Renal 6 - sodium Flashcards
what kind of hormone is ADH
peptide
what is the role of osmoreceptors
sense increase in plasma osmolarity
where are osmoreceptors
in the hypothalamus
where is ADH made
cell of the supra-optic nucleus in the hypothalamus
where is ADH secreted
posterior pituitary
where is the site of ADH action
collecting duct cells
work on specific aquaporins
what is the mechanism of action of ADH
alters water permeability of the luminal membrane of cortical collecting ducts (increases reabsorption)
what are aquaporins
water channels found in renal tubule cells (and other cells)
which aquaporins in the proximal convoluted tubules
AQP1
which aquaporins in the collecting ducts
AQP 2 3 4
what aquaporin does ADH regulate and how and where
AQP2
increase gene transcription
luminal side of collecting duct
(physiological regulation)
are AQPs on the basolateral membranes regulated by ADH
no
what happens to AQP2 when there is no vasopressin
the channels are reabsorbed into vesicles
less water reabsorption
what happens to permeability of water without ADH to the cortical collecting ducts
nearly impermeable to water
what is water diuresis
lots of fluid loss through urine
what causes water diuresis
absence of ADD
what can cause an increase in ADH (environment)
warm, shock, pain, no water
what can cause an decrease in ADH (environment)
cold, humid, alcohol
what does high ADH cause
retain water
what does low ADH cause
lose water
what is central diabetes insipidus
failure to release ADH from posterior pituitary
what is nephrogenic diabetes insipidus
defect at level of nephron tubule cells,
weak collecting duct cells
does diabetes insipidus involve sugar?
nah fam, has to do with ADH or ADH RECEPTORS
where does most of the gradient come from
50% from NaCl
how does the interstitial space change in dry environments
more of a gradient
how does the interstitial space change in non dry environments
less of a gradient
what is water diuresis
when excess water is excreted without excess solute in urine
what condition is associated with water diuresis
diabetes insipidus
what causes diabetes insupidus
messed up vasopressin/ADH
what is osmotic diuresis
excess solute in urine that is associated with high levels of water excretion
what condition is associated with omsotic diuresis
diabetes mellitus
what are short term handlings of low Na in plasma
baroreceptors regulate CFR, they become desensitized
what are long term handlings of low Na in plasma
aldosterone promotes Na reabsorption
what does atrial natriuretic peptide do
regulates GFR and inhibits Na+ reabsorption
inhibits aldosterone actions
how does the body adapt to high Na in plasma
releases atrial natriuretic peptide (regulate GFR, inhibit Na reabsorption, inhibit aldosterone).
what are baroreceptors
nerve endings that are sensitive to stretch, change in blood volume & peripheral resistance
where are baroreceptors located
carotic sinus, aortic arch, major veind, intrarenal (JG cells of JGA)**
do baroreceptors directly or indirectly detect sodium
indirectly by sensing water volume
what do baroreceptors dectect
change in blood volume, BP and stretch
what does activation of baroreceptors cause (5 things)
increased nerve impulse frequency and activation of the ANS
increate afferent arteriolar constriction, decrease GFR, increase Na reabsorption
what kind of hormone is aldosterone
steroid
where is aldosterone secreted from
adrenal cortex
what triggers the synthesis and release of aldosterone
low sodium
is the effect of aldosterone short or long term
long term
where is the site of action of aldosterone
late distal and cortical collecting duct
what are the 3 actions of aldosterone
induces synthesis of Na transport proteins
stimulates Na reabsorption reduces Na excretion
what is Na+ reabsorption linked to
K secretion
what regulates aldosterone secretion
low total body [Na+]
what does angiotension 2 do and where
acts on adrenal cortex to control secretion of aldosterone
where is renin secreted from
the juxtaglomerular cells of the JGA in the kidney
what do the baroreceptors of the JGA sense
low NaCl
what secretes angiotensinogen
the liver
what does ACE do
angiotension 1 to 2
what does angiotension 2 do
cause vasoconstriction and raises blood pressure
where does angiotension 2 cause
aldosterone release from the adrenal cortex
what secretes renin
juxtaglomerular cells on the wall of afferent arterioles
what kind of cells are juxtaglomerular/ what do they sense
mechanoreceptors that sense circulating plasma volume
where are macula densa
wall of distal convoluted tubule
what kind of cells are macula densa/ what do they sense
chemoreceptors that sense NaCl
is renin involved in tubular glomerular effect
no, it only reacts to low Na+
which three things determine [renin] in plasma
JG cells receive three inputs:
- sympathetic input from external baroreceptors,
- intrarenal baroreceptors(afferent arteriole),
- signals from macula densa*
what does decreased stretch do to renin release
stimulates renin release
what does increased stretch do to renin release
inhibits renin release
which 3 things are the most important triggers for aldosterone response
- sympathetic stimulation of renal nerves
- decreased filtrate osmolarity
- decreased BP
where is artial natriuretic peptide made
cardiac atria
where does artial natriuretic peptide act
cells of several tubular segments
what does artial natriuretic peptide cause (3 things)
inhibit aldosterone
inhibit Na+ rabsorption
increases GFR and Na+ excretion
what stimulates atrial natriuretic peptide secretion (3 things)
increased Na+ concentration
increase blood volume
atrial distension*
where is most of the filtered K+ reabsorbed
proximal tubule and loop of henle
where can some K+ be secreted
collecting duct
where is [K+] in urine regulated
cortical collecting duct
what is hyperkalemia
excess K+ in blood
what happens with an increase in extracellular K+
stimulate aldosterone production, more K+ in urine
what happens with an decrease in extracellular K+
no aldosterone produced, less K+ in urine
what does aldosterone do to K and Na and where
stimulates Na reabsorption and K secretion in the cortical collecting duct
what does water reabsorption depend on
Na reabsorption
