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39 Cards in this Set
- Front
- Back
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What are the general properties of sensory receptors? |
*sensory transduction *receptor potential *adaptation |
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What is sensory transduction? |
converting stimulus energy to nerve energy |
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What is receptor potential? |
local electrical change in receptor cell |
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What is adaptation? |
conscious sensation declines with continued stimulation (forget you are wearing a shirt after you put it on) |
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What are unencapsulated receptors? |
*free nerve endings: pain, temp, crude touch *tactile disks/merkel cells: light touch *hair receptors: detect hair movement |
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What are encapsulated receptors? |
*axons wrapped in Schwann cells of CT cells *Meissner's corpuscles: phasic, adapting, discriminative touch and texture, beneath epidermis, abundant in fingertips and lips *Lamellated/pacinian corpuscles: phasic, deep in dermis, deep pressure, stretch, tickle, vibration *Ruffini corpuscles: tonic (slow), heavy touch, pressure, skin stretching, important for hard grip |
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What type of sense is mediated by free nerve endings? |
temp, pain perception, crude touch |
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What type of sensation is mediated by pacinian corpuscles? |
deep pressure, stretch, tickle, and vibration |
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What type of sensation is mediated by Meissner's corpuscles? |
discriminative touch and texture |
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What is nociception? |
It allows awareness of tissue injuries and is found in all tissues except the brain |
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What pathways does nociception use for signals? |
*fast pain: myelinated fibers--sharp, local, stabbing pain *slow pain: unmyelinated fibers--long lasting, dull, diffuse feeling *somatic: pain from skin, muscle, joint *visceral: pain from stretch, chemicals, ischemia *injured tissues release chemicals that stimulate pain fibers (bradykinin, histamine, prostaglandin) |
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What is referred pain? |
it is pain in the viscera and is often mistaken to come from the skin or other superficial site (ex. pain of heart attack is felt along the left shoulder and medial side of the arm) |
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What are the different types of papillae of the tongue and which contain taste buds? |
*filiform=texture *foliate *fungiform: tips and sides of tongue (has taste buds) *circumvallate: rear of tongue, (has taste buds) |
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What are the 5 primary taste sensations throughout the tongue? |
*sweet: tip *salty: lateral *sour: lateral *bitter: posterior *umami: last of amino acids (MSG) |
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What 3 nerves innervate taste buds and what region does each transmit taste sensation? |
*facial nerve 7: anterior 2/3 *glossopharyngeal nerve 9: posterior 1/3 *vagus 10: palate, pharynx, epiglottis |
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Where do receptors of olfaction reside? |
In the olfacotry mucosa |
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What are the different regions of the brain to which the sense of olfaction project? |
hippocampous, hypothalamus, and amygdala |
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What is the function of the auricle of the external ear? |
Also called pinna--directs air vibrations down external auditory meatus |
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What are the function of tympanic membrane and the ossicles of the middle ear? |
It transmits sound waves to inner ear with enough force/unit area at the oval window to vibrate perilymph in scala vestibuli |
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What is the function of the tympanic reflex of the middle ear? |
It contracts muscles. It responds to slowly building loud sounds and occurs while speaking |
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What is otitis media? |
It is a bulging, red tympanic membrane that may indicate a middle ear infection, common in young children because their tubes have a narrower angle and drainage is impaired |
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What are the potential consequences of otitis media? |
can cause perforation of tympanic membrane, perhaps will need tympanovstomy (lancing of membrane to drain fluid from the cavity) |
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Where would high versus low frequency sound be detected in the ear? |
High (7,000 to 20,000Hz)=hair cells near the narrow proximal end/stapes footplate Low (20-800Hz)=hair cells near wider distal end/cochlear duct |
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What are the various causes of hearing loss? |
*constant exposure to loud sounds at specific frequencies that can damage hair cells *hair cells don't regenerate *aspirin and certain antibiotics are ototoxic *injured vestibulocochlear nerve by schwannoma (acoustic neuroma) *conductive deafness *sensorineural deafness |
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What is conductive deafness? |
When conditions interfere with transmission of vibrations to inner ear from damage tympanic membrane, otitis media, blockage of auditory canal, and otosclerosis (fusion of auditory ossicles that prevent vibration) |
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What is sensorineural nerve deafness? |
The death of hair cells or any nervous system element concerned with hearing--common in factory workers, musicians, construction workers--can be caused by acoustic neuroma |
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What is the basic function of the vestibular system? |
*controls coordination/balance *otoliths add to density and inertia to enhance sense of gravity/motion *detect angular acceleration (semicircle canals) *sense of linear acceleration (saccule & utricle) |
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What do the receptors in the vestibular system consist of? |
*3 semicircular ducts *2 chambers--anterior saccule and posterior utricle |
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What are the tunics of the eyeball? |
*fibrous layer: sclera and cornea *vascular layer: choroid, cillary body and iris *internal layer: retina and optic nerve |
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Explain path through the cornea, aqueous humor, lens, vitreous humor, and retina. |
*light refracted on retina *cornea: transparent cover on eye surface *aqueous humor: serous fluid, post cornea, anterior to lens *lens: changes shape to focus light, rounds with no tension, flattens due to pull of ligaments *vitreous humor: jelly fills space between lens and retina |
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What are the 3 components of the near response of the optic system? |
*allows eyes to focus on nearby objects by 1. convergence of eyes: orient to visual axis 2. constriction of pupil: blocks peripheral light 3. accommodation of lens: ciliary muscle contracts, lens takes convex shape, light reflects onto retina |
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Describe the retinal neurons. |
*bipolar: 1st order--synapse on ganglion cells, large amount of convergence *ganglion: 2nd order--axons form optic nerve, more convergence (114 receptors to one fiber) *horizontal/amacrine cells form connections to other cells, enhance contrast, edges, light intensity |
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What are the basic functional differences between rods and cones? |
*rods: rhodopsin (absorbs light)--peaks at 500nm. Has 2 parts: opsin (protein) and retinal (Vit A derivative) *cones: contain photopsin (iodopsin)--opsin has different amino acids that determine wavelength absorbed, 3 kinds of cones that absorb different wavelengths for color vision |
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What is scotopic vision? |
*night vision *rods sensitive to dim light *extensive neuronal convergence *600 rods/bipolar cell *edges of retina have wide spaced rods to act as motion detectors |
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What is photopic vision? |
*day vision *fovea contains only cone cells--no rods *no neuronal convergence *each foveal cone has private line to braine *high resolution color vision, less sensitive to dim light |
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In what region of the cerebral cortex does the visual projection pathway end? |
visual cortex (occipital lobe) |
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What are cataracts? |
It is opacity of the lens--condition of lacking transparency or translucence. Usually in advanced age, people with diabetes, high glucose/sorbitol levels, storm draws water into the region and causes the cataract, can thicken lens causing diabetic myopia |
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What is vascular degeneration? |
two types--both separate photoreceptors from blood supply (black circle in middle of lens=loss of vision) *dry ARMD: 90% of patients *wet ARMD: 10% of patients, most severe, greatest vision loss |
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What is glaucoma? |
*primary open angle is most common type *major cause of blindness *myopia (near sighted) people and diabetes are more likely to develop this *angle appears normal *caused by slow blockage of canal of Schlemm *slow, insidious problem and often unnoticed |
