Block A Lecture 1 - Hypertension

Question 1

What is systemic circulation?

Answer 1

When blood is pumped from the left ventricle into the Aorta, to the body, and is then pumped back into the heart via veins such as the vena cava
(Slide 3)

Question 2

What is pulmonary circulation?

Answer 2

When blood is pumped from the right ventricle to the pulmonary artery and into the lungs before being pumped from the lungs back to the heart via the pulmonary vein
(Slide 3)

Question 3

What is bronchial circulation?

Answer 3

It is complementary to pulmonary circulation and supplies lung cells with oxygen and nutrients
(Slide 3)

Question 4

Compare the structures of veins and arteries.

Answer 4

Arteries have small lumen and a thick wall whereas veins have large lumen and a thin wall, while also having a valve in them

(Slide 4)

Question 5

What do valves present in veins do?

Answer 5

They prevent the backflow of blood

(Slide 4)

Question 6

Why do veins have valves but arteries don’t?

Answer 6

As veins are responsible for carrying blood against gravity, especially in the lower body

(Slide 4)

Question 7

What is blood pressure created as a result of?

Answer 7

The force of blood pushing against the walls of blood vessels (arteries) as it is pumped by the heart

(Slide 6)

Question 8

What 2 factors does blood pressure depend on?

Answer 8

Peripheral Vascular Resistance (PVP) * Cardiac Output (CO) = BP

Note: Heart Rate (HR) * Stroke Volume = CO

(Slide 6)

Question 9

How does peripheral vascular resistance affect blood pressure?

Answer 9

As PVR is the diameter of arteries / arterioles which determines resistance to flow, if dilated, there’s a low resistance to flow, a low PVR and therefore low blood pressure.

(Slide 7)

Question 10

What are 4 factors which affect arterial BP?

Answer 10

Answers Include:

Stroke volume

Heart Rate

Peripheral Resistance

Elastic Vessels

Blood Volume

Ventricular Ejection

(Slide 7)

Question 11

What are 4 examples of systems / mediators / receptors which affect blood pressure?

Answer 11

Autonomic nervous System (immediate)

Renin-angiotensin System (not immediate)

Local Mediators released from vascular endothelium (such as NO)

Sympathetic nervous system (β1-adrenoceptors increase CO, α1-adrenoceptors cause vasoconstriction, causing increased BP, or stimulation of them causing venoconstriction, increasing CO and BP)

(Slide 8)

Question 12

What are 2 types of endothelium-derived factors?

Answer 12

Endothelium-Derived Relaxing Factors (EDRFs) and Endothelium-Derived Contracting Factors (EDCFs)
(Slide 11)

Question 13

What do EDRFs and EDCFs do?

Answer 13

They modulate vascular smooth muscle and therefore vessel diameter

(Slide 11)

Question 14

What are 3 examples of endothelium-derived relaxing factors (EDRFs)?

Answer 14

Nitric Oxide (NO)
Prostacyclin (PGI2)
Hyperpolarizing Factor (EDHF)

(Slide 11)

Question 15

What are 2 examples of EDCFs?

Answer 15

Endothelin (ET-1)
Thromboxane (TXA2)

(Slide 11)

Question 16

Why do arteries have thick muscular walls, which contain elastic fibres?

Answer 16

To help them carry blood at high blood pressures

(Slide 12)

Question 17

What diseases can hypertension increase the risk of?

Answer 17

Heart, brain, kidney or other disease

(Slide 16)

Question 18

What is etiology?

Answer 18

The study of the causes or origins of diseases or medical conditions

(Slide 17)

Question 19

What is the etiology of hypertension?

Answer 19

It’s complicated as hypertension is the result of many factors which interact to raise blood pressure

(Slide 17)

Question 20

What is systolic pressure (SP)?

Answer 20

The maximal arterial pressure reached during peak ventricular ejection

(Slide 18)

Question 21

What is diastolic pressure (DP)?

Answer 21

The minimal arterial pressure just before ventricular ejection begins

(Slide 18)

Question 22

What is pulse pressure (PP)?

Answer 22

The difference between SP and DP

(Slide 18)

Question 23

What is mean arterial pressure (MAP)?

Answer 23

The average pressure in the cardiac cycle

(Slide 18)

Question 24

How is blood pressure measured using a sphygmomanometer (cuff on arm thingy) and how does this relate to hearing a pulse?

Answer 24

At first, cuff pressure blocks blood flow, and then pulse can be heard when systolic pressure exceeds cuff pressure. Then pulse cannot be heard when diastolic pressure exceeds cuff pressure
(full blood flow resumes).

(Slide 19)

Question 25

What is a normal BP range?

Answer 25

< 130 systolic and <85 diastolic for normal or 130-139 systolic &/or 85-89 diastolic for high normal (Slide 20)

Question 26

What are the systolic and diastolic ranges for grade 1 and 2 hypertension?

