1. Unit 3: Biological Bases of Behavior
3.2 The Nervous System

2. The Nervous System
System that regulates the body’s responses to internal and external stimuli
Neurons are the building blocks
Split into 2 main parts:
Central Nervous System
Peripheral Nervous System

3. The Nervous System Central Nervous System (CNS)
brain & spinal cord
Peripheral Nervous System (PNS)
communicates between CNS & all other parts of the body

4. Central Nervous System
Neurons work in groups called neural networks
Brain – most neurons here are small & have diff. functions/neurotransmitters
Spinal cord – column of nerves in spine transmits messages to/from brain
Send sensory info up to the brain
Send motor-control info back down
These spinal reflexes happen so fast we often don’t feel pain/sensation until after the reaction

5. Peripheral Nervous System
Broken up into 2 parts
Somatic Nervous System (SNS)
Controls body’s skeletal muscles
Voluntary movements
Also transmits senses to CNS like temp. and pressure
Autonomic Nervous System (ANS)
Regulates body’s vital functions – heart beating, breathing, digestion, etc
Can sometimes be consciously overridden, but usually operates on it’s own

6. Peripheral Nervous System
ANS is a dual system too
Sympathetic Nervous System
Expends energy, “fight or flight”
Makes heart beat faster, breathing get faster, raises blood pressure
Parasympathetic Nervous System
Conserves energy by calming you, “rest and digest”
Decreases heartbeat, lowers blood pressure, breathing slows
Work together to keep body in balance (homeostasis)