BP and the Kidney

Question 1

How is mean arterial BP calculated?

Answer 1

= CO (SV x HR) x TPR

Question 2

Outline the process that occurs when your BP/blood volume is low

Answer 2

Baroreceptors = increase CO/vasoconstriction to increase BP, increase thirst to increase ECF to increase BP

Kidney = increase NaCl/water reabsorption to increase ECF to increase BP

Question 3

What factors get activated by the kidney is poorly perfused?

Answer 3

1) RAAS
2) sympathetic NS
3) prostaglandins
4) ADH

Question 4

What are the 3 mechanisms that cause renin release?

Answer 4

1) reduced NaCl delivery to distal tubule
2) reduced perfusion detected by baroreceptors
3) sympathetic stim to JGA

Question 5

Briefly outline the systemic effects of Ang II

Answer 5

Arteriolar vasoconstriction

PP to secrete ADH = increase H2O reabsorption

Adrenal grand to secrete aldosterone = increase NaCl reabsorption

Increased sympathetic activity

Question 6

Outline the action of Ang II on the kidney

Answer 6

Vasoconstriction of efferent > afferent arterioles = renal blood flow falls

Enhanced Na reabsorption at PCT

ADH = increase H2O reabsorption

Aldosterone = increase NaCl reabsorption

Question 7

Outline how Ang II causes an increase in Na reabsorption

Answer 7

Ang II binds receptor AT1 = stim Na/K ATPase

Question 8

How does aldosterone increase Na reabsorption?

Answer 8

Increases expression of ENaC and Na/K ATPase in the collecting duct

Question 9

How do prostaglandins help resolve low renal perfusion?

Answer 9

Vasodilation of afferent arterioles in kidney = increasing blood flow = increasing GFR

Enhance renin release

Question 10

How does ADH work?

Answer 10

Release is stim by plasma osmolarity

Causes vasoconstriction

Increases water reabsorption in distal nephron = increased transcription of Aquaporin channels into the apical membrane of collecting tubule and collecting duct

Question 11

What occurs in response to an acute increase in BP?

Answer 11

Recognised by baroreceptors

Decrease in sympathetic output = vasodilation, decrease in peripheral resistance

Increase in parasympathetic output = decreased HR, decreased CO

Question 12

Outline what ANP is and how it works?

Answer 12

Atrial natriuretic peptide = released in response to cardiac stretch

Causes = vasodilation, inhib Na reabsorption in the kidney

Question 13

What are the causes of secondary hypertension?

Answer 13

Renovascular hypertension

Coarctation of the aorta

Primary hyperaldosteronism

Cushing syndrome

Question 14

What is renovascular disease?

Answer 14

Renal artery stenosis

2 main types = atheroma, fibromuscular dysplasia

Unilateral = hypertension but no fluid overload

Bilateral = hypertension and fluid overload

Question 15

How does coarctation of the aorta cause hypertension?

Answer 15

Lower perfusion of kidneys = hypertension

Question 16

How does primary hyperaldosteronism cause hypertension?

Answer 16

Excess aldosterone = 1) adrenal adenoma, 2) adrenal hyperplasia

Measure aldosterone : renin = renin should be low

Question 17

What are the causes of generalised oedema?

Answer 17

Heart failure

CKD

Nephrotic disease

Liver disease

Pregnancy

Question 18

Briefly outline CDK in regards to hypertension

Answer 18

Inability to excrete Na/CL and water due to reduced kidney function = hypertension, oedema

Question 19

Briefly outline nephrotic syndrome in regards to hypertension

Answer 19

Hypoalbuminaemia = reduced oncotic pressure = reduced perfusion press = activation of RAAS

Alterations in Na/water excretion due to reduced kidney function