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Medicine Year 1 - Semester 2 - Part 1 > Structure of Autonomic Nervous System > Flashcards

Structure of Autonomic Nervous System Flashcards

1
Q

State the 2 main division of the ANS

A

Sympathetic
Parasympathetic

Enteric

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2
Q

Branches of the peripheral nervous system

A

Sensory (afferent)
Motor (efferent)

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3
Q

Function of the enteric nervous system

A

Self-contained autonomous control system for the gut
(heavily influenced by the ANS - can work on its own)

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4
Q

Describe the somatic motor system

A

Upper motor neurones which leave the cortex, come down and either in the brain stem or spinal cord synapse with lower motor neurones.

Lower motor neurones then head out into the periphery acting on skeletal muscle.

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5
Q

Describe the visceral motor system

AKA: Autonomic nervous system

(2 neurone system)

A

Origins of the 1st neurone is in the hypothalamus.

Neurones come out of the hypothalamus, head down and synapse onto a neurone either in the brainstem or spinal cord.

That neurone heads out, doesn’t go all the way to an effector, it goes to a ganglion and synapses.

Post-ganglionic neurone goes to an effector (smooth muscle etc.)

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6
Q

What is a ganglion ?

A

A collection of nerve cell bodies outwith the CNS

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7
Q

Nucleus

A

A collection of nerve cell bodies within the CNS

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8
Q

What is the ANS served by ?

A

A 2 neurone system

  • Pre-ganglionic fibres originate from CNS
  • Post-ganglionic fibres originate from autonomic ganglia
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9
Q

State pre-ganglionic fibre origins in the :

  1. Sympathetic
  2. Parasympathetic
A
  1. Thoracolumbar
  2. Craniosacral
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10
Q

State post-ganglionic fibre origins in the :

  1. Sympathetic
  2. Parasympathetic
A
  1. Paravertebral Chain/ Prevertebral ganglia
  2. In or near target origin
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11
Q

Parasympathetic cranial nerves from the brain

What do they innervate ?

A

Innervate :

  • eye
  • lacrimal gland
  • salivary gland
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12
Q

Vagus nerve innervations

What do they innervate ?

A
  • heart
  • lungs
  • upper GI tract
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13
Q

Parasympathetic sacral nerves

What do they innervate ?

A
  • Lower GI tract
  • Bladder
  • Genitalia
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14
Q

Location of Vagus Nerve

A

Behind thorax
Running behind the lung root and onto the oesophagus.

Neck to splenic flexure of colon

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15
Q

Sympathetic supply

What do they innervate ?

A

Same as Parasympathetic

Also body wall and limbs

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16
Q

Sympathetic chain

Where does it run to and from ?

A

Runs form the base of the skull to the base of the coccyx

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17
Q

Describe sympathetic chain

A

Connections of ganglia (1mm)

Run all the way from the base of the skull down to the bottom end of pelvis

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18
Q

How to get sympathetics from the thorax up to the head and neck ?

Option 2

A

The neurone :

Comes out of the CNS into the sympathetic chain but don’t synapse.

Ascending, up the connected chain of ganglia to a higher ganglion, synapse in this ganglion and leave back to either a spinal nerve in the neck or a plexus in the neck, travel up into the head to supply things like the eye etc.

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19
Q

Describe how a neurone supplies a spinal nerve at the same segment

Option 1

A

Come out of the CNS, come into a sympathetic ganglion and synapse at the same level, either return to a spinal nerve or leave the sympathetic chain and go to some viscera.

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20
Q

How to get sympathetics from the thorax downwards ?

Option 3

A

Neurone leaves from a lower segment into the sympathetic chain, not synapse and descend.

Synapse at the level they are innervating, return to a spinal nerve, travel out to do things in lower limbs.

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21
Q

Option 4

A

Leave the CNS, enter the sympathetic chain

Don’t synapse

Leave the sympathetic chain as a presynaptic neurone in a thoracic splanchnic nerve.

These head down into the abdomen where they synapse in pre-vertebral ganglia.

These lie on the aorta.

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22
Q

What is the thoracic splanchnic nerve ?

A

A collection of un-synapsed pre-ganglionic sympathetic neurones.

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23
Q

What supplies abdominal viscera ?

A

Thoracic Splanchnic Nerves from the thorax

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24
Q

Describe the autonomic nervous reflex

A

Sensory afferent neurone heads to the CNS, interneurons involved, motor efferent neurone leaves.

Since ANS, 2 neurones in the effector pathway.
Pre-ganglionic –> Postganglionic

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25
Q

Describe neurons in autonomic reflexes

What supply do they follow ?

A

Neurones involved in autonomic reflexes tend to follow parasympathetic supply.

26
Q

Visceral afferents and referred pain

A

Visceral pain neurones travel back along the same direction as sympathetic supply.

