lecture 8 - autonomic NS Flashcards
axons of postganglionic neurons exit the sympathetic trunk ganglion in 4 ways
- join spinal nerves
- form cephalic periarterial nerves
- for sympathetic nerves
- form splanchnic nerves
4 ways postganglionic neuron axons exit the sympathetic trunk ganglion - 1. joint spinal nerves
axon follows grey com rami to rejoin spinal nerve
4 ways postganglionic neuron axons exit the sympathetic trunk ganglion - 2. form cephalic periarterial nerves
nerve exits trunk ganglion, wraps around an artery (such as carotid artery) and extends to the head to innervate skin of the face and its glands
4 ways postganglionic neuron axons exit the sympathetic trunk ganglion - 3. form sympathetic nerves
exits trunk ganglion and extends to visceral effectors in thoracic cavity
makes up axons that form cardiac plexus
4 ways postganglionic neuron axons exit the sympathetic trunk ganglion - 4. form splanchnic nerves
exit trunk ganglia NOT thru grey com rami, and becomes a splanchnic nerve
these innervate blood vessels in abdominopelvic organs, and chromaffin cells in suprarenal medulla
parasympathetic preganglionic cell bodies are found in:
4 cranial nerve nuclei (3,4,9,10)
and lateral grey matter of s2-s4
this is called the craniosacral division
are parasympathetic ganglia close or far from the CNS
far, this means preganglionic neruons are long, and post ganglionic neurons are short, the opposite of sympathetic
how to preganglionic nerves work in the parasympathetic half if some of the nuclei are in cranial nerves?
they emerge as part of the cranial nerve and split off
terminal ganglia
where all preganglionic neurons in PSNS synapse with postganglionis neurons
located very close or in the wall of the effector
how many postganglionic neurons can one preganglionic neuron synapse with in the terminal ganglia?
4-5, allows for specific localized response
cranial parasymapthetic outflow is formed by
axons taht extend from the brainstem in the 4 cranial nerves
sacral parasympathetic outflow is formed by;
axons from teh anterior roots of s2-s4 as spinal nerves
80% of craniosacral outflow is transmitted by
the vagus nerve
is supplies the heart, airways, adn abdominal area
4 ganglia in the cranial outflow
ciliary
pterygopalatine
submandibular
otic
pelvic splanchnic nerves branch from
s2-s4
preganglionic axons do one of two things in the PSNS
- join cranial nerves (PS cranial outflow)
- exit is splanchnic nerves from the sacrum (PS Sacral outflow)
cholinergic neurons release
ACh - acetylcholine
adrenergic neurons release
NE - norepinephrine
what neurons are cholinergic (release ACh)
- all preganglionic neurons
- all parasympathetic postganglionic neurons
- symapthetic postganglionic neurosn that supply sweat glands, and smooth muscle for blood vessels
ACh can cause:
excitation or inhibition depending on the type of receptor and cell involved
duration of action of ACh (short/long), why?
short, because acetycholinesterase quickly degrades it
cholinergic receptors (what is it, waht types are there)
integral membrane proteins in postsynaptic cell membranes
two types: nicotinic and muscarinic
nicotinic receptors
type of cholinergic receptor
- ionotropic
- activation causes excitation
- found on postganglionic neurons
- nicotine binds to these
muscarinic receptors
type of cholinergic receptor
- metabotropic
- activation causes either excitation or inhibition
- found on all parasympathetic effectors
- muscarine binds to these
only thing that can bind to both nicotinic and muscarinic recptors
ACh
where are nicotinic receptors found?
postganglionic cells, all types of them
where are muscarinic receptors found?
most effectors
(all PS effectors, some sympathetic (sweat/blood/smooth M)
most sympathetic postganglionic neurons are
adrenergic
duration of action of NE is (long/short), why?
long, enzymes have to inactivate it
why are effects triggered by adrenergic neurons typically longer lasting?
because NE takes longer to be inactivated by enzymes
alpha 1 and beta 1 receptors generally produce (excitation / inhibition)
excitation
a2 and b2 receptors generally produce
inhibition
Beta 3 receptors are only found on
brown adipose tissue, controls thermogenesis
alpha and beta receptors are subtypes of
adrenergic receptors
agonist
substance that binds to and activates a receptor
mimics a NT or hormone
antagonist
substance that binds to and blocks a receptor
prevents NT or hormone function
example for adrenergic agonists
increased NE release to increase HR
example for adrenergic antagonist
decrease NE
example for cholinergic agonists
stimulate ACh release to increase muscle contraction
example for cholinergic antagonists
decrease release of ACh
