L2- Hypertension

Question 1

What is hypertension?

Answer 1

An elevation of systolic and/or diastolic blood pressure to the point where it increases risk of CVD
• Major risk factor for stroke, coronary artery disease, heart failure

Question 2

What damage is caused by hypertension?

Answer 2

• High pressure damages endothelium of conduid arteries causing atherosclerosis
• Increased afterload causing hypertrophy and ischaemia
• Damage to endothelium of microcirculation of kidney and brain leads to renal failure and stroke

Question 3

What are the types of hypertension?

Answer 3

• Mid-life hypertension- mechanisms which regulate BP are dysfunctional due to defect in Na+ excretion by kidneys or neurohormonal dysfunction
• Old-age hypertension- age related stiffening of arteries

Question 4

What are the causes of hypertension?

Answer 4

• Primary- no identifiable cause, genetic or environmental
• Hypertensinogenic factors- obesity, insulin resistance
• Secondary- cause can be identified as it is secondary to known condition e.g renal issues

Question 5

How does pressure work?

Answer 5

• Pressure is lower in small arteries/arterioles due to high TPR
• Pressure is high in large arteries due to lower TPR

Question 6

What are the pressure equations?

Answer 6

TPR= R(total)
CO= SV x HR
Change in pressure= CO x TPR

Question 7

What are the blood pressure regulation mechanisms?

Answer 7

• Autonomic nervous system

* Renin-angiotensin-aldosterone system

Question 8

How does the autonomic nervous system regulate blood pressure?

Answer 8

• Baroreceptors in carotid sinus and aortic arch send signals to medulla oblongata in brain
• BP too low- MO sends signals to heart via sympathetic ANS to increase HR and cause vasoconstriction
• BP too high- MO sends signals to heart via parasympathetic ANS to decrease HR and cause vasodilation

Question 9

How does RAAS regulate high BP?

Answer 9

• In high BP, increased CO causes release of ANP hormone

* Causes inhibition of RAAS so more Na+ excreted in urine resulting in a lower blood volume and lower BP

Question 10

How does RAAS regulate low BP?

Answer 10

• In low BP, decreased CO means less ANP hormone

* RAAS activated so less Na+ and water is excreted in urine resulting in an increased blood volume and higher BP

Question 11

How does the RAAS work?

Answer 11

• Kidney releases renin
• Liver needs to convert angiotensinogen to angiotensin 1- renin catalyses
• Angiotensin 1 converted to active Angiotensin 2 by ACE enzyme

Question 12

What does AT2 do?

Answer 12

• Vasoconstriction of smooth muscle in arteries
• Acts on adrenal gland which releases aldosterone
• Aldosterone causes increased reabsorption of Na+ and water
• Adrenal gland causes increased ADH so increased water reabsorption

Question 13

What does ACE do to bradykinin?

Answer 13

Bradykinin (vasodilator) is converted to inactive metabolite by ACE
Inhibition of ace causes cough due to bradykinin build up