Final answer:
A sensation is the activation of sensory receptor cells by a stimulus that leads to a receptor potential, a type of graded potential that can trigger an action potential if it reaches a threshold.
Step-by-step explanation:
The activation of sensory receptor cell:
A sensation is fundamentally the activation of sensory receptor cells by an external stimulus, which leads to the generation of an electrical signal in the nervous system. The process begins with the reception of a stimulus by sensory receptors, each having a specific receptive field. Various stimuli such as mechanical pressure, chemicals, or temperature can activate these receptors.
Transduction is the crucial link between physical energy from the environment and the electrical signals within the nervous system. When the sensory receptors are stimulated, they undergo a change leading to the opening of ion channels in the membrane of the sensory neuron. This ion flow results in an electrical change - the receptor potential, which is a type of graded potential.