Functions Of The Nervous System

Question 1

What are the functions of the nervous system?

Answer 1

Sensation- taking information from the outside world, integration, initiation of motor activity

Question 2

What do sense organs do?

Answer 2

Sense/take specific information from the external environment and turn it into an action potential

Eg ear turns vibrations of the air into action potentials

Sensory neurones respond to temperatures, pain etc turning external stimuli into APs

Question 3

What does the PNS include?

Answer 3

All nerves and ganglia (collection of cell bodies of neurones) outside brain and spinal cord.

Question 4

How does the brain change during development?

Answer 4

• CNS initially develops as a simple hollow tube
• the cerebral hemispheres develop as outgrowths in ether side from the cranial end of this tube
• as they grow they sweep back over the surface of the tube, hiding the central core of the developing brain

Question 5

What does the brain comprise generally?

Answer 5

A central core and two cerebral hemispheres

Question 6

What are the types of 31 spinal nerves?

Answer 6

Cervical (8)
thoracic (12)
lumbar (5)
sacral (5) 
coccygeal (1)

Question 7

Why are spinal nerves ‘mixed’?

Answer 7

They contain sensory and motor axons, associated with a defined region in the body

Question 8

What are cranial nerves?

Answer 8

12 pairs of highly specialised nerves extending from the base of the brain through the cranium to the periphery - concerned with head and neck

Question 9

What cranial nerves are involved in eye movements?

Answer 9

Oculomotor, Abducens, trochlear

Question 10

Why are motor neurones easiest to study + most understood?

Answer 10

They send axons outside the NS, and the targets of them are really large (eg muscle) so relatively easy to identify subsets of motor neurones

Question 11

What does the grey matter contain?

Answer 11

Predominately cell bodies, some axons

Question 12

What does the white matter contain?

Answer 12

Axons connecting spinal cord to the brain and vice versa

Question 13

What’s located in the dorsal root ganglion?

Answer 13

Cell bodies of afferent sensory neurones - their single axon divides into peripheral and central branches

Question 14

Explain the knee jerk effect/ patellar reflex:

Answer 14

Sharp tap on patellar tendon (below kneecap) slightly stretches the quadriceps, stretch receptors cause an AP to be fired, causing motor neurones to fire an AP, causing the contraction of the muscle which tends to straighten the leg in a kicking motion

Question 15

How do we know about the different regions in the brain having different functions?

Answer 15

Tumours, bullets in the head affecting certain functions of the body

MRI scans

Placing electrodes on the brain and stimulating different areas

Question 16

What is a sensory pathway?

Answer 16

A three neurone pathway that conveys information in afferent neurone from periphery to spinal cord, in a neurone that ascends up the spinal cord to thalamus and in a neurone that projects from the thalamus to the appropriate region of the sensory cortex

Question 17

What are the three major divisions of the autonomic nervous system? (Not voluntary)

Answer 17

Sympathetic, parasympathetic, enteric

Question 18

What does the enteric system do?

Answer 18

Innervates the gastrointestinal tract, from upper oesophagus to anus

Question 19

What are the functions of the sympathetic autonomic NS?

Answer 19

FIGHT OR FLIGHT

• increases heart rate
• restricts blood flow to skin (more to muscle)
• sweating
• dilation of pupils

Question 20

What are the functions of the parasympathetic autonomic NS?

Answer 20

REST AND DIGEST

• decreases heart rate
• increases blood flow to skin and gut
• causes airway relaxation

Question 21

Where might you find motor neurone cell bodies?

Answer 21

In the grey matter of the ventral horn (dorsal = sensory)