Podcast
Questions and Answers
Which receptor is primarily responsible for detecting vibrations?
Which receptor is primarily responsible for detecting vibrations?
What term describes the ability of Pacinian corpuscles to quickly cease responding to continuous stimulus?
What term describes the ability of Pacinian corpuscles to quickly cease responding to continuous stimulus?
Which sensory modality is NOT part of the somatic senses?
Which sensory modality is NOT part of the somatic senses?
What characteristic distinguishes fine or discriminatory touch from crude touch?
What characteristic distinguishes fine or discriminatory touch from crude touch?
Signup and view all the answers
What types of sensations do Ruffini's corpuscles primarily detect?
What types of sensations do Ruffini's corpuscles primarily detect?
Signup and view all the answers
Which of the following describes the concept of spatial discrimination?
Which of the following describes the concept of spatial discrimination?
Signup and view all the answers
What is the role of lateral inhibition in sensory perception?
What is the role of lateral inhibition in sensory perception?
Signup and view all the answers
Which cutaneous receptor is primarily responsible for detecting light touch?
Which cutaneous receptor is primarily responsible for detecting light touch?
Signup and view all the answers
What determines the effectiveness of two-point discrimination?
What determines the effectiveness of two-point discrimination?
Signup and view all the answers
Which area of the body has the smallest receptive fields?
Which area of the body has the smallest receptive fields?
Signup and view all the answers
What is the primary role of lateral inhibition in sensory perception?
What is the primary role of lateral inhibition in sensory perception?
Signup and view all the answers
Which type of receptor changes its firing rate in response to temperature changes?
Which type of receptor changes its firing rate in response to temperature changes?
Signup and view all the answers
What is the function of the labelled line code in the somatosensory system?
What is the function of the labelled line code in the somatosensory system?
Signup and view all the answers
Which of the following best describes spatial discrimination ability?
Which of the following best describes spatial discrimination ability?
Signup and view all the answers
How do receptive fields differ in size across various body parts?
How do receptive fields differ in size across various body parts?
Signup and view all the answers
Which process occurs at each relay point in the sensory pathway to enhance signal processing?
Which process occurs at each relay point in the sensory pathway to enhance signal processing?
Signup and view all the answers
Which mechanoreceptors are primarily responsible for sensing stretch around joints?
Which mechanoreceptors are primarily responsible for sensing stretch around joints?
Signup and view all the answers
What characteristic describes the receptive fields of mechanoreceptors in the somatosensory cortex?
What characteristic describes the receptive fields of mechanoreceptors in the somatosensory cortex?
Signup and view all the answers
Lateral inhibition primarily enhances which aspect of sensory processing?
Lateral inhibition primarily enhances which aspect of sensory processing?
Signup and view all the answers
Thermoreceptors are mainly responsible for detecting what type of sensory information?
Thermoreceptors are mainly responsible for detecting what type of sensory information?
Signup and view all the answers
The capacity for spatial discrimination in the somatosensory cortex is enhanced by which of the following?
The capacity for spatial discrimination in the somatosensory cortex is enhanced by which of the following?
Signup and view all the answers
Which layer of the somatosensory cortex is primarily involved in processing specific sensory modalities?
Which layer of the somatosensory cortex is primarily involved in processing specific sensory modalities?
Signup and view all the answers
Which area of the somatosensory cortex is known for integrating information from different sensory systems?
Which area of the somatosensory cortex is known for integrating information from different sensory systems?
Signup and view all the answers
Damage to the somatosensory cortex would likely impair which of the following functions?
Damage to the somatosensory cortex would likely impair which of the following functions?
Signup and view all the answers
Study Notes
Somatosensory System
- Somatic senses perceive touch, temperature, proprioception (position sense), and pain.
- Information comes from skin, joints, muscles, and viscera.
Sensory Receptors
- Touch receptors are specialized epithelial cells or neuronal endings in the skin.
