1 - autonomic Flashcards
what are the divisions of the peripheral nervous system
somatic and autonomic
what are the divisions of the autonomic nervous system
sympathetic, parasympathetic and intrinsic
what is the autonomic nervous system (general)
not under direct conscious control
what is the somatic nervous system (general)
voluntary, using skeletal muscle
what part of the nervous system controls nearly every organ in the body
the autonomic nervous system (para/sympathetic)
how can drugs affect the autonomic nervous system
positively-heart disease, resp. disease, GI… lots
negatively- as bad side effects from other drugs
where in the spine does the sympathetic nervous system originate
thoracic and lumbar
where in the spine does the parasympathetic nervous system originate
cranial and sacral
where does the vagus nerve originate from in the spine
cranial
what is the autonomic division that is thoracolumbar
sympathetic
what is the autonomic division that is cranialsacral
parasympathetic
what makes up the intrinsic divisions of the ANS
the enteric nervous system and the intracardiac nervous system
what is the enteric nervous system
innervation in the gut, doenst go beyond the gut
how can you compare the effects of the parasympathetic and the sympathetic nerves
they exert opposite effects (usually)
what do all nerves leaving the CNS use as a neurotransmitter
ACh
what happens in the somatic efferent system (neurotransmitters and locations)
ACh released from CNS onto nic receptors onto skeletal muscle
what happens in the parasympathetic efferent system (neurotransmitters and locations)
ACh released on Nic receptor, then ACh released on mus receptor
what happens in the sympathetic efferent system (neurotransmitters and locations)
pre releases ACh on nic receptor, then post releases NA on most things
but some post release ACh onto mus receptors (sweat glands)
and some release ACh on nic recpetors (adrenal medulla)
where do the sympathetic ganglia lie
paravertebral and prevertebral sympathetic chain
what is the neurotransmitter used by sympathetic preganglionic fibres
where does it act on
ACh, acts on ganglionic nicotinic receptors (nAChR)
what is the neurotransmitter used by sympathetic postganglionic fibres
where does it act on
NA (mainly)
but ACh on sweat glands (mus) and ACh on adrenal medulla (nic)
what are chromaffin cells and where are they found
postganglionic sympathetic neurons in the adrenal medulla
what do chromaffin cells release
NA
are neuropeptides used in the signalling of sympathetic or parasympathetic nervous system
both
what does the sympathetic nervous system do to to smooth muscle (+the exception)
causes smooth muscle contraction
but relaxes the gut
what does the hypothalamus and medulla do with the sympathetic nervous system
interacts the sensory and the motor side of the sympathetic nervous system
what parts of the body interact with the sensory and motor side of the sympathetic nervous systems
the hypothalamus and the medulla
what is sympathetic syndrome
the fight or flight discharge or the SNS
which nerve is the vagus nerve
the Xth cranial nerve
where do parasympathetic ganglia lie
in target tissues
what do parasympathetic preganglia use as a neurotransmitter
which receptors does it go to
ACh which acts on ganglionic nicotinic receptors (nAChR)
what do parasympathetic postganglia use as a neurotransmitter
which receptors does it go to
ACh which acts on muscarinic receptors (mAChR)
what is parasympathetic syndrome
a lie! not real. it would involve you being dead (heart stope and poop pants)
what does the reflex system of parasympathetic nervous system have
afferent fibres (idk random bullet point)
does the hypothalamus & medulla work with both sympathetic and parasympathetic?
yes
what makes up the enteric nervous system
myenteric plexus
submucous plexus
what does the myenteric plexus do and where is it
buried in muscle of gut, makes the peristaltic movements
what does the submucous plexus do and where is it
under the mucous and helps with stomach acid and digestive enzyme secretion
does the myenteric plexus or the submucous plexus have more neurons
myenteric plexus
what really does the enteric system mean/do (general definition)
endogenous gut neurons involved in peristaltic and secretory reflexes
what kind of input is given from sympathetic nerves to the enteric nervous system
inhibitory adrenergic input
what kind of input is given from parasympathetic nerves to the enteric nervous system
excitatory cholinergic input
what are 4 of the transmitters used in the enteric nervous system
ACh, 5-HT, ATP, neuropeptides
draw the structure of acetylcholine
yeet
where is acetyl CoA synthesized ?
mitochondria
how is choline transported into the nerve terminals
Na+ dependent carrier
how is ACh synthesized in the cytoplasm
choline acetyl transferase
how is ACh transported into vesicles
antiporter that exchanges ACh for protons
what molecule does ACh release depend on?
Ca2+
what is Ca2+ influx triggered by
action potential
what happens once ACh is released from the neuron
acts on postsynaptic receptors (nicotinic and muscarinic) OR it is decgraded by acetylcholinesterase
what enzyme degrades ACH
acetylcholinesterase
where does ACh interact with nAChR
in autonomic ganglia or skeletal muscle
where does ACh interact with mAChR
visceral targets
what does ACh from parasympathetic postganglionic nerves activate
mAChR (muscarinic cholinergic receptors)
what kind of structure is mAChR
heptahelical, transmembrane
what kind of system does the mAChR receptor follow
G protein coupled
what does metabotropic mean
G protein coupled (has 2nd messenger)
what G protein messenger system does M1 act through
Gq
what G protein messenger system does M3 act through
Gq
what G protein messenger system does M2 act through
Gi and Go alpha
what is the Gq pathway (3 steps)
phospholipase C turns PIP2 into IP3 and DAG, IP3 gets Ca released from ER, PKC is activated by DAG
how does M3 agonist cause vasodilation in endothelial cells
Gq increases Ca++, activates nitric oxide synthase which makes NO whichdiffuses into smooth muscle cells, activates guanylyl cyclase, cGMP generated, relaxes vascular smooth muscle
are there cholinergic receptors in endothelial cells that relax blood vessels
no, they are relaxed indirectly via M3 agonists & NO(nitric oxide)
what are the steps of Gi (3 things)
adenylyl cyclase is inhibited which reduces cytosolic levels of cAMP
-act through beta gamma subunits of Gi and Go to open GIRK channels (K+ leaves, hypopolarization)
what are GIRK channels
G-protein coupled inwardly rectifying K+ channels
what kind of channels are nAChR
ligand gated ion channels which are Na+/K+ permeable
-depolarization
what are nAChR like in the ganglia
excitatory post synaptic potential
what are nAChR like in the skeletal muscle (voluntary, like diaphragm)
excitatory junction potential
what are the subunits of the nAChR channel
transmembrane
-alpha (1-10), beta (1-4), gamma, delta, epsilon
what binds to nAChR ion channels and where
there are 2 ACh binding sites at the interface between alpha subunits
whats the difference with ganglionic and neuromuscular nicotinic receptors
the adult muscle (neuromuscular) has alpha 1 and the ganglionic has alpha 3 (not 1)
