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Sight Hearing Taste Smell Touching

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Presentation on theme: "Sight Hearing Taste Smell Touching"— Presentation transcript:

1 Sight Hearing Taste Smell Touching
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 types of stimuli include:
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)
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

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 Conjunctivitis – infection of 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 Structure : External ear Middle ear Inner ear Function: Hearing: sound vibrations Equilibrium and balance: fluid movements 3 smallest bones in body External Auditory tympanic membrane

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

17 through the canal, strike the eardrum, and cause it to vibrate.
sound waves travel through the canal, strike the eardrum, and cause it to vibrate. (function) - contains hairs that respond to ear fluid set in motion by sound waves Eustachian Tube: connects middle ear to the throat

18 TASTE (chemoreceptors)
Papillae – contain tastebuds Taste buds – chemoreceptors for taste

19 “Primary” taste sensations: 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)

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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