3.1 The Neuron Is the Building Block of the Nervous System

Question 1

nervous system

Answer 1

a collection of hundreds of billions of specialized and interconnected cells through which messages are sent between the brain and the rest of the body

Question 2

central nervous system (CNS)

Answer 2

made up of the brain and the spinal cord

Question 3

peripheral nervous system (PNS)

Answer 3

the neurons that link the CNS to our skin, muscles, and glands

Question 4

endocrine system

Answer 4

the chemical regulator of the body that consists of glands that secrete hormones

Question 5

neuron

Answer 5

a cell in the nervous system whose function it is to receive and transmit information

Question 6

soma

Answer 6

contains the nucleus of the cell and keeps the cell alive

Question 7

dendrite

Answer 7

collects information from other cells and sends the information to the soma

Question 8

axon

Answer 8

transmits information away from the cell body toward other neurons or to the muscles and glands

Question 9

myelin sheath

Answer 9

a layer of fatty tissue surrounding the axon of a neuron that both acts as an insulator and allows faster transmission of the electrical signal

Question 10

terminal button

Answer 10

the end of each axon branch

Question 11

neurotransmitters

Answer 11

communicate with other neurons across the spaces between the cells

Question 12

synapses

Answer 12

areas where the terminal buttons at the end of the axon of one neuron nearly, but don’t quite, touch the dendrites of another

Question 13

resting potential

Answer 13

a state in which the interior of the neuron contains a greater number of negatively charged ions than does the area outside the cell

Question 14

action potential

Answer 14

change in electrical charge that occurs in a neuron when a nerve impulse is transmitted

Question 15

node of Ranvier

Answer 15

breaks between the sausage-like segments of the myelin sheath

Question 16

refractory period

Answer 16

a brief time after the firing of the axon in which the axon cannot fire again because the neuron has not yet returned to its resting potential

Question 17

excitatory

Answer 17

make the cell more likely to fire

Question 18

inhibitory

Answer 18

make the cell less likely to fire

Question 19

reuptake

Answer 19

a process in which neurotransmitters that are in the synapse are reabsorbed into the transmitting terminal buttons, ready to again be released after the neuron fires

Question 20

agonist

Answer 20

a drug that has chemical properties similar to a particular neurotransmitter and thus mimics the effects of the neurotransmitter

Question 21

antagonist

Answer 21

a drug that reduces or stops the normal effects of a neurotransmitter