Structure of Neurones & Glia

Question 1

What are the 3 parts of a neuron?

Answer 1

Cell body/ soma
Dendrites- input
A single axon- ouput

Question 2

What are dendrites and axons are sometimes called collectively?

Answer 2

Neurites

Question 3

What is contained within the soma?

Answer 3

Nucleus

Perikaryon

Question 4

What is perikaryon?

Answer 4

Cytoplasm of a neuron

Question 5

What organelles of the cell body are found in the neuron?

Answer 5

Nucleus
Ribosomes
Golgi apparatus
Microtubules
Mitochondria
Lysosomes 
Lipofucin bodies

Question 6

What is the nucleus responsible for?

Answer 6

Contains DNA, replicate cells
Most adult neurons (after the age of 7) do not replicate- DNA involved only in protein synthesis
Protein made by transcription and translation (ribosomes)

Question 7

What are ribosomes responsible for?

Answer 7

Translation
Most commonly associated with endoplasmic reticulum (ER)
Rough ER or Nissl bodies (making proteins and peptide sequences)

Question 8

What is the golgi apparatus responsible for?

Answer 8

Protein assembly completed here

Question 9

What are microtubules responsible for?

Answer 9

Cell body, dendrites and axon
Transporting packaged proteins
Forms part of the cytoskeleton (gives neuron some degree of rigidity)

Question 10

How many neurons are in the mitochondria and what is it’s job?

Answer 10

Numerous in neurons

Supply energy

Question 11

What are lysosomes responsible for?

Answer 11

Break down organelles

Question 12

What are lipofucin bodies for?

Answer 12

Contain all neurons rubbish
Electron dense
Waste products in ‘old’ cells

Question 13

What happens to lipofucin bodies as people get older?

Answer 13

As you get older your body obtains more lipofucin bodies

Question 14

What is the role of dendrites?

Answer 14

Continuation of the cell body
Contain free ribosomes and mitochondria
Form branching patterns like trees
Synapses are formed on dendrites
Some synapses on spines

Question 15

What is the role of axons?

Answer 15

Unique to neurons
Specialised for transmission of electrical impulses
Can be up to 1m in length

Question 16

What are the part of the axon?

Answer 16

The axon hillock
Axon proper
Axon collaterals
Axon terminal

Question 17

What does the axon hillock do?

Answer 17

Merges from soma
Generates electrical impulse
Causes neuron to fire

Question 18

Where is the axon proper?

Answer 18

Long part of the axon

Emerges form axon hillock

Question 19

Where are the axon collaterals?

Answer 19

Branch from the axon

Question 20

What are the two cells that make up the brain and the spinal chord?

Answer 20

Neurons

glia

Question 21

What are axons terminals?

Answer 21

Form swelling or boutons

Make synapses

Question 22

What does an axon not contain?

Answer 22

Ribosomes

Question 23

How do axons transport proteins?

Answer 23

Along microtubules

Question 24

What are the ways of axonal transport in a neuron?

Answer 24

Axoplasmic transport (up to 1000mm/day)
Axoplasmic transport- both directions
Away from the cell body (anterograde transport)
Towards the cell body (retrograde transport)

Question 25

What are the reasons for retrograde transport?

Answer 25

To get rid of things of no values | Some molecules can convey messages from axon terminals to cell body (i.e. enzyme requirement)

Question 26

What is the composition of the nerve cell membrane?

Answer 26

Acts as a membrane Consists of a phospholipid bilayer Protein molecules embedded in the membrane confer unique properties Allow ions to pass in or out of the cell selectively i.e. semi permeable membrane

Question 27

How can neurons be classified?

Answer 27

``` Number of neurites Shape Connections Axons Neurotransmitters ```

Question 28

What are the different number of neurites which can be classified in neurons?

Answer 28

Unipolar Bipolar Multipolar

Question 29

What are the different shapes neurons can be?

Answer 29

Pyramidal | Sellate- star shaoe

Question 30

What are the different connections for the classification of neurons?

Answer 30

Primary sensory neurons Moto neurons Interneurons

Question 31

What are primary sensroy neurons?

Answer 31

Connections with sensory neurons surfaces of the body

Question 32

What are the moto neurons?

Answer 32

Connections with muscles

Question 33

What are the interneurons?

Answer 33

Connections with other neurons

Question 34

How can axons classify neurons?

Answer 34

Golgi type I- long axons | Golgi type II- local axons

Question 35

How can neurotransmitters classify neurons?

Answer 35

E.g. cholinergic- contains acetylcholine

Question 36

How much of cells in the brain are glia?

Answer 36

90%

Question 37

What are the 3 principle classes of glia?

Answer 37

Astrocytes Oligodendrocytes Microglia Astrocytes and oligodendrocytes= macroglia

Question 38

What are astrocytes?

Answer 38

Star shaped Most numerous type of glia Few organelles

Question 39

What is the function of astrocytes?

Answer 39

Function is not fully understood Provide mechanical and metabolic support Repair process (nervous system damaged, cause scar over and this is impenetrable, stops infection) Regulate flow of ions and molecules in extracellular fluid

Question 40

What are Oligodendrocytes?

Answer 40

Many organelles and microtrubules

Question 41

What is the function of oligodendrocytes?

Answer 41

Make Myelin (fatty substance which rolls itself around axons, insulting it and allowing conduction of axons to be increased)

Question 42

What is myelin?

Answer 42

Lipid sheath around axons Electrically insulates axons, not continuous Node of Ranvier Peripheral nervous system- myelin formed by Schwann cell

Question 43

What are microglia?

Answer 43

Microglia are really phagocytes, i.e. they remove waste. | About 100,000 neurons in your CNS die every day and microglia remove the debris.