The autonomic nervous system Flashcards
What is the autonomic nervous system (ANS)?
A sub-division of the peripheral nervous system
It’s involuntary
Divided into sympathetic and parasympathetic
What nerves are involved in the sympathetic outflow to the periphery?
Pre-ganglionic neurones in the thoracic and upper 2/3 of lumbar
Whats the journey impulses travel along in sympathetic outflow to the periphery?
Pre-ganglionic axons in spinal nerve enter sympathetic chain of ganglia through white ramus communicans
Post ganglionic sympathetic neurones in lateral horn of grey matter leave spinal cord in ventral nerve root and join spinal nerve via grey ramus communicans and travel to effector organ
What is a prevertebral trunk?
Aka. sympathetic chains
Pre-vertebral trunks contain post-ganglionic cell bodies outside spinal cord- they lie either side of the plexus
What nerves are involved in sympathetic outflow to the heart?
T1-T4
What’s the journey impulses travel along in sympathetic outflow to the heart?
Pre-ganglionic nerve goes towards sympathetic chain of ganglia via white ramus communicans
It synapses and sends post ganglionic nerve to heart
What are collections of neurones around the heart called?
The cardiac plexus
Whats the journey impulses travel along in sympathetic outflow to the viscera?
Preganglioic neurones travel to sympathetic chain of ganglia
They don’t synapse here
Preganglionic neurone travel towards the gut via splanchnic nerves- group to form greater, lesser and least splanchnic nerves
When they get close to organ they synapse at ganglia which sit around the aorta- pre-aortic ganglia. Here we find cell bodies of post ganglionic neurones
What nerves are in solved in parasympathetic outflow to viscera?
CN 3, 7, 9 and 10
Whats the journey impulses travel along in parasympathetic outflow to the viscera?
There’s specialised ganglia where pre-ganglionic nerves synapse
Vagus nerve travels towards heart and gut structures
Some pre-ganglionic nerves go to pelvic viscera and carry out functions
How is acetylcholine made and released?
Choline and acetyl Coa converted by choline acetyl transferase to ACh
Packed into vesicles
AP causes ca2+ influx and exocytosis
NT release and receptor activation
ACh rapidly degraded by acetylcholinesterase in synapse
Choline taken up by choline uptake protein into presynaptic terminal
How is noradrenalin made and released?
Tyrosine converted to DOPA by tyrosine hydroxylase
DOPA converted to dopamine by DOPA carboxylase
Dopamine is packages into vesicles with dopamine beta hydroxylase
Noradrenalin is product
AP causes ca2+ influx and exocytosis
NT release and receptor activation
Removal of NT by reuptake in pre synaptic terminal (monamine oxidase) or glial cell (COMT)
How is adrenalin from adrenal glands made and released?
Tyrosine converted to DOPA by tyrosine hydroxylase
DOPA converted to dopamine by DOPA carboxylase
Dopamine is packages into vesicles with dopamine beta hydroxylase
Noradrenalin is product
Noradrenalin converted to adrenalin in cytoplasm by phenyl ethanol methyl transferase
AP causes ca2+ influx and exocytosis
NT release
Adrenalin diffuses into capillaries and transported into tissues
Where do visceral motor neurones originate and where do they project to?
Originate in hypothalamus
Project to brainstem or spinal cord where they synapse with autonomic neurones
What kind of nerves does the parasympathetic nervous system have?
Long pre-ganglionic fibres
Ganglions close to effector tissue
Short post-ganglionic fibres
