Introduction to Autonomic Nervous System Flashcards
where does the autonomic NS fit into whole NS?
part of the efferent division of Peripheral NS:
a) somatic NS
b) Autonomic NS !
i) Parasympathetic NS
ii) Sympathetic NS
iii) enteric NS
what does ANS regulate?
what is good way of remembeing between afferent and efferent neurons?
Autonomic NS: involuntary physiolgical processes (HR, BP, resp, digestion, arousal)
afferent arrives (to CNS), efferent exits (from CNS)
what happens at dendrite?
located near cell body - bit that recieves inputs to neurons
in the SNS and PNS where do you find the preganglionic and postganglionic neuron?
what do SNS and PNS use for their NTs at their pre and post synaptic neurons?
sympathetic and parasympathetic NS:
a) preganglionic neuron in CNS
b) postganglionic neuron in periphery NS
Neurotransmitters:
a) presynaptic SNS and PNS use Ach
b) postsynaptic:
i) PNS: Ach
ii) SNS: norepinephrine
how do u describe the enteric NS?
= extensive web-like structure capable of function independently of the remainder of the NS
what do enteric neurons use as their major NT?Ac
Ach, NO and seratonin
where are the cell bodies of preganglionic SNS and PNS found?
cells bodies of preganglionic SNS and PNS are found in the CNS
where do the autonomic output signals go via from the hypothalamus?
what does hypothalamus maintain homeostasis of ?
integration centre for ANS: hypothalamus:
- Receives sensory stimuli and visceral sensations from the periphery (input signals, afferent fibers)
- output signals go via medulla oblongata and pituitary to target organs (smooth & cardiac muscles, exocrine glands)
- maintains homeostasis of: BP, body temp and electrolyte balance
where in the spinal cord do the neurons leave from for SNS?
thoracolumbar (T1-L2) outflow
how is SNS organised?
- which part of the spinal cord?
where are cell bodies of SNS found?
where do SNS preganglionic fibres synapse (3)
thoracolumbar outflow:
- T1-L2 spinal cord
- cell bodies in lateral horn of the spinal cord
- (short preganglionic nerves, long post-ganglionic nerves)
preganglionic fibres synapse in:
i) paravertebral ganglia of the sympathetic chain (T1-4 sympathetic chain).
ii) prevertebral ganglia: T5-L2 the nerve fibres from the spinal cord pass through the sympathetic ganglia and synapse outside the sympathetic trunk (prevertebral or collateral ganglia).)
iii) chromaffin cells of the adrenal medulla (pass independently)
which part of spinal cord is lateral horn?
what does dual innervation of organs mean?
that organs recieve innervation from both the sympathetic and parasympathetic NS.
do SNS nerve fibres orginate from one place or many places of the spinal cord?
many places (T1-L2)
(FYI: what is paravertebral chain aka?)
sympathetic chain !
what is a sympathetic chain?
which pre & post ganglionic fibres synapse within the sympathetic trunk?
which nerve fibres from the spinal cord pass through the sympathetic ganglia and synapse outside the sympathetic trunk?
made of how many ganglia?
sympathetic chain: sympathetic chain is a paired bundle (one each side of vert. column) of nerve fiberes that runs from the base of the skull to the coccyx, just lateral to the vertebral bodies.
T1 – T4 pre & post ganglionic fibres synapse within the sympathetic trunk (paravertebral ganglia).
T5-L2 the nerve fibres from the spinal cord pass through the sympathetic ganglia and synapse outside the sympathetic trunk (prevertebral or collateral ganglia)
sympathetic chain: 25 ganglia
where are sympathetic postganglionic neurons that innervate abdominal viscera located?
what ^ made from?
in prevertebral ganglia:
T5-T9 = great splanchnic nerve (The greater splanchnic nerve is formed from the preganglionic fibres of T5–T9, which traverse the paravertebral ganglion and terminate in the coeliac and superior mesenteric ganglia) Function: Sympathetic supply of foregut and adrenal medulla
T10-T12 = lesser splanchnic nerve
Function: Sympathetic supply of midgut
BOTH SYNAPSE ON POSTGANGLIONIC NEURONS IN THE CELIAC GANGLION
- postganglionic fibres innervate smooth muscle and glands in stomach, small intestines, liver, kidney and spleen
how is the PNS organised?
do nerve fibres orginate at differe or same levels of spinal cord?
most organs recieve dual or single innervation?
(aka?) Craniosacral outflow:
a) Cranial nerves: III, VII, IX, X: organs in head
b) Sacral nerves: S2-S4: rectum, bladder and genitals
2. nerve fibres originate different levels of spinal cord
3. dual innervation
How is the enteric NS organised?
what does ENS control?
organisation: two major plexuses:
a) Myenteric plexus
b) submucosal plexus
controls: motility of intestine, exchange of fluids across mucosal surface, blood flow and secretion of gut hormones (The enteric nervous system (ENS) controls effector systems of the digestive tract, consisting of the musculature, secretory glands, and blood vessels)
label where the myenteric and submucosal plexi are
describe the pathway for synapse for the release of adrenaline
- sympathetic pre-ganglionic fibres leaves spinal cord (via lateral horn) and goes through sympathetic trunk without synapsing
- goes through pre-vertebral ganglia without synapsing
- directly goes to cells of adrenal medulla: stimulates medullary cells to secrete adrenaline and noradrenaline
