Nervous SystemAP Biology—Unit 9

Nervous System Major Divisions

Central Nervous System—brain and spinal cord—contains interneurons and cell bodies of motor neurons Brain—different parts in charge of

different functions

Peripheral Nervous System—everything outside of central nervous system

Peripheral Nervous System

Peripheral Nervous System

Motor Sensory movement senses

Somatic AutonomicFrom CNS to skeletal From CNS to smooth

muscle and glands

SympatheticParasympathetic

Energy giving—”fight or flight” Energy conserving—back to normal

Peripheral Nervous System

Neurons

a. Parts—See Picture

b. Typesi. Sensory (afferent)—bring information into

integrating center (brain and spinal cord)

ii. Interneuron—connectors, make-up CNS

iii. Motor (efferent)—take information out to effectors (muscles and glands)

Neurons

Neurons

Action Potential

Action Potential Animation

Action Potential

Action Potential

Saltatory Conduction

Conduction

Conduction—from 1 neuron to another neuron, muscle, or gland

Electrical—action potential passes to next touching neuron—fast and steady

Example: HeartImportant if fast and steady is neededSynapse is very small and so charge can keep passing down the line

Conduction

Chemical—necessary because of synapse

a. Synapse—gap between neurons

b. Neurotransmitters—chemicals that cause depolarization1. Excitatory—open Na+ channels in the cell receiving

the action potential2. Inhibitory—open Cl- channels to decrease ability to

get action potential

Conduction

How Synapses Work Animation

Conduction

Acetylcholine—muscle contraction and brain

Epinephrine—adrenaline

Glutamate—excitatory

Glycine—inhibitory

GABA—inhibitory

Norepinephrine—excitatory for ANS

Dopamine—affect sleep, mood, attention, and learning

Seratonin—affect sleep, mood, attention, and learning

Reflexes Reflex—the body’s automatic

response to certain stimuli

• Spinal cord acts without brain—involuntary

• Protects body because it’s rapid

Reflexes