CNS Chapter 11

Question 1

Neuroglia

Answer 1

– non-excitable, renewable (mitotic)
– Provide a supportive / protective scaffolding for neurons, protective
– Segregate and insulate neurons

Question 2

Structural classification of neurons

Answer 2

1) Unipolar: one short single process. Dendrites and axons are continuous. (afferent neurons, ganglion). Most abundant in PNS.
2) bipolar: one dendrite one axon continues, (special sensory organs: olfactory, retina)
3) multipolar: many dendrites, one axon. Most common class of neurons (interneurons, cerebellum, cerebral cortex, purkinje cells in heart). Most abundant in CNS

Question 3

Sensory Neurons

Answer 3

• Afferent neurons.

- Action Potential from PNS to CNS

Question 4

Motor neurons

Answer 4

• Efferent neurons

- Action Potential from CNS to PNS

Question 5

Interneurons

Answer 5

• Association neurons

- Most of the neurons in the CNS (90%)

Question 6

Neuroglia in CNS

Answer 6

1) Oligodendrocytes
2) Astrocytes
3) Ependymal cells
4) Microglia

Question 7

Neuroglia in PNS

Answer 7

1) Schwann cells

2) Satelite cells

Question 8

Satellite cells

Answer 8

• Surround neuron cell bodies in ganglia.

- Regulates O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia.

Question 9

Schwann cells

Answer 9

• Surround axons in PNS, spinal cord
• Are responsible for myelination of peripheral axons.
• Participate in repair process after injury

Question 10

Oligodendrocytes

Answer 10

• Myelinate CNS axons

- Provide structural framework

Question 11

Astrocytes

Answer 11

• Maintain blood-brain barrier
• Provide structural support
• Regulate ion, nutrient, and dissolved gas concentrations.
• Absorb and recycle neurotransmitters
• Form scar tissue after injury.

Question 12

Microglia

Answer 12

• Remove cell debris, wastes, and pathogens by pahgocytosis

Question 13

Ependymal cells

Answer 13

• Line ventricles (brain) and central canal (spinal cord)

- Assist in producing, circulating, and monitoring of cerebrospinal fluid.

Question 14

Nodes of Ranvier

Answer 14

Periodic gap in the insulating sheath (myelin) on the axon of neurons that serves to facilitate the rapid conduction of nerve impulses.

Question 15

Myelination

Answer 15

• Fatty sheath along the length of axon
• Electrically insulates axon
• Increases the speed of nerve impulse transmission
• Helps neural regeneration in PNS

Question 16

Multiple Sclerosis

Answer 16

destruction of myelin sheath (demyelination)

Question 17

Repair in PNS

Answer 17

1) The axon becomes fragmented at the injury site. Wallerina degeneration occurs distal to injury
2) Macrophages clean out the dead axon distal to the injury
3) Axon sprouts, or filaments, grow through a regeneration tube formed by Schwann cells.
4) The axon regenerates and a new myelin sheath forms

Question 18

Wallerian degeneration

Answer 18

degeneration of nerve fibers that occurs following injury or disease and that progresses from the place of injury along the axon away from the cell body while the part between the place of injury and the cell body remains intact

Question 19

Nerve signals direction

Answer 19

1) Dendrite 2) Cell body 3) Axon 4) Axon bulbs - Terminal 5) next neuron / effector

Question 20

Development of the the neural tube from embryonic ectoderm

Answer 20

1) The neural plate forms from surface ectoderm.
2) the Neural plate invaginates, forming the neural groove flanked by neural folds.
3) Neural fold cells migrate, form the nural crest, will form much of the PNS and other surfaces.
4) the Neural groove becomes the neural tube, which will form CNS structures.