17.2 Kidneys

By Yoon Kim and Allen Shin

IntroductionUrinary System removes certain slats and

nitrogenous wastesHelps 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 bloodPair of tubular ureters- transport urine from

kidneyTubular urethra- conveys urine to the outside of

the body

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

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.

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

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

Nephrons Kidney contains 1 million nephrons Nephrons consists of renal corpuscle and

renal tubuleFluid flows through renal tubules out of the

body

Nephrons Renal corpuscle is composed of glomerulus

blood capillaries.Glomerulus capillaries filter fluidsThin walled, saclike structure called

glomerular capsule surrounds the glomerulus

Nephron Blood SupplyAfter passing through the glomerular

capillaries, blood enters efferent arterioleEfferent arteriole resists blood flow which then

backs up blood into the glomerulus Peritubular capillary system surrounds the

renal tubule

Juxtaglomerular Apparatus

Juxtaglomerular cells: smooth muscle cells attached to the walls of arterioles near glomerulus

Juxtaglomerular apparatus: fuction in the control of renin secretion

Review Questions

Review Questions1. Kidneys activates vitamin ____2. __________: Supply blood to the kidneys3. _______________: the final branches of the

interlobular arteries; lead to the nephrons4. ________: joins the inferior vena cava as it

courses through the abdominal cavity5. ________ capillaries filter fluids