Blood Pressure

Question 1

How many litres of blood in the body?

Answer 1

4-6L

Question 2

What is the pulmonary circuit?

Answer 2

Lungs

Question 3

What is the systemic circuit?

Answer 3

Rest of the body - not lungs

Question 4

What is the cardiac output?

Answer 4

5L/min

Question 5

Define maxima

Answer 5

Systolic pressure

Question 6

Define minima

Answer 6

Diastolic pressure

Question 7

What is the incisura/dicrotic notch?

Answer 7

Brief drop caused by back flow which closes atrioventricular valves

Question 8

How do you calculate mean arterial pressure?

Answer 8

Diastolic + 1/3 pulse pressure

Question 9

How you calculate pulse pressure?

Answer 9

Systolic - diastolic

Question 10

Measuring blood pressure

Answer 10

1) Cuff at heart level on brachial artery
2) Inflate above expected systolic pressure
3) Release pressure (arterial pressure > cuff pressure) - Korotoff sound
4) Record systolic pressure
5) Release pressure. Sound: tapping –> muting –> pounding –> muffling –> silence
6) Muffle (UK) or silence (US) is diastolic pressure

Question 11

What are the two main determinants of systolic pressure?

Answer 11

• Ejection velocity

- Stroke volume

Question 12

What are the two main determinants of diastolic pressure?

Answer 12

• Total peripheral resistance

- Blood flow: arterial –> venous

Question 13

Define orthostasis

Answer 13

Standing up

Question 14

What occurs during orthostasis?

Answer 14

Raise MABP as fall in bp is detected by baroreceptors
Increase sympathetic input to the heart
Increase sympathetic flow to vessels (constriction)
Decrease parasympathetic flow to heart

Question 15

How can drugs affect blood pressure?

Answer 15

As MABP = CO x TPR, any drugs that affect either cardiac output or total peripheral resistance will affect the mean arterial blood pressure

Question 16

Give some examples of drugs that affect total peripheral resistance

Answer 16

• Angiotensin II
• Sympathetic agonist at α1 receptors
• Sympathetic antagonist at α1 receptors

Question 17

Effect on total peripheral resistance by angiotensin II

Answer 17

Increase total peripheral resistance by vasoconstriction

Question 18

Give an example of a sympathetic agonist at α1 receptors which will increase TPR by vasoconstriction

Answer 18

Phenylephrine

Question 19

Give an example of a sympathetic antagonist at α1 receptors which will decrease TPR by vasodilation

Answer 19

Prazosin

Question 20

Give examples of drugs that affect cardiac output

Answer 20

• Sympathetic agonists at ß1 receptors
• Digitalis/Digoxin
• Sympathetic antagonists at ß1 receptors
• Ca2+ channel blockers

Question 21

Give an example of a sympathetic agonist at ß1 receptors which will increase CO by increasing HR or stroke volume

Answer 21

Dobutamin

Question 22

Give an example of a sympathetic antagonist at ß1 receptors which will decrease CO by decreasing HR or stroke volume

Answer 22

Atenolol

Question 23

Which part of the body always receives the same volume of blood?

Answer 23

The brain