Nerve Flashcards
What are the 2 major types of glia?
- microglia = immune cells of the CNS
- 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
- Fibrous: intermediate filaments, mostly in white matter
What are the components of a neuron?
- cell body = has a nucleus, where metabolic processes happen
- dendrites = branches out from cell body; receives impulses from other cells
- 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 - +/- myelin
- in between each myelin = nodes of Ranvier
What’s myelin?
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
What is orthograde axonal trasnport?
going from the cell body towards axon
- occurs along microtubules
- needs dynein and kinesin
- has both fast and slow components
What’s retrograde axonal trasnport?
going from the axon twaords the cell body
- also occurs along microtubules
about 200mm/day
ex. nerve growth factor (NGF)
What’s the function of neurotrophins?
it’s associated with neuronal development, growth, and survival
What are the 4 different neurotrophins?
- nerve growth factor
- brain-derived neurotrophic factor
- Neurotrophin 3
Neurotrophin 4/5
Describe each of the 7 steps.
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
What are the different types of nerve fibers?
Describe spinal cord anatomy.