cardiovascular control mechanisms

Question 1

branches of autonomic nervous system

Answer 1

parasympathetic and sympathetic

Question 2

where does the parasympathetic arise from

Answer 2

cranial and sacral part of spinal cord

Question 3

where does the sympathetic arise from

Answer 3

thoracic and lumbar vertebra

Question 4

parasympathetic: pre-ganglion: length, neurotransmitter and receptor

Answer 4

pre-ganglionic neurone long, acetylcholine, nicotinic receptor

Question 5

parasympathetic: post-ganglion: length, neurotransmitter and receptor

Answer 5

post-ganglionic neurone short, acetylcholine, muscarinic receptor

Question 6

sympathetic: pre-ganglion: length, neurotransmitter and receptor

Answer 6

pre-ganglionic neurone short, sympathetic chain, acetylcholine and nicotitic receptors

Question 7

sympathetic: post-ganglion: length, neurotransmitter and receptor

Answer 7

post-ganglionic neurone long, noradrenaline, muscarinic receptor

Question 8

why is response from sympathetic innervation to blood vessels difficult to predict

Answer 8

different receptors so difficult to predict as it is variable

Question 9

what nervous system has no innervation to blood vessels

Answer 9

parasympathetic

Question 10

where does sympathetic innervation occur

Answer 10

innervates heart and all vessels except capillaries, precapillary sphincters and some metarterioles

Question 11

sympathetic innervation: where is heavily innervated

Answer 11

kidneys, gut, spleen, skin

Question 12

sympathetic innervation: where is poorly innervated

Answer 12

skeletal muscle, brain

Question 13

sympathetic innervation: where does noradrenaline preferentially bind to on vessels and what does it cause

Answer 13

a1 adrenoreceptors to cause smooth muscle contraction and vasoconstriction

Question 14

vasomoter centre: where is it located

Answer 14

bilaterally in reticular substance of medulla and lower third of pons

Question 15

vasomoter centre: what is it composed of

Answer 15

vasoconstrictor (pressor) area, vasodilator (depressor) area and cardioregulatory inhibitory area

Question 16

vasomoter centre: what do high centres of brain exert; specifically lateral and medial

Answer 16

e.g. hypothalamus; exert powerful excitatory or inhibitory effects on vasomotor centre (e.g. preparing for exercise); lateral control heart activity influencing HR and contractility, medial control traffic down vagus nerve to change HR

Question 17

nervous control of vessel diameter: what neurotransmitter allows for SNS post-ganglionic innervation

Answer 17

noradrenaline

Question 18

nervous control of vessel diameter: define tonic activity

Answer 18

frequency of firing of action potential

Question 19

nervous control of vessel diameter: why is there baseline constriction

Answer 19

to allow both vasoconstriction and vasodilation

Question 20

nervous control of vessel diameter: effect of more tonic activity

Answer 20

vasoconstriction

Question 21

nervous control of vessel diameter: effect of less tonic activity

Answer 21

vasodilation

Question 22

cardiac innervation: parasympathetic effect on heart rate

Answer 22

decrease heart rate (decrease speed of depolarisation towards threshold of SAN)

Question 23

cardiac innervation: sympathetic effect on heart rate

Answer 23

increase heart rate (increase speed of depolarisation towards threshold of SAN)

Question 24

cardiac innervation: sympathetic effect on circulating plasma adrenaline

Answer 24

increase circulating plasma adrenaline

Question 25

what happens if both parasympathetic and sympathetic neurones are cut and significance

Answer 25

slight increase in heart rate, so always some parasympathetic nerve activity on heart at rest

Question 26

how does sympathetic nervous system influence force of contraction (pathway) when binding to heart

Answer 26

noradrenaline binds to B1 receptor → increases cAMP and PKA → L-type Ca2+ channels open → more Ca2+ influx → bind to SR Ca2+ release channel → more Ca2+ act in muscle contraction → greater force of contraction → increases Ca2+ uptake into IC stores

Question 27

controlling stroke volume: extrinsic (hormonal and neuronal) methods

Answer 27

increase SNS efferents to heart, increase plasma adrenaline

Question 28

controlling stroke volume: intrinsic methods

Answer 28

increase atrial pressure, increase venous return (Starling’s law of heart)

Question 29

what increases both stroke volume and heart rate to increase cardiac output

Answer 29

increasing plasma adrenaline and SNS efferents to heart

Question 30

what is reciprocal innervation

Answer 30

where increased afferent input from increased baroreceptor activity stimulates parasympathetic nerves to heart

Question 31

effect of reciprocal innervation

Answer 31

increases parasympathetic nerve activity, decreases sympathetic nerve activity, causing vasodilation and decrease in heart rate

Question 32

in reciprocal innervation, how is sympathetic nerve activity decreased

Answer 32

inhibitory neurone inhibits tonic activity

Question 33

4 ways to increase venous return and atrial pressure

Answer 33

increase blood volume, SNS activation of veins (vasoconstriction), increase skeletal muscle pump, increase respiratory movements