Week 2: Neurons and Glia

Question 1

What is meant by “the neuron doctrine.”

Answer 1

Each neuron is a structural and functional unit. Neurons adhere to cell theory. Thought of following use of Golgi stain

Question 2

Distinguish between the Nissl and Golgi stains.

Answer 2

The Golgi stain shows a small percentage of neurons in their entirety and are good for neuronal morphology. Nissl stains bind to DNA and RNA and so show the nuclei and cytoplasmic Nissl bodies: they show cytoarchitecture.

Question 3

List the major structural features of the soma of a typical neuron.

Answer 3

The soma is the cell body. It is roughly spherical and approximately 20 micrometers in diameter. It contains a prominent nucleus and the cytoplasm (cytosol and all organelles except the nucleus).

Question 4

List the major structural features of the axon of a typical neuron.

Answer 4

Axon hillock
Axon proper
Axon terminal

Axons are highly specialized. They transfer information over distances. They begin at the axon hillock, which tapers away from the soma to the axon proper. Axons often branch - branches are called axon collaterals. Recurrent collaterals returns to communicate to the same cell it’s from of neighbouring dendrites. Axons end in the axon terminal. The terminal usually appears as a swollen disk.

Question 5

List the major structural features of the dendrites of a typical neuron.

Answer 5

Dendrites branch (called dendritic branches). Some have dendritic spines. Dendrites from a particular neuron collectively called dendritic tree.

Question 6

List and describe the main components of the neuronal cytoskeleton.

Answer 6

Internal scaffolding of neuronal membrane has three structures:
• Microtubules
• Microfilaments
• Neurofilaments

Question 7

What are the two mechanism of axoplasmic transport.

Answer 7

Slow axoplasmic transport

Fast axoplasmic transport

Question 8

List the main ways that neurons may be classified.

Answer 8

• Number of neurites
• dendritic and somatic morphology
• connections
• axonal length
• neurotransmitter type
• gene expression

Question 9

List the major types of glial cells.

Answer 9

1. Astrocytes
2. Oligodendrocytes
3. Microglia
4. Ependymal cells
5. Schwann cells
6. Satellite cells

Question 10

What was Cajal’s major contribution to neuroscience?

Answer 10

• Cajal’s contribution
– Neural circuitry
– Neurons communicate by contact, not continuity.
• Neuron doctrine
• Neurons adhere to cell theory.
• Use of Golgi stain

Question 11

What are two differences between axon and soma?

Answer 11

Differences between axon and soma:
– Rough ER does not extend into axon.
– Protein composition: unique

Question 12

What is the difference between anterograde and retrograde transport?

Answer 12

Anterograde is soma to terminal

retrograde is terminal to soma

Question 13

What is the function of microglia?

Answer 13

Equivalent to macrophages in other tissues - like the immune system. Remove debris.

other potential roles of microglial cells:
• reuptake of neurotransmitters (especially Glu);
• synaptic plasticity (memory/ adaptation);
• control of chemical environment (including blood-brain barrier)
• release of cytokines.

Question 14

List the glia cells found in the PNS.

Answer 14

Schwann cells

2. Satellite cells

Question 15

List the types of glia cells found in the CNS.

Answer 15

1. Astrocytes
2. Oligodendrocytes
3. Microglia
4. Ependymal cells

Question 16

How many neurites in the following types of neurons:

a. Unipolar
b. Multipolar
c. Bipolar

Answer 16

Unipolar: Single neurite
• Bipolar: two
• Multipolar: more
than two

Question 17

What is the role of oligodendrocytes?

Answer 17

They form myelin sheaths in the CNS.

Question 18

If an axon in the PNS is damaged, what happens?

Answer 18

Wallerian degeneration leads to removal of damaged axons and stimulation of growth factors to promote axon regrowth back into the periphery.

Question 19

What causes the following process?
- prolonged breakdown of damaged axons
– an increase in the proliferation of astrocytes at the site of injury
– inhibition of axonal regrowth.

Answer 19

CNS injury

Question 20

What is atypical about the amacrine cell of retina?

Answer 20

It has no axon

Question 21

Based on dendritic and somatic morphology, star shaped neurons are called…?

a. Spiny
b. Stellate cells
c. Pyramidal cells
d. Aspinous

Answer 21

b. Stellate cells

Question 22

List three major differences between fast axoplasmic transport and slow axoplasmic transport.

Answer 22

1. Slow is Unidirectional while fast is bidierectional (Anterograde and retrograde)
2. Fast involves proteins being enclosed in vesicles that move along the microtubules by kinesin.
3. Slow is mostly at a rate of 1mm/day; fast can be up to 300mm/day

Question 23

Which neuroglial forms myelin sheaths in the PNS?

Answer 23

The Schwann cell.

Question 24

What precedes the atrophy of the axons and neurons distal to an injury site.

Answer 24

Loss of transmission across the injury

Question 25

Based on dendritic and somatic morphology, star shaped neurons are called…?

a. Spiny
b. Stellate cells
c. Pyramidal cells
d. Aspinous

Answer 25

b. Stellate cells

Question 26

What precedes the atrophy of the axons and neurons distal to an injury site.

Answer 26

Loss of transmission across the injury

Question 27

What is a primary sensory neuron?

a. Cells with connections to the sensory surfaces of the body
b. Cells that form synapses with muscles
c. Cells with connections only with other neurons
d. Cells with dendritic spines

Answer 27

a. Cells with connections to the sensory surfaces of the body

Question 28

Cells with dendritic spines are called…?

a. Spiny
b. Stellate cells
c. Pyramidal cells
d. Aspinous

Answer 28

a. Spiny

Question 29

The most numerous glia in the brain is?

Answer 29

Astrocytes

Question 30

Golgi Type I neurons are also called:

a. Local circuit neurons
b. Interneurons
c. Pyramidal cells
d. Projection neurons

Answer 30

d. Projection neurons

They have long axons that extend from one part of the brain to the other

Question 31

Pyramidal cells are usually: (Select all that apply)

a. Golgi Type I neurons
b. Golgi Type II neurons
c. Projection neurons
d. Local circuit neurons
e. Spiny
f. Aspinous
g. Pyramid shaped
h. Classified by their dendritic and somatic morphology
i. In the cerebral cortex

Answer 31

a. Golgi Type I neurons
c. Projection neurons
e. Spiny
g. Pyramid shaped
h. Classified by their dendritic and somatic morphology
i. In the cerebral cortex

Question 32

Pyramidal cells are usually: (Select all that apply)
a. Golgi Type I neurons
b. Golgi Type II neurons
c. Projection neurons
d. Local circuit neurons
e. Spiny 
f. Aspinous 
g. Pyramid shaped 
h. Classified by their dendritic and somatic
morphology
i. In the cerebral cortex

Answer 32

a. Golgi Type I neurons
c. Projection neurons
e. Spiny
g. Pyramid shaped
h. Classified by their dendritic and somatic
morphology
i. In the cerebral cortex

Question 33

What are Golgi Type II neurons?

Answer 33

Neurons with short axons that do not extend past the vicinity of the cell body. They are also called “local circuit neurons”. Stellate cells are examples of these.