chapter 2

Question 1

neurons (what do they do? What are the main components of a neuron?)

Answer 1

Basic building blocks of the nervous
system
Transmit messages throughout the brain
and between the brain and the rest of
the body

Question 2

glial cells (what are they? functions?)

Answer 2

• Provide physical and
functional support for
neurons
• Create a matrix to hold
neural circuits together
Chapter 2-1a: Neurons: Into the Fabulous Forest
• Provide neurons with nutrients

Question 3

myelin sheath (what does it do? speed of action potential? Why is it important?)

Answer 3

Immune cells produce too much
glutamate, which damages/kills
myelin producing glial cells

Question 4

efferent (motor) neurons (what do they do? which division of the nervous
system?)

Answer 4

carry information from the Central Nervous System (CNS) to

destinations outside the brain (muscles, glands)

Question 5

interneurons (what do they do? which division of the nervous system?)

Answer 5

• process information
• CNS is made entirely of interneurons
• About 99% of neurons in nervous system are interneurons

Question 6

action potential (what is it? approximate voltage of action potential pulse?)

Answer 6

a brief electrical charge that travels down the axon.

Neurons are bathed in liquid, and this liquid is rich in ions.

Question 7

ions (what is an ion?)

Answer 7

atoms that carry an electrical charge (+/-)

Question 8

resting potential of neuron (what is it? what voltage?)

Answer 8

-70

Question 9

excitatory vs. inhibitory impulses

Answer 9

Excitatory - more likely to cause an action potential (make inside of cell more positively
charged compared to outside)

Inhibitory - less likely to cause an action potential (make inside of cell more negatively
charged compared to outside)

Question 10

excitation threshold (what is it? what voltage?)

Answer 10

Excitation threshold is about -55mv for mammals
• if voltage changes from -70mv resting potential to the -55mv excitation threshold, neuron
will fire
• if voltage doesn’t change all the way to threshold (e.g. -60mv), neuron will not fire

Question 11

ions involved in action potential (how does ionic activity create action potential)?

Answer 11

• There are ions inside and outside the cell
• They are distributed differently inside and outside the cell because of the cell’s
membrane – it has the property of selective permeability

Question 12

selective permeability (what is it?)

Answer 12

some ions pass through membrane more easily than others

Question 13

sodium-potassium pump (what is it?)

Answer 13

active mechanism that pumps out Na+ ions
at same rate that they leak in, and pumps in K+ ions at same rate that
they leak out

Question 14

basic action potential process (what triggers it? voltage-gated ion channels?)

Answer 14

– K+ ions continue to exit cell, lowering inner voltage
– Na+ ions also start moving outside cell again (sodium-potassium pump helps out)
– Once repolarized, K+ channels gradually close, causing a few extra K+ ions to exit and
leaving axon hyperpolarized momentarily before stabilizing at resting potential again

Question 15

hyperpolarization (what causes it?)

Answer 15

momentarily before stabilizing at resting potential again

Question 16

refractory period (what is it? how long does it last?)

Answer 16

• brief period (1-2ms) after
action potential when neuron is
unable to fire
• axon not sufficiently polarized
to fire

Question 17

difference between absolute refractory period and relative refractory period?

Answer 17

Absolute Refractory Period
• brief period (1-2ms) after
action potential when neuron is
unable to fire
• axon not sufficiently polarized
to fire
Relative Refractory Period
Chapter 2-1b: The Neural Impulse: “The Body Electric”
• period of time where axon has sufficiently repolarized, but
hyperpolarization makes it more difficult to elicit another action
potential
• Higher-than-normal stimulation is required to elicit another action
potential during this period, but it is possible

Question 18

all-or-none response of neuron (how nervous system signals different degrees of
neural stimulation?)

Answer 18

Action potential always has the same strength and
speed
The neuron either fires, or it doesn’t!

Question 19

synapse (what is it?)

Answer 19

In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron

Question 20

synaptic gap (what is it?)

Answer 20

The minute space between the cell membrane of an axon terminal and of the target cell with which it synapses

Question 21

vesicles (what are they?)

Answer 21

a fluid- or air-filled cavity or sac, in particular.

Question 22

neurotransmitters (what are they?)

Answer 22

When a neurotransmitter makes contact with a matching receptor
site, it triggers a voltage change in the receiving neuron

Question 23

receptor sites (what are they?)

Answer 23

the place that revises neurotransmitters

Question 24

reuptake (what is it? why is it important?)

Answer 24

The effects of neurotransmitters normally only last long enough to
affect a voltage change in the post-synaptic neuron
• If reuptake didn’t occur, receptor sites would be continuously
stimulated.