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THE SENSES

THE SENSES. Sight Hearing Taste Smell Touching. General Sense Organs. widely distributed throughout the body detect stimuli (pain, touch, temperature, pressure); Ex.: free nerve endings, Meisners & Pacinian corpuscles. Special Sense Organs.

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THE SENSES

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  1. THE SENSES Sight Hearing Taste Smell Touching

  2. General Sense Organs • widely distributed throughout the body • detect stimuli (pain, touch, temperature, pressure); • Ex.: free nerve endings, Meisners & Pacinian corpuscles

  3. Special Sense Organs • large and complex grouping of specialized receptors (eye, ear, tongue, nose) • types of stimuli include: Photoreceptors  light Chemoreceptors  chemicals Mechanoreceptors  movement

  4. Converting a Stimulus into a Sensation 1. Detect stimulus. 2. Stimulus  converted to a nerve impulse. 3. Nerve impulse  perceived as a sensation in the CNS.

  5. THE EYE (photoreceptors) http://www.youtube.com/watch?v=GMGSw3GDyJQ http://www.youtube.com/watch?v=RE1MvRmWg7I CORNEA – transparent part of sclera that covers the Iris tough outer coat; the white of the eye PUPIL– hole in center of the Iris IRIS – colored part SCLERA http://www.youtube.com/watch?v=JunCyiGfreo

  6. contains rods (night vision) and cones (colorvision) -pigmented layer that prevents scattering of light -nourishes eye Ciliary muscle – muscles that control the opening & closing of the eye

  7. fluid in anterior of lens fluid in posterior of lens

  8. directs light rays to retina no receptors

  9. To view distant objects: ciliary muscle relaxes & lens flattens To view near objects: ciliary muscle contracts & lens curves

  10. Conjunctiva – membrane that lubricates the eye Conjunctivitis – infection of conjunctiva

  11. Normal focusing: clear, upside down image on retina, brain rights the image automatically

  12. Myopia (nearsightedness): eyeball is too long; lens focuses image in front of retina • Hyperopia (farsightedness):eyeball is too short; lens focuses image behind retina

  13. Astigmatism: irregular curvature of lens / cornea; ripples or flat spots in image • Glaucoma: fluid build up • in the eye; damages optic • nerve & restricts blood • flow; can cause blindness

  14. Colorblindness: color perception problem; 1) lacking green and/or red cones and/or blue cones or 2) absorbs an abnormal wavelength of color

  15. THE EAR (mechanoreceptors) or auricle - surrounds external auditory canal 3 smallest bones in body Structure : • External ear • Middle ear • Inner ear Function: • Hearing: sound vibrations • Equilibrium and balance: fluid movements External Auditory tympanic membrane http://www.youtube.com/watch?v=0jyxhozq89g

  16. Tympanic membrane Normal Swimmer’s ear (Otitis Media)

  17. sound waves travel • through the canal, strike the • eardrum, and cause it to • vibrate. http://www.youtube.com/watch?v=ahCbGjasm_E (function) - contains hairs that respond to ear fluid set in motion by sound waves Eustachian Tube: connects middle ear to the throat http://www.blackwellpublishing.com/matthews/ear.html

  18. TASTE(chemoreceptors) http://www.youtube.com/watch?v=0hwOL91cjwM Papillae – contain tastebuds Taste buds – chemoreceptors for taste http://www.bbc.co.uk/science/humanbody/body/factfiles/taste/taste_ani_f5.swf

  19. “Primary” taste sensations: 1. Sweet 2. Sour 3. Bitter 4. Salty 5th Taste: UMAMI ??

  20. chemicals (odors/tastes) must be dissolved in nasal mucus / saliva in order to be detected; sent as an impulse to be interpreted • olfactory receptors (detect odors) are extremely sensitive but easily fatigued • impulses are closely associated with areas of the brain important in memory / emotion • a cold that interferes with olfactory receptors will dull taste sensations

  21. SMELL (chemoreceptors) http://education-portal.com/academy/lesson/the-sense-of-smell-olfactory-bulb-and-the-nose.html#lesson

  22. Concept Check #1 1. What are 3 types of receptors that your special sense organs detect. State the organ that detects each stimuli. Photoreceptors – eye Chemoreceptors–tongue/nose Mechanoreceptors - ear 2. Explain how a stimulus turns into a sensation. a) stimulus detected b) converted into an impulse c) Perceived as a sensation in the CNS 3. Draw a picture of an eye and label the cornea, sclera, pupil, & iris. 4. What are the 2 layers behind the sclera? Choroid – prevents scattering of light Retina – contains rods & cones for night / day vision.

  23. Concept Check #2 5. How does the lens change to view distant and near objects? Distant – lens flattens Near – lens curves 6. What happens during normal focusing? Clear, upside down image on retina – brain rights it automatically. 7. Name and describe any 3 diseases/disorders associated with the eye. Myopia, hyperopia, colorblindness, glaucoma, astigmatism 8. Draw the ear and label the pinna (auricle), external auditory canal, ossicles, eustachian tube, and cochlea.

  24. Concept Check #3 9. Why is the ear considered a mechanoreceptor? Detects fluid movements set in motion by sound waves 10. What must happen 1st before odors and tastes can be interpreted as stimuli? dissolved in mucus and/or saliva 11. Draw a picture of the tongue and label the location of the 4 different taste sensations.

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