Final answer:
Graded potentials are crucial for sensory neurons, such as influencing action potential generation or neurotransmitter release. Generator potentials in dendrites can trigger action potentials in sensory neuron axons, while receptor potentials result in neurotransmitter release without needing to reach a threshold.
Step-by-step explanation:
When evaluating the mechanisms governing graded potentials and action potentials, it would be accurate to state that graded potentials are particularly important to sensory neurons and that graded potentials can trigger action potentials. Graded potentials are local changes in membrane potential that occur in response to a stimulus. In sensory neurons, such as those with free nerve endings or encapsulated endings, a graded potential called a generator potential develops in the dendrites, which influences the generation of an action potential in the axon. Similarly, specialized sensory receptor cells, like taste cells or photoreceptors, produce a receptor potential that results in neurotransmitter release at synapses with sensory neurons.
For receptor potentials, reaching threshold potential is not necessary for neurotransmitter release. However, generator potentials and postsynaptic potentials can summate, leading to an axon reaching its threshold and thus initiating an action potential. This occurs at the initial segment of the axon for sensory neurons, or the axon hillock in other neurons, both areas rich in voltage-gated Na+ channels vital for action potential initiation. Understanding this interplay between graded potentials and action potentials is essential for grasping neuronal function and signal transduction.