1. The Nervous System

2. Peripheral Nervous System
Sympathetic system: prepares body for stress or action & triggers fight or flight reactions
Parasympathetic system: returns body systems to normal, lowers heart & breathing rates, promotes digestion

4. The Neuron: A Powerful Computer
Neurons
Sensory neurons
Motor neurons
Interneurons
Glial cells

5. Reflexes

7. The Neuron

8. Major Parts of a Neuron

9. The Neuron: A Powerful Computer
Neural impulses: The brain in action
Ions
Action potential
All-or-none law
Myelin

11. Ion Flow that Produces an Action Potential

13. Neural Firing A resting neuron is negatively charged
If a portion is stimulated beyond its threshold, it briefly reverses polarity
This polarity reversal travels down the neuron
Neurotransmitters are released at the axon terminals

17. Synapse Synaptic Vesicles:
Tiny gap between an axon terminal & another neuron (or specialized cell).
Firing neurons release neurotransmitters that cross the synapse.
Synaptic Vesicles:
Hold the neurotransmitter.
Neural firing drives them to the synapse, where they release their chemicals.

18. Synapse
The neurotransmitter binds to the receptor site on the target cell
Ion gates open
Excess neurotransmitter is reuptaken

19. Neurotransmitters
After crossing the synapse, the neurotransmitter is reuptaken or degraded
There are more than 40 known types
Different neurotransmitters have different effects
Drugs, neural diseases often affect neurotransmitters

20. Neurotransmitters
Acetylcholine: important for learning, memory, muscle movement
Serotonin: influences mood and regulates food intake
Dopamine: important to movement and to frontal lobe activity
GABA: important in inhibiting neural activity
Norepinephrine: maintains alertness & wakefulness
Endorphins: regulate firing of pain neurons

22. Drugs Many drugs influence synaptic transmission
Drugs can be agonistic or antagonistic

24. Agonistic Drugs Increase synthesis of neurotransmitter, or
Increase release of neurotransmitter, or
Activate receptors, imitate neurotransmitter, or
Inhibit reuptake of neurotransmitter

26. Antagonistic Drugs Interfere with release of neurotransmitter, or
Occupy and block neurotransmitter sites, or
Cause neurotransmitter loss from vesicles.

27. Psychology and Neurons
Tying human behavior to neurons is difficult.
There may be 100 billion neurons in your body.
Each neuron has many connections.