Autonomic Nervous System

Question 1

What is the visceral efferent component?

Answer 1

The autonomic nervous system (ANS)

Question 2

What type of involuntary activities does the autonomic nervous system control?

Answer 2

• Smooth muscle activity
• Cardiac muscle activity
• Various glands

Question 3

What are the 2 divisions of the autonomic nervous system?

Answer 3

Sympathetic and parasympathetic

Question 4

Where are the cell bodies of pre-ganglionic neurons located in the parasympathetic division of the ANS?

Answer 4

• Brainstem: CN 3, 7, 9, 10

- Sacral spinal cord: S 2, 3, 4

Question 5

Where are the cell bodies of pre-ganglionic neurons located in the sympathetic division of the ANS?

Answer 5

• Thoracic and lumbar regions of the spinal cord: T1 - L2

Question 6

Describe the pre and post ganglionic neurons in the parasympathetic NS

Answer 6

Long preganglionic neuron synapse with short postganglionic neuron near effector or in effector organ

Question 7

Describe the pre and post ganglionic neurons in the sympathetic NS

Answer 7

Preganglionic and postganglionic neurons are similar in length. Synapse in sympathetic chain or one of the collateral ganglia in the adrenal medulla

Question 8

Describe the effects the parasympathetic NS has on the body

Answer 8

• Generally has discrete actions on single organs, in the body ‘core’: salivary glands, heart
• Conservative, anabolic effects: storing energy, digestion, slowing the heart
• Rest & digest

Question 9

Describe the effects the sympathetic NS has on the body

Answer 9

• More widespread actions, often affecting the whole body (distribution of sympathetic nerves, circulating adrenaline)
• Homeostasis: blood pressure, thermoregulation
• Flight, fight or fright: meeting demands of active muscles, anxiety

Question 10

What effect does the sympathetic NS have on the iris (radial muscle, spinchter muscle)?

Answer 10

Contraction

Question 11

What effect does the sympathetic NS have on the ciliary muscle of the eye?

Answer 11

Relaxation

Question 12

What effect does the sympathetic NS have on salivary glands?

Answer 12

Secretion (viscous, low volume)

Question 13

What effect does the sympathetic NS have on lacrimal glands?

Answer 13

Secretion

Question 14

What effect does the sympathetic NS have on blood vessels?

Answer 14

Constriction (alpha)

Dilation (beta)

Question 15

What effect does the parasympathetic NS have on the iris (radial muscle and sphincter muscle)?

Answer 15

Contraction

Question 16

What effect does the parasympathetic NS have on the ciliary muscle?

Answer 16

Contraction

Question 17

What effect does the parasympathetic NS have on salivary glands?

Answer 17

Secretion (copious, watery)

Question 18

What effect does the parasympathetic NS have on lacrimal glands?

Answer 18

Secretion

Question 19

What effect does the parasympathetic NS have on nasal glands?

Answer 19

Secretion

Question 20

Which neurotransmitters are used in the parasympathetic NS?

Answer 20

Acetylcholine (ACh) - at pre and post ganglionic neuron synapse and also at post ganglionic neuron/effector synapse

Question 21

Which neurotransmitters are used in the sympathetic NS?

Answer 21

Acetylcholine (ACh) - at pre and post ganglionic neuron synapse
Noradrenaline at post-ganglionic neuron/effector synapse
Adrenaline released from adrenal medulla

Question 22

What is another name for adrenaline?

Answer 22

epinephrine

Question 23

What effects does noradrenaline have?

Answer 23

Depends on the receptor

1) alpha receptor: noradrenaline causes vasoconstriction
2) beta receptor: bronchodilation

Question 24

What effects does adrenaline have?

Answer 24

Depends on the receptor:

1) alpha-1 = contraction of smooth muscle
2) beta-2 = relaxation of smooth muscle
3) beta-1 = increase heart rate and force of heart contraction

Question 25

Which receptor do beta blockers act on?

Answer 25

Beta-1 receptors | Effects are restricted to the heart

Question 26

Why do many local anaesthetics contain adrenaline?

Answer 26

Used as a vasoconstrictor | Less blood to wash away anaesthetic -> prolongs activity of anaesthetic

Question 27

What are the 2 classes of cholinergic receptor?

Answer 27

Muscarinic and nicotinic

Question 28

Where are muscarinic receptors located?

Answer 28

Post-ganglionic/neuro-effector junctions

Question 29

What can muscarinic receptors be blocked by?

Answer 29

Atropine

Question 30

Where are nicotinic receptors located?

Answer 30

``` Pre-ganglionic/post-ganglionic synapse Neuromuscular junctions (NMJs) ```

Question 31

What type of receptor does acetylcholine act on?

Answer 31

Cholinergic receptors: muscarinic and nicotinic

Question 32

Many organs in the head, thorax, abdomen and pelvis receive both sympathetic and parasympathetic supply. They usually have opposing effects. How is control achieved?

Answer 32

By balancing the effects of sympathetic and parasympathetic nervous supply

Question 33

Blood vessels and glands in the periphery (e.g. skin) receive sympathetic supply only. How is control achieved?

Answer 33

Varying amount of activity in sympathetic neurons