- Two main touch submodalities:
- Fine/discriminatory touch (two-point discrimination)
- Crude touch (itch, tickle - poorly localized)
Cutaneous Sensory Receptors
- Four distinct receptor types transduce touch:
- Pacinian corpuscle
- Meissner's corpuscle
- Ruffini's corpuscle
- Merkel's disc
Pacinian Corpuscle
- Encapsulated receptor deep in subcutaneous layers of hairy and non-hairy skin.
- Consists of a group II myelinated fiber encased in a lamellar structure (approximately 1mm in diameter).
- Rapidly adapting receptor, suited to detecting vibrations.
- Adaptation results from lamellae adjusting shape during deformation, preventing continuous depolarization for signaling.
- Frequency of firing reflects vibratory signal intensity.
- Poorly localizing due to large receptive fields.
Meissner's Corpuscle
- Consists of group II myelinated fibers in a small capsule.
- Found densely in fingertips, lips.
- Rapidly adapting receptor, useful for encoding tapping and flutter.
- Small receptive fields, enabling two-point discrimination.
Merkel's Discs
- Unencapsulated mechanoreceptors in non-hairy skin epidermis.
- Merkel cell enclosed by a nerve ending.
- Small receptive fields, enabling precise location.
- Slowly adapting receptors.
- Ideal for detecting stimulus location.
Ruffini's Corpuscles
- Nerve terminal in a liquid-filled collagen capsule.
- Depolarize in response to skin deformation (any input).
- Slowly adapting receptor.
- Large receptive fields.
- Encoding information regarding stimulus magnitude.
Thermoreceptors
- Located on free nerve endings of myelinated (Aδ) and unmyelinated (C) fibers.
- Separate receptors for cold (optimum sensitivity at 25°C) and warmth (optimum sensitivity at 45°C).
- Very cold (<5°C) or hot (>45°C) stimuli activate pain fibers (thermal nociceptors).
- Receptors transiently change firing rate in response to temperature change direction.
Where is it?
- Somatosensory system provides brain information about body part being stimulated.
- Imagine losing touch sensation to understand possible effects.
Sensory Pathways
- Two primary pathways:
- Dorsal column pathway: transmitting fine touch, pressure, proprioception.
- Anterolateral pathway: conveying pain, temperature, and crude touch.
Dermatomes
- Refers to body areas innervated by neurons in a single spinal nerve.
Clinical Application
- Examples of clinical scenarios involving spinal cord damage and associated sensory losses.
Brown-Sequard Syndrome
- Specifically relates hemisection of spinal cord at T12 and resulting pattern of sensory loss.
Thalamus
- Relay station for all sensory input to the cerebral cortex, except olfaction.
Cortical Processing
- Different cortical areas involved in processing somatosensory information:
- Primary somatosensory cortex (SI): post-central gyrus, Brodmann's areas 1, 2, and 3 - topographic map "homunculus".
- Secondary somatosensory cortex (SII): superior bank of the lateral fissure, another map but more diffuse.
- Somatosensory association cortex: areas 5 and 7, integrating information from different sensory systems.
Primary Somatosensory Cortex
- Contra-lateral representation of somatic senses (except fibers from face).
- Larger areas for lips, thumb, face; smaller areas for other body parts.
- Columns arranged in vertical column, each for a specific sensory modality - tactile, pain, temperature.
- Contains orientation and direction-sensitive properties.
Somatosensory Association Cortex
- Synthesizes primary and secondary input.
- Involved in complex sensory associations.
- Stimulating this area can elicit complex body sensations, like the sensation of a tool.
Damage to Somatosensory Cortex
- Damage can affect drawing, spatial relations and two-point discrimination.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on the somatosensory system, including the various types of sensory receptors and their functions. This quiz covers touch perception, from fine discriminative touch to crude touch, as well as the different cutaneous sensory receptors. Perfect for students studying human anatomy or physiology.
