General Senses

General Senses

Senses that are widespread across the body, such as touch, temperature, pain, and proprioception.

Special Senses

Localized senses such as vision and taste, distinct from general senses.

Sensory Receptors

Specialized cells that detect changes in the environment and send signals to the CNS.

Mechanoreceptors

Receptors that detect physical forces like pressure, vibration, and touch.

Thermoreceptors

Receptors sensitive to temperature changes, located in skin and deeper tissues.

Nociceptors

Pain receptors that respond to stimuli that may cause tissue damage.

Chemoreceptors

Receptors that detect changes in chemical concentration, such as blood pH, CO2, and O2 levels.

Proprioceptors

Receptors that provide awareness of body position and movement, found in muscles, tendons, and joints.

Exteroceptors

Receptors located near body surfaces that detect external stimuli.

Interoceptors

Receptors found in internal organs that detect internal stimuli like stretch and blood pressure.

Cutaneous Receptors

Receptors in the skin that detect touch, pressure, temperature, and pain.

Light Touch Receptors

Receptors like Meissner's corpuscles, sensitive to gentle touch.

Deep Pressure Receptors

Receptors such as Pacinian corpuscles, which respond to deep pressure and vibration.

Thermoreceptors Temperature Range

Cold receptors are active between 10°C and 40°C; warm receptors between 30°C and 45°C.

Tonic Receptors

Receptors that adapt slowly to stimuli.

Phasic Receptors

Receptors that adapt quickly to stimuli.

Sensory Transduction

The conversion of a stimulus into an electrical signal in the nervous system.

Sensory Adaptation

A decrease in receptor sensitivity to a constant stimulus over time.

First-Order Neuron

Neurons that carry sensory information from the receptor to the spinal cord.

Second-Order Neuron

Neurons that relay signals from the spinal cord to the thalamus.

Third-Order Neuron

Neurons that conduct information from the thalamus to the cerebral cortex.

Somatosensory Cortex

Area in the brain responsible for processing sensory information from the body.

Sensory Homunculus

A visual representation of the body based on sensory receptor density in the somatosensory cortex.

Two-Point Discrimination

The ability to distinguish two points of touch on the skin.

Thalamus

Acts as a sensory relay, directing signals to appropriate cortical areas.

Sensory Modality

Each type of sensation (e.g., pain, temperature) perceived by the brain.

Lateral Inhibition

Process that sharpens sensory signals for better localization.

Dermatome

A skin area supplied by a single spinal nerve, useful for diagnosing nerve damage.

Phantom Limb Sensation

Feeling that an amputated limb is still present due to central processing.

Referred Pain

Pain felt in a part of the body other than its actual source.

Gate Control Theory

Theory suggesting that the spinal cord controls pain signal transmission.

Acute Pain

Sharp, immediate pain that alerts the body to injury.

Chronic Pain

Persistent pain lasting for weeks or longer, often less intense than acute pain.

Pain Threshold

The minimum level of stimulus that activates pain receptors.

Pain Tolerance

The maximum level of pain an individual is willing to tolerate.

A-Delta Fibers

Myelinated fibers that transmit fast, sharp pain.

C-Fibers

Unmyelinated fibers that transmit slow, dull, aching pain.

Cold Receptors

Thermoreceptors that respond to cooling.

Warm Receptors

Thermoreceptors that respond to heating.

Adaptation of Thermoreceptors

Thermoreceptors adapt rapidly to constant temperatures.

Merkel Discs

Receptors that respond to sustained touch and pressure, found in the basal epidermis layer.

Meissner's Corpuscles

Receptors found in fingertips and lips, sensitive to light touch.

Pacinian Corpuscles

Receptors that detect deep pressure and vibration in the deep dermal layers.

Ruffini Endings

Receptors sensitive to skin stretch, located in the dermis and joint capsules.

Vibrational Sensitivity

Primarily detected by Pacinian corpuscles, important for perceiving texture.

Tactile Acuity

The ability to detect fine details on surfaces, highest in fingertips.

Proprioception

The body's sense of position and movement, critical for balance and coordination.

Muscle Spindles

Proprioceptors in skeletal muscles that detect stretch and prevent muscle damage.

Golgi Tendon Organs

Receptors that detect tension in tendons, preventing excessive force on muscles.

Joint Kinesthetic Receptors

Receptors located in joints that provide information about joint angle and movement.

Stretch Reflex

Reflex arc triggered by muscle stretch, maintaining muscle tone and posture.

Spinal Reflex

Automatic response involving sensory input, integration in the spinal cord, and motor output.

Vestibular Sense

Sense associated with balance, involving structures in the inner ear.

Muscle Tone

Continuous, passive partial contraction of muscles, essential for posture.

Sensory Integration

The brain's process of combining sensory information from various sources.

Stereognosis

The ability to recognize objects by touch alone.

Kinesthesia

The sense of movement, closely linked with proprioception.

Sensory Mapping

A process where each part of the body corresponds to an area in the somatosensory cortex.

Postural Reflexes

Reflexes that maintain body balance and posture.

Reflex Arc Components

Receptor, sensory neuron, integration center, motor neuron, effector.

Sensory Processing Disorder

Condition where sensory input is improperly processed by the brain, affecting response.