1. Nervous Systems Part 3 RA # 4.3

2. What is a synapse?  Gaps between neurons or between neurons and effectors

3. Nerve Impulse is approaching the axon terminal by Saltatory Conduction Cell body Schwann cell Depolarized region (node of Ranvier) Myelin sheath Axon

4. Explain the steps of nerve impulse conversion Postsynaptic cell Presynaptic cell Synaptic vesicles containing neurotransmitter Presynaptic membrane Voltage-gated Ca 2+ channel Ca 2+ Postsynaptic membrane Postsynaptic membrane Neuro- transmitter Ligand- gated ion channel Na + K+K+ Ligand-gated ion channels Synaptic cleft

5. Post synaptic membrane Resting potential Threshold Membrane potential (mV) Action potential Time –100 –50 +50 0 Potassium channel Extracellular fluid Plasma membrane Na + Resting state Inactivation gate Activation gates Sodium channel K+K+ Cytosol Na + Depolarization K+K+ Na + Rising phase of the action potential K+K+ Na + Falling phase of the action potential K+K+ Na + Undershoot K+K+ Na +

6.  The ability of the postsynaptic membrane to either turn on (EPSP) or turn off (IPSP) a nerve impulse. COMPARE EPSP’s TO IPSP’s.

7. Explain the purpose of summation Motor unit 1 Motor unit 2 Nerve Synaptic terminals Motor neuron cell body Spinal cord Motor neuron axon Muscle Tendon Muscle fibers To reach threshold more quickly

8. What is the most common neurotransmitter in the human body?  Acetylcholine What is the “sleep” neurotransmitter?  Serotonin What neurotransmitter relays pain?  Substance P Which gas is AKA “laughing gas?”  Nitric oxide

9. What do GABA’s do?  Inhibit transmission Which neurotransmitters create the “fight or flight” response?  Epinephrine and norepinephrine Which neurotransmitter is the “happy” neurotransmitter?  Dopamine What affect does carbon monoxide have on nerve transmission?  Inhibits What do endorphins do?  Block Substance P