Renal II Flashcards
(55 cards)
difference between osmolarity and osmolality?
R= osmol/L L= osmol/kg
what is antidiuresis?
normal land-dweller state: when you have high ADH in the blood, urine excretion is low, high reabsorption of urea
what contributes to the hyperosmotic gradient from cortex to medulla?
urea- 50%- 600 osmol
Na- 25%- 300 osmol
Cl- 25%- 300 osmol
3 mechanisms that generate hyperosmotic gradient from from cotex to medulla?
- countercurrent multiplier- permeability differences for Na and H20
- urea cycle- leaking out in collecting duct & only participating in right loop
- countercurrent exchanger- slow vasa recta flow (permeable to everything) allows time for Na to move in and H20 to move out
5 requirements for hyperosmolarity
1) long loops of Henle
2) blood & urine flowing in opposite direction
3) active salt pumping (in basolateral membrane of cells near TAL/DT/CD)
4) differential permeabilities
5) destruction takes days to re-establish
equation for osmolar clearance (Cosm)
Cosm= V * Uosm/Posm
what is Ch20? what is -Ch20 also called? what is the equation for Ch20?
Ch20= the amount of pure water kidney adds to urine -Ch20= TcH20
Ch20= V-Cosm
do alterations in Na change the volume or Na concentration of the ECF?
only the volume!!
what is the ECV?
effective circulating volume- the portion of the ECF that is effectively perfusing the tissues (normally direction proportional to ECF)
what are the 4 ways of regulating renal salt excretion via afferent sensors?
a- venous (increased atrial stretch, increased ANP, natriuresis)
b- arterial (increased barros, decreased symp, decreased ADH)
c- hepatic sensors (increased liver p, decreased symp)
d- CNS sensors (increased Na in CSF, decreased symp)
what is natriuresis?
increased sodium secretion in urine, followed by water
what is the sympathetic pathway
increased sympathetics decreases GFR by constricting afferent arteriole, which increases renin (RAAS) and increases Na reabsorption
what are the affects of angiotensin II and aldosterone?
angiotensin II- Na is reabsorbed proximally, causes secretion of ADH
aldosterone- increases NA reabsorption in TAL, DT, CD
how do ANP, BNP, and urodilatin work?
decrease aldosterone, decrease renin (decreases Na reabsorption), (decrease sympathetics- increase GFR- increase Na in tube- increase Na excretion)
what are the 3 things that stimulate renin secretion?
1) perfusion pressure sensed by baroreceptors in afferent arteriole
2) sympathetic nerves that innervate afferent arterioles
2) tubuloglomerular feedback senses decreased NaCl in macula densa
when is ANP released from atria?
1) increase in extracellular fluid volume
2) increase in arterial pressure (increase in LV pressure)
3) increase in venous pressure (increase in right atrial pressure)
what does reabsorption depend on in 3 parts of kidney?
1- proximal- filtered load
2- TAL- Na delivery rate
3- DT/CD- Na load remaining
during euvolemia, you have a _______; what percent of Na is filered?
net zero Na balance
-99% is filtered
what happens to GFR during volume expansion?
GFR increases, decrease reabsorption in proximal tubule and collecting duct
- see decrease sympathetics, increased urodilatin, increased ANP and BNP
what happens during edema? how can it be fixed?
- see decrease in ECV and plasma volumes
- fixed by giving diuretics to decrease Pc and increase PIc
what are 3 things that cause K+ release from the cell?
1) epinephrine acting on alpha receptors
2) cell lysis (burns, surgery)
3) hyperosmolarity
what are 5 things that cause K+ uptake by the cell?
1) epinephrine activating B2 receptors, especially during exercise
2) increased extracellular K+ stimulating the Na/K ATPase
3) insulin (especially following a meal)
4) aldosterone
5) hyposmolarity
what percent of K+ in kidneys is reabsorbed? what percent is excreted?
85-95% is reabsorbed (decreases with more in diet)
15-80% is excreted (increased with more in diet)
what 3 factors regulate K+ secretion in the DT & collecting duct
1) Na-K atp pump
2) cell-lumen -40 electrochemical gradient
3) K+ permeability of apical membrane
