Blood pressure and the kidney

Question 1

What are juxtaglomeular cells?

Answer 1

Specialised smooth muscle cells in blood vessels of the kidney that synthesise, store and secrete renein

Mainly found in aferent arterioles

Secrete renin in response to a drop in BP detected by stretch receptors or in response to signals from macula densa cells

Question 2

What is the role of macula densa cells?

Answer 2

• Sense NaCl levels
• Low NaCl = lo BP

Question 3

Where is angiotensinogen produced?

Answer 3

Liver

Question 4

What is the role of renin?

Answer 4

Cleaves angiotensinogen - angiotensin 1

Question 5

What is the role of angiotensin converting enzyme?

Answer 5

Converts angiotensin 1 - angtiotensin 2

Question 6

Where is angiotensin converting enzyme found?

Answer 6

Lung capillaries

Endothelial and kidney epithelial cells

Question 7

What does angiotensin 2 do?

Answer 7

1. Increases sympathetic activity
2. Increases arteriolar vasoconstriction
3. Promotes aldosterone release from the adrenal cortex (thus promoting water retention)
4. Stimulates the posterior putuitary to release ADH which works on the collecting duct to promote water re-uptake (AQP2)

Question 8

What is the most common cause of nephropathy?

Answer 8

Hypertension

Question 10

What is the consequence of high blood pressure, regarding the kidney?

Answer 10

Systemic hypertension - increased flow in the glomerulus - constriction of afferent arteriole - flow and pressure decreases in glomerulus - efferent arteriole dilates - smooth muscles in the arterioles hypertrophy - over time high blood pressures cause barotrauma in afferent

Question 11

Which drugs function to alter the RAAS?

Answer 11

• ACEi e.g. captorpil, enalapril
• Ang II blockers e.g. losartan, candesartan
• Direct renin inhibitors e.g. aliskiren

Question 12

Which part ofthe kidney is most affected by ischaemia?

Answer 12

Thick ascending limb because it contains the most ATP dependant pumps