chapter four

Question 1

homeostasis

Answer 1

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

Question 2

antidiuretic

Answer 2

the suppression of urine production

Question 3

membrane

Answer 3

a thin, limiting covering of a cell

Question 4

cell body

Answer 4

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

Question 5

dendrites

Answer 5

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

Question 6

axon

Answer 6

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

Question 7

axon terminals

Answer 7

the end region of the axon

Question 8

receptors

Answer 8

recognition mechanisms that respond to specific chemical signals

Question 9

neurotransmitter

Answer 9

chemical messengers released from axon terminals

Question 10

synaptic vesicles

Answer 10

small bubbles of membrane that store neurotransmitters

Question 11

myelin

Answer 11

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

Question 12

autoimmune disease

Answer 12

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

Question 13

multiple sclerosis

Answer 13

an autoimmune disease caused by damage to the myelin sheath that wraps axons

Question 14

blood-brain barrier

Answer 14

the structure that prevents many drugs from entering the brain

Question 15

semipermeable

Answer 15

allowing some, but not all, chemicals to pass

Question 16

neurotransmission

Answer 16

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

Question 17

action potential

Answer 17

the electrical signal transmitted along the axon when a neuron fires

Question 18

ion channels

Answer 18

pores formed in the cell membrane that allow the passage of ions from one side of the membrane to the other

Question 19

ion

Answer 19

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

Question 20

resting potential

Answer 20

the voltage maintained by a cell when it is not generating action potentials

Question 21

hyperpolarized

Answer 21

when the membrane potential is more negative

Question 22

depolarized

Answer 22

when the membrane potential is less negative