23  •  Nervous and Motor Systems 917

Actions, reactions, sensations, and addictions: meet your nervous system

What is the nervous system? 918

23.1

Why do we need a nervous system? 918

23.2

Neurons are the building blocks of all nervous systems. 919

23.3

The vertebrate nervous system consists of the peripheral and central nervous systems. 921

How do neurons work? 924

23.4

Dendrites receive external stimuli. 924

23.5

The action potential propagates a signal down the axon. 925

23.6

At the synapse, neurons interact with other cells. 928

23.7

There are many types of neurotransmitters. 929

Our senses detect and transmit stimuli 931

23.8

Sensory receptors are our windows to the world around us. 931

23.9

Taste: an action potential serves up a taste sensation to the brain. 933

23.10

Smell: receptors in the nose detect airborne chemicals. 934

23.11

Vision: seeing is the perception of light by the brain. 936

23.12

Hearing: sound waves are collected by the ears and stimulate auditory neurons. 938

23.13

Touch: the brain perceives pressure, temperature, and pain. 940

23.14

Other senses help animals negotiate the world. 942

The muscular and skeletal systems enable movement 943

23.15

Muscles generate force through contraction. 943

23.16

Skeletal systems enable movement, among several other important functions. 946

The brain is organized into distinct structures dedicated to specific functions 948

23.17

The brain is organized into several distinct regions. 948

23.18

Specific brain areas are involved in the processes of learning, language, and memory. 952

23.19

This is how we do it: Can intense cognitive training induce brain growth? 954

Drugs can hijack pleasure pathways. 957

23.20

Our nervous system can be tricked by chemicals. 957

23.21

A brain slows down when it needs sleep. Caffeine wakes it up. 959

23.22

Alcohol interferes with many different neurotransmitters. 960

StreetBIO: KNOWLEDGE YOU CAN USE

“We Use Only 10% of Our Brain!” Fact or fiction? 962