L21 - Cardiovascular System 4

Question 1

Where are baroreceptors located and what is their role?

Answer 1

located in the carotid sinus and aortic arch

stabilise pressure and smooth out variations by responding to BP within 1-2 heartbeats

Question 2

How is blood pressure controlled?

Answer 2

changing cardiac output; heart rate and contractility
changing peripheral resistance; diameter of vessels
sympathetic
parasympathetic

Question 3

What happens when humans stand up?

Answer 3

↓ MAP resulting in ↓ stretch and nerve firing
augmented sympathetic tone results in ↑ heart rate and contractility and ↑ TPR
withdrawal of cardiac parasympathetic tone results in ↑ heart rate

Question 4

What happens when humans lie down?

Answer 4

↑ MAP resulting in ↑ stretch and nerve firing
withdrawal of vascular sympathetic tone results in ↓ TPR and ↓ venous return
augmented cardiac parasympathetic tone results in ↓ heart rate

Question 5

How is blood pressure regulated long-term?

Answer 5

predominantly through changes in cardiac output and TPR

Question 6

How is cardiac output increased?

Answer 6

increased ECF and reduced renal salt excretion

Question 7

How is TPR increased?

Answer 7

thickening of the arterial wall - hypertrophy

high levels of vasoconstrictive hormones

Question 8

What is an example of a low pressure receptor and what is its role?

Answer 8

atrial baroreceptors which monitor changes in pressure that result from changes in central blood volume

Question 9

What does anticipation and initial movement of exercise cause?

Answer 9

activation of sympathetic nerves, suppression of parasympathetic nerves, ↑ HR, ↑ myocardial contractility and ↑ blood vessel tone (vasoconstriction)

Question 10

During exercise will there be generalised vasodilation or vasoconstriction?

Answer 10

generalised vasoconstriction from sympathetic stimulation of peripheral vessels

Question 11

How does the body respond to increasing demand on muscles during excercise?

Answer 11

generalised vasoconstriction from sympathetic stimulation of peripheral vessels
blood flow to active muscles; local vasoactive mediators and metabolic changes, vasodilation
blood flow to brain remains steady

Question 12

How does TPR change during exercise and why?

Answer 12

TPR decreases over time due to vasodilation in exercising muscle which is greater than vasoconstriction occurring elsewhere in the body

Question 13

What do you predict happens to blood pressure during exercise?

Answer 13

increases

Question 14

Why does MAP increase during exercise?

Answer 14

initially pre-exercise responses constrict arterioles, therefore increasing TPR and MAP
as exercise proceeds: TPR falls overall due to vasodilation to working muscles however CO increases substantially

Question 15

Why doesn’t the baroreceptor reflex prevent an increase in MAP during exercise?

Answer 15

allows a rise in both MAP and CO as the medulla resets the baroreflex set point

Question 16

Would you predict a larger increase in MAP during static exercise or dynamic exercise?

Answer 16

larger increase in MAP during static exercise

Question 17

Why is there a larger increase in MAP during static exercise?

Answer 17

because less muscle groups are being used and therefore less vasodilation occurs resulting in increasing TPR rather than decreasing TPR
as a result there is a larger increase in MAP