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