autonomic nervous system

Question 1

what is the baroreceptor reflex involved in

Answer 1

blood pressure control

Question 2

what is the equation for calculating mean arterial blood pressure

Answer 2

cardiac output x total peripheral distance

Question 3

how do you calculate cardiac output

Answer 3

heart rate x force of contraction

Question 4

how do you calculate total peripheral resistance

Answer 4

1/r^4

Question 5

what branch of the motor nervous system has some influence over heart rate at rest

Answer 5

parasympathetic

Question 6

function of baroreceptors

Answer 6

sense pressure in system and send signals to brain

Question 7

along what nerve do signals from baroreceptors reach the brain

Answer 7

afferent vagus nerve

Question 8

what branch of the motor nervous system do baroreceptors stimulate

Answer 8

parasympathetic nervous system

Question 9

what branch of the motor nervous system do baroreceptors inhibit

Answer 9

sympathetic nervous system

Question 10

how do baroreceptors cause blood pressure to be maintained at rest

Answer 10

constant firing rate from baroreceptor to brain (afferent vagus nerve) activates parasympathetic nerve (efferent vagus nerve) to heart and activates the inhibitory nerve to the sympathetic nerve; this reduces the sympathetic response and increases the parasympathetic response to heart, arterioles and veins, meaning heart rate is lowered and diameters of blood vessels are increased, maintaining the correct blood pressure

Question 11

how do baroreceptors cause high blood pressure to be lowered

Answer 11

arterial baroreceptor firing rate increases so much bigger signal sent to brain, causing a much bigger activation of the parasympathetic nerve to heart and a much bigger activation of inhibitory nerve to sympathetic nerve; this causes a much bigger reduction in the sympathetic response to heart, arterioles and veins, meaning heart rate is lowered and diameters of blood vessels are increased, lowering blood pressure

Question 12

how do baroreceptors cause low blood pressure to be increased

Answer 12

arterial baroreceptor firing rate decreases so much smaller signal sent to brain, causing a much smaller activation of parasympathetic nerve to heart and a much smaller activation of inhibitory nerve to sympathetic nerve; this causes a much bigger sympathetic response to heart, arterioles and veins, meaning heart rate is increased and diameters of blood vessels are decreased, increasing blood pressure

Question 13

how does changing posture alter blood pressure

Answer 13

gravity

Question 14

where is blood pressure neutralised when standing

Answer 14

at heart

Question 15

where is blood pressure lower when standing

Answer 15

above heart

Question 16

where is blood pressure higher when standing

Answer 16

below heart

Question 17

when standing, how does increased hydrostatic pressure in leg blood vessels lead to lower arterial blood pressure

Answer 17

increased hydrostatic pressure in leg blood vessels → venous distension so more blood in venous system than normal → less blood in arteries → less pressure in arteries

Question 18

when standing, what does increased hydrostatic pressure in leg blood vessels also cause in capillaries

Answer 18

extra capillary fluid loss

Question 19

what is the result of venous distension and capillary fluid loss when standing

Answer 19

reduced venous return so lower cardiac output and less TPR so lower blood pressure in arterial system

Question 20

how is cardiac output increased when standing up to increase blood pressure by noradrenaline

Answer 20

increase heart rate or force of contraction via sympathetic nervous system (noradrenaline)

Question 21

how is cardiac output increased when standing up to increase blood pressure by adrenaline

Answer 21

adrenal gland sympathetic nerve produces adrenaline which travels up to heart and increases HR and FOC (also causes vasoconstriction to increase TPR)

Question 22

what is postural hypotension

Answer 22

impaired autonomic function so less effective at increasing cardiac output, causing blood pressure to stay low especially at the brain (cerebral hypo-perfusion), causing fainting

Question 23

why do people faint with postural hypotension

Answer 23

by lying down, gravity has no effect

Question 24

what drives the pupillary light reflex

Answer 24

autonomic control of iris muscle

Question 25

parasympathetic nerve: location of pre- and post-ganglionic fibres

Answer 25

longer pre-ganglionic fibre to ganglion near eye, short post-ganglionic fibre to control iris muscle

Question 26

what neurotransmitter is released by the parasympathetic nerves in the pupillary light reflex

Answer 26

acetylcholine

Question 27

what drug is also used to mimic acetylcholine

Answer 27

pilocarpine

Question 28

what is the outcome on the pupil of parasympathetic activation

Answer 28

constriction

Question 29

what drug can block parasympathetic activation and cause pupil dilation

Answer 29

tropicamide

Question 30

what branch of the motor nervous system has some influence over pupil constriction at rest

Answer 30

parasympathetic, as pupil is mildly constricted

Question 31

pupillary light reflex: when light enters, what nerve is activated

Answer 31

sensory optic nerve II

Question 32

pupillary light reflex: where is the information sent to

Answer 32

pretecal nucleus in brain

Question 33

pupillary light reflex: once effector response is created, what nerve is activated

Answer 33

pre-ganglionic ocular nerve III to ciliary ganglion, then post-ganglionic ocular nerve III to iris muscle

Question 34

pupillary light reflex: what is the outcome of light presence

Answer 34

constriction (more light caused more constriction)

Question 35

pupillary light reflex: what occurs if the stimulus is only present in one eye

Answer 35

both eyes respond - doesn’t matter if stimulus is only present in one eye

Question 36

pupillary light reflex: if there is a response in the right eye but not left, what does this indicate

Answer 36

sensory optic nerve II and the right side of parasympathetic neurone is fine, but there is a problem in efferent parasympathetic supply in left eye