AP Biology—Unit 9
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
Motor
Sensory
movement
Somatic
From CNS to skeletal
senses
Autonomic
From CNS to smooth
muscle and glands
Sympathetic
Parasympathetic
Energy giving—”fight or flight”
Energy conserving—back to normal
a.
Parts—See Picture
b.
Types
i.
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)
Action Potential
Animation
Conduction—from 1 neuron to another neuron,
muscle, or gland
Electrical—action potential passes to next
touching neuron—fast and steady
Example: Heart
Important if fast and steady is needed
Synapse is very small and so charge can keep passing
down the line
Chemical—necessary because of synapse
a. Synapse—gap between neurons
b. Neurotransmitters—chemicals that cause
depolarization
1.
2.
Excitatory—open Na+ channels in the cell receiving the
action potential
Inhibitory—open Cl- channels to decrease ability to get
action potential
How Synapses Work Animation
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
 Reflex—the
body’s automatic response to
certain stimuli
• Spinal cord acts without brain—involuntary
• Protects body because it’s rapid