1: Intro to ANS Flashcards
ANS effects on eye
S: dilation of pupil
PS: constriction of pupil, contraction of ciliary muscle
ANS effects on salivary glands
S: thick, viscous secretions
PS: copious, watery secretions
ANS effects on trachea/ bronchi
S: dilation by adrenaline
PS: constriction
ANS effects on heart
S: increased rate and contractility
PS: decrease rate and contractility
ANS effects on the GI system
S: reduced motility, causes sphincter contraction
PS: increased motility and tone and increases secretions
ANS effects on urinary sys and bladder
S: relaxes detrusor, constriction of trigone and sphincter
PS: contracts detrusor, relaxation of trigone and sphincter
ANS effects on skin
S: increased sweating (cholinergic) and piloerection
ANS effects on liver
S: gluconeogenesis, glycogeneolysis
ANS effects on adipose
S: lipolysis
ANS effects on kidney
S: increased renin secretion
ANS effects on blood vessels
S: dilatation at skeletal muscles, constriction at skin, mucuous membranes and splanchnic area
Which PS nerve drives gut secretions and motlity
vagus nerve
Which limb of ANS dominates at rest to control basal HR
PS
Structure of PS and its origin and NTs
Long pregang and short postgang fibres
Origin: craniosacral
NT: ACh for both pregang and postgang
Structure of S and its origin and NTs
Short pregang and long postgang
Origin: thoracolumbar regions
NT: ACh pregang and NA postgang
How does neural controlled secretions of adrenaline and NA from adrenal medulla work
Exception as has only 1 autonomic fibre innervating it and it acts as pregang, releasing ACh which binds receptors in adrenal medulla. It then releases A + NA into bloodstream
All pregang fibres release…
ACh
ENS: how it works
The sensory neuron is connected to mucosal chemoreceptors + stretch receptors. They detect chem substances in gut lume/tension in gut wall bc of food
- Info is relayed to submucosal and myenteric plexus via interneurons
- Motor neurons release ACh/substance P to contract SM/vasoactive intestinal peptide/NO to relax SM
How is somatic NS diff
has only 1 motor neuron which releases ACh as NT and innervates skeletal muscle
Which receptors does ACh bind to
Memb bound receptors: nicotinic + muscarinic
Where are nicotinic receptors present
pregang
in all autonomic ganglia
Nicotnic receptor properites (speed, stimulated by and type of receptor)
V fast, stimulated by ACh/nicotine, Type 1 ionotropic receptor
How do nicotinic receptors work
ACh binds it, opens ion channel that allows Na/Ca influx = AP transmission
Where are muscarinic receptors
postgang receptors in tissues innervated by PNS only
Muscarinic receptor proerties (speed, stimulated by, and type of receptor)
V slow, stimulated by muscarine/ACh, type 2 G-protein coupled receptor.
Subtype M1 receptor
neural control (forebrain - learning and memory)
Subtype M2 receptor
cardiac control (brain inhibitory autoreceptors) inhibitory receptor
Subtype M3 receptor
exocrine and SM control (hypothalamus - food intake)
Where are adrenoreceptors found
at end of sympathetic NS at the effector organ innervated by postgang S fibers
Adrenoreceptor properties (stimulated by, type of receptor)
Stimulated by NA and by circulating A produced by adrenal medulla,
Type 2 g-protein coupled receptor
how many subtypes of adrenoreceptors
4
alpha 1
alpha 2
beta 1
beta 2
Via which receptors does SNS control vasculature
Alpha 1 constricts
Beta 2 dilates
Biosynthesis of ACh
Acetyl Co A + Choline forms ACh + Co A, using choline acetyl transferase.
ACh is then packaged into vesicles and released when stimulated
Metabolism of ACH
ACH is broken down in the synapse via acetylcholine esterase to forme acetate _ choline.
NA Biosynthesis
Dopamine is formed from tyrosine using tyrosine hydroxylase + DOPA decarboxylase.
It is packaged into vesicles and converted to NA by dopamine beta hydroxylase.
NA is then released when AP comes along and triggers Ca influx.
NA Metabolism
Uptake 1: back into neuronal tissue, broken down using monoamine oxidase A ( MAO-A)
Uptake 2: intro extraneuronal tissue, broken down using catechol-O-methyl transferase (COMT)
