| When eating a meal, what changes happen to blood vessels | Increased gut activity leads to vasodilation
Total resistance then falls so arterial pressure falls and venous pressure increases
Rise in venous pressure causes a rise in cardiac output while fall in arterial pressure increases cardiac output and heart rate
Venous pressure reduced due to extra pumping of the heart |
| Why is there a risk of pulmonary oedema during exercise | Due to the drastic increase in venous pressure
This tends to overfill the heart since the outputs of the right and left ventricles cannot be matched
This can be prevented by a rise in heart rate which occurs when exercise begins |
| What events in the blood vessels happen when standing up | Due to gravity, blood pools in the superficial veins in the legs
So central venous pressure falls
By starling's law, arterial pressure falls as well
This is detected by the baroreceptors which raises heart rate
TPR is increased to defend arterial pressure |
| What can happen when reflexes don't work when standing up | Postural hypotension |
| What events can a hemorrhage lead to | Reduced blood volume lowers venous pressure so cardiac output falls
Due to starling's law there is a decrease in arterial pressure as well
Baroreceptors detect this which raises heart rate
Heart rate increases which increases arterial pressure but not venous pressure
TPR also increases which helps arterial pressure but not venous pressure
So it does not solve the problem --> oedema etc. |
