receptors in hypothalamus second convoluted tubule and collecting ducts less water reabsorbed blood water potential becomes more negative becomes less negative less ADH produced

23. normal water potential of blood receptors in hypothalamus second convoluted tubule and collecting ducts less water reabsorbed blood water potential becomes more negative becomes less negative less ADH produced becomes more negative

24. normal water potential of blood receptors in hypothalamus second convoluted tubule and collecting ducts less water reabsorbed blood water potential becomes more negative becomes less negative less ADH produced becomes more negative more ADH released

25. normal water potential of blood receptors in hypothalamus second convoluted tubule and collecting ducts less water reabsorbed blood water potential becomes more negative becomes less negative less ADH produced becomes more negative more ADH released more water reabsorbed

26. normal water potential of blood receptors in hypothalamus second convoluted tubule and collecting ducts less water reabsorbed blood water potential becomes more negative becomes less negative less ADH produced becomes more negative more ADH released more water reabsorbed blood water potential becomes less negative

27. Control of water reabsorbtion by ADH When ADH is produced more water is reabsorbed A more concentrated (hypertonic) urine is produced

28. Control of water reabsorbtion by ADH A fall in blood concentration inhibits the release of ADH – the walls of the second convoluted tubule and collecting duct become impermeable to water Less water is reabsorbed and a hypotonic urine is produced

29. Control of water reabsorbtion by ADH Another example of negative feedback!