Chapter 4 - The Nervous System

Question 1

homeostasis

Answer 1

maintenance of an environment of body functions within a certain range (e.g. temperature, blood pressure)

Question 2

membrane

Answer 2

a thin, limiting covering of a cell

Question 3

cell body

Answer 3

the central region of a neuron, which is the control center

Question 4

dendrites

Answer 4

branchlike structures that extend from the cell body and specialize in receiving signals from other neurons

Question 5

axon

Answer 5

a thin tube that extends from the cell body and specializes in transmitting signals to other neurons

Question 6

axon terminals

Answer 6

the end region of the axon

Question 7

receptors

Answer 7

recognition mechanisms that respond to specific chemical signals

Question 8

neurotransmitter

Answer 8

chemical messengers released from axon terminals

Question 9

synaptic vesicles

Answer 9

small bubbles of membrane that store neurotransmitters

Question 10

myelin

Answer 10

a fatty white substance that is wrapped around portions of the axons

Question 11

autoimmune disease

Answer 11

a condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue

Question 12

multiple sclerosis

Answer 12

an autoimmune illness caused by damage to the myelin sheath that wraps axons. A wide range of symptoms can accompany this disorder including muscle spasms, vision loss, severe pain, dizziness, fatigue, and intestinal problems

Question 13

blood-brain barrier

Answer 13

structure that prevents many drugs from entering the brain

Question 14

semipermeable

Answer 14

allowing some, but not all, chemicals to pass

Question 15

neurotransmission

Answer 15

the process of transferring information from one neuron to another at a synapse

Question 16

action potential

Answer 16

the electrical signal transmitted along the axon when a neuron fires

Question 17

ion channels

Answer 17

a protein in the cell membrane forms a pore that allows the passage of ions from one side of the membrane to the other

Question 18

ion

Answer 18

an atom or molecule that has a net electrical charge because of a difference in the number of electrons and protons

Question 19

resting potential

Answer 19

the voltage maintained by a cell when it is not generating action potentials. The resting potential of neurons is about -65 mV

Question 20

hyperpolarized

Answer 20

when the membrane potential is more negative

Question 21

depolarized

Answer 21

when the membrane potential is less negative