The Autonomic nervous system Flashcards
Difference between central nervous system & peripheral nervous system
Central Nervous system = brain and spinal cord
Peripheral nervous system = ganglion and nerve
Cephalisation
Cerebral Cortex (telencephalon) = memory, attention, thought language consciousness.
Thalamus and hypothalamus (diencephalon) = metabolism, autonomic nervous system.
Midbrain (mesencephalon) = motor behaviour, alertness, temp and regulation
Pons and cerebellum (metencephalon) = sleep, respiration, equilibrium taste
Roles of the hypothalamus
- control of autonomic nervous system
- controls the pituitary gland which releases hormones
- control eating and drinking
- control of body temp
- regulation of circadian rhythm
Chemical transmission
- communication between neurons is mediated by chemical transmission at synapses.
- synapses release neurotransmitters which act on receptors.
STEPS IN CHEMICAL TRANSMITTERS :
- TRANSMITTER SYNTHESIS
- TRANSMITTER STORAGE
- TRANSMITTER RELEASE
- TRANSMITTER BINDING TO AND ACTIVATION OF RECEPTOR
- TRANSMITTER ACTIVATION
Process of chemical transmission
- transport of metabolite/molecule into presynaptic button
- biochemical processing of metabolite into the neurotransmitter
- uptake of the neurotransmitter into vesicles
- action potential reaches the presynaptic area
- calcium influx is triggered. calcium mobilises neurotransmitter vesicles towards the presynaptic membrane
6.neurotransmitter is released in the synaptic cleft - neurotransmitter binds to receptors on the postsynaptic membrane
- this triggers a response in the synaptic neuron/cell
- neurotransmitter is inactivated and processed into its original precursor
- neurotransmitter reuptake into the neuron
Peripheral nervous system
composed of :
- somatic efferent system = innervates skeletal muscle
- sympathetic system
- parasympathetic nervous system
SYMPATHETIC AND PARASYMPATHETIC MAKES UP THE AUTONOMIC NERVOUS SYSTEM
MAIN NEUROTRANSMITTERS ARE ACH AND NORADRENALINE
SUMMARY OF SYMPHATEITC ( FIGHT OR FLIGHT RESPONSE) NEURONS AND SYNAPSES
PREGANGLIONIC NEURONS
- short
- synapse with postganglionic neurons near spinal cord
- release ACH to activate nicotinic receptors on postganglionic neurons
POSTGANGLIONIC NEURONS
- long
- synapse on the target organ
- release norepinephrine activate adrenergic receptors on target organs
SUYMMARY OF PARASYMPATHETIC ( REST AND DIGEST) AND SYNAPSES
PREGANGLIONIC NEURONS
- long
- synapses with postganglionic neurons at or near organ
-release ACH to activate nicotinic receptors on postganglionic neurons
POSTGANGLIONIC NEURONS
- short
synapse on the target organ
- release ACH to activate muscarinic receptors on the target organ
SYMPATHETIC SYSTEM
- liver releases glucose into blood to increase energy supply
- increased heart rate, blood pressure, respiration
- increased blood flow to skeletal muscles, heart, brain
- decrease GI activity
PARASYMPATHETIC SYSTEM
- decreased heart rate, blood pressure, respiration
- increased GI activity facilitates digestion
Choline transport
most choline is derived of ACh in synaptic cleft.
choline is transported is inhibited by :
- hemicholinium
- triethylcholine
What are the two subtypes of cholinergic receptors
- nicotinic = ligand gated ion channels
- muscarinic = G protein coupled receptors
Ligand gated ion channels
- ion channels is integral part of receptor
- generally composed of 4-5 protein sub-units
- agonist binding has direct effect on ion channel function.
Nicotinic receptors
categorised into three classes based on location :
- muscle = skeletal neuromuscular junction
- ganglia = autonomic nervous system
- brain = synapses between neurons
Muscarinic receptors
categorised into classes based on difference in location :
-M1 ( neural ) = nervous system, ganglia, gastric parietal cells
M2 ( cardiac ) = heart, auto receptors on presynaptic terminals
M3 ( GLANDULAR ) = glands, visceral and vascular smooth muscle
