nerves Flashcards
ANS: how long is the chain of neurones
2
what is affected by ANS
cardiac, smooth muscle and glands
ANS: NT for preganglionic
ACh
ANS: NT for post ganglionic
NA and ACh
what does ANS regulate
- heart beat
- smooth muscle contraction
- exocrine secretions
- energy metabolism
how do PNS and SNS function in relation to each other
SEPARATELY, opposing effects
which part of the ANS is increased in stress
SNS
which part of the ANS is responsible for rest and digest
PNS
craniosacral outflow
cell bodies of preganglionic neurones are in cranial and sacral spaces
what do SNS preganglionic axons end in
- paravertebral sympathetic chains
- prevertebral ganglia/plexuses
- adrenal medulla
3 main prevertebral ganglia/plexuses in SNS
- coeliac
- superior
- hypogastric
nerves involved in PNS
- oculomotor
- facial
- glossopharyngeal
- vagus
how does ACh act in receptors in PNS
post synaptically on nicotinic receptors or post functionally on muscarinic receptors
What do nicotinic ACh receptors act as
ion channels (ionotropic)
what do muscarinic ACh receptors act as
Metabotropic (g-protein coupled)
where is M1
neuronal/gut
where is M2
cardiac/presynaptic
where is M3
glandular
what effect does a parasympathomimetic drug have on the body
increase PNS
example of parasympathomimetic drug
pilocarpine, nicotine
what effect does a parasympatholytic drug have on the body
decrease PNS, muscarinic antagonist (blocks action)
example of parasympatholytic drug
atropine
what effect does a cholinesterase inhibitor have on the body
increase PNS, no break down of ACh
example of cholinesterase inhibitor
physostigmine
what effect do ganglionic blocking drugs have on the body
decrease BOTH PNS and SNS
how does PNS effect the heart
1.postganglionic nerves release ACh
2. binds to M2
3. DECREASE function
PNS effect on atrial muscle
decreases contractility
PNS effect on AV node
decrease rate of conduction
SNS on radial muscle in eye
leads to MYDRIASIS (dilation)
SNS on circular muscle in eye
leads to MIOSIS (contraction)
what receptors does ACh act on in eye
M3
Atropine effect on eye
blocks circular musc contraction - MYDRIASIS
PNS for accomodation
ACh at M3 leads to ciliary musc contraction so suspensory ligs relax and lens fattens (focus)
cycloplegia
paralysis of ciliary musc - loss of accomodation
what do anticholinesterases do to the PNS
enhance its stimulation
what NT is used in PNS co-transmission
Vasoactive intestinal polypeptide (VIP)
what does VIP do
work w ACh to modulate saliva secretion
what are alpha and beta receptors like
metabotroptic
how do alpha and beta receptors work
- attach to g protein
- 2nd messenger sys
- enzyme activation/ ion transport
- response
which is the only prejunctional adrenoceptor
alpha 2
what is an alpha 1 agonist used to treat/ for
glaucoma, mydriasis
what is a beta 2 agonist used to treat
asthma -> salbutamol
what is a beta 1 agonist used for
prevention of heart attack, enhance heart contraction
what is an alpha 1 antagonist used for
antihypertensive - BLOCKS NA
what is a beta antagonist used to treat/ for
cardiac arrythmia, angina, essential hypertension
example of beta antagonist
beta blockers
what adrenoceptors increase SNS postjunctionally
alpha 1 and 2, beta agonists
what adrenoceptors decrease SNS postjunctionally
alpha 1 and 2, beta antagonists
what adrenoceptors increase SNS prejunctionally
alpha 2 antagonist
what adrenoceptors decrease SNS prejunctionally
alpha 2 agonist
SNS control of pupil diameter
- NA
- alpha adrenoceptors on radial musc
- radial muscle contracts
- mydriasis
sympathomimetic drug effect on vasculature
vasoconstriction
what does neuropeptide Y do
enhances NA action
what happens when NA + ATP + NPY act together
vasoconstriction
