In which type of receptor phasic or tonic does the receptor

In which type of receptor, phasic or tonic, does the receptor potential fall below threshold, even as the stimulus continues?

Solution

Tonic Receptors

•Tonic Receptors are slowly adapting receptors that respond rapidly when first activated, then slow down and maintain their response.

•Pressure sensitive baroreceptors, irritant receptors, and some tactile receptors and proprioceptors fall into this category. In general, the stimuli that activate tonic receptors are parameters that must be monitored continuously by the body.

•It is important that these receptors do not adapt to a stimulus and continue to generate action potentials to relay this information to the CNS.

Phasic receptors

•Phasic receptors are rapidly adapting receptors that respond when they first receive a stimulus but stop responding if the strength of the stimulus remains constant. Many of the tactile receptors in the skin belong to this class.

•Some phasic receptors, most notably the Pacinian corpuscle, respond with a slight depolarization called the off response when the stimulus is removed. They are important in situations where it is important to signal a change in stimulus intensity rather than the status quo information.

•When you put something on, you soon become accustomed to it, because of these receptors’ rapid adaptation. When you take the item off , you are aware of its removal because of the “off” response.

So the answer is TONIC RECEPTORS

because in tonic receptors, receptor potential decreases below threshold~stimulus continues but no Aps, they adapt slowly to the stimulus example :- Merkel;s receptor in skin ; detect steady pressure; encodes duration & intensity of stimuli