1. Neural Communication

2. Will Explain Why We FEEL…… Nervous Strong Sick Pain

3. It all Starts with the Neuron 42-44

5. What are neurons? • Nerve cells (smallest unit of Nervous System) • Billions/Cells do not regenerate but can adapt • Conduct impulses that carry signals • Types • Sensory • Respond to incoming stimuli • Transmit information from senses to brain • Motor • Relay information from the brain to rest of the body • Interneurons • Process information between sensory and motor

7. What are the parts of a neuron? • Cell Body • Life support center • Dendrites • Receive messages from other cells (INPUT) • Axons • Passes messages away from the cell body to other neurons (OUTPUT) • Myelin Sheath • covers the axons and helps speed neural impulses • Terminal Branches • Ends of axons; contain neurotransmitters • Synaptic Gap • Space between terminal branches and dendrites

8. Neuron: Internally: message electrical. Externally: message chemical

9. How are messages sent? Neurons do NOT touch each other – space b/w = synapse

10. How are messages sent? • Neuron fires (action potential) through the synapses b/w neurons • In the form of a neurotransmitter • Process is electrochemical

11. The All-or None Response • The idea that either the neuron fires or it doesn’t- no part way firing. • Like a gun

12. Steps of Action Potential • Electrically charged atoms that stimulate neuron = ions • Interior of resting neuron = negative ions • Exterior of resting neuron = positive ions • Start of action potential comes from depolarization = positive ions let in

13. Steps of an Action Potential • Ions enter the receiving neuron = exciting or inhibiting • Excitatory signals = pushing neuron’s accelerator • Inhibitory signals = pushing neuron’s brake • Threshold = Excitatory minus Inhibitory signals. If more excitatory, neuron will “fire” • toilet flush analogy

14. How are messages sent? Refresh • Depolarization • Semipermeable cell membrane lets positively charged ions in. • Action Potential • If excitatory signals minus inhibitory signals exceed threshold • “all-or-none” response: neurons either fire or don’t • Release of Neurotransmitter • Cross synaptic gap and bind to receptors on receiving neuron • Refractory Period • Positively charged ions are pumped back outside; then neuron can fire again.

15. TRANSITION SLIDE

16. How do neurotransmitters influence us? P. 44-47 Chemical messengers released by terminal buttons through the synapse (over 60, you need to know 4). • Particular neurotransmitters have particular effects on behavior and emotions • Particular brain pathways use particular neurotransmitters • Examples: • Acetylcholine and memory • Dopamine and mobility • Serotonin and depression • Endorphins and pain

17. Acetylcholine & Memory • Its function is motor movement and memory. • Lack of is linked to Alzheimer’s • When it’s released, muscles contract Botulin blocks transmission of Ach = paralysis

18. Dopamine & mobility • Its function is motor movement and alertness. Lack of dopamine (death of nerve cells) is associated with Parkinson’s disease. Overabundance is associated with schizophrenia.

19. Serotonin & depression • Function deals with mood control. Lack of serotonin has been linked to depression.

20. Endorphins & Pain • Function - deals with pain control. • Natural opiates “runners high” • Response to pain & vigorous exercise We become addicted to endorphin causing feelings.

21. How do drugs influence neurotransmitters? • 1. Block reuptake • … of neurotransmitter at pre-synaptic neuron  overabundance 0f neurotransmitter • Examples: Prozac = serotonin, cocaine = dopamine • 2. Mimic neurotransmitters- similar enough to occupy receptor site • Called agonists • morphine mimics endorphins • THC (in marijuana) & nicotine mimic dopamine • 3. Block receptor site – not similar enough to stimulate the receptor • Called Antagonist • Prevent neurotransmitter message from being relayed • Example: curare poison, Ach (no muscle contraction) • Essentially stop producing own natural opiates/endorphins • Always need a fix, dependency, more, unpleasant feelings

22. Agonists and Antagonists