Control Of Arterial Blood Pressure 1

Question 1

In clinical practise what is often measured in term of blood pressure

Answer 1

Systemic arterial blood pressure

And express it as systolic and diastolic

Question 2

What su systolic arterial blood pressure

Answer 2

Pressure exerted by the blood on walls of aorta and systemic arteries when heart contracts
Should not exceed 140mmHg under resting conditions

Question 3

What is diastolic arterial bp

Answer 3

Is the pressure exerted by blood on walls of aorta and systemic arteries when heart relaxes
Should not normally exceed 90mmHg under resting conditions

Question 4

What is pulse pressure

Answer 4

Is the difference between systolic and diastolic blood pressure
40mmHg (difference between 120mmHg and 80mmHg)

Question 5

What is mean arterial blood pressure

Answer 5

The average arterial blood pressure during a single cardiac cycle which invokes contraction and relaxation of the heart

Question 6

Why is the MAP not obtained by averaging the systolic and diastolic pressures

Answer 6

During a normal cardiac cycle:

The relaxation (diastolic) portion of the cardiac cycle is about twice as long as the contraction (systolic) portion of the cardiac cycle

Question 7

What is the simplest formula to estimate the map

Answer 7

MAP = (2x diastolic) + systolic divided by 3

93.3mmHg

Question 8

What is another way to estimate MAP

Answer 8

Map= DBP + 1/3 difference between SBP and DBP

Question 9

What is normal arterial blood pressure

Question 10

What is the norm,a range of the map

Answer 10

70-105 mmHg

Question 11

What so the minimum map and what is it needed for

Answer 11

60mmHg

Needed to perfuse the Coronary arteries, Braun and kidney

Question 12

Map must be naimteined in a narrow range to ensure

Answer 12

So pressure high enough to perfuse internal organs (brain, heart and kidney)

Pressure not too high to damage the blood vessels or place an extra strain on the heart

Question 13

What is the map in relation to co and tpr

Answer 13

MAP (mean arterial pressure) = CO (cardiac output) x TPR (total peripheral resistance)

Question 14

What is cardiac output

Answer 14

Volume of blood pumped by each ventricle of heart per minute
Co = SV x HR

Question 15

What so the stroke volume

Answer 15

Volume of blood pumped by each ventricle of the heart per heart beat

Question 16

What is the total peripheral resistance

Answer 16

Sum of resistance of all peripheral vasculature in systemic circulation

Question 17

What is tpr regulated by

Answer 17

Vascular smooth muscle

Question 18

What are the main sites of tpr

Answer 18

Arterioles

Question 19

What increases and decreases tpr?

Answer 19

Vasoconstriction increases tpr and map

Vasodilation decreases tor and Map

Question 20

What supplies the vasc smooth muscles with a nervous supply

Answer 20

Sympathetic nerve fibres

Neurotransmitter noradrenaline acting on alpha receps

Question 21

What is vasomotor tone

Answer 21

Vasc smooth muscle partially constricted at rest

Question 22

What causes the vasomotor tone

Answer 22

Tonic discharge of symp nerves resulting in continuous release of noradrenaline

Question 23

What happens if the sympathetic discharge increases or decreases in relation to the vasomotor tone

Answer 23

If the symp inv increases - increase vasomotor tone lead to vasoconstriction increasing tpr and map

If symp is decreases - decrease vasomotor tone lead to vasodilation decreasing tpr and map

Question 24

Is there parasymp inv to vasc smooth muscle

Answer 24

No Exocet the clitoris and penis

Question 25

What is the baroreceptors reflex imp in

Answer 25

Moment to moment regulation of arterial bp including prevention of postural changes

Question 26

Where are baroreceptors

Answer 26

Aortic arch

Carotid sinus

Question 27

What do bothe th baroreceptors signal to

Answer 27

Both signal to medulla

Carotid - via 9th CN
Aortic - via 10th CN

Question 28

What does the baroreceptors reflex do in relation to map

Answer 28

Short term regulation of map

Negative feedback acts to minimise any disturbances to controlled variables

Question 29

What are some baroreceptors responses

Answer 29

Arterial bp increases
Carotid sinus afferent nerve fibres firing increases
Cardiac vagal efferent nerve fibres firing increases
Cardiac symp efferent nerve fibres firing decreases
Symp vasoconstrictor nerve fibres firing decrease

Question 30

What does the baroreceptors do if there is a decreases in ABP.

Answer 30

Decreases discharge
Decrease vagal activity/ increase cardiac symp/increase symp constrictor tone
Etc

Question 31

What to baroreceptors only respond to

Answer 31

Acute changes in blood pressure

Baroreceptors firing decreases if high blood pressure is sustained

Question 32

What is blood pressure

Answer 32

Outward (hydrostatic) pressure exerted by the blood on blood vessels walls