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Renal 3
renal 3
31
Physiology
Undergraduate 3
10/06/2015

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Term
Describe what the RAAS system does in response to lowered blood pressure
Definition
1. BP drops
2. JG cells secrete renin
3. Renin acts on angiotensinogen to produce ANG I
4. ACE converts ANG I to ANG II
5. ANG II causes vasoconstriction
6. BP increases
Term
Low blood pressure can lead to ____ heart failure
Definition
hypotensive
Term
Where does ACE come from?
Definition
the lungs
Term
Where does renin come from
Definition
JG cells
Term
Where does angiotensinogen come from
Definition
the liver
Term
ANG II binds to an ____ receptor to promote vasoconstriction
Definition
AT1
Term
Describe what the RAAS does in response to low blood volume
Definition
ANG II promotes aldosterone secretion from the adrenal cortex

ANG II & aldosterone tell kidneys to increase retention of salt & water

blood volume is increased
Term
______ leads to heart attacks
Definition
high blood pressure
Term
What would be prescribed to treat chronic high blood pressure?
Definition
ACE inhibitors, which prevent conversion of ANG I to ANG II
Term
Describe what happens with reabsorption
Definition
-Excess K+ in glomerular filtrate is returned to peritubular capillaries, reabsorbed in the PCT & descending loop of henle
Term
Where does resorption of salt & water occur?
Definition
65% in the peritubular capillaries of the PCT

20% through descending loop of henle
Term
Does reabsorption occur through PCT cells, or between them?
Definition
both!

leaky junctions between cells allows Na+ & K+ through (paracellular)

can also be transported through the cells (transcellular)
Term
_____ is the opposite of reabsorption
Definition
secretion
Term
Is resorption passive or active?
Definition
passive
Term
What is secretion?
Definition
active transport of substances from peritubular capillaries into the tubular fluid
Term
What comes out in the descending loop of henle? What happens to osmolality?
Definition
water

increases from 300 to 800 to 1200
Term
What comes out in the ascending loop of henle? What happens to osmolality?
Definition
various salts

decreases from 1200 to 700 to 200
Term
What is the concentration of blood entering the glomerulus?
Definition
300 mOsm/L
Term
What happens in the ascending loop of Henle?
Definition
-salt is actively removed, to decrease osmolality from 1200 to 300
Term
The ascending loop of Henle is rich in _____
Definition
mitochondria
Term
The ascending loop of henle is _____ to salt but _____ to water
Definition
permeable to salt
impermeable to water
Term
Which has a thicker wall, the ascending or descending loop of henle?
Definition
ascending
Term
What happens in the descending loop of henle?
Definition
-water is drawn out, so filtrate concentration increases from 300 to 1200
Term
The descending loop of Henle is _____ to Na but _____ to water
Definition
impermeable to Na
permeable to water
Term
What is the countercurrent multiplier system?
Definition
1. NaCl extruded from ascending limb, increases fluid concentration

2. Concentration effect is augmented by passive permeability of descending limb to water
Term
What happens in the collecting ducts? describe the steps
Definition
ADH promotes further removal of water from filtrate by osmosis

1. ADH binds to receptor
2. Signals via cAMP pathway
3. AQP2 inserted in apical side of mmb
4. H2O is absorbed by osmosis into the blood
Term
What must be present in order to make urine hyperosmotic (more concentrated than blood)?
Definition
ADH
Term
Why doesn't water enter the interstitial fluid dilate the standing gradient?
Definition
vasa recta prevent this
Term
What is the countercurrent exchange system?
Definition
Descending limb of vasa recta has lower solute concentration than the ascending limb

NaCl diffuses from ascending to descending limb, water from descending to ascending

Works in conjunction with loop of henle to take the water that is being removed & added
Term
What prevents backflow of urine from the bladder?
Definition
flap valve
Term
True or False

It is normal to find glucose in the urine
Definition
false
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