27 28 Blood pressure control

Question 1

What happens when we can we a slight dicrotic notch on the ECG? (normal)

Answer 1

Backflow of blood in the arteries when aortic valve is closed,

it indicates the end of systole and the start of diastole

Question 2

What is pulse pressure?

How is it determined?

Answer 2

difference between the systolic and diastolic pressure;

determined by stroke volume and compliance of
the arteries

Question 3

How does ageing affect pulse pressure?

Answer 3

Ageing increases arterial stiffness and thus pulse pressure

Question 4

What is the equation to MAP from SP and DP;

and what does it mean?

Answer 4

MAP is the average pressure in the cardiac cycle

MAP = DP + 1/3 (SP-DP)

Question 5

What is the relationship of MAP with CO and TPR?

Answer 5

MAP = CO x TPR

Question 6

• Average arterial BP is
________ mm Hg.
• Average pulmonary BP
is _____ mm Hg.

Answer 6

120/80;

22/8

Question 7

What are the factors that impact MAP?

Answer 7

CO
Peripheral resistance
Elasticity decreases > BP increases
Volume of blood

Question 8

How will the RAA system affect MAP? (Neurohormonal factor)

Answer 8

increase renal and sodium rentention , increase water retention = blood volume, increase CO and thus MAP

Question 9

Endothelial factors can affect MAP, why?

Answer 9

They can affect the TPR

MAP = CO x TPR

Question 10

How do Na and adrenaline affect arterial and venous diameters?

Answer 10

NA cause arterial and venous constriction via a1 receptors

Adrenaline has higher affinity for beta than alpha receptors
If we block beta receptors, adrenaline can cause constriction in skeletal muscle via alpha receptors

Question 11

How do ANP work?

Answer 11

Atrial natriuretic peptide hormone reduces blood pressure by antagonising aldosterone;
it increases water excretion from the kidney

Question 12

The ________ of the brain regulates ANS and neurohormonal system

Answer 12

hypothalamus

Question 13

What are the 3 main reflexes in the cardiovascular system?

Answer 13

1. Baroreceptor reflex (most important) monitors BP
2. Cardiopulmonary reflexes monitor blood volume
3. Chemoreceptor reflexes monitor gas (CO2)

Question 14

Which of the following is false?
A. Baroreceptors are most sensitive between 80-120 mmHg
B. The sensitivity of baroreceptors is increased by small pulse pressure
C. Baroreceptors in the carotid sinus continuously monitor the mean arterial pressure and the pulse pressure
D. A rise in MAP or increase in pulse pressure reduce the firing frequency of AP

Answer 14

B and D

increased by a large pulse pressure

increases the firing frequency upon a rise in MAP

Question 15

In baroreceptor reflex,an increase in blood pressure cause more signals to be sent to the __________. This _______ a part of the brain which increases the blood pressure.

(Negative feedback)

Answer 15

brainstem

inhibits

Question 16

How can a baroreceptor fire signals?

Answer 16

When there is change in pressure stretching the wall of blood vessel, non selective cation channels like Na+ and Ca2+ on the baroreceptor nerve endings will open. More Na+ and Ca2+ flow into the cell, causing depolarization.

Question 17

What does cardiopulmonary receptors react to and what is their actions?

Answer 17

The react to a change (decrease) and blood volume and they will cause the secretion of ADH

“volume receptors”

Question 18

An increase bp will cause increase firing of AP by baroreceptors in carotid arteries and aorta, triggering cardiovascular control in _______________ (part of the brain).

Answer 18

Medulla oblongata

Question 19

Where can cardiopulmonary receptors be found?

Answer 19

In low pressure regions like pulmonary arteries and atria of the heart

> detect change in blood volume

Question 20

What are chemoreceptor sensitive to? Where are they located?

Answer 20

They are sensitive to vascular O2 deficiency, CO excess and H+ excess.
They are located in the aortic and carotid bodies