Introduction to Autonomic Nervous System Flashcards

1
Q

where does the autonomic NS fit into whole NS?

A

part of the efferent division of Peripheral NS:

a) somatic NS

b) Autonomic NS !

i) Parasympathetic NS
ii) Sympathetic NS
iii) enteric NS

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2
Q

what does ANS regulate?

what is good way of remembeing between afferent and efferent neurons?

A

Autonomic NS: involuntary physiolgical processes (HR, BP, resp, digestion, arousal)

afferent arrives (to CNS), efferent exits (from CNS)

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3
Q

what happens at dendrite?

A

located near cell body - bit that recieves inputs to neurons

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4
Q

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?

A

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

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5
Q

how do u describe the enteric NS?

A

= extensive web-like structure capable of function independently of the remainder of the NS

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6
Q

what do enteric neurons use as their major NT?Ac

A

Ach, NO and seratonin

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7
Q

where are the cell bodies of preganglionic SNS and PNS found?

A

cells bodies of preganglionic SNS and PNS are found in the CNS

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8
Q

where do the autonomic output signals go via from the hypothalamus?

what does hypothalamus maintain homeostasis of ?

A

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
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9
Q

where in the spinal cord do the neurons leave from for SNS?

A

thoracolumbar (T1-L2) outflow

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10
Q

how is SNS organised?

  • which part of the spinal cord?

where are cell bodies of SNS found?

where do SNS preganglionic fibres synapse (3)

A

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)

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11
Q

which part of spinal cord is lateral horn?

A
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12
Q

what does dual innervation of organs mean?

A

that organs recieve innervation from both the sympathetic and parasympathetic NS.

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13
Q

do SNS nerve fibres orginate from one place or many places of the spinal cord?

A

many places (T1-L2)

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14
Q

(FYI: what is paravertebral chain aka?)

A

sympathetic chain !

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15
Q

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?

A

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

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16
Q

what is divergence and convergence of sympathetic chain?

A

divergence: the number of postsynaptic fibres a single preganglionic fiber creates a synapse with. pre-ganglionic fibres branch out to postganglionic fibres at the different level of the chain

convergence: a postganglionic nueron can recieve infromation from many pre-ganglionic fibres

17
Q

where are sympathetic postganglionic neurons that innervate abdominal viscera located?

what ^ made from?

A

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
18
Q

which sympathetic preganglionic fibres pass through the sympathetic chain and travel in lumbar splachnic nerves? what do they synapse on?

A
  • L1-L2 sympathetic preganglionic fibres
  • Synapse on postganglionic neurons in inferior mesenteric ganglion: innervates colon, rectum, bladder and genital
19
Q

how is the PNS organised?

do nerve fibres orginate at differe or same levels of spinal cord?

most organs recieve dual or single innervation?

A

(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

20
Q

does the enteric NS act with or independently of central NS?

A

Independently: intrinsic neuronal circuits of ENS are able to generate reflex gut contractile independently of any CNS intervention

BUT: also recieves extrinisc parasym and sym innervation

21
Q

How is the enteric NS organised?

what does ENS control?

A

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)

22
Q

where is the myentric and submucosal plexi located?

each function?

A

myenteric plexus:

located: between circular and long. muscle layers

function: motility (peristalsis?)

submucosal plexus:

located: between submucosal and circular muscle layer

function: controls secretion and muscle function in the mucosal layer

23
Q

label where the myenteric and submucosal plexi are

A
24
Q

what does activation of SNS lead to?

what does activation of PNS lead to?

what does activation of ENS lead to?

A

SNS: fight or flight. E activities (Exercise, excitement, emergency)

(increased: HR, bloodflow to skeletal muscle, adrenaline and noradrenaline release from adrenal medula. decreased: bloodflow to GI, skin and tract. dilation of pupils

PNS: rest and digest D activities (digestion, diuresis, defecation)

(Increased: salivary glands, GI motility, bladder conraction, sphincter relaxation, lacrimaation and erection (vasodilation). decrease: HR)

ENS: reflex pathways -> digestive functions of muscle contraction / relaxation, secretion / absorbtion and blood flow

25
Q
A
26
Q

describe the pathway for synapse for the release of adrenaline

A
  • 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
27
Q
A
28
Q

which of the somatic or autonomic is voluntary?

which of the somatic or autonomic uses one neuron?

which of the somatic or autonomic is stimulatory or inhibitory?

A

volutary: somatic NS

one neuron: somatic NS (autonomic NS is two neurons)

stimulatory or inhibitory: autonomic NS (somatic is always stimulatory)

29
Q
A
30
Q
A
31
Q

what is difference in somatic vs autonomic motor reflex?

A

main difference: in efferent branch:

autonomic = 2 step pathway -> preganglionic nerve synapse at post ganglionic neuron, which in turn project to effector

somatic: projects directly onto skeletal muscle