Control of Blood Pressure

Question 1

What is normal blood pressure?

Answer 1

90/60 - 120/80 mmHg

Question 2

What is hypertension?

Answer 2

Sustained increase in blood pressure

Question 3

What is stage 1 hypertension?

Answer 3

> 140/90

Question 4

What is stage 2 hypertension?

Answer 4

> 160/100

Question 5

What is severe hypertension?

Answer 5

> 180 systolic

>110 diastolic

Question 6

What is primary hypertension?

Answer 6

Unknown cause

Question 7

What is secondary hypertension?

Answer 7

Hypertension with an underlying cause

Question 8

What are the effects of hypertension?

Answer 8

Increased afterload

• left ventricular hypertrophy
• increased myocardial oxygen demand

Arterial damage

• atherosclerosis
• weakened vessels

Question 9

What are potential side effects of hypertension?

Answer 9

Retinopathy
Heart failure
MI
Stroke 
Aneurysm 
Renal failure

Question 10

How is blood pressure regulated in the short term?

Answer 10

Baroreceptor reflex

Question 11

How does the baroreceptor reflex work?

Answer 11

Nerve endings in carotid sinus/aortic arch
Stimulate medulla
Bradycardia / vasodilation
Counteract BP

Question 12

How is blood pressure regulated in the longer term?

Answer 12

Neurohumoral responses - regulate sodium balance

Question 13

What are the neurohumoral pathways controlling circulating volume?

Answer 13

RAAS
Sympathetic nervous system
Antidiuretic hormone
Atrial natriuretic peptide

Question 14

What is RAAS?

Answer 14

Renin-angiotensin-aldosterone system

Question 15

What factors stimulate renin release?

Answer 15

Reduced NaCL delivery to distal tubule
Reduced perfusion pressure in kidney
Sympathetic stimulation

Question 16

Where is renin released from?

Answer 16

Granular cells of juxtaglomerular apparatus

Question 17

What is the effect of renin?

Answer 17

Acts on angiotensinogen to release angiotensin 1

Question 18

Draw out RAAS

Answer 18

Angiotensinogen 
(renin)
Angiotensin I
(ACE)
Angiotensin II

Question 19

What are the effects of angiotensin II?

Answer 19

Vasoconstriction
Stimulares Na+ reabsorption at kidney
Stimulates aldosterone release

Question 20

What are the actions of aldosterone?

Answer 20

Acts on prinicpal cells of collecting ducts

Stimulates sodium reabsorption

• activates apical Na+ channel (ENaC
• increases action of Na/K/ATPase

Question 21

How does the sympathetic nervous system affect BP?

Answer 21

High levels of sympatheric stimulation - reduce renal blood flow

• decreases GFR
• decreases Na+ excretion

Activates apical Na/H exchanger + Na/K/ATPase in PCT

Stimulates renin release from JGA

Question 22

What is the effect of ADH?

Answer 22

Formation of concentrated urine
- increases water reabsorption in distal nephron

Stimulates Na+ reabsorption

• thick ascending limb
• stimulates Na/K/Cl co-transporter

Vasoconstriction

Question 23

What stimulates ADH release?

Answer 23

Increase in plasma osmolarity

Sever hypovolaemia

Question 24

What is ANP?

Answer 24

Atrial natriuretic peptide

Question 25

When is ANP released?

Answer 25

Released from atrial myocytes in response to stretch

Question 26

What is the effect of ANP?

Answer 26

Promotes Na+ excretion

Question 27

What are the actions of ANP?

Answer 27

Vasodilation of afferent arteriole Increased blood flow = increased GFR Inhibits Na+ reabsorption

Question 28

What are the effects of prostaglandins?

Answer 28

Act as vasodilator Enhances GFR - reduces Na+ reabsorption Buffer vasoconstriction by SNS and RAAS

Question 29

What is the effect of dopamine?

Answer 29

Vasodilation Increases renal blood flow Inhibits NH exchanger and Na/K/ATPase

Question 30

What are causes of secondary hypertension?

Answer 30

Renovascular disease Renal parenchymal disease Conn's syndrome Cushing's syndrome

Question 31

How does renovascular disease cause hypertension?

Answer 31

Occlusion of renal artery (renal artery stenosis) Decreased perfusion pressure Increased renin production Activation of RAAS

Question 32

How does renal parenchymal disease cause hypertension?

Answer 32

Earlier stages - loss of vasodilator substances Later stages - Na+ + water retention due to poor GFR

Question 33

How does Conn's syndrome cause hypertension?

Answer 33

Aldosterone secreting adenoma

Question 34

How does Cushing's syndrome cause hypertension?

Answer 34

Excess secretion of cortisol At high concentration acts on aldosterone receptors