autonomic nervous system Flashcards
what is the autonomic NS
a subdivision of the peripheral NS
involved with peripheral sensation and regulation of peripheral function
what does autonomic mean
not under conscious control
the autonomic NS controls non skeletal peripheral function:
cardiac muscle
smooth muscle
internal organs
skin
summarise CNS and PNS in a flow diagram
CNS > PNS
PNS > sensory afferent division and motor efferent division
sensory afferent division > somatic sensory (external) + visceral sensory (internal)
motor efferent division > somatic motor and visceral motor
visceral motor > parasympathetic and sympathetic
which receptors respond to blood pressure
baroreceptors (where firing rate is directly proportional to pressure)
STEPS for detection of low blood pressure
drop in BP
baroreceptors are not firing off at a high rate anymore
less signal through the visceral motor neurones
parasympathetic effect reduces
sympathetic NS is usually inhibited by baroreceptor firing so reduction in firing has dropped > therefore the stimulus to inhibit sympathetic NS has decreased and can then switch on = disinhibition
sympathetic increases HR to bring BP up
(less of a positive stimulus on PS and less of a negative stimulus on the S)
where do visceral motor nuclei originate
in the hypothalamus
where do visceral motor neurones project to
the brainstem or spinal cord where they synapse with autonomic neurones (PS or S)
in general what do autonomic neurones consist of and what is the one exception
2 neurones
a preganglionic and postganglionic neuron
except for in adrenal gland - the sympathetic nerve that innervates the adrenal gland has the function and looks like a preganglionic fibre but it not
describe the parasympathetic nervous system fibres
long preganglionic fibres (originating in the brain or spinal cord) projecting down to tissue it innervates
ganglions are close to or embedded within effector tissues
short postganglionic fibres
describe the sympathetic nervous system fibres
short preganglionic fibres
ganglions close to spinal cord
long postganglionic fibres
what are sympathetic trunks and what do they allow
ganglion for sympathetic nerves
run parallel to spinal cord
more coordinated control of many sympathetic nerves at the same time
many sympathetic nerves come out of spinal cord and synapse with sympathetic trunks and allows mass activation
what NTs do preganglionic nerves release
acetylcholine
(PNS) what NT do preganglionic and postganglionic neurones release
acetylcholine
(SNS) what NTs do preganglionic fibres release
acetylcholine
(SNS) what NTs do postganglionic fibres release
noradrenaline
what does the adrenal gland secrete
a hormone not NT
adrenaline/noradrenaline and some dopamine into the blood where adrenaline acts on tissues via blood
are there any sympathetic neurones that innervate lung tissue
no tehehe
what nerves innervate lung tissue
parasympathetic nerves
how do parasympathetic nerves innervate lung tissue
release ACh to constrict by post and preganglionic nerves
how is the adrenal gland involved in dilation of the bronchi
adrenal glands secrete adrenaline > enters via blood > pass up to lungs > diffuse into lungs and cause bronchodilation
what is the sensory information received in the bladder
pressure of the bladder
what system controls the detrusor muscle (controls bladder)
parasympathetic system
what system controls the internal sphincter
sympathetic system - keeps internal sphincter closed off
STEPS for bladder contraction
1) pressure slowly builds in bladder (don’t want bladder to contract unless full)
2) sympathetic NS is in charge - internal sphincter closed off - contracted
3) when full bladder - sensory info of a full bladder is relayed up to the brain
4) switch on parasympathetic and switch off sympathetic
5) parasympathetic contracts detrusor squeezing bladder forcing the urine out
6) sympathetic NS switches off > relaxation of internal sphincter and urine can leave bladder
what does the somatic nervous system give a voluntary control over when you empty your bladder
another sphincter that has control via somatic NS
what type of receptor would you want at autonomic ganglia
acetylcholine receptor as acetylcholine is released at all autonomic ganglia that responds rapidly
so ION LINKED CHANNEL RECEPTOR (nAChR)
mediated all fast excitatory and inhibitory transmission
what receptors are found in the adrenal gland
nicotinic acetylcholine receptor as adrenal gland releases ACh > acts on receptors > releases adrenaline
what receptors mediate the response to ACh released by sympathetic nerves innervating the adrenal medulla
nAChR
what are the 2 G protein coupled receptors (slow response)
muscarinic receptor - responds to acetylcholine in tissues
adrenergic receptor - responds to noradrenaline in tissues
what are some effectors (for G coupled protein receptors)
ENZYMES adenylyl cyclase, phospholipase C, cGMP-PDE
CHANNELS Ca2+ or K+
BASIC STEPS for NT biosynthesis and metabolism
1) precursor enzymatically converted to NT
2) packaged into vesicles
3) action potential causes Ca2+ influx and exocytosis
4) exocytosis and NT release
5) receptor activation
6) removal of NT from synapse via uptake into presynaptic terminal or glial cell - can be metabolised in the synapse prior to uptake (to prevent permament actiavtion)
STEPS for biosynthesis and metabolism for acetylcholine
1) choline and acetyl coA enzymatically converted by choline acetyltransferase
2) packaged into vesicles
3) AP causes Ca2+ influx and exocytosis
4) exocytosis and NT release
5) receptor activation - muscarinic or nicotinic
6) acetylcholine rapidly degraded by acetylcholinesterase in the synapse > choline is taken up into presynaptic terminal by choline uptake protein
what happens if you block acetylcholinesterase
build up and more powerful response
STEPS for biosynthesis and metabolism of noradrenaline
1) tyrosine is converted to DOPA by tyrosine hydroxylase and DOPA is converted to dopamine by DOPA decarboxylase
2) dopamine is packaged into vesicles with dopamine beta hydroxylase > NA is in vesicle
3) AP causes Ca2+ influx and exocytosis
4) exocytosis and NT release
5) receptor activation (adrenergic)
6) removal of NT from synapse via uptake into presynaptic terminal or glial cell > can be metabolised in the synapse prior to uptake
STEPS for adrenaline release from adrenal glands
1) tyrosine is converted to DOPA by tyrosine hydroxylase and DOPA is converted to dopamine by DOPA decarboxylase
2) dopamine is packaged into vesicles with dopamine beta hydroxylase > NA is the product in vesicle
3) noradrenaline converted to adrenaline in the cytoplasm by phenylethanol methyl transferase
4) AP causes Ca2+ influx and exocytosis
5) exocytosis and NT release
6) adrenaline diffuses into capillary and is transported to tissues in the blood
