The Special Senses<br />Victoria Frawert<br />Anatomy<br />
The Senses<br />There are five general senses: Touch, sight, taste, smell, and hearing. Equilibrium is considered a specia...
Taste buds: located in oral cavity; 10,000; most in tongue papillae; each taste bud has 40-100 epithelial cells made of 3 ...
Physiology of Taste<br />Activation<br />To be tasted, first must be dissolved in saliva, diffuse into the pore and make c...
Gustatory Pathway<br />Taste is carried in two cranial nervers<br />Facial: anterior 2/3rds of tongue<br />Glossopharyngea...
Olfactory & Sense of Smell<br />Structure<br />Detects chemicals in solution<br />Olfactory Epithelium:<br />Located on ro...
Eye & Vision<br />Accessory Structures<br />Eyebrows<br />Shade the eyes<br />Prevent perspiration into eye<br />Eyelids<b...
Lacrimal Apparatus<br />Consist of gland and ducts that drain excess secretions into nasal cavity<br />Secretes saline sol...
Structure of the Eyeball<br />Divided into 3 tunics<br />Fibrous – dense avascular tissue<br />Sclera: white part that pro...
Physiology<br />Wavelength & Color<br />Eyes respond to visible light spectrum<br />Progresses from red to violet<br />Ref...
Photoreception<br />Photoreceptors are modified neurons<br />Outer segment connected to inner, inner connects to cell body...
Ear: Hearing & Balance<br />Structure – three areas: Outer, middle, & inner ear<br />Outer Ear<br />Auricle or Pinna: ear ...
Middle Ear (tympanic cavity)<br />Small air filled mucus lined cavity<br />Between eardrum & bony wall with two openings o...
Sound & Mechanisms of Hearing<br />Sound – a disturbance of pressure<br />Frequency – measurement of offurrences of a repe...
Imbalances of Hearing<br />Deafness – any hearing loss<br />Conduction deafness<br />When something hampers sound conducti...
Meniere’sSyndrom<br />Affects semicircular & cochlear canals<br />Causes vertigo, nausea, vomitting<br />Standing erect is...
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The special senses ~ powerpoint by victoria

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The special senses ~ powerpoint by victoria

  1. 1. The Special Senses<br />Victoria Frawert<br />Anatomy<br />
  2. 2. The Senses<br />There are five general senses: Touch, sight, taste, smell, and hearing. Equilibrium is considered a special sense as well, found in the ear.<br />Chemical Senses (Taste & Smell)<br />Chemoreceptors – Receptors for taste & smell that only respond to chemicals.<br />Excited by chemicals dissolved in saliva & airborn chemicals dissolved in nasal membranes.<br />
  3. 3. Taste buds: located in oral cavity; 10,000; most in tongue papillae; each taste bud has 40-100 epithelial cells made of 3 major types.<br />Supporting Cells: separate and insulate<br />Receptor Cells: deal with taste<br />Basal cells: like stem cells, they give rise to new cells<br />Taste Sensations<br />Sweet at tip of tongue<br />Salty & sour on the sides<br />Bitter in the back<br />
  4. 4. Physiology of Taste<br />Activation<br />To be tasted, first must be dissolved in saliva, diffuse into the pore and make contact with gustatory hairs which trigger neurotransmitters to elicit action potentials in these fibers.<br />Adapt rapidly 3-5 seconds & completely in 1-5 minutes<br />Taste Transduction<br />Process in which stimulus energy is converted into a nerve impulse due to influx of different ions<br />
  5. 5. Gustatory Pathway<br />Taste is carried in two cranial nervers<br />Facial: anterior 2/3rds of tongue<br />Glossopharyngeal: posterior 1/3rd<br />Taste triggers reflexes in digestion such as increasing saliva & gastric juice<br />Influence of other sensations on taste<br />Taste is 80% smell, when olfactory receptors are blocked food becomes bland<br />Thermoreceptors, mechanoreceptors, nociceptors, temperature and texture can enhance or detract<br />
  6. 6. Olfactory & Sense of Smell<br />Structure<br />Detects chemicals in solution<br />Olfactory Epithelium:<br />Located on roof of nasal cavity<br />Contain olfactory receptor cells with columnar supporting cells<br />Covered by mucous to trap airborn molecules<br />Physiology<br />In order to smell the substance must be in a gaseous state<br />Must be water soluble to dissolve in olfactory epithelium<br />Bind to protein receptors which open ion channels that send action potentials to olfactory bulb<br />Pathway<br />Send impulses from bulb down tract<br />Thalmus Frontal Lobe or Hypothalmus to interpret and elicit emotional responses to odor<br />Imablances include anosmias (without smells) from head injuries; unicinate fits (olfactory hallucinations)<br />
  7. 7. Eye & Vision<br />Accessory Structures<br />Eyebrows<br />Shade the eyes<br />Prevent perspiration into eye<br />Eyelids<br />Palpabrae protects eye<br />Levatorpalpebraesuperioris raises eyelid<br />Eyelashes trigger blinking<br />Conjunctiva<br />Mucous membrane over eyelids and anterior surface of eyeball (white part)<br />Vascular, when irritated eyes are blood shot<br />
  8. 8. Lacrimal Apparatus<br />Consist of gland and ducts that drain excess secretions into nasal cavity<br />Secretes saline solution (tears)<br />Contains mucous, antibodies, and lysosomes to clean eye & destroy bacteria<br />Eye muscles<br />Movement is controlled by 6 muscles<br />Four Rectus muscles: Superior, Inferior, Lateral, Medial<br />Two Oblique muscles: Superior, Inferior<br />Nerve Innervation: abducens, trochlear, oculomotor<br />Lens : Divides eye into anterior and posterior segments<br />Transparent, flexible structure that can change shape to allow focus of light on retina<br />Avascular<br />Becomes less elastic through life causing focus impairment<br />Cataract – cloudy lens due to thickening of lens or diabetes<br />
