5. Hypertension

Question 1

How is BP calculated?

Answer 1

Flow x Resistance

Question 2

How is mean arterial blood pressure calculated?

Answer 2

CO x TPR

Question 3

What response is relevant to acute changes in blood pressure?

Answer 3

Baroreceptor reflex

Question 4

How does the baroreceptor reflex respond to increases in blood pressure?

Answer 4

Nerve endings in the carotid sinus and aortic arch which are sensitive to stretch.
Signals to medulla oblongata which reduces sympathetic NS to case bradycardia and vasodilation.

Question 5

Why is the baroreceptor reflex only effect at regulating short-term, acute changes in blood pressure?

Answer 5

The threshold resets after around 15 minutes

Question 6

What are the 4 neurohormonal pathways that control blood volume and pressure over medium and longer term?

Answer 6

1. RAAS
2. SNS
3. ADH
4. ANP

Question 7

Where is renin released from?

Answer 7

Granular cells of juxtaglomerular apparatus (JGA)

Question 8

What 3 factors stimulate renin release?

Answer 8

1. Reduced NaCl delivery to distal tubule
2. Reduced perfusion pressure in the kidney
3. Sympathetic stimulation

Question 9

Where is renal perfusion detected?

Answer 9

Macula densa - baroreceptors in afferent arteriole

Question 10

What are the major functions of angiotensin II?

Answer 10

1. Aldosterone release
2. Na+ reabsorption in kidney
3. Vasoconstriction
4. Increase NA release
5. Thirst sensation in hypothalamus

Question 11

The main actions of aldosterone act via which receptor?

Answer 11

AT1 - GPCR

Question 12

What are the main actions of aldosterone?

Answer 12

Stimulates Na+ reabsorption in the kidney:

• Activates apical Na+ channel (ENaC)
• Na+/K+ ATPase

Question 13

Other than catalysing Angiotensin conversion, what other reaction does ACE catalyse?

Answer 13

Bradykinin (vasodilator) breakdown into peptide fragments, contributing to further vasoconstriction.

Question 14

What is the most common side effect of ACE inhibitors?

Answer 14

Dry cough due to bradykinin accumulation

Question 15

How does SNS affect renal blood flow?

Answer 15

High levels of sympathetic stimulation reduces renal blood flow by vasoconstriction of arterioles.

Question 16

How does decreased renal blood flow alter GFR blood pressure?

Answer 16

Decrease GFR which decreases excretion of Na+ and increase retention of Na+ and water, raising blood pressure in short term.

Question 17

How does SNS alter renin release from JG cells?

Answer 17

Stimulates renin release which increases Ang II levels and increase Na+ reabsorption.

Question 18

How does the SNS alter expression of transporters in the kidney?

Answer 18

Activates apical Na+/K+ exchanger and basolateral Na+/K+ ATPase in PCT to increase Na+ absorption.

Question 19

In what conditions is ADH secretion stimulated?

Answer 19

Dehydration

Severe hypovolaemia

Question 20

What is the function of ADH?

Answer 20

Increase water absorption in distal tubule
Stimulates Na+ reabsorption in thick ascending limb
Vasoconstriction

Question 21

Where is ANP synthesised and stored?

Answer 21

Atrial myocytes

Question 22

What stimulates ANP release?

Answer 22

Stretch - low pressure sensors in atria reduce ANP secretion when there is decreased filling and pressure is low

Question 23

What are the actions of ANP?

Answer 23

Tries to decrease blood pressure:
Vasodilation of afferent arteriole to kidney
Increased BF increases GFR
Inhibits Na+ reabsorption in the kidney

Question 24

What effect do prostaglandins have on blood vessels?

Answer 24

Cause vasodilation

Question 25

Why is decreased blood pressure a common complication of Parkinson's treatment?

Answer 25

Dopamine is a vasodilator: | Inhibits reabsorption of NaCl

Question 26

What is classified as stage 1 hypertension?

Answer 26

140/90 mmHg

Question 27

What is classified as stage 2 hypertension?

Answer 27

160/100 mmHg

Question 28

What is classified as severe hypertension?

Answer 28

> 180 systolic or >110 diastolic

Question 29

What is primary or "essential" hypertension?

Answer 29

Cause is unknown or multifactorial | 95% of cases

Question 30

What is secondary hypertension?

Answer 30

Cause can be identified

Question 31

What are some common causes of secondary hypertension?

Answer 31

Reno vascular disease Chronic renal disease Hyperaldosteronism Cushing's syndrome

Question 32

What factors might contribute to primary hypertension?

Answer 32

- Genetic factors | - Environmental factors

Question 33

How is hypertension diagnosed?

Answer 33

Sustained elevation of BP on 3 different occasions. | Systolic > 140 or diastolic > 90 mmHg

Question 34

How does renovascular disease lead to hypertension?

Answer 34

Occlusion in renal artery causes a fall in perfusion and increased renin production and RAAS activation.

Question 35

What are some adrenal causes of secondary hypertension?

Answer 35

Conn's syndrome - aldosterone secreting adenoma Cushing's syndrome - cortisol has mineralocorticoid actions at high conc Pheochromocytoma

Question 36

What non-pharmacological methods can be used to manage hypertension?

Answer 36

``` Exercise Diet Reduce Na+ intake Reduce alcohol intake Lifestyle changes have a limited effect. ```

Question 37

Which anti-hypertensive drugs target RAAS?

Answer 37

ACE inhibitors | Ang II receptor antagonists

Question 38

Which antihypertensive drug decreases blood volume as well as causing vasodilation?

Answer 38

Ang II receptor antagonist

Question 39

What anti-hypertensive drugs target the blood vessels?

Answer 39

L-type Ca2+ channel blockers - reduce entry into VSMC's

Question 40

What anti-hypertensive drugs target the kidney?

Answer 40

Diuretics - Thiazide - inhibit Na/Cl so-transporter on apical membrane of distal tubule Spironolactone and amiloride are potassium sparing

Question 41

When are beta blockers used to treat hypertension?

Answer 41

Never hypertension alone - only if other indications such as previous MI or angina.