Autonomic Nervous System

Question 1

what are the two arms of the autonomic nervous system?

Answer 1

sympathetic and parasympathetic

Question 2

what does the autonomic nervous system control?

Answer 2

non-skeletal peripheral function: cardiac muscle, smooth muscle internal organs, skin

Question 3

which part of ANS is used for ‘rest and digest’?

Answer 3

parasympathetic

Question 4

which part of ANS is used for ‘fight and flight’?

Answer 4

sympathetic

Question 5

is ANS under conscious control?

Answer 5

no

Question 6

what is the exception to the rest and digest/fight or flight rule?

Answer 6

sympathetic nervous system both constricts and dilates blood vessels

Question 7

which visceral sensory receptors determine parasympathetic/sympathetic control of heart rate?

Answer 7

baroreceptors

Question 8

if blood pressure rises, what happens?

Answer 8

baroreceptors detect change and activate parasympathetic nervous system to reduce heart rate

Question 9

if blood pressure falls eg. due to blood loss, what happens?

Answer 9

baroreceptor firing rate slows down, so brain receives less stimulation and therefore less signal to parasympathetic and less inhibition to sympathetic so sympathetic increases heart rate

Question 10

which part of the brain is autonomic sensory (afferent) information relayed to?

Answer 10

hypothalamus in CNS

Question 11

where do visceral motor neurons project to and what do they synapse with?

Answer 11

brainstem or spinal cord, where they synapse with autonomic neurons (parasympathetic or sympathetic)

Question 12

what do autonomic neurons consist of?

Answer 12

pre-ganglionic and post-ganglionic neuron

Question 13

what is a ganglion?

Answer 13

nerve cell cluster or group of nerve cell bodies

Question 14

where are the ganglia located within the parasympathetic nervous system, and what is the relative length of pre-ganglionic neurons compared to post ganglionic?

Answer 14

close to, or embedded in the effector tissue eg. stomach and they are long in comparison to post ganglionic neurons

Question 15

where are the post ganglionic neurons in the parasympathetic nervous system in comparison to pre ganglionic?

Answer 15

synapse in or close to effector organ eg.stomach, very short and protude out into efffector, producing the effect

Question 16

where are the ganglia located within the sympathetic nervous system, and what is the relative length of pre-ganglionic neurons compared to post ganglionic?

Answer 16

ganglions are very close to originating site of pre-ganglionic neuron

short pre-ganglionic fibres and long post ganglionic fibres which project to various tissues and organs.

Question 17

why are the pre-ganglionic fibres so short in the sympathetic nervous system?

Answer 17

The key is that this allows each ganglion to influence other ganglia. This is what allows the whole response to occur globally and simultaneously, which is crucial to an effective fight or flight response.

Question 18

what is the exception to the two ganglia rule, and what is it?

Answer 18

There is only one sympathetic nerve to the adrenal gland

the adrenal gland acts like a post ganglionic fibre, releasing the HORMONE, ADRENALINE, (and some noradrenaline) into the BLOODSTREAM instead of neurotransmitter into a synapse

Question 19

which neurons in the ANS release acetylcholine?

Answer 19

preganglionic in both parasympathetic and sympathetic

post ganglionic in parasympathetic fibres

Question 20

which neurons in the ANS release noradrenaline?

Answer 20

post-ganglionic in the sympathetic

Question 21

which part of the adrenal gland produces adrenaline?

Answer 21

adrenal medulla

Question 22

what is the enteric nervous system?

Answer 22

the nervous system of the gut

Question 23

what is special about the lung?

Answer 23

there are NO sympathetic neurons innervating the lung tissue

BUT the sympathetic system secretes a hormone - adrenaline (causing dilation) instead of innervation

Question 24

which muscle of the bladder does the parasympathetic nervous system innervate?

Answer 24

detrusor muscle

Question 25

which muscle of the bladder does the sympathetic nervous system innervate?

Answer 25

sphincter

Question 26

what does the sphincter muscle do?

Answer 26

keeps the bladder closed

Question 27

what does the detrusor muscle do upon contraction?

Answer 27

forces urine out of the bladder

Question 28

which part of information about the bladder is relayed to the brain?

Answer 28

pressure

Question 29

what happens when the bladder gets full?

Answer 29

parasympathetic switches on and contracts detrusor muscle and sympathetic nervous system switches off and relaxes the sphincter muscle

however, the somatic motor also has control so there is some conscious control involved

Question 30

which type of receptor would you want at the autonomic ganglia and adrenal gland? What would be the speed of response?

Answer 30

NICOTINIC ACh receptor - a receptor coupled to ION CHANNELS producing a FAST response

Question 31

which receptors would you need to detect neurotransmitters from post ganglionic fibres? What would be the relative speed of the response? What is the advantage?

Answer 31

parasympathetic - muscarinic (ACh) G-protein coupled receptor

or

sympathetic - adrenergic (NA) G-protein coupled receptor

SLOW responses (secs/mins)

cell has control over receptors

Question 32

how are neurotransmitters biosynthesized?

Answer 32

precursor digested and then comes into nerve via bloodstream

nerve enzymatically converts into neurotransmitter at pre-synaptic vesicle

packaged into vesicles

Question 33

why do we need to remove the neurotransmitter from the synapse?

Answer 33

so we don’t get an overly prolonged effect

Question 34

how can you metabolise a neurotransmitter?

Answer 34

enzymes in synapse

remove via transport protein into pre-synaptic terminal to be recyled or glial cell

can also be metabolised in synapse prior to uptaking

Question 35

which enzyme converts precursors into acetylcholine and what are the names of the two precursors?

Answer 35

choline acetyl transferase

choline and acetyl CoA

Question 36

what are the two main types of acetylcholine receptors?

Answer 36

nictonic and muscarinic

Question 37

which enzyme degrades acetylcholine in the synapse?

Answer 37

acetylcholinesterase

Question 38

what happens if you block acetylcholinesterase?

Answer 38

overaccumulation of acetylcholine and its effects

Question 39

which precursors are involved in production of noradrenaline and what is the process of conversion and enzymes involved?

Answer 39

tyrosine from diet is converted to DOPA in nerve cell

DOPA converted to dopamine by DOPA decarboxylase

dopamine packaged into vesicles with enzyme dopamine B hydroxylase

noradrenaline is the product (produced in vesicle)

Question 40

how is noradrenaline removed from the synaptic cleft?

Answer 40

no enzyme in synapse (unlike ACh)

uptake into pre-synaptic terminal then broken down by MOA-O (monoamine oxidase)

OR uptaken into glial cell and metabolised by COMT

Question 41

how does production and release of adrenaline into bloodstream from adrenal medulla differ to that of noradrenaline from pre-synaptic terminal into the synapse?

Answer 41

after dopamine B hydroxylase is used in the vesicle to convert dopamine into noradrenaline, one more enzyme is used to convert this to adrenaline

when cells are depolarised, adrenaline is released into the bloodstream

Question 42

how is adrenaline removed?

Answer 42

in bloodstream