  9. 9. Structure of the Eyeball<br />Divided into 3 tunics<br />Fibrous – dense avascular tissue<br />Sclera: white part that protects, shapes, and provides attachment for eye muscles<br />Cornea: buldgesanteriorly and allows light into eye<br />Vascular<br />Choroid – highly vascular & provides nutrition<br />Ciliary Body – encircles lense and keeps it in place<br />Iris – contains pupil and changes in shape due to light<br />Sensory – contains the retina, which are photoreceptors of rods & cones<br />Optic Disc (blind spot) – Where optic nerve exits eye<br />Rods – dim light <br />Cones – bright light and color<br />Filled with humors to maintain shape<br />Vitreous humor – in posterior<br />Aqueous humor – in anterior (if undrained causes glaucoma)<br />
  10. 10. Physiology<br />Wavelength & Color<br />Eyes respond to visible light spectrum<br />Progresses from red to violet<br />Refraction & lenses<br />Light travels in straight lines and blocked by nontrasnparent objects<br />Light reflects or bounces off a surface<br />Reflection accounts for most of light reaching our eyes; as light changes mediums it can bend or refract.<br />Focus<br />Your lens refracts the light to your focal point which projects on your retina<br />Images are upside down & reversed<br />Myopia – nearsighted<br />Hyperopia – farsighted <br />Astigmatism – unequal curvature of lens leading to blur<br />
  11. 11. Photoreception<br />Photoreceptors are modified neurons<br />Outer segment connected to inner, inner connects to cell body which has synaptic endings.<br />Rods<br />Sensitive to low light, best at night<br />Cones<br />Require high light, provides color<br />
  12. 12. Ear: Hearing & Balance<br />Structure – three areas: Outer, middle, & inner ear<br />Outer Ear<br />Auricle or Pinna: ear composed of elastic cartilage & skin to direct sound waves to external auditory canal<br />External auditory meatus: Short curved tube from auricle to eardrum<br />Lined with skin, sebaceous glands, & ceruminous glands (secrete earwax)<br />Tympanic membrane ( ear drum ) boundary between outer & middle ear<br />
  13. 13. Middle Ear (tympanic cavity)<br />Small air filled mucus lined cavity<br />Between eardrum & bony wall with two openings oval (vestibular) & round (cochlear) window<br />Contains pharyngotympanic (auditory tube) running from middle ear to nasopharynx & helps equalize pressure<br />Otitis Media – middle ear inflammation<br />Inner Ear<br />Behind eye socket & contains receptor information<br />2 Major divisions<br />Bony (osseous ) labyrinth<br />Vestibule – contains saccule and utricle which have equilibrium receptors that respond to gravity & changes of head position<br />Cochlea – contains the organ of corti which is the sensory organ for hearing<br />Semicircular Canals – respond to movement of head<br />Membranous Labyrinth<br />Series of sacs and ducts containing endolymph fluid to help conduct sound vibrations.<br />
  14. 14. Sound & Mechanisms of Hearing<br />Sound – a disturbance of pressure<br />Frequency – measurement of offurrences of a repeated event per unit of time<br />Distance between two crests is a wavelength<br />Frequency is expressed in hertz<br />Range for humans is 20-20,000 Hz<br />Amplitude or height of wave is related to intensity<br />Loudness is measured in decibles<br />We can hear from .1 dB to over 120 dB<br />Threshold for pain is 130 dB<br />Hearing loss occurs with exposure to 90 dB<br />Noisy restaurant is 70 dB, normal talking is 50 dB<br />A rock concert is 120 dB. You do the math.<br />Transmission<br />Sound waves move through the air, membranes, bones, fluids to reach receptor cells in the organ of corti.<br />Vibrations excite hair cells which send messages to cochlear nerve and brings the impulses to the brain for processing<br />
  15. 15. Imbalances of Hearing<br />Deafness – any hearing loss<br />Conduction deafness<br />When something hampers sound conduction to fluids of inner ear<br />Ruptures, perforated eardrum can cause problems<br />Sensorinerual<br />Damage to neural structures of cochlear hair cells<br />Can be partial or complete & generally there is gradual loss of hearing throughout life<br />Cells can be damaged to extremely loud noises or prolonged exposure<br />Can be fixed with cochlear implants<br />Tinnitus<br />Ringing of ear<br />Symptom of pathology and not disease<br />1st symptom of cochlear nerve degeneration<br />Can be from inflammation or medication or trauma<br />
  16. 16. Meniere’sSyndrom<br />Affects semicircular & cochlear canals<br />Causes vertigo, nausea, vomitting<br />Standing erect is near impossible<br />Caused by excess fluid, rupture or infection<br />Mild cases can be cleared with anti motion drugs, sometimes surgery<br />Equilibrium & Orientation<br />Responds to head movement without awareness<br />Receptors of inner ear are divided into two parts<br />Static<br />Sensory receptors for static are the maculae<br />Found in saccules and utricle<br />Monitor position of head in space, control posture<br />Dynamic<br />Receptor for dynamic are the cristaampullaris<br />Excited by head movement but major stimuli are rotatory<br />These areas are at work when twirling or feeling ill on a boat<br />
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