Question

The response of the postsynaptic cell at a chemical synapse is determined by a. the type of neurotransmitter released at the synapse. b. the type of receptors the postsynaptic cell has. c. whether or not an axon is myelinated. d. whether the synapse is on a dendrite or directly on the cell body of the postsynaptic cell. e. a and b, both.

Short answer

So the correct answer is e. both a and b, i.e., the type of neurotransmitter released at the synapse and the type of receptors the postsynaptic cell has determine the cell's response.

Step-by-step solution

Analyze the Potential Factors

Evaluate each of the given options in the context of their influence on a postsynaptic cell's response at a chemical synapse.

Understand the Role of Neurotransmitters and Receptors

Neurotransmitters are chemicals that transmit signals from a neuron to a target cell across a synapse. The type of neurotransmitter released at the synapse can certainly alter the response of the postsynaptic cell. Similarly, the type of receptors the postsynaptic cell has can dictate how the cell reacts to a neurotransmitter. If the cell does not have the appropriate receptors for a certain neurotransmitter, it will not react, regardless of how much of the neurotransmitter is present.

Evaluate the Other Factors

The myelination of an axon is responsible for the speed of electrical impulse transmission, not the response of the postsynaptic cell at a chemical synapse. Whether the synapse is on a dendrite or directly on the cell body of the postsynaptic cell determines the distance over which the signal needs to travel and might impact the strength of the signal received, but this does not determine the type of response of the postsynaptic cell. Hence, these can be eliminated.

Arrive at the Conclusion

Out of the given options, the type of neurotransmitter released (a) and the type of receptors the postsynaptic cell has (b) are key determining factors of the response of the postsynaptic cell at a chemical synapse.

Key concepts

Neurotransmitter Function

Understanding the role of neurotransmitters is crucial when exploring how the nervous system communicates. Neurotransmitters are the chemicals responsible for transmitting signals across the synaptic gap between neurons. Each neurotransmitter binds to specific receptor sites on the postsynaptic cell in a lock-and-key fashion, which triggers a change in the cell's state.

The diversity in neurotransmitters allows for a range of responses in the postsynaptic neuron. For instance, excitatory neurotransmitters such as glutamate may cause the postsynaptic neuron to become more likely to fire an action potential. Conversely, inhibitory neurotransmitters like GABA reduce the likelihood of the postsynaptic neuron firing.

In the context of the exercise, the neurotransmitter released dictates whether the response in the postsynaptic cell will be excitatory or inhibitory, ultimately affecting communication within the nervous system.

Receptor Types in Neurons

Receptors in neurons are specialized protein structures embedded in the cell membrane. They are highly selective, responding only to specific neurotransmitters. The two broad categories of receptors are ionotropic and metabotropic receptors.

Ionotropic Receptors

These receptors act as gateways for ions when the neurotransmitter binds to them. This direct and swift response leads to an immediate change in the postsynaptic neuron’s membrane potential, which can result in an action potential.

Metabotropic Receptors

Unlike ionotropic receptors, metabotropic receptors trigger a series of metabolic steps involving second messengers within the postsynaptic cell. This process is slower but can lead to more prolonged and diverse effects, including changes in gene expression.

The exercise implies that without the correct receptor types, a neurotransmitter, regardless of its amount, cannot elicit the intended response in the postsynaptic neuron. Recognizing the appropriate receptor is as vital as recognizing the neurotransmitter itself.

Synaptic Transmission

Synaptic transmission is the process through which neurons communicate with each other. This communication happens at synapses, which are specialized junctions where the axon terminal of one neuron (presynaptic neuron) connects to the dendrite, soma, or axon of another neuron (postsynaptic neuron).

During synaptic transmission, an action potential reaches the axon terminal of the presynaptic neuron, triggering the release of neurotransmitters into the synaptic cleft. These neurotransmitters then cross the cleft and bind to receptors on the postsynaptic neuron, leading to a response.

From the problem solving steps of the exercise, we understand that the synaptic transmission's efficiency is influenced by a combination of several factors, essentially the neurotransmitter type and postsynaptic receptors, but not by the myelination of the axon or the location of the synapse regarding whether it’s on a dendrite or the cell body.