Which of the following receptors is responsible for measuring the intensity of a steady pressure on the skin surface?
## **Core Concept**
The question tests the understanding of mechanoreceptors in the skin and their functions. Mechanoreceptors are specialized sensory receptors that respond to mechanical stimuli, such as pressure, vibration, and stretch. They play a crucial role in sensing touch, pressure, and vibration.
## **Why the Correct Answer is Right**
The correct answer, , corresponds to **Pacinian corpuscles**. These are rapidly adapting mechanoreceptors found in the dermal and hypodermal layers of the skin. They are responsible for detecting changes in pressure and vibration, particularly steady pressure on the skin surface. Pacinian corpuscles have a large, encapsulated structure that allows them to respond to high-frequency vibration and pressure changes, making them ideal for sensing the intensity of steady pressure.
## **Why Each Wrong Option is Incorrect**
* **Option A:** corresponds to **Meissner's corpuscles**, which are rapidly adapting mechanoreceptors sensitive to light touch and changes in texture. They are not primarily responsible for measuring steady pressure.
* **Option B:** corresponds to **Merkel discs**, which are slowly adapting mechanoreceptors involved in sensing sustained pressure and texture. While they do respond to pressure, they are more about the sustained nature rather than the intensity of the pressure.
* **Option D:** corresponds to **Ruffini's corpuscles**, which are slowly adapting mechanoreceptors that respond to skin stretch and contribute to the perception of slip of skin. They are not primarily responsible for measuring the intensity of steady pressure.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that different mechanoreceptors have distinct functions: Pacinian corpuscles for vibration and rapid pressure changes, Meissner's corpuscles for light touch, Merkel discs for sustained pressure, and Ruffini's corpuscles for skin stretch. This specificity allows for a wide range of tactile sensations to be perceived.
## **Correct Answer:** . Pacinian corpuscles