Lecture 10 Flashcards
Which structure generates pressure for systemic circulation?
Left ventricle generates lots of power which is needed to highly pressurise the system
Why is a large pressure difference importance?
Used to drive blood around our system.If there was a decrease in pressure there would be reduced circulation to the brain
Describe the change in blood pressure throughout systemic circulation?
BP high in major arteries (oscillatory) - falls around arterioles, capillaries and venules (oscillatory. nature is reduced) - very low in veins
How does blood flow in affect arterial blood volume and pressure?
Fills arteries
Increases arterial blood volume
Raises arterial pressure
How does blood flow out affect arterial blood volume and pressure?
Drains arteries
decreases arterial blood volume
Lowers arterial pressure
What determines mean arterial blood pressure?
balance between flow in and flow out
what is cardiac output?
flow of blood out of ventricles into arteries
What is cardiac output dependent on?
Resistance of drainage of blood out of arteries into capillary beds
What happens if mean arterial pressure is too low?
Cardiac output increases
what happens if mean arterial pressure is too high?
Increases resistance, making it more difficult for blood to flow out into capillary beds which will increase pressure again
What is the equation for mean arterial pressure?
MAP = CO x TPR
What is stroke volume?
Volume of blood that is getting pushed out every time your heart beats (measured in L per minute)
What is the purpose of stroke volume?
Determines how strongly and quickly our heart is contracting
How can cardiac output be driven differently?
Low stroke volume but very fast heart beat.
Or High stroke volume but slow heartbeat
Heart disease?
When the walls of the heart become stiff and don’t contract as well, stroke volume goes down however metabolic needs stay the same. To compensate for this the heart rate increases which puts the heart under immense stress
Ids cardiac output s set value?
No, it is highly variable considering our metabolic needs fluctuate.
How is homeostasis of arterial blood pressure maintained?
The brain is able to determine blood pressure out in our arteries and then make changes to it if necessary
What is afferent input?
Communication/signals from various parts of the body which the brain receives
What is efferent output?
Signals sent from brain to make changes around the body
What are baroreceptors?
Blood pressure sensors that measure blood pressure.
Where are baroreceptors located?
Heavily concentrated in aortic and carotid sinus/arteries
How do baroreceptors measure BP?
They sense a stretch in arteries. They are constantly sending afferent input (signal with a pce) to the brain.
How does gravity effect stroke volume?
In an upright position blood vessels are working against gravity which decreases stroke volume. This means cardiac output also falls slightly. Only slightly because as stroke volume falls , heart rate will compensate by increasing
