Which one of the following sensory receptors are found in epidermis
**Core Concept**
The epidermis, the outermost layer of the skin, contains various sensory receptors responsible for detecting mechanical, thermal, and chemical stimuli. These receptors play a crucial role in maintaining the body's homeostasis and responding to external stimuli.
**Why the Correct Answer is Right**
The correct answer is Merkel's discs, which are mechanoreceptors found in the epidermis. Merkel's discs are specialized nerve endings that respond to light touch and pressure, providing essential information about the texture and shape of objects. They are composed of a Merkel cell and a nerve terminal, which form a synapse to transmit sensory information to the central nervous system. Merkel's discs are activated by the deformation of their receptor cell membrane, which leads to the opening of mechanosensitive ion channels and the generation of action potentials.
**Why Each Wrong Option is Incorrect**
* **Option A:** Free nerve endings are found in the epidermis but are primarily responsible for detecting pain, temperature, and itch sensations.
* **Option B:** Ruffini's corpuscles are mechanoreceptors found in the dermis, not the epidermis, and are responsible for detecting stretch and skin stretch.
* **Option C:** Pacinian corpuscles are rapidly adapting mechanoreceptors found in the dermis, primarily responsible for detecting vibration and pressure.
**Clinical Pearl / High-Yield Fact**
Merkel's discs are often referred to as "touch receptors" due to their role in detecting mechanical stimuli. They are essential for our ability to perceive the texture and shape of objects, and their dysfunction can lead to tactile agnosia or a loss of touch sensation.
**Correct Answer:** C.