Nerve

Question 1

What are the 2 major types of glia?

Answer 1

1. microglia = immune cells of the CNS
2. Macroglia
   a. Oligodendrocytes: in the gray matter, helps with neuron supports. Acts like myelin in white matter
   b. Schwann Cells: provides myelin for the PNS
   c. Astrocytes:
   
   • Fibrous: intermediate filaments, mostly in white matter
     
     • Protoplasmic: mostly in gray matter, sends processes to blood vessels, forms the Blood-Brain-Barrier. Also produces tropic substances and maintain ion concentration

Question 2

What are the components of a neuron?

Answer 2

1. cell body = has a nucleus, where metabolic processes happen
2. dendrites = branches out from cell body; receives impulses from other cells
3. axons = originates from axon hillock from the cell body
   - Initial segment: first portion
   - Divides into presynaptic terminals
   - Ends in terminal buttons (boutons) –> contains vesicles or granules of synaptic transmitters
4. +/- myelin
5. in between each myelin = nodes of Ranvier

Question 3

What’s myelin?

Answer 3

protein-lipid complex that’s wrapped up around an axon
- Compaction of the myelin sheaths occurs when the extracellular portion of the protein P0 is locked to the extracellular P0 of the opposing membrane
- Speeds up nerve conduction –> travels at nodes of Ranvier rather than along the axon

Question 4

What is orthograde axonal trasnport?

Answer 4

going from the cell body towards axon
- occurs along microtubules
- needs dynein and kinesin
- has both fast and slow components

Question 5

What’s retrograde axonal trasnport?

Answer 5

going from the axon twaords the cell body
- also occurs along microtubules
about 200mm/day
ex. nerve growth factor (NGF)

Question 6

What’s the function of neurotrophins?

Answer 6

it’s associated with neuronal development, growth, and survival

Question 7

What are the 4 different neurotrophins?

Answer 7

1. nerve growth factor
2. brain-derived neurotrophic factor
3. Neurotrophin 3
   Neurotrophin 4/5

Question 8

Describe each of the 7 steps.

Answer 8

1 = resting
2 = opening voltage gated Na+ gate in response to depolarizing stimulus –> brings the voltage to threshold potential
3 = positive feedback - membrane potential moves towards 60+mV
4 = doesn’t reach 60+mV during action potential, cause the increase in Na+ conductance is short-lived
- The Na+ channel remains in inactive state for a few milliseconds, before returning to a resting state when they can activated again
5 = Opening of the voltage gated K+ channels (slower to open than the Na+ channel) –> repolarization
6 = after-hyperpolarization, due to slow closing of the K+ channels
7 = return to resting potential

Question 9

What are the different types of nerve fibers?

Answer 9

Question 10

Describe spinal cord anatomy.

Answer 10