16. The Autonomic Nervous System

Question 1

Define efferent, in terms of neurones.

Answer 1

Neurone that carried signals from the brain or spinal cord to the periphery using motoneurone or autonomic neurones.

Question 2

Define ganglion, in terms of neurones.

Answer 2

Collection of neuronal cell bodies in the peripheral nervous system.

Question 3

What’s the difference between pre-ganglionic neurone and post-ganglionic neuron?

Answer 3

Neurone immediately proximal to the ganglion in pre and immediately distal to the ganglion in post.

Question 4

What is the effector in the nervous system?

Answer 4

The target organ thorough which the nervous system exerts its actions.

Question 5

What are the three sections of the nervous system according to the region?

Answer 5

Brain, spinal cord and nerves.

Question 6

What are the two sections of the nervous system according to anatomical overview?

Answer 6

Grey matter and white matter.

Question 7

What are the two sections of the nervous system according to general anatomical classification?

Answer 7

Central nervous system and peripheral nervous system, although they are not independent of one another.

Question 8

What is the CNS characterised by?

Answer 8

Encasement of the cranium and vertebral column which are suspended in cerebrospinal fluid and are responsible for the sophisticated functions of the nervous system.

Question 9

What five things make up the PNS?

Answer 9

Axons of cranial nerves, axons of spinal nerves, ganglia, nerve plexuses and enteric nervous system.

Question 10

How can the nervous system be classified according to direction of signalling?

Answer 10

Afferent and efferent.

Question 11

How can the efferent nervous system be classified by function?

Answer 11

Somatic and autonomic nervous systems.

Question 12

What are the three classifications of the autonomic nervous system?

Answer 12

Sympathetic, parasympathetic and enteric.

Question 13

What is the effector organ if the somatic nervous system?

Answer 13

Skeletal muscle.

Question 14

When do somatic efferents get fully developed?

Answer 14

By puberty.

Question 15

What is the layout of the somatic nervous system?

Answer 15

One neurone carries output and the efferent neurone terminates directly on the effector organ.

Question 16

What came first, somatic or autonomic control?

Answer 16

Autonomic.

Question 17

How does the autonomic nervous system control functions?

Answer 17

By the continuous output in two opposing systems.

Question 18

What are the two general actions of the autonomic nervous system?

Answer 18

Constancy - establishes and maintains homeostasis of internal environments in the body through regulation of various systems of the body.
Intermittent change in bias - promotes excretory mechanism of the body as and when necessary and appropriate.

Question 19

What are the effector organs of the autonomic nervous system?

Answer 19

Visceral organs, smooth muscle, secretory glands and cardiac muscle.

Question 20

What is the general layout of the autonomic nervous system?

Answer 20

2 neurones in a pathway. One cell body in the CNS and one in the PNS.

Question 21

What does over activity of the parasympathetic nervous system lead to?

Answer 21

Over activity leading to dilated blood vessels and shortage of substrate to the brain.

Question 22

What does over activity of the sympathetic nervous system lead to?

Answer 22

Constriction of blood vessels and profound problems, e.g. shortage of substrate to tissues of the body.

Question 23

What is the consequence of activity in the sympathetic nervous system?

Answer 23

Expenditure of energy, diversion of blood to muscles and heart, increase in heart rate, increase in blood pressure and reduced blood flor to GIT and skin.

Question 24

Where can a sympathetic neurone synapse?

Answer 24

In chain at a level corresponding to level of origin, at a different level to origin or in paravertebral chain.

Question 25

What are the two classes of adrenoceptors?

Answer 25

a and B receptors. Both can exercise presynaptic inhibition of the other.

Question 26

What happens when the parasympathetic nervous system is active?

Answer 26

Reduces the heart rate, promotes digestion and other bodily functions and promotes sleep.

Question 27

Define afferent.

Answer 27

Carried incoming signals from the periphery to the CNS using sensory neurones.