1. AP Biology Nervous Systems Part 3

2. Synapse and Neurotransmitter

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

4. Synapse at the axon terminal 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. Synapse with effector cell Motor unit 1 Motor unit 2 Nerve Synaptic terminals Motor neuron cell body Spinal cord Motor neuron axon Muscle Tendon Muscle fibers