General Organisation of the Nervous System

Question 1

What is the role of the nervous system?

Answer 1

To control and adjust the activities of the systems of the body

Question 2

What is the NS split into

Answer 2

CNS- the brain and spinal chord

PNS- axons, ganglia and supporting cells
ie. anything coming from central area

Question 3

Describe what is meant by neural tissue

Answer 3

Combination of the nerve cells and support cells

Question 4

Describe what nerve cells are

Answer 4

High differentiated cell- limited/no capacity for cell division
Limited capacity to repair itself after injury

Transmit electrical impulses along the cell membrane
Can transmit materials from the cell body along the axon
via microtubules

Question 5

Describe the various functions of support cells

Answer 5

Important for:
physical support
Regulating the interstitial fluid
Bringing nutrients

Question 6

Describe what a multipolar neurone is like

Answer 6

A multipolar neurone has a cell body containing numerous dendrites- which is highly branched
The synapses on the dendrites are the way in which nerve cells communicate with each other.
Cell body contains RER making material which is going to be transported along the nerve cells
The axon terminated into one or more synaptic terminals- nerve cells comes into contact with either another nerve cell receptor or effector organ

The fact that there are lots of synaptic knobs coming into contact with the cell body means that lots of information is transferred.
Behaviour and response can be variable- adjusting to circumstances

Question 7

List the different support cells coming out from the CNS

Answer 7

Astrocytes
Microglia
Oligodendrocytes
Ependymal cells

Question 8

Describe the astrocytes

Answer 8

Looks star shaped and is the largest glial cell

Connects to the capillary wall,axon and the cell bodies

• it maintains the blood-brain barrier
• Like a net- contain microfilaments which give structural strength to the CNS
• Stabalise structure after injury and thereby produce scar tissue (xxx- scar tissue prevents axon from returning)
• Direct neural growth during development
• Control the interstitial environment including recycling NTs

Question 9

Describe Microglia

Answer 9

(macrophage of the CNS)

Numerous cytoplasmic processes which have fine branches
From the same stem cells as macrophage and monocytes
Numbers increase when there is an infection

Question 10

Describe ependymal cells

Answer 10

Cells line the chambers and passageways of the CNS, filled with cerebrospinal fluid
Have branching process making contact with glial cells

Function: Monitoring the CSF and ensure there is an integrated system

Question 11

Describe the Oligodendrocytes

Answer 11

Its processes come into contact with axons either by:

• wrapping them together
• forming the myelin to improve the conducting velocity of the axons

Question 12

List the support cells coming out of the PNS

Answer 12

Schwann cells

Satellite cells

Question 13

Describe the schwann cells

Answer 13

Schwann cell wrapping itself around the myelinated axon

Participate in the repair process after injury

Question 14

Describe the role of Satellite cells

Answer 14

Surround the neuron cell bodies in ganglia

Regulate O2 CO2 and nutrients and Its levels around neurone in ganglia

Question 15

What are ganglia?

Answer 15

nerve cell bodies of neurone which lie outside the CNS are collected in groups called ganglia

Sensory ganglia
Motor ganglia

Question 16

Describe the Sensory ganglia

Answer 16

Sitting in vertebral columns
No synapses
Pseudo-unipolar

Question 17

Describe the Motor ganglia

Answer 17

MULTI-polar
does have synapses
Pre ganglionic comes in- myelinated
post ganglionic comes out-unmyelinated usually

Question 18

Major Divisions of the brain

Answer 18

Cerebrum 
Cerebellum
medulla oblongata 
thalamus 
hypothalamus

Question 19

How is the brain and spinal chord supported and protected and why is important?

Answer 19

Neural tissue is delicate even with support of glial cells

Protection comes in two forms:

Bony cranium- vertebral column ( this ensures that there is a rigid barrier between the internal and external environment)

BUT this is not enough as it can be damaged by gravity!
therefore..
Meninges

Question 20

Describe what are meninges

Answer 20

Composed of 3 layers:

Dura Mater - Periosteal and Meningeal
Arachnoid Mater
Pia Mater

Question 21

Describe the Dura Mater

Answer 21

2 layered structure

Outer layer fuses with periosteum and lining the canal cavity
Inner layer has several specialised fold which further supports the brain

The venous sinuses run between the two layers- it drains the blood from the brain

Question 22

Describe the Arachnoid Mater

Answer 22

Covers the surface of the brain and deep to it lies the
SARCHNOID SPACE- contains a meshwork of collagen nd elastic fibres- linking it to the Pia Mater
CSF also fills this space

Question 23

Describe the Pia Mater

Answer 23

tightly attached to the brain by ostrocytes and follows its contours

Question 24

Describe the flow of CSF

Answer 24

Made in the ventricles constantly- to prevent the build up of pressure it constantly requires to be reabsorbed so goes back into venous sinuses via arachnoid villi