Short term control of blood pressure

Question 1

importance of regulating mean arterial pressure

Answer 1

MAP is the driving force pushing blood through the circulation and so has to be regulated if too low u can faint if too high hypertension

Question 2

arterial baroreflex

Answer 2

sensors in the aortic arch and internal carotid arteries. stretch receptors which sense stretch and start firing action potentials. aortic arch travels up to medulla in vagus nerve, carotid sinus travel up in cranial nerve. this comes back to heart and blood vessels via sympathetic nerves, parasympathetic nerves and adrenaline

Question 3

inputs to medullary cardiovascular centres

Answer 3

cardiopulmonary baroreceptors, central chemoreceptors, chemoreceptors in muscle, joint receptors, higher centres

Question 4

effect of changes in posture on cardiovascular system

Answer 4

when you stand up blood pools in the venules and veins of feet and legs so end diastolic volume is reduced, preload is reduced so stroke volume is reduced so cardiac output is reduced so MAP is reduced

Question 5

valsalva manoeuvre

Answer 5

forced expiration against a closed glottis. stops venous return and reduces the preload on the heart and therefore reduces cardiac output. used to asses strength of baroreflex

Question 6

valsalva manoeuvre process

Answer 6

increased thoracic pressure transmitted to aorta, reduces filling pressure from veins which reduces venous return, end diastolic volume, stroke volume, cardiac output, MAP, reduced MAP is detected by baroreceptors which initiate reflex increase in CO and TPR, then manoeuvre ends, decrease in thoracic pressure is transmitted to aorta, so VR is restored so SV increases so CO and MAP increases