I'm studying my second human biology subject and am doing an assignment on renal physiology.
My question involves someone who was stranded and drank 3L of seawater. I need to explain why her glomerular filtration rate (GFR) is reduced (85 instead of the normal 125). My answer has to include the neural and hormonal influences that are involved to decrease GFR.
In a previous question, I have already answered why she is so dehydrated. The high sodium chloride intake leads to high Na+ and Cl- plasma levels, which increases interstitial fluid osmolarity and draws water into the plasma. This increases blood volume, leading to atrial natriuretic peptide (ANP) secretion and inhibition of renin/angiotensin/aldosterone secretion. This decreases renal reabsorption of Na+ and Cl-, thus increasing the loss of these ions in urine. This increases loss of water in urine as 'water follows solutes'.
I'm thinking that due to the resulting decrease in blood volume, ANP secretion decreases and renin-angiotensin-aldosterone pathway is activated. Angiotensin II decreases GFR via vasoconstriction. I was also thinking that the decreased blood pressure (due to decreased blood volume) then stimulates the baroreceptor reflex to increase heart rate and contractility (so that's the neural regulation involvement).
Is this the correct line of thought? I was a little confused that it involved both ANP/increased blood volume then decreased blood volume/the RAA pathway.
Thank you for any guidance!
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