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physio sensory
physio
Question | Answer |
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Functions of Sensory Organs | Detect and relay somatosensory information coming from external environment to integrating centers in CNS |
Functions of Sensory Organs include maintaining balance and? | equilibrium, vision, and hearing ability Use somatosensory information to make proper adjusts in order to maintain homeostasis. |
Sensation: | the mental perception of a stimulus |
Somatic sensation: | sensations from skin, muscles, bones, tendons, and joints |
Perception | understanding of objects and events of external world that we acquire from neural processing of sensory information. For example, feeling pain in a sensation, but awareness that a tooth hurts is a perception |
Sensory transduction | process by which a stimulus is transformed into an electrical response |
Stimulus modality | another term for stimulus type (heat, cold, sound, or pressure) |
Association Neuron | multipolar neuron located entirely within CNS |
Sensory neuron | (afferent neuron): transmits impulses from a sensory receptor to CNS |
Motor neuron | (efferent neuron): transmits impulses from CNS to an effector organ |
Somatic motor nerve | stimulates contraction of skeletal muscles |
Autonomic motor nerve | stimulates contraction (or inhibits contraction) of smooth muscle and cardiac muscle and that stimulates glandular secretion |
Ganglion | grouping of neuron cell bodies located outside of CNS |
Tract | grouping of axons that interconnect regions of CNS |
Mechanoreceptors (mechanical force) | Deforms cell membranes of sensory dendrites or deforms hair cells that activate sensory nerve endings. Cutaneous touch & pressure receptors Vestibular apparatus and cochlea |
Pain receptors (tissue damage) | Damaged tissue release chemicals that excite sensory endings Cutaneous pain receptors |
Chemoreceptors (dissolved chemicals) | Chemical interaction affects ionic permeability of sensory cells Smell and taste (exteroceptors) Osmoreceptors & carotid body Chemoreceptors (interoceptors) |
Photoreceptors (light wave detection) | Photochemical reaction affects ionic permeability of receptor cell Rods and cons in retina of eye |
Nociceptors | free-nerve endings without any form of specialization and detect the sensation of pain caused by a stimulus in the process of (or) is on the verge of causing tissue damage. |
Nociceptors respond to mechanical deformation, excess heat, and? | toxic chemicals For example, Substance P, histamine, and prostaglandin E2 are often released by damaged cells and thus elicit an appropriate sensation of pain |
Free sensory nerve endings of either ? | myelinated or unmyelinated fibers. Myelinated axons: rapidly conducting fibers that transmit the initial sharp sensation of pain (as from a pinprick) Unmyelinated axons: slower conducting fibers that transmit a dull, persistent ache |
Sensory Adaptation: Phasic receptors-quick adaptation to stimuli | respond with burst of activity when stimulus first applied, but quickly decrease their firing rate(adapt to stimuli)if the stimulus is maintained Sensation of pressure detected by pacinian corpuscles when you wear a hat or put a pencil in your ear. |
Sensory Adaptation: Tonic receptors-Very slow if at all adaptation to stimuli | maintain their higher firing rate the entire time that a stimulus is applied. Sensation of heat when your hand touches a hot stove. Prevents fatal tissue damage due to some external stimulus. |
Free nerve endings | slowly adapting, unmyelinated dendrites of sensory neurons Light touch, temperature, nociception Location: around hair follicles; throughout skin |
Merkel’s discs | slowly adapting, enlarged dendritic endings Sustained touch & pressure Location: base of epidermis |
Pacinian corupuscles | rapidly adapting, dendritic encapsulated by concentric lamellae Deep pressure; fast vibrations Location: deep in dermis |
Meissner’s corpuscles | rapidly adapting, dendrites encapsulated in connective tissue Changes in texture; slow vibrations Location: upper dermis |
Ruffini corpuscles | slowly adapting, enlarged dendritic endings with open, elongated capsule Sustained pressure Location: deep in dermis and hypodermis |
Two-point Touch Threshold Test | If each point touches the receptive field of different sensory neurons, two separate points of touch will be felt. If both caliper points touch the receptive field of one sensory neuron, only on point of touch will be felt |
Receptive Fields and Sensory Acuity | The minimum distance at which two points of touch can be perceived as separate Measure of the distance between receptive fields The Two-Point Threshold Test gives an indication of tactile acuity, (or sharpness of touch perception) |
The tactile acuity of the fingertips is exploited in ? | the reading of braille. The braille symbols are formed by raised dots on the page and separated from each other by 2.5 nm. Distance between symbols is slightly greater than two-point touch threshold of fingertips. 100 wpm for with experience |
Monosynaptic stretch reflex | reflex in which the afferent neuron directly activates motor neurons. |
Polysynaptic reflex | reflex employing one or more interneurons in its reflex arc. |
Crossed extensor reflex | affects muscles on contralateral side of body. For example, if you step on a tac, the foot is withdrawn by contraction of flexors and simultaneous relaxation of extensors |
The Knee-jerk Reflex | Striking patellar ligament stretches tendon and quad. muscles Spindle is stretched activating sensory neuron. Sensory neuron activates alpha motorneuron Alpha motorneuron stimulates extrafusal fibers to contract. |
Process of Hearing | malleus carries vibes to Incus, Stapes receives bivest transmits them to oval window |
Rods | provide black and white vision under low light conditions |
Cones | provide sharp color vision when light intensity is high |
TRICHROMATIC color | humans have due 3 cones which detect blue red green |
Emmetropia (normal sight) | - rays are focused exactly on retina |
Hyperopia (farsightedness) | – if eye is too short for the lens, images of near objects are focused at a point behind the retina. Unable to see near objects clearly Corrected with Convex lens |
Myopia (nearsightedness) – | if the eye is too long in relation to focusing power of lens, images of faraway objects focus at a point in front of the retina. Unable to see distant objects clearly Corrected with Concave lens |
Astigmatism | – when lens or cornea lack a smooth spherical surface, leading to the inability to focus rays at any one point on retina. Corrected with Toric lens |
Five categories of taste | Salty Sour Sweet Bitter Umami |