renin and angiotension and aldosterone

Question 1

An 85-year-old woman is found collapsed in her home. She is taken to the hospital for further investigations and is found to be hypotensive secondary to dehydration. Which of the following is the most likely physiological reaction

Answer 1

renin is released due to under-refused organs

Aldosterone secretion would increase due to the raised levels of angiotensin II

Angiotensin II causes vasoconstriction of the efferent arteriole to the glomerulus. This is to increase the pressure across the glomerulus and increase filtration fraction, ultimately preserving GFR.

Angiotensin II would stimulate the pituitary gland to secrete more ADH. ADH acts on the collecting duct increasing water absorption.

The baroreceptor reflex is another mechanism of blood pressure homeostasis, along with the renin-angiotensin-aldosterone system. As blood pressure increases baroreceptors in the aortic arch/carotid sinus detect increased stretching of the vessel. This causes inhibition of sympathetic tone and increased parasympathetic tone, decreasing blood pressure. In hypotension the baroreceptors detect less stretch in the vessel, this causes increased sympathetic tone and decreased parasympathetic tone. In this case increased sympathetic tone would lead to an increase in heart rate.

Question 2

when you are hypotensive what does angiotensin II do and what effect does this have

Answer 2

it increases

this vasoconstrcts the efferent arterial to the glomerulus increasing pressure re

aldosterone increases as an affect to

Question 3

when is renin released

other causes to do with sodium

Answer 3

an enzyme that is released by the renal juxtaglomerular cells in response to reduced renal perfusion

also hyponatraima

Question 4

function of angiotensin II

Answer 4

causes vasoconstriction of vascular smooth muscle leading to raised blood pressure and vasoconstriction of efferent arteriole of the glomerulus → increased filtration fraction (FF) to preserve GFR. Remember that FF = GFR / renal plasma flow
stimulates thirst (via the hypothalamus)
stimulates aldosterone and ADH release
increases proximal tubule Na+/H+ activity

Question 5

aldosterone causes retention of what

Answer 5

sodium

Question 6

angiotensinogen into angiotensin I what enzyme

Answer 6

renin

Question 7

angiotensin I to angiotensin II

Answer 7

ACE

Question 8

what do podocytes do

Answer 8

Podocytes are cells found in the Bowman’s capsule in the kidneys. They wrap around the capillaries of the glomerulus. Blood in the glomeruli is filtered through filtration slits, which are the spaces between the foot processes of podocytes.

Question 9

what do macula densa cells do

what ion
if it detects low levels of this iron what two effects are seen

Answer 9

The cells of the macula densa detect the sodium chloride concentration of the fluid in the limb lumen. If it detects low levels of sodium chloride it causes an increase in the release of renin from the juxtaglomerular cells, as well as vasodilation of the afferent arterioles.

Question 10

before giving someone hypertension drugs what should you say

Answer 10

lifestyle advice

Question 11

ARB work how

same as the angiotensin II

Answer 11

Increases filtration fraction through vasoconstriction of the efferent arteriole of the glomerulus to preserve GFR

Angiotensin II increases filtration fraction, through vasoconstriction of the efferent arteriole of the glomerulus to preserve GFR