27
Q

Parasympathetic nervous system

A

Rest and Digest

28
Q

Sympathetic nervous system

A

Fight or Flight

29
Q

ANS

A

2 neurone system with differences in origin and site of synapses in the parasympathetic and sympathetic nervous system.

30
Q

State the effect on the : heart

  1. Parasympathetic
  2. Sympathetic
A
  1. Decreases HR
  2. Increases HR and Force of contraction
31
Q

State the effect on the : digestive tract

  1. Parasympathetic
  2. Sympathetic
A
  1. Increases motility and secretion
  2. Decreases motility and secretion
32
Q

State the effect on the : lungs

  1. Parasympathetic
  2. Sympathetic
A
  1. Broncho-constriction
  2. Broncho-dilation
33
Q

State the effect on the : urinary bladder

  1. Parasympathetic
  2. Sympathetic
A
  1. Release of Urine
  2. Urinary Retention
34
Q

State the effect on the : pupil of the eye

  1. Parasympathetic
  2. Sympathetic
A
  1. Constricts
  2. Dilates
35
Q

State the effect on the : Male sexual organs

  1. Parasympathetic
  2. Sympathetic
A
  1. Erection
  2. Ejaculation
36
Q

State the effect on the : blood vessels

  1. Parasympathetic
  2. Sympathetic
A
  1. NO effects (mostly)
  2. Constriction (mostly)
37
Q

State the effect on the : salivary gland

  1. Parasympathetic
  2. Sympathetic
A
  1. Increased secretion
  2. Increased secretion
38
Q

State the effect on the : sweat glands

  1. Parasympathetic
  2. Sympathetic
A
  1. No effect
  2. Increased secretions
39
Q

State the effect on the : liver

  1. Parasympathetic
  2. Sympathetic
A
  1. NO effect
  2. Glycogenolysis + Gluconeogenesis
40
Q

State the effect on the : pilomotor

  1. Parasympathetic
  2. Sympathetic
A
  1. No effect
  2. Piloerection
41
Q

What effect would increased parasympathetic drive have on heart rate ?

A

Decreased rate of contraction

42
Q

What effect would a sympathetic agonist have on the eye ?

A

Mydriasis (dilation)

43
Q

Mydriasis

A

Pupillary dilator muscle - Sympathetic innervation ONLY

44
Q

Miosis

A

Pupillary constrictor muscle - Parasympathetic innervation

45
Q

What effect would a parasympathetic antagonist have on the eye ?

A

Mydriasis - dilation

46
Q

Canal of Schlemm

A

This is a drainage route through which the fluid inside the eye.

If fluids build up and can’t drain, pressure builds up inside the eye.

47
Q

What control dominates when the bladder is filling ?

A

Sympathetic control predominates.

  • Relaxation of the detrusor muscle
  • Contraction of the internal sphincter muscle
48
Q

What control dominates when the bladder is full ?

A

Parasympathetic control predominates

  • Contraction of detrusor muscle
  • Relaxation of the internal sphincter muscle
49
Q

Function of autonomic reflex arcs

A

Exists for visceral control

  • Path of afferent fibres can explain referred pain
50
Q

When do parasympathetic and sympathetic innervation have the same function ?

A

Salivary control

51
Q

What do varicosities contain ?

A

Vesicles containing neurotransmitters
Mitochondrion

52
Q

Somatic motor efferent control

What is released ?
Describe the type of system

A

Releasing ACh on nicotinic ACh receptors.

One neurone system coming from CNS to peripheral control of muscle.

53
Q

Parasympathetic system - Function

communication

A

Communication between preganglionic fibre and postganglionic fibres.

Requires a neurotransmitter released by preganglionic fibre (ACh) and postganglionic fibre (ACh)

54
Q

Describe NT release in parasympathetic system

A

In all tissues under parasympathetic control, the NT released from the post-ganglionic fibre is also ACh, but acts on muscarinic receptors.

55
Q

Sympathetic system broad rule NT

A

Broad rule : preganglionic fibre will release ACh onto the post-ganglionic nicotinic ACh receptor.

Post-ganglionic fibre, will release noradrenaline in almost ALL circumstances

56
Q

Exception to broad NT rule of sympathetic system

A

Sweat Glands

Innervated by pre-post ganglionic communication

But NT released from post-ganglionic fibres is ACh acting on muscarinic receptors.

57
Q

Describe sympathetic innervation of the adrenal gland

A

Pre-ganglionic fibres synapse on chromatin cells.

Chromatin cells release adrenaline (80%) and noradrenaline (20%) into systemic circulation.

Widespread tissue response.

58
Q

What do pre-ganglionic receptors in parasympathetic and sympathetic system release ?

A

ACh which acts on nicotinic receptors

59
Q

What do post-ganglionic parasympathetic neurons release ?

A

ACh acts on Muscarinic receptors

60
Q

What do most post-ganglionic sympathetic neurons release ?

A

Noradrenaline

Some release ACh

Medicine Year 1 - Semester 2 - Part 1 (51 decks)

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