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Senses
Lecture Unit 2
Question | Answer |
---|---|
Two classes of receptors | General senses-temperature, pain, touch, stretch, & pressure. Controlled by other nerves. Special senses-gustation, olfaction, vision, equilibrium, & audition. Rely on cranial nerves. |
Chemoreceptors | Detect chemical molecules |
Termoreceptors | Detect changes in temperatures |
Photoreceptors | Detect changes in light. Vision. |
Mechanoreceptors | For hearing & balance. Detect mechanical changes like touch, vibration, & stretch. ex. Proprioceptors detect the position & the state of contraction of muscles. |
Baroreceptors | Detect changes in blood pressure w/i body structures. |
Nociceptors | Detect pain |
General Sense: Tactile Receptors | Most numerous type of receptor. Mechanoreceptors that react to touch, pressure, & vibration. Located in the dermis & hypodermis. |
Special Sense: Gustation | Taste buds. Papillae: Filiform, Fungiform, Vallate (Circumvallate), Foliate. |
Taste buds | Microscopic chemoreceptors on tongue, posterior palate, cheeks, pharynx, epiglottis. |
Papillae | Macroscopic structures on tongue that may contain taste buds. Help with friction. Move food around. 4 types: filiform, fungiform, vallate (circumvallate), foliate. |
Filiform | Anterior 2/3 tongue. No taste buds. |
Fungiform | Tip and sides of tongue, only few taste buds. |
Vallate (Circumvallate) | Back of tongue, larges, least numerous type, contain most taste buds. |
Foliate | Lateral tongue, used during infancy and early childhood. |
Taste Bud Cytology | Gustatory cells, Supporting cells, Basal cells. After age 50, the ability to distinguish taste begins to decline. Be able to label picture. |
Gustatory cells | Chemoreceptor cells. Replaced every 7-10 days. Gustatory microvillus-taste hair. |
Supporting cells | Insulate gustatory cells from each other & surrounding epithelium. |
Basal cells | Immature; replace other two cell types. |
Gustatory Sensations | 5 flavors detected over broad regions of the tongue: Salty, Sweet, Sour, Bitter, Umami (Savory). Facial nerve 7 innervates anterior 2/3 of tongue. Glossopharyngeal nerve 9 innervates posterior 1/3 of tongue. |
Special Sense: Olfaction | Olfactory neurons-chemoreceptors, bipolar. Supporting cells-surround olfactory neurons. Basal cells-stem cells for renewal of others. 50-60 different primary odors & thousands of chemical stimuli can be recognized. Label pic. |
Vision | Special Sense |
Conjunctiva | Provides a superficial covering over the eye's anterior exposed surface. Translucent connective tissue. Connects eyelid to eye. Function: Protect Brain-trough catches stuff. |
Eyebrows, eyelashes, & palpebrae (eyelid) | Prevent foreign objects from coming into contact with the eye. |
Lacrimal glands | Keep the exposed surface moist, clean, & lubricated. Superior & lateral to eye. Tears created. Evaporate in nose. |
Eye structures | Lens, Pupil, Anterior chamber (filled with thin aqueous humor-water like-make new a lot), Posterior chamber (filled with thin aqueous humor), Vitreous chamber (filled w/ thick vitreous humor-jelly-don't make a lot of new), Optic nerve. |
Cataracts | Major cause of blindness. Lens becomes opaque. Causes: aging, diabetes, UV exposure, glaucoma, eye infections. Treatment: artificial lens. |
Regions of the eye | Fibrous tunic, vascular tunic, neural tunic. |
Fibrous tunic | Most superficial. Sclera (white), Cornea. |
Vascular tunic | Choroid, Cilliary body (thicker portion of choroid-anterior), Ciliary zonules-suspensory ligaments. Iris. |
Neural tunic | Retina-photoreceptors. |
Photoreceptors | Neural layer of retina. Rod cells and Cone cells |
