Neurons, Glia, and Brain Tissue

Question 1

In general, white matter is _________ to gray matter in the cortex. In the spinal cord, however, it is opposite: ___________.

Answer 1

deep; gray matter is on the inside

Question 2

Tracts, peduncles, and fasciculi are all examples of ______ matter.

Answer 2

white matter

Question 3

Nuclei are an example of _________ matter.

Answer 3

gray

Question 4

Once stimuli pass from dendrites to the cell body, the _________ regulates whether the signal will continue down the axon.

Answer 4

axon hillock

Question 5

What stain selects for RNA?

Answer 5

Nissl

Question 6

Why do neurons need to make a lot of protein?

Answer 6

They are large cells, requiring extensive cytoskeletons to transport proteins to the periphery of axons and dendrites.

Question 7

Which kind of neuron (peripheral or central) can regrow damaged axons?

Answer 7

Peripheral (CNS axons can regrow – demonstrated in vitro – but they are prevented from doing so by astrocytes)

Question 8

Stacks of rough endoplasmic reticulum are called ___________.

Answer 8

Nissl bodies

Question 9

Necrosis due to damaged axons is called ___________.

Answer 9

chromatolysis (loss of coloring)

Question 10

What are myelin cells in the CNS called?

Answer 10

Oligodendrocytes or oligodendroglia

Question 11

What are myelin cells in the PNS called?

Answer 11

Schwann cells

Question 12

Embryologically, the nervous system comes from _____-derm.

Answer 12

ecto-

Question 13

The microglia are the __________ of the brain.

Answer 13

macrophages

Question 14

Why does ATP activate microglia?

Answer 14

ATP outside cells is a sign of lysis

Question 15

What are the three types of supportive cells in the CNS?

Answer 15

Astrocytes
Oligodendrocytes
Microglia

Question 16

Astrocytes provide what function in the CNS?

Answer 16

They fill in the spaces between cells.

Question 17

What is the most common neurotransmitter?

Answer 17

Glutamate

Question 18

What cell type is responsible for maintaining the blood-brain barrier?

Answer 18

Astrocytes (by instructing endothelial cells to form tight junctional complexes preventing leakage of plasma into extracellular space)

Question 19

List the functions of astrocytes.

Answer 19

• Neurotransmitter clearance
• Neuronal support
• Blood-brain barrier
• Local control of blood flow

Question 20

What is the cellular difference between white and gray matter?

Answer 20

White matter is myelinated.

Question 21

The white matter can be thought of as merely the ______________.

Answer 21

cables connecting the processing areas of the brain

Question 22

Cell bodies all live in ________ matter.

Answer 22

gray

Question 23

Most pathways are named using a __________ system.

Answer 23

“from-to” (so the corticospinal tract connects the motor system in the cortex to the spin)

Question 24

In terms of action potentials, how do dendrites and cell bodies differ from axons?

Answer 24

Dendrites and cell bodies are generally passive – meaning the electrical signal decreases with distance – while axons have voltage-sensitive channels that propagate an action potential.

Question 25

In general, axons greater than ________ are myelinated.

Answer 25

1 micron

Question 26

Recent research has indicated that __________ dysfunction may be a source of chronic pain.

Answer 26

microglia

Question 27

Unlike oligodendrocytes, which can myelinate _________ cell(s), Schwann cells can myelinate ________ cell(s).

Answer 27

many; only one

Question 28

___________ envelop all blood vessels in the central nervous system.

Answer 28

Astrocytes

Question 29

What two sites in the brain do not have the blood-brain barrier?

Answer 29

The circumventricular organs: caudal medulla and the hypothalamus

Question 30

By what two mechanisms do neurons communicate to the blood vessels that they need more oxygen?

Answer 30

They generate NO (which itself causes vasodilation); and the increased in glutamate uptake by astrocytes leads to activation of a phospholipase that produces EET; EET leads to hyperpolarization of the arteriolar membrane and thus vasodilation.