10.0 Sensory Physiology Flashcards
What are the relative diameters/velocities of A-alpha fibers vs C fibers?
A-alpha have a large diameter and a fast conduction velocity
C fibers have a small diameter and a slow conduction velocity
What receptors are supplied by SENSORY (afferent) A-alpha, A-beta, A-delta, and C fibers?
A-alpha: primary muscle spindles and Golgi tendon organs
A-beta: Secondary muscles and skin mechanoreceptors
A-delta: Skin mechanoreceptors, thermal receptors, and nociceptors
C: Skin mechanoreceptors, thermal receptors, and nociceptors
What receptors are supplied by MOTOR (efferent) A-alpha, A-gamma, B, and C fibers?
A-alpha: Extrafusal skeletal muscle fibers
A-gamma: Intrafusal muscle fibers
B: Preganglionic autonomic fibers
C: Postganglionic autonomic fibers
What sensation is detected by Meissner corpuscles? Where is it found?
Touch and vibration less than 100 Hz. Flutter and tapping.
Found on glaborous skin.
What sensation is detected by Pacinian corpuscles? Where is it found?
Rapid indentation of the skin such as that during high-frequency vibration (100-400 Hz).
Found on both hairy and glaborous skin.
What sensation is detected by Ruffini corpuscles? Where is it found?
Magnitude and direction of stretch. Touch and pressure and proprioception.
Found on both hairy and glaborous skin.
What sensation is detected by Merkel cells? Where is it found?
Pressure.
Found on glaborous skin.
What is the role of Somatosensory area 1 (S1)? Where is it located?
Involved in the integration of the information for position sense as well as size, shape discrimination. Located in post-central gyrus.
What is the role of Somatosensory area 2 (S2)? Where is it located?
Responsible for comparisons between objects, different tactile sensations and determining whether something becomes a memory. Located in Sylvian fissure.
What is the role of the parieto-temporal-occipital association area (PTO)?
Responsible for high-level interpretation of sensory inputs.
What is TRPV1 receptors sensitive to? What kind of pain does it detect?
Sensitive to vanilloid compounds such as capsaicin. Also sensitive to endogenous substances such as bradykinin and heat greater than 43 C.
Involved in migraines, dental pain, cancer pain, inflammatory pain, neuropathic pain, visceral pain, and OA.
What is TRPA1 receptors sensitive to? What kind of pain does it detect?
Sensitive to allyl isothiocyanate, active ingredient in mustard oil, wasabi, and horseradish. Used in anesthetics.
Involved in allergic contact dermatitis, chronic itch, painful bladder syndrome, migraine, irritable bowel syndrome, and pancreatitis.
What is TRPM8 receptors sensitive to?
Sensitive noxious cold temperatures and cooling agents.
What is the difference between peptidergic nociceptors and non-peptidergic nociceptors?
Peptidergic: Expresses neuropeptides, responsive to NGF, used in most visceral afferents, used in half of cutaneous afferents.
Non-peptidergic: Does not express neuropeptides, responsive to GDNF, used in very few visceral afferents, used in half of cutaneous afferents.
What is the role of the insular cortex in nociception?
Important for interpretation of nociception. Processes information about internal state of the body. Contributes to autonomic response to pain. Integrates all signals related to pain.
