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Flashcards in 6. Control of the Cardiovascular System Deck (16)
1

At a constant cardiac output, a rise in total peripheral resistance does what to arterial and venous pressures?

Arterial pressure rises
Venous pressure falls

2

At a constant total peripheral resistance, a rise in cardiac output does what to arterial and venous pressures?

Arterial pressure rises
Venous pressure falls

3

At a constant total peripheral resistance, a fall in cardiac output does what to arterial and venous pressures?

Arterial pressure falls
Venous pressure rises

4

How can stroke volume be increased?

Increase end diastolic volume by increasing ventricular filling
Decrease end systolic volume by ejecting more blood

5

What is preload?

The end diastolic stretch of the myocardium, determined by venous pressure

6

What is after load?

Force required to expel blood into the arteries

7

Describe Starling's law of the heart

The more the heart fills, the harder it contracts

8

Describe a stroke volume against venous pressure graph

Stroke volume increases as venous pressure increases, it then peaks and falls due to overfilling and over stretching

9

What is contractility and how is it increased?

Contractility is the stroke volume that occurs for a given venous pressure (the gradient of the stroke vol against venous pressure graph)
It is increased by sympathetic activity

10

At a constant cardiac output, a fall in total peripheral resistance does what to arterial and venous pressures?

Arterial pressure falls
Venous pressure rises

11

What is the response of the cardiovascular system after consuming a meal?

Increased activity of the gut leads to local vasodilatation
TPR falls, arterial pressure falls, venous pressure rises
Rise in venous pressure causes a rise in cardiac output
Fall in arterial pressure triggers a rise in heart rate and cardiac output
Extra pumping of the heart reduces venous pressure and increases arterial pressure

12

How does the cardiovascular system respond to exercise without overfilling the heart?

Enormous increase in demand
Muscles force extra blood back to the heart (venous pressure increases)
Increase in heart rate allows cardiac output to increase without stroke volume increasing to the point of over stretching
Demand met

13

How does the cardiovascular system respond to standing up?

Upon standing blood pools in superficial veins in legs
Venous pressure falls
Cardiac output falls
Arterial pressure falls
Baroreceptors detects all in arterial pressure
Heart rate increases, venous pressure still low
TPR increases to defend arterial pressure

14

What is the condition known as when baroreceptor reflex to standing up doesn't work?

Postural hypotension

15

What is the cardiovascular response to haemorrhage?

Reduced volume of blood lowers venous pressure
Cardiac output falls
Arterial pressure falls
Baroreceptor cause increase in heart rate and TPR
Rise in heart rate further decreases venous pressure
Heart rate continues to increase
Venous pressure needs to be increased to solve problem
Venoconstriction and blood transfusion/auto transfusion

16

What is the cardiovascular system response to long term blood volume increase?

Blood volume controlled by kidneys
If blood volume increases for days, venous pressure increases
Cardiac output rises
Arterial pressure rises
More blood to tissues which cause increase in TPR
Arterial pressure rises further and stays up