11-2. Classification of Neurons and Myelination

Question 1

What are the ways to classify neurons?

Answer 1

structural (# of processes from cell body) or functional (what they do)

Question 2

multipolar neuron

Answer 2

many processes extend from the cell body; all are dendrites except for a single axon.

Question 3

What is the most common structural neuron?

Answer 3

multipolar

Question 4

What type of neuron is found in the brain and spinal cord?

Answer 4

multipolar

Question 5

bipolar neuron

Answer 5

two processes, one dendrite and one axon.

Question 6

Where are bipolar neurons found?

Answer 6

retina, inner ear and lining of nose

Question 7

unipolar neuron

Answer 7

one process extends from the cell body, then splits into a centraol process (axon) and a peripheral process (dendrite)

Question 8

What are sensory neurons classified as structurally?

Answer 8

unipolar

Question 9

sensory neuron

Answer 9

transmits impulses from receptors (in the periphery) into the CNS

Question 10

motor

Answer 10

carries impulses away from the CNS, out to effectors

Question 11

Motor neurons are usually ____.

Answer 11

multipolar neurons

Question 12

association neuron

Answer 12

lies between sensory and motor neurons - 90% of all neurons

Question 13

Association neurons are usually ____, and are found entirely in the ____.

Answer 13

multipolar; CNS

Question 14

myelin sheath

Answer 14

white, phospholipid covering around many axons; insulates the neurons electrically (prevents “cross-talk”) and increases the speed of nerve impulse conduction

Question 15

white matter

Answer 15

myeline is responsible for the white color in the brain and spinal cord

Question 16

What are elements of myelination in the PNS?

Answer 16

schwann cells, neurilemma, nodes of ranvier

Question 17

What are elements of myelination in the CNS?

Answer 17

oligodendorcytes

Question 18

schwann cells

Answer 18

flat neuroglial cells that wrap around the axon many times in a jelly-roll fashion. Inner layers compose the myelin sheath

Question 19

neurilemma

Answer 19

the outer, thick layer that contains the nucleus and most of the cytoplasm. It helps injured neurons repair themselves

Question 20

nodes of ranvier

Answer 20

gaps that occur at regular intervals along the myelin sheath; spaces between adjacent Schwann cells (which do not touch). The gaps force the nerve impulse to jump from node to node, increasing the speed of conduction

Question 21

oligodendrocytes

Answer 21

form the myelin sheath around axons in the CNS. Have nodes of Ranvier but lack a neurilemma

Question 22

Injured PNS neurons [can / cannot] repair themselves.

Answer 22

can - have a neurilemma

Question 23

Injured CNS neurons [can / cannot] repair themselves.

Answer 23

cannot - lack a neurilemma

Question 24

A nerve impulse revolves around the ____ and ____ of 2 ions across the plasma membrane: ___ and ____.

Answer 24

diffusion; active transport; Na+; K+