Reponse Of Whole System (6)

Question 0

How does the body react to exercise?

Answer 0

• Ventricles match stroke volume
• But right pumps blood to left and causes overfilling if not due to the body increasing the heart rate so the blood is pumped away
• When venous pressure starts to increase the stroke volume increases and heart rate increases. So no pulmonary oedemas occur.

Question 1

What change in the veins does a fall in arterial pressure cause?

Answer 1

• Venoconstriction

Question 2

How does the circulation system cope with standing up?

Answer 2

• Blood pools in superficial veins of the legs
• Central venous pressure falls
• Baroreceptors detect fall in arterial pressure
• Raise heart rate but venous pressure’s still low
• TPR increase to defend arterial pressure
• Turns off blood supply to the skin and gut until blood flow is re-established.

Question 3

What happens in a haemorrhage?

Answer 3

• Decrease in blood volume which lowers venous pressure
• Cardiac output decreases
• Arterial pressure falls - baroreceptors detect
• Increase in heart rate to cope, but really lowers venous pressure more. Not good
• Increase in TPR which helps arterial pressure and lowers venous pressure. But need to increase venous pressure
• Venoconstriction and auto-transfusion do this

Question 4

What happens when there’s a long term increase in blood volume?

Answer 4

• Kidneys control blood volume
• If high for days -> venous pressure increase
• Cardiac output increase and therefore arterial pressure increase
• Forces more blood through tissues
• Autoregulates and increase in TPR
• So increase in arterial pressure and stays up