cardiovascular control mechanisms

Question 1

role of baroreceptors

Answer 1

detect blood pressure

Question 2

negative feedback of blood pressure

Answer 2

new blood pressure detected by baroreceptors → cardiovascular control centre → increase/decrease pressure → baroreceptor → cardiovascular control centre → return to target blood pressure

Question 3

ways of increasing blood pressure (SNS, PNS, Ang II, ADH)

Answer 3

increase SNS, decrease PNS, increase Ang II, increase ADH

Question 4

ways of decreasing blood pressure (SNS, PNS, Ang II, ADH)

Answer 4

decrease SNS, increase PNS, decrease Ang II, decrease ADH

Question 5

peripheral nervous system innervation of baroreceptors: location and nerve

Answer 5

baroreceptors (mechanoreceptors) in carotid sinus (down glossophayngeal afferent to vasomotor centre) or aortic arch (down vagus afferent to vasomotor centre)

Question 6

peripheral nervous system innervation of baroreceptors: mode of action

Answer 6

change firing rate in reponse to change in pressure e.g. fire more when arterial pressure builds up as greater stretch

Question 7

pressure range of carotid sinus baroreceptors

Answer 7

60-180 mmHg

Question 8

what pressure are baroreceptors most sensitive

Answer 8

90-100 mmHg

Question 9

PNS innervation: control centres

Answer 9

cardioregulatory and vasomotor centres in medulla oblongata

Question 10

PNS innervation: effect of increasing parasympathetic stimulation on heart rate, blood pressure and baroreceptor stretch

Answer 10

decreases heart rate; a decrease in blood pressure decreases baroreceptor stretch

Question 11

SNS innervation: effect of increasing sympathetic stimulation on heart rate, blood vessels and baroreceptor stretch

Answer 11

increases heart rate; vasodilation; increase in blood pressure increases baroreceptor stretch

Question 12

reflexes controlled by carotid sinus nerve activity: pathway

Answer 12

baroreceptors → carotid sinus glossopharyngeal nerve → vasomotor centre in medulla → vagus nerve (SAN), sympathetic cardiac nerves (ventricles), sympathetic vasoconstrictor nerves (resistance and capacitance vessels to control venous return e.g. less resistance when dilated so lowers pressure, causing less stretch by baroreceptors)