Introduction to the Autonomic Nervous System

Question 1

What does the autonomic nervous system do?

Answer 1

Provides involuntary information from the CNS to peripheral organs

Question 2

What are the 3 divisions of the ANS and what do they do?

Answer 2

-Sympathetic and parasympathetic: link CNS to peripheral organs and have opposite effects
Enteric: controls the GI tract

Question 3

Which cells does the ANS control?

Answer 3

Sino-atrial (heart) cells, muscle cells, gland cells and smooth muscle

Question 4

How many neurones connect the CNS to the peripheral organ in the parasympathetic system?

Answer 4

2

Question 5

How many neurones connect the CNS to skeletal muscle in the sympathetic system?

Answer 5

1

Question 6

Where do pre-ganglionic fibres from the sympathetic system come from?

Answer 6

The thoraco-lumbar region of the spinal cord

Question 7

What is the length of the pre-ganglionic fibre relative to the post-ganglionic fibre in the sympathetic system and what is the exception to this?

Answer 7

Pre-ganglionic= shorter than the post-ganglionic
Except for the adrenal medulla where the pre-ganglionic fibre doesn’t synapse and it’s just one single fibre straight to the organ

Question 8

Where do pre-ganglionic fibres from the parasympathetic system come from?

Answer 8

The cranio-sacral region of the spinal cord

Question 9

What is the length of the pre-ganglionic fibre relative to the post-ganglionic fibre in the parasympathetic system?

Answer 9

Pre-ganglionic= longer than post-ganglionic

Question 10

What do pre-ganglionic sympathetic and parasympathetic nerves release, which receptors do they act on and on which ganglia?

Answer 10

Releases Ach
Acts at nicotinic receptors (Nic)
Acts on all autonomic ganglia

Question 11

What do post-ganglionic parasympathetic nerves release, which receptors do they act on and on which ganglia, what is the exception to this?

Answer 11

Releases Ach
Acts at muscarinic receptors (Mus)
Exception= erectile tissue which is innervated by non-adrenergic-non-cholinergic (NANC) nerves= release of nitric oxide

Question 12

What do post-ganglionic sympathetic nerves release, which receptors do they act on and on which ganglia, what is the exception to this?

Answer 12

Releases noradrenaline (NA)
Acts at alpha/beta adrenoreceptors
Exceptions=
-sweat glands, releases Ach which acts at Mus receptors
-adrenal medulla, releases Ach at Nic receptors

Question 13

What is the sympathetic system generally for?

Answer 13

Fear, fight and flight

Question 14

What general effects does the sympathetic system have on the body?

Answer 14

Increase in:

• heart rate
• force of contraction
• blood pressure
• blood flow to skeletal muscle
• pupil diameter
• O2 intake
• glycogen breakdown

Question 15

What is the parasympathetic system generally for?

Answer 15

Rest and digest

Question 16

What general effects does the parasympathetic system have on the body?

Answer 16

Decrease in:
-heart rate
-pupil diameter
Increase in:
-GI secretion 
-glucose uptake

Question 17

Give an example of an organ at which the sympathetic and parasympathetic systems have opposite reactions

Answer 17

Heart-

• sympathetic= increase in heart rate
• parasympathetic= decrease in heart rate

Question 18

Give an example of an organ at which the sympathetic and parasympathetic systems have the same reactions

Answer 18

Both increase secretions from the salivary gland

Question 19

Give examples of organs that are only innervated by the sympathetic system

Answer 19

Sweat gland, kidneys, blood vessels

Question 20

Give an example of an organ that is only innervated by the parasympathetic system

Answer 20

Lungs

Question 21

What are afferent and efferent fibres important in doing?

Answer 21

Mediating homeostatic involuntary mechanisms such as blood pressure