Somatosensory System: Touch and Proprioception

These flashcards cover key concepts in the somatosensory system, focusing on touch, proprioception, and related neural pathways.

Two-point discrimination

Minimum interstimulus distance required to perceive two simultaneously applied stimuli as distinct.

Somatosensory receptive field

Area of skin surface that alters action potentials of a sensory neuron.

Proprioception

Awareness of body position in space based on input from mechanoreceptors.

Sensory transduction

Process of converting energy from a stimulus into an electrical signal.

Mechanoreceptors

Receptors that detect mechanical stimuli like touch, pressure, and vibration.

Cutaneous mechanoreceptors

Specialized receptors in the skin that respond to mechanical stimulus.

Free nerve endings

Afferent fiber terminals that detect pain and temperature.

Pseudounipolar neurons

Neurons in the dorsal root ganglia that have a single process diverging into two branches.

Afferent nerve endings

Sensory neurons that transmit sensory information from the periphery to the central nervous system.

Dorsal root ganglia (DRG)

Clusters of sensory neurons located in the dorsal root of the spinal cord.

Myelinated fibers

Nerve fibers with a myelin sheath that conducts impulses quickly.

Non-myelinated fibers

Nerve fibers without a myelin sheath, conducting impulses more slowly.

Receptor potential

Change in membrane potential in response to a stimulus.

Action potential

Electrical impulse that travels along a neuron, triggered by a sufficient stimulus.

Receptive field size

The area of skin that influences the response of a sensory neuron.

Dense innervation

High density of sensory neurons in a specific area of skin.

Somatosensory cortex

Brain region responsible for processing sensory information from the body.

Brodmann's areas

Regions of the cerebral cortex defined by their distinct structure and function.

Functional remapping

Changes in the organization of the somatosensory cortex based on experience.

Somatic acuity

The sensitivity and resolution of the sensory system's ability to detect touch.

Cortical representation

The mapping of sensory information onto the brain's cortex.

Afferent pathways

Nerve pathways that transmit sensory information towards the central nervous system.

Thermoreceptors

Sensory receptors that detect temperature changes.

Nociceptors

Pain receptors that respond to harmful stimuli.

Reflex arc

Neural pathway that controls reflex actions.

Pain sensation

Sensation resulting from the activation of nociceptors.

Primary somatosensory cortex

Region of the brain that processes sensory input from the body.

Dermatome

An area of skin innervated by sensory fibers from a single spinal nerve root.

Gracile nucleus

Nucleus in the medulla that processes touch information from the lower body.

Cuneate nucleus

Nucleus in the medulla that processes touch information from the upper body.

Spinal cord decussation

The crossing of nerve fibers from one side of the body to the opposite side of the brain.

Trigeminal ganglion

Cluster of sensory neurons that convey sensory information from the face.

Trigeminothalamic system

Pathway conveying somatosensory information from the face to the brain.

Cerebellum

Brain region involved in motor control and proprioceptive processing.

Mechanosensory afferents

Sensory neurons dedicated to the sensation of touch.

Merkle cells

Specialized cells responsible for detecting pressure and texture.

Meissner corpuscles

Rapidly adapting mechanoreceptors that detect light touch and vibrations.

Ruffini endings

Afferents that respond to skin stretch and provide feedback on finger position.

Pacinian corpuscles

Rapidly adapting receptors that detect deep pressure and high-frequency vibrations.

Somatosensory information

Sensory data related to touch, temperature, pain, and body position.

Active touching

Haptics, or the exploration of tactile information through movement.

Stereognosis

The ability to perceive the shape and texture of an object through touch.

Action potentials in mechanoreceptors

Electrical signals generated in response to mechanical stimuli.

Highly convergent pathways

Connections in the nervous system where multiple inputs converge onto a single neuron.

Innervation density

Measurement of how densely sensory neurons are distributed in a given area.

Spinal reflexes

Automatic responses of the body to stimuli without conscious control.

Central pathways

Neural routes that carry information from sensory receptors to processing centers in the brain.

Functional plasticity

The brain's ability to reorganize itself based on experience and learning.

Neural encoding

The way sensory information is represented in the nervous system.

Sensory adaptation

Decreased sensitivity to constant stimulation over time.

Dynamic stimuli

Stimuli that change over time, requiring rapid response from sensory neurons.

Spatial acuity

The ability to discern fine details in sensory input.

Touch receptors

Nerve endings that respond to mechanical stimuli applied to the skin.

Proprioceptors

Receptors that provide information about body position and movement.

Subcutaneous tissue

Layer of tissue beneath the skin that contains mechanoreceptors.

Somatosensory pathways

Neural routes that convey sensory information from the body to the brain.

Pain and temperature pathways

Systems that carry nociceptive signals to the central nervous system.

Fast conducting fibers

Myelinated fibers that conduct sensory signals quickly.

Slow conducting fibers

Unmyelinated fibers that conduct signals more slowly.

Brain organization

The hierarchical arrangement of neural circuits and pathways in the nervous system.

Neural module

Basic functional unit within the nervous system responsible for specific processing tasks.