Final answer:
The amount of neurotransmitter released at the axon terminal depends on the intensity of the nerve impulse, with excitatory and inhibitory neurotransmitters facilitating or inhibiting the continuation of an action potential. Neurotransmitter release is determined by the number and readiness of synaptic vesicles as well as the action of voltage-gated calcium channels. Both sensory and motor neurons communicate through neurotransmitters despite their functional differences.
Step-by-step explanation:
The total amount of neurotransmitter released at the axon terminal is directly related to the intensity of the nerve impulse. During the neurotransmission process, when a nerve impulse, or action potential, reaches the axon terminal, neurotransmitters are released from synaptic vesicles into the synaptic cleft. Neurotransmitters then bind to receptors on the postsynaptic membrane, allowing the signal to be transmitted to the next neuron or to another type of cell, such as a muscle cell.
This process of signal transmission can be excitation or inhibition, depending on the type of neurotransmitter. Excitatory neurotransmitters, such as acetylcholine (ACh) or epinephrine, increase the likelihood of an action potential in the postsynaptic neuron, while inhibitory neurotransmitters, such as serotonin or GABA, decrease this likelihood. The action potential operates on an all-or-none principle; once initiated, it travels down the axon unchanged in amplitude. The intensity of the nerve impulse fails to alter the strength of the action potential directly, but it can influence the number of action potentials over time and the amount of neurotransmitter released.
The linkage between the strength of a neurological signal and neurotransmitter release is complex, involving factors like the number of synaptic vesicles in the axon terminal and the presence of voltage-gated calcium channels necessary for vesicle fusion and neurotransmitter release. Sensory and motor neurons, while having differences in function and location, both utilize neurotransmitters to communicate with other neurons or target cells. Following binding, neurotransmitters are quickly degraded or reabsorbed by the presynaptic neuron to allow the postsynaptic cell to return to its resting state and be ready for the next signal.