L23 - autonomic nervous system Flashcards
afferent neurones
sensory input from periphery to CNS
efferent neurones
output from CNS to periphery (somatic or autonomic), causes skeletal muscles to move
what does the ANS do?
provides input to tissue that’s not under voluntary control (smooth & cardiac muscle and glandular tissue)
2 branches of ANS
sympathetic & parasympathetic
(have opposite actions but not equal)
sympathetic nervous system
fight or flight
parasympathetic
rest and digest
somatic motor fibre
neurone that goes from spinal cord to skeletal muscle to enable us to have voluntary control of it (neurone releases ACh)
ganglian
collection of cell bodies
sympathetic branch of ANS has what type of ganglion?
short pre ganglion fibre and long post ganglionic fibre
parasympathetic branch has what type of ganglion?
long pre ganglion fibre and short post ganglionic fibre
what do the short pre ganglionic neurones tend to project to from the sympathetic nervous system?
paravertebral sympathetic chain
what do the long post ganglionic neurones in the sympathetic nervous system send?
long axonal projections where the synapse ends on the target organ
where does output from CNS from parasympathetic ns come to?
cranial nerves
sympathetic division of ANS
- fight or flight mode
- sensors perceive you are in dangerous situation, tell the brain
- pupils dilate: better peripheral vision, see out corner of eye better
- inhibition of saliva and tears: saliva is part of digestion to not use up energy
- oxygenated blood sent to skeletal muscle
- airways dilate, relax airways in lungs so we can breath deeper
- accelerated heartbeat pumps blood around body faster
- liver stores glycogen which is metabolised into glucose (liver can still produce glucose without glycogen)
- intestines shut down
- bladder relaxes so can store more urine
parasympathetic divison
- comes from vagus nerve
- constriction of pupil
- stimulation of saliva to digest food for nutrients
- lungs constrict, no more heavy energy demands
- stimulation of pancreas (insulin, enzymes etc)
- heart slows
- activation of rectum and bladder to use toilet
vagus nerve
provides output from brain to periphery to parasympathetic
is chemical or electrical signal responsible for slowing heart down?
chemical (ACh is released from vagus nerve)
somatic efferents NT and receptors in ANS
ACh acts on nicotinic receptors to stimulate skeletal muscle
sympathetic NT and receptors in ANS
ACh acts on nicotinic receptors on post ganglionic, post ganglionic neurone releases noradrenaline which activates adrenergic receptors on heart, blood vessels
parasympathetic NT and receptors in ANS
ACh acts on nicotinic receptors on post ganglionic, post ganglionic neurone releases ACH to act on muscarinin receptors on heart, smooth muscle, sweat glands
adrenal medulla exception for sympathetic NT and receptors
- one big long axon
- only produces ACh to act on adrenal medulla
what does sympathetic input do?
- increase heart rate
- dilate pupils
-relax airways
what are adrenoreceptors?
receptors that respond to adrenaline
muscarinic receptors
respond to ACh
what type of of receptors are adrenoreceptors and muscarinin receptors?
g protein coupled receptors
G protein coupled receptors
- Gs-coupled: activates adenylate cyclase - leading to production of cAMP
- Gi/Go-coupled: inhibits adenylate cyclase, and affects ion channels
- Gq-coupled: activated phospholipase C - leading to production of IP3
