Final answer:
Keratin is a structure-providing protein, not a sensory receptor. The skin, particularly the dermis, contains sensory receptors like Merkel cells, Meissner's corpuscles, and Pacinian corpuscles, which detect various touch stimuli and provide tactile sensations to the brain.
Step-by-step explanation:
The student's question seems to be a mix-up, as keratin is a protein found in the epidermis, primarily responsible for the structural integrity of hair, nails, and the outer layer of skin, but it does not contain sensory receptors. The correction for the substance that contains sensory receptors for touch would be skin, specifically within the dermis layer. The skin has specialized cells and nerve endings that are responsible for tactile sensations.
Examples of these sensory receptors include Merkel cells, which respond to light touch and texture, Meissner's corpuscles, which are sensitive to light touch and low-frequency vibration, and Pacinian corpuscles, which are designed to detect deeper pressure and high-frequency vibration. These receptors provide the brain with information about touch stimuli, helping us interact with our environment.