Renal 4: Salt Balance Flashcards
the kdneys match salt out to salt ___
in
____ is the main determinant of extracellular fluid volume
na
Na reabsorption is regulated by the ____ system of hormones; by ____ and also by ____ nervous system activity
renin-angiotensin; ANP; sympathetic
increased Na / blood volume causes a ___ in Na excretion
increase
decreased Na / blood volume causes a ___ in Na excretion
decrease
Na reabsorption is inhibited by ___ drugs that are used to reduce BP
diuretic
the kidneys match K excretion to K ___
intake
K can be secreted by ___ parts of the nephron to allow control of body K homeostasis
distal
K secretion is regulated by plasma ___ and the hormone ___
K concentration; aldosterone
as Na increases, the extracellular fluid volume __
increases
what is the effect of the renin-angiotensin-aldosterone system on Na reabsorption and excretion?
increase reabs ; decrease excretion
what is the effect of ANP on the reabsorption and excretion of Na>
decrease reabsorption; increase excretion
what is the effect of sympathetic activity on Na excretion?
decreases GFR by constricting BV; lowers excretion
decribe the pathway of the renin-angiotensin-aldosterone system
low na –> low ECF volume –> release of renin / formation of angiotensin 2 –> aldosterone –> increase Na and water reabsorption –> increased ECF volume
angiotensin 2 ____ (directly or indirectly) increases Na reabsorption in the nephron
directly
angiotensin 2 acts on ___ receptors of tubular epithelial cells
AT1
angiotensin 2 increases the activity of ___
Na transport proteins
angiotensin 2 stimulates the secretion of ___ from the adrenal gland
aldosterone
aldosterone increases the activity of apical ___ channels in the collecting duct and also increases the ___ of ENaC and Na/K pump
ENac Na; genetic expression
aldosterone ___ the reabsorption of Na
increases
describe the pathway of ANP
high sodium –> high ECF volume –> release of ANP –> decrease Na and water reabs –> decreased ECF
ANP is the antagonist to ___
aldosterone
ANP is released from the
heart
diuretic drugs act on the ____ to ___ Na reabsorption
renal tubular Na transport proteins; reduce
how much more urine does a person produce when on diuretics?
very little, because the Na out will be matched to Na in
loop diuretics act on what transport proteins? where?
NKCC; loop of henle
thiazide diuretics act on what transport proteins? where?
NCC; distal tubule
K sparing diuretics act what transport proteins? where?
ENaC; late distal tubule and collecting duct
what are 2 ENaC channel mutations?
- Pseudohypoaldosteronism
2. liddle’s syndrome
what happens in pseudohypoaldosteronism?
loss of ENaC function, more Na excretion, reduced ECF, hypotension
what happens in liddle’s syndrome?
excessive ENaC function, decreased Na excretion, raised ECF, hypertension
K homeostais must be maintained within a very ___ rnage
narrow
t/f a small rise in K in the plasma can be fatal
t
K homeostasis is controlled by the ___
kidneys
K excretion is highly __
variable
K secretion is regulated by what hormone?
aldosterone
1% excretion of K in cases of ___
hypokalemia
100% excretion of K in cases of ___
hyperkalemia
depending on the K concentration, the distal tubule is capable of either ___ or ___
K reabsorption or K secretion
____ cells in the ____ and ___ parts of the nephron secrete K
principal; late distal tube and collecting duct
____ cells in the ____ and ____ parts of the nephron reabsorb K
intercalated; late distal tube and collecting duct
how is K absorbed by intercalated?
H/K atpase pump in apical membrane
how is K secreted by principle cells?
K channels
what happens in a principle cell when plasma K is incresed?
Na/K pump on baso side bring K in then out on apical end by K channels, aldosterone in secreted by the adrenal cortex
aldosterone increases the expression of __ and ___ and the permeability of K on the ___ end of the principle cells
Na/K pump on baso; ENac channels; apical
