06 Renal Endocrine

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Renin

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• JG (juxto glomerulus): modified smooth muscle cells of afferent arteriole. Sits between afferent/efferent, distal tubule and glomerulus

• macula densa: DCT

• macula densa: sense NaCl levels

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• Ang: made by liver, in blood

• renin finds Ang, convert to AI

Ang II

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• increase Na/H2O

• increase bicarb absorption in PCT

• harder to get blood through whole system, thus lower RPF, FF goes up

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Hydrostatic effect:

• less fluid go to peritubular because of constriction

• low hydrostatic pressure in peritubular capillaries

• result: water drawn out

Oncotic effect:

• protein stay in efferent, increase oncotic pressure

• high oncotic pressure

• fluid out

• AII activate Na/H antiporter

• Na absorption, H2O absorption

• Contraction alkalosis: more H+ out to lumen, combine with bicarb to form water, absorption

Aldosterone

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• adrenal makes too much aldosterone

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ANP

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• released by heart

• opposite of renin

• relax smooth muscle via cGMP to dilate afferent

PTH

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• low Ca most important

• alcoholics very low Mg

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• increase Ca absorption in DCT

Vid D

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• D2 less active, not important

• 25- OH longest half life

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• renal failure: increase phosphate from unable to excrete

• secondary hyper PTH from renal failure

EPO

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• peritubular interstitial cells

• acts in bone marrow

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• association with increased mortality