Mr. Koch AP Psychology Forest Lake High School

 Neuron = 1 cell  Nerve = a bundle of neurons

Dendrites Cell body (soma) Axon Myelin sheath Axon Terminals (end branches) Synapse Cell Nucleus

 Dendrites – receive messages  Cell Body (soma) – direct activity  Axon – passage way  Myelin Sheath – pushes messages / protects  Axon Terminal – sends info  Synapse – space between neurons

Neurons use an electro-chemical process to send messages  Why electrical ?  Pushing information through axon is based on process of positive and negative charges of electrical atoms (ions)  Potassium (K+), Sodium (Na+), Chloride (Cl-)  Why chemical ?  Neurotransmitters cross synapse: different ones send different impulses and need to find receptors  It can either excite (fire) or inhibit (prevent firing)  Messages are sent at a speed of mph  Neurons are altered with use (learning) – unused neurons die (“neural sculpting)

1. Neuron is stimulated by light, heat, pressure or chemical messages (neurotransmitters) from other neurons. If signals (excitatory-inhibitory) reach minimum threshold, will trigger action potential 2. The electrical impulse ( action potential ) travels down the neuron. 3. The neuron signals other neurons to react

The impulse is called the action potential 1. Resting potential  Polarized – positive outside, negative inside (Na+) (Cl- & K+) 2. Action potential  If stimulated – depolarizes  Sodium (Na+) rushes in 3. Refractory period  “recharging” – “Sodium pump” pumps sodium ions back out 4. Back to resting potential - repolarized

 Acetylcholine (ACh)  Involved in muscle action, learning, memory  (Black Widow venom = convulsions)  Dopamine  Major role in regulating movement, emotions, reward & pleasure, learning, memory  Low levels → Parkinson’s  (L-dopa – synthetic derivative)  Norepinephrine  Reward, mood regulation, arousal, activation, fight/flight behavior  Low levels connected to severe depression  Serotonin  Involved in sleep, mood, appetite, sensory/pain perception, regulates body temp  Deficit connected to severe depression  Endorphins (opioids)  Minimize pain, produce feelings of pleasure, memory  Gamma amino butyric acid (GABA)  Inhibits neurons  Glutamate  Excites neurons