negative feedback in cardio system

Question 1

blood pressure

Answer 1

outwards pressure exerted by the blood on vessel walls

Question 2

systolic pressure

Answer 2

pressure on walls when heart contracts

Question 3

diastolic pressure

Answer 3

pressure when heart relaxes

Question 4

when is BP measured

Answer 4

during systemic circulation

Question 5

normal BP

Answer 5

normal systolic can vary between 90-120. Normal diastolic can vary between 60-80. 120/80.

Question 6

hypertension

Answer 6

high BP. daily average 135/85

Question 7

pulse pressure

Answer 7

difference between systolic and diastolic. normally between 30 - 50

Question 8

MAP

Answer 8

Mean arterial BP. average arterial BP during a single cardiac cycle

Question 9

does S or D last longer?

Answer 9

D lasts twice as long as S

Question 10

MAP equation

Answer 10

(2D + S)/3 normal is 70-105

Question 11

narrow range for MAP

Answer 11

The minimum for MAP is 60 or it will affect vital organs. Therefor it must be regulated within a narrow range to ensure presser to organs is high enough, but pressure isn’t too high it will damage blood vessels.

Question 12

baroreceptor reflex of MAP

Answer 12

regulated variable = mean arterial pressure. Sensor = baroreceptors. Control centre = medulla. Effectors = heart. Compensatory response = blood vessels. Results on restoration of regulated variable which leads to negative feedback to shut off system responsible for response

Question 13

where are the baroreceptors in the heart

Answer 13

in heart there are the carotid BRs and aortic BR. These send signals to the medulla

Question 14

how are the baroreceptors triggered

Answer 14

baroreceptors are mechanoreceptors which are sensitive to stretch, more stretch more signals sent to medulla to tell it if there’s a problem

Question 15

cardiac output

Answer 15

CO is the volume of blood pumped by each ventricle per minute

Question 16

stroke volume

Answer 16

the volume of blood pumped by each ventricle per heartbeat

Question 17

what factors regulate MAP

Answer 17

heart rate, stroke volume and SVR (systemic vascular resistance)

Question 18

autorhythmicity

Answer 18

the heart is electrically controlled muscular pump, the signals that control the heart are generated in the heart itself. meaning its capable of beating without external stimuli

Question 19

heart rate

Answer 19

Heart rate is modified by the autonomic nervous system. Sympathetic and parasympathetic.

Question 20

sympathetic division

Answer 20

stimulation accelerates heart rate (tachycardia)

Question 21

parasympathetic

Answer 21

stimulation of vagus nerve slows heart rate (bradycardia)

Question 22

how is stroke volume controlled

Answer 22

• SV is modified by autonomic nervous system
• SV increases if the contractile strength of heart is increased
• Sympathetic nerves innervate the ventricular myocardium and stimulation increases the force of contraction and increases SV
• Intrinsic control (within heart itself)

Question 23

systemic vascular resistance (SVR)

Answer 23

• SVR is regulated by vascular smooth muscles, Contraction causes vasoconstriction, increases SVR and MAP. Relaxation does the opposite

Question 24

vascular smooth muscles

Answer 24

regulated systemic vascular resistance. supplied by sympathetic nerve fibres. they are partially constricted at rest (vasomotor tone).

Question 25

how is vasomotor tone caused

Answer 25

cause by tonic discharge of sympathetic nerve s resulting in continuous release of noradrenaline