1. RENAL SYSTEM ANATOMY AND PHYSIOLOGY

2. PYRAMID POINTS Functions of the kidney Functions of the nephron
Process of urine formation
Maintenance of homeostasis

3. KIDNEYS
There are two; each is attached to the abdominal wall at the level of the last thoracic and first three lumbar vertebrae
Enclosed in the renal capsule
The cortex is the outer layer of the renal capsule
The medulla is surrounded by the cortex
The nephron makes up the functional unit of the kidneys

4. RENAL SYSTEM AND INTERNAL STRUCTURE OF A KIDNEY
From Herlihy, B. & Maebius, N. (2000). The human body in health and illness. Philadelphia: W.B. Saunders.

5. FUNCTIONS OF KIDNEYS Maintain homeostasis of the blood
Excrete end-products of body metabolism
Control fluid and electrolyte balance
Excrete bacterial toxins, water-soluble drugs, and drug metabolites
Secrete renin and erythropoietin, which play a role in the function of the parathyroid hormones and vitamin D

6. NEPHRON
Functional renal unit
Composed of glomerulus and tubules

7. NEPHRON
From Potter PA, Perry AG: Fundamentals of Nursing, ed. 5, St. Louis, 2001, Mosby.

8. GLOMERULUS Is encased in Bowman’s capsule
Filters the fluid out of blood

9. TUBULES Include proximal, distal, and Henle’s loop
Fluid is converted to urine in the tubules and then the urine moves to the pelvis of the kidney
The urine flows from the pelvis of the kidney through the ureter, and empties into bladder

10. TUBULAR AND VASCULAR STRUCTURES OF THE NEPHRON
From Herlihy, B. & Maebius, N. (2000). The human body in health and illness. Philadelphia: W.B. Saunders.

11. TUBULAR STRUCTURES OF THE NEPHRON
From Herlihy, B. & Maebius, N. (2000). The human body in health and illness. Philadelphia: W.B. Saunders.

12. BLADDER
The ureterovesical sphincter prevents reflux of urine from the bladder to the ureter
The total capacity of the bladder is 1 liter

13. KIDNEYS AND BLADDER
From Herlihy, B. & Maebius, N. (2000). The human body in health and illness. Philadelphia: W.B. Saunders

14. PROSTATE GLAND Surrounds the male urethra
Contains a duct that opens into the prostatic portion of the urethra and secretes the alkaline portion of seminal fluid

15. PROSTATE GLAND AND OTHER STRUCTURES
From Herlihy, B. & Maebius, N. (2000). The human body in health and illness. Philadelphia: W.B. Saunders.

16. URINE FORMATION
As fluid flows through the proximal tubules, water and solutes are reabsorbed
Water and solutes that are not reabsorbed become urine
The process of selective reabsorption determines the amount of water and solutes to be secreted

17. URINE FORMATION
From Herlihy, B. & Maebius, N. (2000). The human body in health and illness. Philadelphia: W.B. Saunders.

18. HOMEOSTASIS OF WATER
The antidiuretic hormone (ADH) is primarily responsible for the reabsorption of water by the kidneys
ADH is produced by the hypothalamus and secreted from the posterior lobe of the pituitary gland
Secretion of ADH is stimulated by dehydration or high sodium intake and by a fall in blood volume
ADH increases the permeability to water of the distal convoluted tubules and collecting duct

19. HOMEOSTASIS OF WATER
Water is drawn out of the tubules by osmosis into a high salt concentration of fluid in the medulla and its capillaries; water returns to the blood and concentrated urine remains in the tubule to be excreted
When the client lacks ADH, they develop diabetes insipidus
Clients with diabetes insipidus produce very large amounts of dilute urine and without treatment have difficulty drinking sufficient water to survive

20. HOMEOSTASIS OF SODIUM
When the amount of sodium increases, extra water is retained to preserve osmotic pressure
An increase in sodium and water produces an increase in the blood volume and blood pressure (BP)
When the BP increases, glomerular filtration increases, and extra water and sodium are lost; blood volume is reduced and returns the BP to normal

21. HOMEOSTASIS OF SODIUM
Reabsorption of sodium in the distal convoluted tubules is controlled by the hormones of the renin-angiotensin system
Renin is secreted when the BP or concentration of fluid in the distal convoluted tubule is low
Renin is an enzyme and splits angiotensin I from angiotensinogen, which converts to angiotensin II as blood flows through the lung

22. HOMEOSTASIS OF SODIUM
Angiotensin II, a potent vasoconstrictor, stimulates the secretion of aldosterone
Aldosterone stimulates the distal convoluted tubules to reabsorb sodium and secrete potassium
The additional sodium increases water reabsorption and increases blood volume and BP, returning the BP to normal; the stimulus for the secretion of renin is then removed

23. RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM
From Herlihy, B. & Maebius, N. (2000). The human body in health and illness. Philadelphia: W.B. Saunders

24. HOMEOSTASIS OF POTASSIUM
Increases in potassium stimulate the secretion of aldosterone
Aldosterone stimulates the distal convoluted tubules to secrete potassium; this acts to return the potassium concentration to normal

25. HOMEOSTASIS OF ACIDITY (pH)
Blood pH is controlled by maintaining the concentration of buffer systems
Carbonic acid and sodium bicarbonate form the most important buffer for neutralizing acids in the plasma
The concentration of carbonic acid is controlled by the respiratory system
The concentration of sodium bicarbonate is controlled by the kidneys

26. HOMEOSTASIS OF ACIDITY (pH)
Normal blood pH is 7.35 to 7.45, maintained by keeping the ratio of concentrations of sodium bicarbonate to carbon dioxide constant at 20:1
Strong acids are neutralized by sodium bicarbonate to produce carbonic acid and the sodium salts of the strong acid; this process quickly restores the ratio and thus blood pH

27. HOMEOSTASIS OF ACIDITY (pH)
The carbonic acid produced dissociates into carbon dioxide and water; because the concentration of carbon dioxide is maintained at a constant level by the respiratory system, the excess carbonic acid is rapidly excreted
Sodium combined with the strong acid is actively reabsorbed in the distal convoluted tubules in exchange for hydrogen or potassium ions; the strong acid is neutralized by the secretion of ammonia and is excreted as ammonia or potassium salts