NONotomic nervy sistem Flashcards
Describe autonomic nervous system
efferent system for involuntary control of body functions
Two efferent divisions of ANS
Parasympathetic and sympathetic
True or false, some organs/tissue only innervated by sympathetic or parasympathetic
True
Describe the preganglionic fibres
Mostly myelinated
Slow/medium velocity
Cell bodies in CNS…
send pre-ganglionic fibres to synapse on ganglion cells outside the CNS. Preganglionic neurotransmitter is Ach.
Describe post ganglionic neurone structure
Non myelinated
Slow
What do ganglion cells do
Send post ganglionic fibres to cardiac, smooth muscle and glands etc
Where is cell body for preganglionic neurone
Brain/spinal cord (lateral horn)
Where does preganglionic neurone synapse
In ganglion
Where does post ganglionic neurone synapse
Visceral effector
Describe preganglionic output of sympathetic division
- Thoracic and lumbar spinal cord (T1-L2) to all viscera
For sympathetic division, not outflow from…
from cervical spinal cord, lumbar spinal cord, brain
2 main groups of sympathetic ganglia
paravertebral and prevertebral (or preaortic), on the basis of their location within the body.
Where are paravertebral ganglia
on each side of the vertebrae
What do paravertebral ganglia do
connected to form the sympathetic chain ganglia
Sympathetic division is formed by chin of ganglia that…l
lie lateral to vertebral column
Where does sympathetic innervation of head come from
Superior cervical ganglion
Where do prevertebral ganglia lie
lie between the paravertebral ganglia and the target organ
What happens to presynaptic axons as they come out of spinal cord into white communicating ramus…
terminate in either the paravertebral ganglia or prevertebral ganglia. Nerves can pass up/down chain ganglia, and giving more widely distributed action, stimulating many nerves/interconnecting neurones
What happens as axon enters the paravertebral ganglion at the level of its originating spinal cord
it can then either synapse in this ganglion, ascend to a more superior or descend to a more inferior paravertebral ganglion and synapse there, or it can descend to a prevertebral ganglion and synapse there with the postsynaptic cell.
Describe lengths of preganglionic and post ganglionic neurones in sympathetic division
Short preganglionic
Long post ganglionic
Describe innervation of adrenal gland
large nerves passing from sympathetic chain in thorax (great splanchnic nerves) innervate adrenal gland and upper gut. The adrenal medullary cells are modified ganglion cells secrete adrenaline into the blood. preganglionic autonomic nerve fibers lead to them directly from CNS
Give exception to chain ganglia
• 3 mid line ganglia
What do midline ganglia release normally
Noradrenaline
What is unique about innervation of adrenal gland
are no postganglionic neurons involved…there are only preganglionic neurons Their axons exit the cord, pass through the nearest sympathetic ganglion and penetrate adrenal cortex
What are midline ganglia example of
Prevertebral/collateral ganglia
What happens to nerves that synapse at prevertebral ganglia
that synapse in the prevertebral ganglia the individual neurons comprising the nerve synapse with their postganglionic neuron which then innervate the gut/abdominal organs and pelvic organs
What supplies preganglionic neurones that synapse in prevertebral ganglia
supplied by greater, lesser and least splanchnic nerves
What are the 3 midline ganglia
- The coeliac ganglion
* The superior mesenteric ganglion • Inferior mesenteric ganglion