Rod cells | Function in dim light. Don't provide sharp vision or color vision. 100 million per eye. Use in the dark. More peripheral. Black and white. |
Cone cells | Operate best in bright light. Provide high acuity color vision. 10 million per eye. In the center. Need bright light. |
Regions of the Retina | Macula lutea, fovea centralis, optic disc |
Macula lutea | contains mostly cones |
Fovea centralis | Contains only cones. Maximal visual acuity. |
Optic disc | Contains no rods or cones. Axons & ganglion cells converge to exit eye. Blind spot-where nerves enter. Brain fills in blank using other eye. |
Emmetropia | Normal vision |
Hyperopia | Farsightedness. Eyeball is too short so near objects are blurry. |
Myopia | Nearsightedness. Eyeball is too long so far objects are blurry. |
Eye development | Eye buds directly off the brain. |
Special sense: Equilibrium & Hearing. Divisions of the Ear: | External ear, Middle ear, Inner ear. |
External Ear Structures | Defined from the auricle to the tympanic membrane. External auditory meatus: narrow external opening prevents large objects from entering middle ear. Ceruminous glands produce cerumen. Cerumen+dead skin cells=earwax. |
Earwax | Helps reduce infection by impeding microorganism growth. Best bug repellent. |
Middle Ear Structures (Inside Petrous Part) | Air filled tympanic cavity. Tympanic membrane. Tensor tympani muscle & stapedius. Auditory ossicles-malleus, Incus, Stapes. Oval (vestibular) window. Round (cochlear) window. Auditory (Eustachian) tube connects ear to nasopharynx. |
Inner Ear Structures (3 regions for balance) | VESTIBULE-Utricle & saccule (bags). Detect acceleration/deacc. Helps sense equilibrium. SEMICIRCULAR CANALS-detect rotational movements. Help sense equilibrium. COCHLEA-senses audition-continues hearing. VESTIBULAR & COCHLEAR NERVES. |
Spiral Organ of Corti | Label! Fluid detects waves. Membranes move-detected by cochlear nerve. To temporal lobe. Cochlear nerve, Scala vestibuli-perilymph, vestibular membrane, scala tympani-perilymph, cochlear duct,-endolymph, cochlear hair cells-mechanoreceptors, tectorial mem |
Sound wave pathways through the ear part 1 | 1. Sound waves enter external aud meatus & make tymp membrane vibrate. 2. Tymp membrane vibrations causes movement by auditory ossicles; sound waves amplified. Stapes moves w/i oval window; pressure waves generated. |
Sound wave pathways through the ear part 2 | 3. Pressure waves begin at oval window & travel through scala vestibuli. 4. High & upper medium-frequency pressure waves in scala vestibuli cause vestibular mem to vibrate-pressure wave formation in endolymph of cochlear duct. |
Sound wave pathways through the ear part 3 | 4 cont. Pressure waves displace region of basilar membrane. Hair cells in spiral organ are distorted-stimulus in cochlear branch of CN 8. 5. Remaining pressure wave vibrations transferred to the scala tympani & exit the inner ear via the round window. |
Cochlear Implant | Surgical implant. Sound waves received at antenna, transmitter, & receiver. Turned into electrical impulses. Lead goes to the cochlea. Electrical impulses relayed through lead & stimulate cochlear nerve directly adjacent to cochlea. |
Otitis Media | An infection of the middle ear. More common in children because their auditory tubes are horizontal-bacteria from throat infection can migrate through into middle ear. Less common in adults because their auditory tubes are more vertical. |
Gustation | Gustatory cell, chemoreceptor, CN 7 & 9. |
Olfaction | Olfactory neuron, chemoreceptor, CN 1. |
Vision | Rods & cones, photoreceptor, CN 2. |
Audition | Cochlear hair cells, mecanoreceptor, CN 8. |
Equilibrium | Hair cells, mechanoreceptor, CN 8. |