Exam 2: Somatosensory System Flashcards
Somatosensory System
The system responsible for detecting touch, pressure, temperature, pain, and body position.
Primary Somatosensory Cortex
The region of the brain that processes somatosensory information from the body, located in the postcentral gyrus.
Somatotopic Organization
The orderly mapping of the body’s surface onto the somatosensory cortex, where adjacent body parts are represented in adjacent cortical areas.
Sensory Homunculus
A visual representation of the body mapped onto the somatosensory cortex, with exaggerated areas for more sensitive regions (e.g., hands and lips).
Secondary Somatosensory Cortex
A brain region that integrates complex sensory information and is involved in higher-order sensory processing.
Cutaneous Mechanoreceptors
Receptors in the skin that detect mechanical stimuli, such as pressure, vibration, and stretch.
Slowly-Adapting Mechanoreceptors
Mechanoreceptors that respond to sustained pressure and slowly adapt to continuous stimuli.
Rapidly-Adapting Mechanoreceptors
Mechanoreceptors that respond to changes in stimuli, such as light touch or vibration, and adapt quickly.
Merkel’s Discs
Touch receptors that detect fine details and texture, located in the skin’s surface layers.
Pacinian Corpuscles
Receptors in the skin that detect deep pressure and high-frequency vibration.
Meissner’s Corpuscles
Touch receptors sensitive to light touch and low-frequency vibration, involved in grip control.
Ruffini Endings
Receptors in the skin that detect skin stretch and help with the perception of hand shape and object manipulation.
Receptive Fields in the Skin
Specific areas of skin that a single sensory neuron is responsible for detecting stimuli.
Two-Point Discrimination Task
A task used to measure tactile spatial acuity by determining the minimum distance at which two points of touch can be distinguished.
Dorsal-Column Medial Lemniscus (DCML) Tract
A major sensory pathway that transmits fine touch, vibration, and proprioceptive information from the body to the brain.
Spinothalamic Tract
A sensory pathway that transmits pain, temperature, and crude touch information from the body to the brain.
Thermoreceptors
Sensory receptors in the skin that detect temperature changes, including cold and heat.
Cold Receptors
Detect temperatures from 59°F to 86°F (TRPM8 channels), also activated by menthol.
Warm Receptors
Detect temperatures from 86°F to 113°F (TRPV3 & TRPV4 channels).
Nociceptive Thermoreceptors
Specialized receptors that detect painful extremes of temperature, leading to sensations of burning heat or freezing cold.
TRP Channels
Ion channels in sensory neurons that respond to temperature changes and chemical irritants, involved in sensing pain and temperature.
TRPM8 Receptor
A type of TRP channel activated by cold temperatures and compounds like menthol, producing cooling sensations.
TRPV1 Receptor
A type of TRP channel activated by heat and chemical stimuli like capsaicin (the compound in chili peppers), producing sensations of heat or burning.
Aδ Fibers
Thin, myelinated nerve fibers that transmit sharp, localized pain quickly to the brain.
C Fibers
Unmyelinated nerve fibers that transmit dull, aching pain more slowly to the brain.
Gate Control Theory
Pain perception is modulated by a “gate” in the spinal cord that can be influenced by sensory input, emotions, and attention. Non-painful stimuli can “close the gate,” reducing pain signals to the brain.
Nociceptors
Sensory receptors that detect painful or noxious stimuli, such as extreme temperatures, mechanical damage, or chemical irritants.
Mechanical Nociceptors
Nociceptors that respond to physical damage or pressure, such as cuts or crushing injuries.
Thermal Nociceptors
Nociceptors that respond to extreme heat or cold, causing pain when temperatures become harmful.
Chemical Nociceptors
Nociceptors that detect chemical irritants, such as those released during inflammation or tissue damage.
Polymodal Nociceptors
Nociceptors that respond to a variety of stimuli, including mechanical, thermal, and chemical irritants, and are involved in generalized pain responses.
Withdrawal Reflex
An automatic reflex that causes an immediate withdrawal of a body part from a painful stimulus (e.g., pulling your hand away from a hot surface).
Proprioception
The sense of the position and movement of the body and its parts, allowing coordination and balance without the need for visual input.
Muscle Spindles
Sensory receptors in muscles that detect changes in muscle length and the speed of stretching, contributing to proprioception and reflexes.
Knee-Jerk Reflex
A simple reflex where tapping the patellar tendon causes a quick contraction of the quadriceps muscle, resulting in a kick.
Golgi Tendon Organs
Sensory receptors located at the junction between muscles and tendons that monitor tension, helping to prevent excessive force that could cause injury.
