Chapter 43

Question 1

CNS

Answer 1

includes the brain and spinal cord; integrates information

Question 2

Three kinds of neurons

Answer 2

Sensory neurons collect information and send it on
* Interneurons pass signals from neuron to neuron
* Motor neurons signal effector cells in glands or muscles

Question 3

peripheral nervous system (PNS)

Answer 3

includes the components of the nervous
system outside the CNS

Question 4

Nerves

Answer 4

Motor neurons and sensory neurons are bundled
together into long strands called

Question 5

Most neurons have three parts

Answer 5

Cell body (soma): Contains the nucleus and controls the cell.

Dendrites: Short, branch-like structures that receive signals.

Axon: A long extension that sends signals to other cells.

Question 6

Synapses

Answer 6

connection points where neurons communicate with other neurons or cells. They can be:

Question 7

The sodium-potassium pump

Answer 7

moves 3 sodium (Na⁺) ions out of the cell and 2 potassium (K⁺) ions in, creating an electrical imbalance.

This makes the outside of the cell more positive and the inside more negative (polarized).

K⁺ leak channels let some potassium ions leak out, maintaining this charge difference.

This difference in charge across the membrane is called the membrane potential and is important for nerve signals.

Question 8

action potential

Answer 8

a rapid, temporary change in
a membrane potential

Question 9

Action potential 3 phases

Answer 9

1. Depolarization – The inside of the cell becomes less negative and shifts toward a positive charge.
2. Repolarization – The cell quickly returns to being negative inside.
3. Hyperpolarization – The cell becomes even more negative than its resting state before stabilizing.

Question 10

Action potential

Answer 10

Action potentials move one way down the neuron because once a sodium (Na⁺) channel opens and closes, it can’t reopen right away (this is called the refractory state). This prevents the signal from going backward, so it only moves forward like a wave of depolarization.

Question 11

synaptic vesicles

Answer 11

The ends of axons have synaptic vesicles that store neurotransmitters (chemical messengers). These neurotransmitters move across the synaptic gap and bind to receptors on the next cell to pass the signal.