Chapter 4

Question 1

Name the three main regions of a typical neuron.

Answer 1

Cell body (soma), dendrites, axon.

Question 2

What is the Nissl substance and where is it not found?

Answer 2

Stacks of rough‑ER ribosomes that make protein; absent from the axon hillock & axon.

Question 3

Which cytoskeletal element serves as the ‘railroad track’ for axonal transport?

Answer 3

Microtubules.

Question 4

Where does an action potential normally start?

Answer 4

Initial segment just beyond the axon hillock.

Question 5

Define a ‘dendritic spine.’

Answer 5

Small protrusion on a dendrite that forms one chemical synapse.

Question 6

Motor protein for fast anterograde transport (soma ➜ terminal).

Answer 6

Kinesin.

Question 7

Typical speed range of fast anterograde transport.

Answer 7

≈ 100‑400 mm per day.

Question 8

Give one example of cargo moved by slow anterograde transport.

Answer 8

Cytoskeletal proteins (e.g., tubulin, actin) or neurofilament subunits.

Question 9

Which direction does dynein carry cargo?

Answer 9

Fast retrograde (terminal ➜ soma).

Question 10

Name a pathogen that reaches the CNS via fast retrograde transport.

Answer 10

Rabies virus (also poliovirus, tetanus toxin, herpes).

Question 11

Most common neuron shape in the CNS.

Answer 11

Multipolar.

Question 12

Sensory neurons in dorsal‑root ganglia are what type?

Answer 12

Pseudo‑unipolar.

Question 13

Where do you find bipolar neurons?

Answer 13

Retina, olfactory epithelium, vestibular & cochlear ganglia.

Question 14

Golgi type I vs type II neurons — key difference.

Answer 14

Type I = long axon (projection cell); Type II = short axon (local interneuron).

Question 15

List the four major glial classes in the CNS.

Answer 15

• Astrocytes
• Oligodendrocytes
• Microglia
• Ependymal cells

Question 16

Which glial filament marker is used to identify astrocytes histologically?

Answer 16

Glial fibrillary acidic protein (GFAP).

Question 17

Two key ion/neurotransmitter homeostasis tasks of astrocytes.

Answer 17

• Buffer extracellular K⁺
• Uptake glutamate

Question 18

What is the ‘glial limiting membrane’?

Answer 18

Sheet of astrocyte end‑feet under the pia mater.

Question 19

Main function of oligodendrocytes.

Answer 19

Form myelin around multiple CNS axons.

Question 20

What embryonic layer gives rise to microglia?

Answer 20

Mesoderm (they are CNS‑resident macrophages).

Question 21

Ependymal cell with long radial process found in cerebellum.

Answer 21

Bergmann glia.

Question 22

Specialized ependymal cells that form CSF‑producing epithelium.

Answer 22

Choroid plexus epithelial cells.

Question 23

One Schwann cell myelinates how many axon internodes?

Answer 23

One (in the PNS).

Question 24

What are Nodes of Ranvier and why are they important?

Answer 24

Small myelin gaps rich in Na⁺ channels; enable saltatory conduction.

Question 25

Name two proteins abundant in CNS myelin.

Answer 25

* Myelin basic protein (MBP) * Proteolipid protein (PLP)

Question 26

Key antigenic difference between CNS & PNS myelin.

Answer 26

PNS myelin contains P0 glycoprotein; CNS myelin does not.

Question 27

Conduction velocity: myelinated vs unmyelinated axon — general rule.

Answer 27

Myelination increases speed roughly 10‑100 ×.

Question 28

CNS autoimmune demyelinating disease with plaques.

Answer 28

Multiple sclerosis (MS).

Question 29

Peripheral post‑infectious demyelinating neuropathy with ascending weakness.

Answer 29

Guillain‑Barré syndrome (GBS).

Question 30

Why does MS affect oligodendrocytes but spare Schwann cells?

Answer 30

CNS myelin proteins differ antigenically from PNS myelin.

Question 31

Genetic PNS demyelination causing high‑arched feet and foot drop.

Answer 31

Charcot‑Marie‑Tooth disease.

Question 32

Term for distal axon breakdown after transection.

Answer 32

Wallerian degeneration.

Question 33

Soma reaction with swelling & dispersion of Nissl substance.

Answer 33

Chromatolysis.

Question 34

Define anterograde transneuronal degeneration.

Answer 34

Death of a postsynaptic neuron because its input neuron was lost.

Question 35

Why do CNS axons fail to regenerate effectively? Give two reasons.

Answer 35

* Astrocyte scar blocks path * Oligodendrocyte/myelin expresses growth‑inhibitory molecules

Question 36

Approximate regrowth rate of a peripheral axon if a Schwann tube is intact.

Answer 36

2–4 mm per day.

Question 37

Two hallmark early symptoms of Guillain‑Barré syndrome.

Answer 37

* Rapidly ascending weakness * Areflexia

Question 38

Main treatments that speed recovery in GBS.

Answer 38

* IV immunoglobulin * Plasma exchange

Question 39

Neurofibrillary tangles in Alzheimer’s disease are aggregates of what mis‑folded protein?

Answer 39

Hyper‑phosphorylated tau.

Question 40

Which glial cell proliferates to form a scar after CNS injury?

Answer 40

Fibrous astrocyte.

Question 41

Name one role of astrocyte Ca²⁺ signaling ('gliotransmission').

Answer 41

Modulate synaptic activity or control local blood vessel diameter.

Question 42

Virus classically tracked in labs for retrograde transneuronal tracing.

Answer 42

Pseudorabies virus.

Question 43

Protein marker lost in Schwann‑cell gap junction disease Charcot‑Marie‑Tooth 1X.

Answer 43

Connexin‑32.