Quiz 2 (ch.12)

Question 1

astrocytes (CNS)

Answer 1

support & brace neuron (blood brain barrier), determine capillary permeability (CNS)

Question 2

microgalia (CNS)

Answer 2

migrate toward injured neuron. phagocytize microorganisms & neural debris

Question 3

ependymal cells (CNS)

Answer 3

line central cavities of the brain and spinal cord. separate CNS interstitial fluid from CSF in cavities

Question 4

oligodendrocytes (CNS)

Answer 4

wrap CNS nerve fibers. forms insulating myelin sheath. can myelinate many axons

Question 5

schwann cells (PNS)

Answer 5

insulate axons w/ myelin. vital to regeneration of damaged peripheral nerve fibers

Question 6

relative refractory period

Answer 6

A period after firing when a neuron is returning to its normal polarized state and will fire again only if the incoming message is much stronger than usual

Question 7

absolute refractory period

Answer 7

ensures that each AP is an all-or-none event. enforces one-way transmission of nerve impulses

Question 8

graded potential

Answer 8

temporary changes in the membrane voltage, the characteristics of which depend on the size of the stimulus

Question 9

theshold stimulus

Answer 9

push the membrane potential toward/beyond threshold

Question 10

subthreshold stimulus

Answer 10

does not reach threshold

Question 11

spatial summation

Answer 11

postsynaptic neuron is stimulated by a large number of terminals at the same time

Question 12

temporal summation

Answer 12

one or more presynaptic neurons transmit impulses in rapid-fire order

Question 13

cholinesterase

Answer 13

enzyme that breaks down acetylcholine

Question 14

acetylcholine

Answer 14

a neurotransmitter that enables learning and memory and also triggers muscle contraction

Question 15

axon hillock

Answer 15

Cone shaped region of an axon where it joins the cell body (soma).

Question 16

ions involved in action potential

Answer 16

The principal ions involved are sodium and potassium.
Sodium ions enter the cell, and potassium ions leave, restoring equilibrium. Na+ and K+

Question 17

EPSP

Answer 17

caused by the flow of positively-charged ions into the postsynaptic nerve. depolarization

Question 18

IPSP

Answer 18

caused by the flow of negatively-charged ions into the postsynaptic nerve

Question 19

depolarization

Answer 19

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

Question 20

repolarization

Answer 20

Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.

Question 21

Continuous conduction

Answer 21

–- Propagation along unmyelinated axon
–- slow because there are always voltage-gated Na+ channels opening, and more and more Na+ is rushing into the cell

Question 22

Saltatory conduction

Answer 22

• along the length of a myelinated axon
• faster because the action potential basically jumps from one node to the next (saltare = “to leap”), and the new influx of Na+ renews the depolarized membrane

Question 23

Synaptotagmin protein

Answer 23

binds Ca2+ and promotes fusion of synaptic vesicles with axon membrane