Sensory Physiology Flashcards
Provides information to the CNS about the state of the body and/or the immediate environment
Sensation
Specialized epithelial cell or neurons that transduce environmental signals into neural signals
Sensory receptors
Change in membrane potential produced by the stimulus; trigger action potential trains
Generator potential/receptor potential
Characteristic of sensory receptors described as specific sensations have specific receptors
Differential sensitivity
Characteristic of sensory receptors described as specific sensations have specific pathways
Labeled line principle
Characteristic of sensory receptors described as a change in a way a receptor responds to sequential or prolonged stimulation
Adaptation
Type of receptors for continuous stimulus strength (detects steady stimulus); exhibited by muscle spindle, golgi tendon, slow pain receptors, baroreceptor, chemoreceptor
Slowly-adapting/tonic receptors
Type of receptors for detecting change in stimulus strength (detects onset and offset of stimulus); has predictive function; exhibited by pacinian corpuscle
Rapidly-adapting/phasic receptors
Region of the skin where stimuli can change the firing rate of the sensory neurons
Receptive field
Difference between Type 1 and Type 2 receptive field
Type 1: smaller RF with well-defined border
Type 2: wider RF with poorly-defined border
Tactile receptor found in the skin for touch and pressure
Free nerve endings
Tactile receptor found in non-hairy skin (fingertips and lips) for movement of objects and low-frequency vibration
Meissner’s corpuscles (FA1)
Tactile receptor for localizing touch sensation and to determine texture
Merkel’s Disc (SA1)
Merkel’s disc combine to form:
Iggo Dome receptors
Tactile receptor found in the hair base to detect movement of object on the skin
Hair-end organ
Tactile receptor found in deep skin, internal tissure and joint capsules for heavy and prolonged touch (pressure) and to signal degree of joint rotation
Ruffini’s end organs (SA2)
Tactile receptor found in skin and deep fascia, with onion-like structure, which detects high-frequency vibration
Pacinina corpuscles (FA2)
First-order neurons have cell bodies located at:
Dorsal root or cranial nerve ganglia
Second-order neurons have cell bodies located at:
Spinal cord or brainstem
Third-order neurons have cell bodies located at:
Thalamus
Fourth-order neurons have cell bodies located at:
Sensory cortex
Somatosensory pathway which uses large myelinated fibers, with temporal and spatial fidelity, crosses near the medulla, for vibration, sensations that signal movement against the skin, position sense and fine pressure, and two-point discrimination.
Dorsal column-medial lemniscus pathway
Somatosensory pathway which uses smaller myelinated fibers, less fidelity and less accurate, crosses immediately, for pain, temperature sensation, crude touch and pressure sensation, tickle and itch sensation and sexual sensation
Antero-lateral system (spinothalamic tract)
Relay station for sensation
Thalamus
Relay station of dorsal column medial lemniscus pathway
VPL nuclei
Relay station of trigeminothalamic pathway
VPM nuclei
Relay station of anterolateral system
VPI nuclei
In the sensory homunculus, the largest areas are for the:
Fingers, hands and face (for precise localization)
Type of pain carried by Type-A delta fibers
Fast pain
Neurotransmitter used by fast pain
Glutamate
Type of pain associated with tissue destruction
Slow pain
Neurotransmitter used by slow pain
Substance P
Fibers that carry slow pain
Type C fibers
This is due to the sharing of 2nd order neurons in the spinal cord of visceral pain fibers and skin pain fibers; follows the dermatome rule
Referred pain
Pain killer system of the body
Endogenous analgesia system
Substances involved in the opioid-mediated endogenous analgesia system
Enkephalin, Dynorphine, Beta-endorphine
Stimulated tactile receptors can inhibit pain in the spinal cord
Lateral inhibition
Pain receptors are stimulated at what temperatures?
43 degrees
What receptors are for warmth? for cold?
Warmth: free nerve endings, Type C fibers
Cold: Type A delta fibers
The visual system detects and interprets electromagnetic waves between:
400 - 750 nm
Refers to the ability to bend light; measured in Diopters
Refractive power
The eyes have a refractive power of __ diopters; 2/3 by the cornea, 1/3 by the lens
59 diopters
Distant vision:
Lens: ____
Suspensory ligaments: _____
Ciliary muscles: _____
Lens flat, thin
Suspensory ligaments tensed
Ciliary muscles relaxed
Close vision:
Lens: ____
Suspensory ligaments: _____
Ciliary muscles: _____
Lens spherical, thick
Suspensory ligaments relaxed
CIliary muscles contracted
Automatic adjustment in the focal length of the lens of the eye to permit retinal focus of images of objects at varying distances
Accomodation
Accomodation provides an additional __ diopters for the lens
14 diopters