Answer 26

140-159 systolic &/or 90-99 diastolic for grade 1 160 or more systolic &/or 100 or more diastolic for grade 2 (Slide 20)

Question 27

How is systemic hypertension usually diagnosed?

Answer 27

It is usually asymptomatic and is often diagnosed when patient presents with a different condition (Slide 21)

Question 28

What is pulmonary hypertension?

Answer 28

It's commonly found in COPD patients where the pulmonary vasculature (the network of blood vessels which pump blood from the heart to the lungs) has been affected leading to increased vascular resistance. Results in shortness of breath and sometimes chest pain. (Slide 21)

Question 29

What does a sustained increase in pulmonary vascular resistance lead to?

Answer 29

Progressive right heart failure (the right side of the heart can't pump blood to the lungs) (Slide 21)

Question 30

What are 5 examples of primary risk factors for hypertension?

Answer 30

Answers Include: High salt consumption Lack of Exercise Excessive use of alcohol Tobacco Obesity Diabetes Age / Sex Lipid Disorders (Slide 22)

Question 31

What are 3 examples of secondary risk factors (factors initiated by another disease) for hypertension?

Answer 31

Aortic coarctation (narrowing of the aorta) Renal Disease Mineralocorticoid excess Thyroid disease Eclampsia (complication of pregnancy - causes seizures) Cancer treatment (Slide 22)

Question 32

What are 4 examples of the effects of hypertension?

Answer 32

Progressive structural changes in vasculature Acceleration of atherosclerosis (narrowing of blood vessels) Stroke, aneurysms, vascular dementia (dementia which occurs when blood flow to the brain is disrupted) Left ventricular hypertrophy (when the left heart muscle thickens and enlarges) Kidney failure (Slide 23)

Question 33

What are 4 differences between a healthy artery and a remodelled artery as a result of hypertension?

Answer 33

Answers include: Proliferation of fibroblasts and infiltration of immune cells in adventitial layer Vascular smooth muscle cells (VSMCs) proliferation and migration in media Double elastic lamina develops due to increased muscularisation Proliferation of apoptosis-resistant endothelial cells Narrowing / occlusion (blocking) of vessel lumen (Slide 24)

Question 34

What are 4 examples of classes of antihypertensive drugs and how do they reduce blood pressure?

Answer 34

Answers Include: Vasodilators (reduce vascular resistance) Sympathetic inhibitors (reduce cardiac output) RAAS inhibitors (decrease venous return) Diuretics (decrease blood volume) Calcium Channel Blockers (vascular smooth muscle dilation, reducing vasconstriction and vascular resistence) (Slides 27 and 31)

Question 35

What are 2 types of sympathetic inhibitors which can be used to decrease hypertension, and how do they work?

Answer 35

β-blockers (such as atenolol or propranolol) - decrease CO and reduce renin production leading to a reduction in Angiotensin II. Can also indirectly cause vasodilation of peripheral arteries α-blockers (such as prazosin) - block post-synaptic α1 adrenoceptors which leads to dilation of arteriolar resistant vessels and lower peripheral resistance. They also dilate venous capacitance vessels, which reduces venous return and CO. (Slide 29)

Question 36

What are 2 examples of RAAS acting drugs which reduce blood pressure and how do they do so?

Answer 36

ACE inhibitors (such as captopril) - reduce angiotensin II levels Angiotensin II receptor antagonists (ARBs) - e.g (such as losartan and valsartan) - selectively block AT1 receptors which mediate the vasoconstrictive, cardiac / vascular hypertrophy effects of angiotensin II (Slide 30)

Question 37

How do diuretics reduce blood pressure?

Answer 37

They act at varying sites in the kidney to increase sodium and water depletion which leads to a hypotensive effect (Slide 30)

Question 38

How do calcium channel blockers (CCBs) reduce blood pressure?

Answer 38

Calcium channel blockers (diltiazem, verapamil, amlodipine) block calcium entry into vascular smooth muscle cells (VSMCs) and / or cardiac muscle cells, promoting relaxation of the muscle and vasodilation (Slide 31)

Question 39

During what scenario are vasodilators used to reduce blood pressure and why?

Answer 39

During a "hypertensive emergency" - as they provide rapid and controlled blood pressure reduction (Slide 31)

Question 40

What are the current treatment guidelines for grade 1 and 2 hypertension?

Answer 40

Grade 1 - Immediate drug treatment in high-risk patients or those with CVD, CKD, DM or HMOD Grade 2 - immediate drug treatment in all patients. Step 1 - ACE inhibitors in patients under 55 or calcium channel inhibitors (patients over 55 and all black people of African or Caribbean descent) (thiazide-like diuretics can be used in place of calcium channel inhibitors in people with oedema) Step 2 - Both of the above Step 3 - Both of the above + a thiazide-like diuretic Step 4 - (Resistant hypertension) all 3 of above plus a further diuretic (such as low dose spironolactone or higher doses of thiazide like diuretic or an α or β blocker) (Slides 32 and 33)