Increase in threshold level on applying a sub-threshold, slowly rising stimulus is known as:

Accommodation:refers to gradual increase in threshold caused by prolonged slowly rising sub-threshold stimulus resulting from the inactivation of sodium channels. Adaptation: Decrease in response with continued application of stimulus. Some receptors of sensory system show this propey. Refractoriness: Is for the second stimulus; if applied during the refractory period of the first stimulus, the second stimulus fails to excite the tissue for one more time. (In accommodation, the tissue fails to respond even for the first time). Electrotonus: refers to passive spread of charge inside a neuron.