1. Compare and contrast electrical and chemical synapses.
Answer: Electrical synapses allow for fast signal transmission and bidirectional communication between cells connected via an electrical synapse. Chemical synaps
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1. Compare and contrast electrical and chemical synapses.
Answer: Electrical synapses allow for fast signal transmission and bidirectional communication between cells connected via an electrical synapse. Chemical synapses allow for a broad range of postsynaptic responses, but the transmission is slower in chemical synapses than electrical synapses.
Textbook Reference: Properties of Neurotransmitters
2. Provide scientific evidence of the existence of chemical synapses.
Answer: Otto Loewi proved that electrical information can be transferred from the vagus nerve to the heart by means of a chemical signal, which was later shown to be acetylcholine.
Textbook Reference: Properties of Neurotransmitters
3. List the steps involved in chemical neurotransmission, beginning with the synthesis of neurotransmitter and ending with the response of the postsynaptic neuron.
Answer:
a) Synthesis of the neurotransmitter
b) Packaging of the neurotransmitter
c) Delivery of the neurotransmitter to the presynaptic terminal (if neurotransmitter is synthesized in the cell body)
d) Arrival of the action potential to the presynaptic terminal
e) Influx of Ca2+ into the presynaptic terminal
f) Fusion of the synaptic vesicles with the presynaptic membrane
g) Release of the neurotransmitter
h) Binding of the neurotransmitter to its receptor on the postsynaptic membrane
i) Response of the postsynaptic membrane or cell, which depends on the particular transmitter and receptor
Textbook Reference: Signaling Transmission at Chemical Synapses
4. What is significant about the quantal nature of MEPPs?
Answer: Each MEPP is evoked by the release of a single packet of neurotransmitter (synaptic vesicle) from the presynaptic terminal.
Textbook Reference: Quantal Release of Neurotransmitters
5. What evidence indicates that EPPs are composed of MEPPs?
Answer: Experiments using Ca2+ and curare in the study of acetylcholine release at the neuromuscular junction led to the discovery of quantal fluctuations in the amplitude of EPPs. The amplitude of the smallest EPPs is similar in size to that of a single MEPP, and increments in the EPP response occur in units about the size of single MEPPs.
Textbook Reference: Quantal Release of Neurotransmitters
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