Week Four - Hypertension and Control Of BP

Question 1

What 3 factor stimulate renin release?

Answer 1

Reduced nacl to distal - macula densa cells
Reduced perfusion pressure on the kidney - baroreceptors in aff arterioles
Symp stimulation of JGA - b1 adrenoreceptors

Question 2

Explain the RAAS system

Answer 2

Angiotensinogen made in the liver, always a stable amount
Cleaved by renin to angiotensin1
at1 cleaved to At2 by ACE which is made in the lungs
AT2 causes vasoconstriction of vessels including aff of kidney
Stims sodium uptake in kidney so water follows
Stims adrenal gland cortex to release aldosterone which also stims sodium reabsorption

Question 3

How does At2 affect the kidney to increase sodium reabsorption?

Answer 3

PCT stims nah exchanger in apical membrane

Question 4

How does aldosterone act to increase sodium absorption in the kidney?

Answer 4

Principle cells of the collecting duct : activates the ENaC and the apical potassium channel. Also increases basolateral nak atpase.

Question 5

What affect does ACE have on bradykinin and why is this important?

Answer 5

It breaks down bradykinin which is a vasodilator. Taking ACE inhibitors will increase the levels of bradykinin and can result in dry cough.

Question 6

How does the sympathetic nervous system control sodium reabsorption in kidney?

Answer 6

Vasoconstriction of arterioles to decrease GFR
Activate nah exchanger and sodium potassium atpase in PCT
Stims renin from jg cells

Question 7

How does antidiuretic hormone increase reabsorbtion of sodium?

Answer 7

Increases water reabsorption in distal nephron via aqauporin2
Also stims TAL by increasing NA k cl transporter
Also causes vasoconstriction

Question 8

What do atrial natriuretic peptide do and how are they released?

Answer 8

Synth is atrial myocytes and released in response to stretch detected by cell sin atria.
Anp increases sodium excretion and therefore water.
Therefore if BP is low p, no stretch, no anp

Question 9

What are the actions of anti natriuretic peptide?

Answer 9

Causes vasodilation of afferent which increases GFR

Inhibits sodium reabsorption

Question 10

What is mild, moderate and severe hypertension?

Answer 10

Mild 140/159 or 90-99
Mod 160/179 or 100-109
Severe >180 or >110

Question 11

Give some examples of secondary hypertension?

Answer 11

Renovascular disease
Chronic renal disease
Aldosteronism
Cushing’s syndrome

Question 12

Where is renin released from in the kidney?

Answer 12

The juxtaglomerular apparatus - granular cells.