4. Control of arterial pressure Flashcards
What is blood pressure defined as?
Blood pressure is the pressure exerted on the walls of the arteries
When does arterial blood pressure peak and nadir?
Peaks during systole
nadir during diastole
What is the pulse pressure?
Diastolic pressure + 1/3 systolic pressure
due to heart spending twice as long in diastole than systole
What are the factors that effect arterial blood pressure?
Pulse pressure
Mean arterial pressure
Effect of posture
Effect of age
What are the determines of BP?
C.O.
Total peripheral resistance
What are the determines of BP?
C.O.
Total peripheral resistance
How is the BP calculated?
C.O. x T.P.R.
What are baroreceptors?
Stretch receptors in the walls of the carotid sinus and aortic arch
Where does the baroreceptors signal?
Signal via the vagal and glossopharyngeal afferents to the medullary cardiac and vasomotor areas
Where do the afferents from the baroreceptors synapse?
They synapse in the NTS of the medulla
What is the relationship between neurons and sympathetic outflow?
Neurons are inhibitory to sympathetic outlfow
What is the relationship between neurons and vagal outflow?
Neurons excitatory to vagal outflow
What is the net effect of baroreceptors?
Net effect is to reduce cardiac output
slow heart and cardiac contractibility
What will a rise in BP lead to?
Increased baroreceptor stimulation Decreased sympathetic output to Heart Increase in vagal tone Decrease in vasomotor tone Decrease in cardiac output Decrease in TPR Both changes acts to reduce BP back to normal
What does a fall in BP lead to?
Increased baroreceptor stimulation Decreased sympathetic output to Heart Increase in vagal tone Decrease in vasomotor tone Decrease in cardiac output Decrease in TPR Both changes acts to reduce BP back to normal
