1. 17.2 Kidneys By Yoon Kim and Allen Shin

2. Introduction • Urinary System removes certain slats and nitrogenous wastes • Helps maintain the normal concentrations of water and electrolyses within body fluids, regulates pH and volume of body fluids, and help control red blood cell production and blood pressure • Pair of kidneys – remove substance from blood • Pair of tubular ureters- transport urine from kidney • Tubular urethra- conveys urine to the outside of the body

3. Kidneys • Kidney is a reddish-brown, bean-shaped organ • Kidneys are located on either side of the vertebral column and are positioned retroperitoneally(behind parietal peritoneum) • Connective tissues and adipose tissues surround the kidneys to hold them in position

4. Structure of the kidneys • Medial depression caused by the lateral and medial surface of the kidneys creates a depression into hollow chamber called renal sinus • Inside the renal pelvis, a funnel-shaped sac expands from the end of the ureter.

5. Functions of the Kidneys • Secretes hormone erythropoietin to help control the rate of red blood cell production • Activates vitamin D • Helps maintain blood volume and blood pressure by secreting the enzyme renin

6. Renal Blood Vessels • Renal arteries : Supply blood to the kidneys • Afferent arterioles : the final branches of the interlobular arteries; lead to the nephrons • Renal Vein: joins the inferior vena cava as it courses through the abdominal cavity

7. Nephrons • Kidney contains 1 million nephrons • Nephrons consists of renal corpuscle and renal tubule • Fluid flows through renal tubules out of the body

8. Nephrons • Renal corpuscle is composed of glomerulus blood capillaries. • Glomerulus capillaries filter fluids • Thin walled, saclike structure called glomerular capsule surrounds the glomerulus

9. Nephron Blood Supply • After passing through the glomerular capillaries, blood enters efferent arteriole • Efferent arteriole resists blood flow which then backs up blood into theglomerulus • Peritubular capillary system surrounds the renal tubule

10. Juxtaglomerular Apparatus • Juxtaglomerular cells: smooth muscle cells attached to the walls of arterioles near glomerulus • Juxtaglomerular apparatus:fuction in the control of renin secretion

11. Review Questions

12. Review Questions • 1. Kidneys activates vitamin ____ • 2. __________: Supply blood to the kidneys • 3. _______________: the final branches of the interlobular arteries; lead to the nephrons • 4. ________: joins the inferior vena cava as it courses through the abdominal cavity • 5. ________ capillariesfilter fluids