Nervous System Flashcards
Organisation
CNS
- brain
-spinal chord
PNS
- sensory system
- somatic system
- autonomic system
- enteric
- sympathetic
- parasympathetic
Autonomic organisation contains….
Contains all motor outputs from the CNS apart from those to skeletal muscles
Pathways contains 2 neurones in series:
- pre ganglionic neurone - cell body in CNS and synapse in the automnic ganglion
- post ganglionic neurone - cell body in autonomic ganglion and synpase with the effector organ
Role of sympathetic and parasympathetic nervous systems
Regulating the internal environment
Function is to maintain homeostasis
Control cardiac function, endo/exorine glands
Sympathetic = fight or flight
Parasympathetic = rest and digest
What does sympathetic do on organs……
Heart rate -> increase
Force of contraction -> increse
Blood vessels body -> constrict
Blood vessels skeletal -> dilate
Blood pressure -> increase
Bronchi smooth muscles-> constrict
Gut motility -> decrease
Bladder -> relax/fill
Pupil -> dialte
Renin secretion -> decrease
Glucose generation -> increase
Exocrine Gand secretion - no effect
What does parasympathetic do on organs……
Heart rate -> decrease
Force of contraction -> decrease
Blood vessels body -> no effect
Blood vessels skeletal -> constrict
Blood pressure -> derease
Bronchi smooth muscles-> relax
Gut motility -> increase
Bladder -> contract/empty
Pupil -> constrict
Renin secretion -> increased
Glucose generation -> decreased
Exocrine Gand secretion -> secrete
2 major neurotransmitters of ANS
Acetylcholine - at target organ for parasympathetic nervous system
Noradrenaline - at target organ for sympathetic nervous system
Dw
Acts at 2 receptor subtypes in the ANS:
- Nicotinic receptors
- Ligand-gated ion channels activated by acetylcholine
Noradrenaline
Acts at adrenoreceptors which are all GPCR’s
2 subtypes of adrenoreceptors
Alpha and beta
Where is synthesis of acetylcholine and what
Pre-synaptic terminal
Simple pathway:
Acetyl coA+choline —choline acetyltransferase —> acetylcholine + coA
CoA goes back to the start again
Acetylcholine once synthesised
Taken into synaptic vesicles by a specific transporter in the vesicle membrane
Acetylcholine released by
exocytosis after an action potential
Acetylcholine broken down by
down in the syaptic cleft by the action of acetylcholinesterase into Choline + acetate
Choline is taken back into pre-synaptic thermal by a choline transporter
Acetylcholine acts as 2 subtypes of receptor:
•Nicotinic receptors are ligand-gated ion channels (ionotropic receptor) - activated by acetylcholine
•Muscarinic receptors are G protein-coupled receptors (metabotropic receptor) - activated by acetylcholine
What happens to salivary gland secretion is a muscarinic antagonist is used
Decrease in excretion
Parasympathetic usually increases it but if have antagonist at muscarinic ecepots; blocks it so less secretion