Physics Test Notes

Test 01 - Introduction
Receptor cells use chemical transmitters to communicate with relay cells or afferent nerve fibers.
In all sensory systems, accessory structures modify, in some way, the stimulus going to the receptor surface.
Receptors are electrically polarized cells and therefore have a resting membrane potential.
Stimuli produce, in the appropriate receptors, a change in the electrical properties that is known as the receptor or generator potential.
The two ways in which sensory stimuli can act on receptors to change their resting membrane potential (RMP) are by directly acting on ion channels or causing production of second messengers that act on ion channels.
The two types of ion channels found in sensory receptors are mechanically gated and chemically gated channels.
In receptors, the appropriate stimulus results in a change in the resting membrane potential because of changes in ionic movement through mechanically gated or chemically gated channels.
Receptor or Generator potentials and Action potentials are similar in that they are produced by conductance changes due to the opening or closing of channels.
Receptor/ Generator Potentials differ from Action Potentials (APs) in that only APs involve the opening of voltage-gated ion channels.
The strength of a stimulus can be coded by an increase in the number of APs from a single receptor and an increase in the number of active receptors.
The property that allows receptors to code aspects of a dynamic or changing stimulus is fast adaptation
The properties of the receptor potential that allow receptors to code stimulus timing and duration are summation and adaptation.
Adaptation allows receptors to signal stimulus change.
Receptor tuning allows receptors to signal stimulus quality such as color, pitch, flutter etc.
The receptive field (RF) of a sensory neuron refers to the area of the sensory receptor surface providing input to that neuron.
Receptors can code (signal) stimulus intensity