When absorbed by receptor sites, what type of message does a neurotransmitter deliver?
A An action potential
B An excitatory message
C Either an excitatory or inhibitory message
D An inhibitory message AND excitatory message
The correct answer and explanation is:
The correct answer is C. Either an excitatory or inhibitory message.
Neurotransmitters are chemical messengers that transmit signals between neurons (nerve cells) across synapses, the small gaps between neurons. When a neurotransmitter is released from the presynaptic neuron, it travels across the synapse and binds to specific receptor sites on the postsynaptic neuron. The type of message it delivers depends on the nature of the receptor it binds to and the specific neurotransmitter involved.
Neurotransmitters can have excitatory or inhibitory effects on the postsynaptic neuron.
- Excitatory neurotransmitters promote the generation of an action potential in the postsynaptic neuron. They typically cause the postsynaptic membrane to become more positive, moving the membrane potential closer to the threshold for an action potential to occur. A common example of an excitatory neurotransmitter is glutamate, which is involved in most of the brain’s excitatory signaling processes.
- Inhibitory neurotransmitters, on the other hand, prevent the generation of an action potential. They cause the postsynaptic membrane to become more negative, making it less likely for the neuron to reach the threshold for firing an action potential. A well-known inhibitory neurotransmitter is GABA (gamma-aminobutyric acid), which has a calming effect on neural activity.
In some cases, a single neurotransmitter can produce both excitatory and inhibitory effects, depending on the type of receptor it binds to. For example, acetylcholine can be excitatory at some synapses, like those in skeletal muscles, but inhibitory at others, such as those in the heart. This flexibility allows the nervous system to regulate complex functions, including muscle contraction, heart rate, and cognitive processes.
Therefore, the key point is that neurotransmitters can deliver either an excitatory or an inhibitory message based on their chemical nature and the receptors involved in the signaling process.