lecture 26: renal physiology 2

Question 1

glomerular filtration

Answer 1

• glomerular capillary hydrostatic pressure drives filtration
• net filtration pressue (how much water and small solutes leave blood) is ~10mmHg
• afferent and efferent arterioles can control the pressure in glomerulus by constricting one or the other (maintain pressure in glomerulus)

Question 2

how is glomerular filtration regulated

Answer 2

• autoregulation: myogenic (blood vessels restrict when pressue is low) in the a/efferent arterioles themselves
• neural: sympathetic vasoconstriction (baro reflex)
• hormomal: angiotension or atrial natriuretic peptide

Question 3

autoregulation in kidney

Answer 3

• blood flow to kidney to kidney is tightly regulated even with rising arterial pressure
• relatively constant filtration rate
• but urine output is directly proportional to renal pressure

Question 4

proximal convoluted tubule

Answer 4

• largest amount of solute and water reabsorption from filtered fluid is hear (60% of what was filtered)

Question 5

descending loop of henle

Answer 5

• low permeability to ions, - highly permeable to water
• water moves hour, leaving very concentrated filtrate

Question 6

thick ascending limb

Answer 6

• impermeable to water
• Na, K, Cl, activley reabsorbed by symporter
• makes solution very dilute

Question 7

distal convoluted tubule and collecting duct

Answer 7

• more reabsorption of NaCL
• water permeability is dependant on antidiuretic hormone, which when absent makes urine dilute

Question 8

productions of dilute urine in terms of water, glucose, and ion movement in each nephron region

Answer 8

• revise