1. Chapter 17 TheUrinarysystem

2. kidneys • Location • The right kidney touches the liver and is lower than the left kidney. • Protected partially by the lower ribs and by the muscles of the lower back. • About 20% of the blood pumped by the heart each minute enters the kidneys.

3. kidneys • Internal Structure • Renal cortex • Renal medulla • Renal pyramids • Renal papilla • Renal pelvis • Calyx

4. kidneys • Microscopic Structure • More than a million microscopic units called nephrons make up each kidney’s interior. • Nephronsare composed of two principle components: the renal corpsule and the renal tubule

5. Kidney function 1. Filters blood and produces urine. - excretes toxins and waste products

6. Kidney function 2. Regulates levels of many chemical substances in the blood such as chloride, sodium, potassium, and bicarbonate.

7. Kidney function 3. Regulate proper balance between water and salt in the blood.

8. Kidney function 4. Help with blood pressure regulation 5. Help maintain adequate RBC numbers

9. FORMATION OF URINE • Filtration – goes on continually in the renal corpuscles. • Glomerularblood pressure causes water and dissolved substances to filter out of glomeruli into Bowman’s capsule. • Normal glomerular filtration rate is 125 mL per minute.

10. FORMATION OF URINE • Reabsorption – the movement of substances out of the renal tubules into the blood capillaries located around the tubules (peritubular capillaries). • Water, nutrients, and ions are reabsorbed. • Water is reabsorbed by osmosis from proximal tubules

11. FORMATION OF URINE • Secretion – the process by which substances move into urine in the distal and collecting tubules from blood in peritubular capillaries. • Hydrogen ions, potassium ions, and certain drugs are secreted by active transport, ammonia is secreted by diffusion.

12. FORMATION OF URINE • Control of Urine Volume – mainly by the posterior pituitary hormone’s ADH, which decreases it

13. ureters • Narrow, long tubes with an expanded upper end located inside the kidney • Function is to drain urine from the renal pelvis to the urinary bladder

14. Urinary bladder • Structure • elastic muscular organ, capable of great expansion • is lined with a mucus membrane. • Functions • storage of urine and voiding

15. urethra • Structure • narrow tube from urinary bladder to exterior • lined with mucus membrane opening of urethra to the exterior is called the urinary meatus • Functions • passage of urine out of the body • male repro fluid

16. micturition • passage of urine from the body • Regulatory sphincters • Internal urethral sphincter – bladder exit - involuntary • External urethral sphincter – circles the urethra just below the neck of the bladder- voluntary

17. Bladder Wall • permits storage of urine with little increase in pressure until a volume of 300mL to 400mL is reached

18. Emptying reflex • It is initiated by stretch reflex in the bladder • Bladder wall contracts • Internal sphincter relaxes • External sphincter relaxes, and urination occurs

19. Retention vs Suppression • urine is produced but not voided • no urine produced but bladder is normal Urinary Retention Urinary Suppression

20. incontinence • Urine is voided involuntarily • May be caused by spinal injury or stroke • Retention of urine may cause cystitis – bladder infection

21. Overactive bladder • Need for frequent urination • Called interstitial cystitis • The amounts voided are small • Extreme urgency and pain are common