24. Regulation of Kidney Function

Glomerular filtration rate is maintained within a tight range, primarily accomplished by dilation of the afferent (incoming) arteriole

distal convoluted tubule is tucked right in by the incoming anf outcoming tubules

if dilation of afferent arteriole does not increase GFR, the kidney releases renin into the blood

1. cause more vasodilation of aferent arteriole, whcih forces more blood across glumerulus into bowmans capsule, low NaCL = large blood volume

2. causes renin release from adjacent cells, low NaCl stimulates to dump renin into the blood

RENIN

1. major role in cascade of a compound called angiotensin

2. angiotensin- hormone

   1. stimulates thirst

   2. stimulates

   3. stimulates peripheral vasoconstriction (not critical body parts)

Regulation of blood osmolarity involves the kidney too!

1. rise in blood osmolarity is detected by osmoreceptors in the hypothalamus (detects ions in blood)

2. this then results in a signal to the pituitary to release anti-diuretic hormone (ADH) into blood

3. ADH then travels to the kidneys where it can cause insertion of aquaporins in the walls of the collecting duct

How does ADH increase H2O permeability in collecting duct?

1. insertion of channels (called aquaporins) allow H2O molecules through

How can the kangaroo rat survive without drinking water?

1. countercurrent multiplier in the loop of henle

2. the loop of henle is extremely long

3. carry seeds to their burrows where they absorb moisture from surrounding soil

   Organism	Urine Concentration (mOsm)
   Human	1400
   Rat	2900
   Camel	2800
   Kangaroo Rat	6000