Study Question Two

• Q2. Discuss and explain the steps involved in chemical synaptic transmission. 
• Step One: Arrival of the action potential at the axon terminal causes the release of neurotransmitter from secretory vesicles by exocytosis at the presynaptic membrane. Exocytosis is how cells release substances by merging vesicles with their membrane. Calcium channels then open, calcium ions flow into the cell, triggering this merging process and allowing the release of the substances.
• Step One: Arrival of the action potential at the axon terminal causes the release of neurotransmitter from secretory vesicles by exocytosis at the presynaptic membrane. Exocytosis is how cells release substances by merging vesicles with their membrane. Calcium channels are important because when they open, calcium ions flow into the cell, triggering this merging process and allowing the release of the substances.
• Step Two: The neurotransmitter diffuses across the synaptic cleft (the space between the axon and the postsynaptic surface) and binds to receptors on the postsynaptic membrane.
• Step Two: The neurotransmitter diffuses across the synaptic cleft (the space between the axon and the postsynaptic surface) and binds to receptors on the postsynaptic membrane.
• Step Three: Receptor binding changes the permeability of the postsynaptic membrane; the resulting effect may be excitatory or inhibitory. In general, excitatory effects promite the generation of action potentials, whereas inhibitory effects reduce the ability to generate action potentials.
• Step Three: Receptor binding changes the permeability of the postsynaptic membrane; the resulting effect may be excitatory or inhibitory. In general, excitatory effects promote the generation of action potentials, whereas inhibitory effects reduce the ability to generate action potentials.
• Step Four: If the excitation is sufficient, receptor binding leads to the generation of an action potential in the axon (if the postsynaptic cell is a neuron) of sarcolemma (if the postsynaptic cell is a skeletal muscle fiber).
• Step Four: If the excitation is sufficient, receptor binding leads to the generation of an action potential in the axon (if the postsynaptic cell is a neuron) of sarcolemma (if the postsynaptic cell is a skeletal muscle fiber).
• Step Five: The effects of one action potential on the postsynaptic membrane are short-lived because the neurotransmitter molecules are either enzymatically broken down or reabsorbed. To prolong or enhance the effect, additional action potentials must arrive at the axon terminal, and additional molecules of the neurotransmitter must be released into the synaptic cleft.
• Step Five: The effects of one action potential on the postsynaptic membrane are short-lived because the neurotransmitter molecules are either enzymatically broken down or reabsorbed. To prolong or enhance the effect, additional action potentials must arrive at the axon terminal, and additional molecules of the neurotransmitter must be released into the synaptic cleft.
• Source

  • Chapter Thirteen: Page 352, Section 13.7 Synaptic Communication