Skin Receptors Quiz

Cutaneous Receptors Overview

• Skin contains various types of receptors, each responding to different stimuli.
• Receptors are innervated by axons.

Meissner Corpuscle

• Sensitive to flutter and light touch.
• Located in the superficial layers of skin.
• Composed of nerve endings enclosed in connective tissue.
• Rapidly adapting, firing only during stimulus onset and offset.

Pacinian Corpuscle

• Responsive to vibration.
• Found in the deep layers of skin.
• Like Meissner, consists of encapsulated nerve endings.
• Rapidly adapting receptor.

Ruffini Ending/Corpuscle

• Detects skin stretching.
• Located in the deep skin layers.
• Consists of enlarged nerve endings.
• Slowly adapting, continuing to fire as long as the stimulus persists.

Merkel Cells

• Respond to steady pressure and texture.
• Situated in the superficial layers of skin.
• Composed of enlarged nerve endings.
• Slowly adapting receptor, providing ongoing stimulus information.

Free Nerve Endings

• Respond to temperature, pain, itch, and hair follicle movement.
• Found around hair roots and beneath the skin surface.
• Comprised of unmyelinated nerve endings.
• Exhibit variable adaptation characteristics.

Nociceptors

• Specialized receptors that respond to noxious stimuli that can damage tissue (chemical, mechanical, thermal).
• Utilized by free nerve endings.
• Activate reflexive responses via spinal cord or send signals to the cerebral cortex for conscious sensation of pain or itch.

Temperature Receptors

• Cold receptors are activated below 37°C; warm receptors function between 37°-45°C.
• Adapt slowly between 20°-40°C, but nociceptors recognize pain outside this range.
• Chemicals (e.g., menthol, capsaicin) can influence temperature receptors.

Transduction Process

• Converts sensory stimuli into action potentials.
• Triggered by membrane stretch opening mechanical gateways for ion influx (e.g., Na+).
• Action potential generated upon reaching the threshold.

Slowly Adapting Receptors

• Trigger continuous nerve impulses as long as the stimulus persists.
• Examples include Merkel cells and Ruffini endings.

Rapidly Adapting Receptors

• Fire briefly during the onset and/or offset of a stimulus.
• Includes Pacinian and Meissner corpuscles.

Transduction Timing

• Slow transduction leads to many action potentials throughout the stimulus duration.
• Rapid transduction is characterized by concentrated bursts of action potentials during changes in the stimulus.

Transduction Intensity

• Higher stimulus intensity correlates with increased frequency of action potentials.

Transduction Modality

• Refers to the type of stimulus, determined by skin indentation and stimulus frequency.
• Specific receptors fire according to their strengths, sending appropriate action potentials.

Transduction Location

• Different receptors exhibit overlapping and variable sensitivity areas.
• Meissner (rapidly adapting) and Merkel (slowly adapting) have small, specific sensory fields.
• Pacinian (rapidly adapting) and Ruffini (slowly adapting) possess larger sensory fields.