Blood pressure and kidneys

Question 1

Describe and explain the kidneys response to reduced blood flow to the kidney. (6)

Answer 1

The kidney perceives this reduced blood flow as a low EVC. As well as the myogenic response of the arterioles, the kidney activates things to conserve salt and water.
RAAS - vasoconstriction
SNS - vasoconstriction, increased HR and BP.
Prostaglandins - vasodilation on afferent.
ADH - water retention.

Question 2

Describe and explain 4 conditions of reduced blood flow to the kidneys with a normal or expanded ECF. (8)

Answer 2

Heart failure - low bp
Liver cirrhosis - portal hypertension leading to hepatorenal syndrome (spleen holds onto blood)
Nephrotic syndrome - glomerular damage
Renal artery stenosis.

Question 3

Describe how kidneys respond to hypertension. (3)

Answer 3

Hypertension causes increased renal blood flow so the kidneys try to lose salt and water. This is done through ANP which vasodilates and a reduction in aldosterone (which should vasoconstrict).

Question 4

Explain the changes in the pressure-natriuresis curve seen in hypertension. (3)

Answer 4

The curve moves to the right because they need a higher MAP to excrete the same amount of Na+, because the resetting of their baroreceptors.

Question 5

Hypertension can be caused by salt retention. Describe two conditions where this occurs.

Answer 5

Primary Hyperaldosteronism (Conn’s syndrome) and Cushing’s syndrome.