Nervous System 2 Flashcards

1
Q

What are bundles of nerve fibres called?

A

fascicles

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2
Q

What forms myelin

A

Schwann cells and oligodendrocytes

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3
Q

Where does action potential occur?

A

Nodes of Ranvier

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4
Q

What makes up a single segment of myelin sheath?

A

Schwann cell

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5
Q

What is grey matter?

A

contains most of neuronal cell bodies and dendrites

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6
Q

What is white matter?

A

Contains most of the axons (myelinated)

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7
Q

What is the most abundant cells in the CNS?

A

Glial cells @ 90%

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8
Q

Where are ependymal cells found?

A

lining ventricles and spinal canal of spinal cord

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9
Q

What is the function of ependymal cells?

A
  1. Secrete CSF

2. Possess cilia to help with flow

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10
Q

What do ependymal cells look like?

A

simple, cuboidal, ciliated cells

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11
Q

What is the most abundant glial cell?

A

Astrocytes

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12
Q

What is the function of astrocytes?

A
  1. Control blood brain barrier (BBB)

2. Metabolic support

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13
Q

What are microglia?

A

Resident immune cells of the brain

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14
Q

What are the different shapes of microglia?

A

Ramified

Amoeboid

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15
Q

What is the function of microglia?

A
  1. Release nerve growth factors in resting state (stationary)
  2. Activated by infection/injury:
    a. Alter shape (amoeboid)
    b. Become phagocytic
    c. Release chemicals
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16
Q

What is the function of oligodendrocytes?

A

Form myelin sheath around axons

17
Q

When does myelin sheath formation begin in CNS?

A

About 4mths

18
Q

What is the function of the BBB?

A

Protect brain from chem fluctuations in blood

19
Q

What makes the BBB?

A

Endothelial cells with tight junctions

20
Q

How does saltatory conduction work?

A
  1. Active node at peak of action potential (Na+ moves in)
  2. Adjacent inactive node into which depolarisation is spreading will soon reach threshold
  3. Remainder of nodes are still @ resting potential
  4. Previous active node returns to resting potential and no longer active
  5. Adjacent node that was brought to threshold by local current flow is active 2 peak of action potential
  6. New adjacent inactive node into which depolarisation is spreading will reach threshold
21
Q

What is the cellular basis for myelination?

A
  1. Aid in debris removal and regeneration of peripheral nerves
  2. Providing fast conductance