Regulation of ECF Flashcards
what are the major ECF osmoles?
> sodium
> chlorine
what are the major ICF osmoles?
potassium
what are the immediate effects of increased slat and water loss from vomiting and diarrhoea?
decreased: > peripheral volume > venous pressure > venous return > atrial pressure > end diastolic volume > systolic volume > cardiac out put > blood pressure
what is the effect of decreased atrial pressure and decreased carotid sinus baroreceptor inhibition of sympathetic discharge on osmolarity?
hypoosmolarity occurs due to the increase in ADH
what is the effect of decreased carotid sinus baroreceptor inhibition of sympathetic discharge?
> increased ADH
increased sympathetic vasoconstriction
increased total peripheral resistance
increased blood pressure
what is the effect of angiotensin 2 on na+ reabsorption?
increased Na+ reabsorption from the proximal tubule
due to greater reabsorpative forces in the peritubular capillaries
true or false:
angiotensin 2 decreases the peritubular capillary hydrostatic pressure
true
true or false:
increase in aldosterone causes an decrease in distal tubule reabsorption
false it causes and increase
where are juxtaglomerular cells found?
the smooth muscle of the media of the afferent arteriole just before it enters the glomerulus
describe juxtaglomerular cells
large epithelial cells filled with granules
what do juxtaglomerular cells produce?
renin
what forms the juxtaglomerular apparatus?
> juxtaglomerular cells
> macula dense
where are macula densa found?
loop of the distal tubule
what Is the rate limiting step in the rennin-angiotensin-aldosterone system?
angiotensinogen being converted into angiotensin 1 on the plasma
what converts angiotensin 1 into angiotensin 2?
angiotensin converting enzyme
what 4 things does angiotensin 2 act on?
> arterioles
cardiovascular control centre in the medulla oblongata
hypothalamus
zona glomerulosa
how does angiotensin 2 cause an increase in blood pressure?
> vasoconstriction
> increased cardiovascular response
what effect does angiotensin 2 have on the hypothalamus?
> increase ADH secretion
> increased thirst
what is the effect of angiotensin 2 on the zona glomerulosa?
> increased aldosterone release
how does angiotensin 2 increase volume and osmolarity?
> increased ADH
increased thirst
Increased Na+ reabsorption
where in angiotensin converting enzyme found?
in vascular endothelium
what increases renin release?
> decrease in NaCl delivery
increase in sympathetic nerve activity
decrease in pressure in afferent arteriole at the level of the juxtaglomerular cells
what causes a decrease in renin release?
> feedback of angiotensin 2
ADH (inhibits renin release)
increased NaCl delivery
how does tubuloglomerular feedback contribute to GFR consistency?
> GFR increases so the flow through the tubule increase
flow past the macula densa increases creating paracrine effects from the macula densa to the afferent arteriole
the afferent arteriole then constricts decreasing the GFR
what are the opposing inputs to ADH secretion in a patient who drinks 2L of pure water after losing 3l of salt and water?
> decrease in ECF osmolarity causes inhibition of ADH via osmoreceptors
increase in ECF volume causes increase in ADH via baroreceptors
what is corrected first osmolarity or ECV?
ECV as an emergency mechanism to save brain perfusion
what does atrial natriuretic peptide promote?
Na+ excretion
what is known as aldosterone escape?
volume expansion due to aldosterone stimulates ANP from atrial cells causing a loss of Na+ and H20
what does aldosterone continue to cause even after ANP kicks in?
K+ Secretion
in Conn’s syndrome primary hyperaldosteronsim leads to what effect of potassium and sodium?
> potassium depletion
> no Na+ change
what is the effect of atrial stretch of ANP?
increased secretion
what is the effect of ANP on the hypothalamus?
less ADH
what is the effect of ANP on the kidney?
> increased GFR
increased NaCl and H20 excretion
decreased renin
what is the effect of ANP on the adrenal cortex?
less aldosterone
how does ANP affect blood pressure?
decreases it
