THE SENSESSight
HearingTasteSmell
Touching
General Sense Organs• widely distributed throughout the body• detect stimuli (pain, touch, temperature,
pressure); • Ex.: free nerve endings, Meisners & Paciniancorpuscles
Special Sense Organs• large and complex grouping of specialized receptors
(eye, ear, tongue, nose)
• types of stimuli include:
Photoreceptors light
Chemoreceptors chemicals
Mechanoreceptors movement
Converting a Stimulus into a Sensation1. Detect stimulus.
2. Stimulus converted to a nerve impulse.
3. Nerve impulse perceived as a sensation in the CNS.
THE EYE (photoreceptors) http://www.youtube.com/watch?v=GMGSw3GDyJQ
http://www.youtube.com/watch?v=RE1MvRmWg7I
SCLERA
tough outer coat; the white of the
eye
CORNEA – transparent part of sclera that covers the Iris
PUPIL – hole in center of the Iris
IRIS – colored part http://www.youtube.com/watch?v=JunCyiGfreo
Ciliary muscle – muscles that control the opening & closing of the eye
-pigmented layer that prevents scattering of light-nourishes eye
contains rods (night vision) and cones (colorvision)
fluid in anterior of lens
fluid in posterior of lens
directs light rays to retina
no receptors
To view distant objects: ciliary muscle relaxes & lens flattens
To view near objects: ciliary muscle contracts & lens curves
Conjunctiva –membrane that lubricates the eye
Conjunctivitis – infection of conjunctiva
Normal focusing: clear, upside down image on retina, brain rights the image automatically
Myopia (nearsightedness): eyeball is too long; lens focuses image in front of retina
Hyperopia (farsightedness): eyeball is too short; lens focuses image behind retina
Astigmatism: irregular curvature of lens / cornea; ripples or flat spots in image
Glaucoma: fluid build upin the eye; damages opticnerve & restricts blood flow; can cause blindness
Colorblindness: color perception problem; 1) lacking green and/or red cones and/or blue cones or 2) absorbs an abnormal wavelength of color
Structure :
1. External ear
2. Middle ear
3. Inner ear
Function: Hearing: sound vibrations Equilibrium and balance: fluid movements
THE EAR (mechanoreceptors)
External Auditory
or auricle - surrounds external auditory canal
3 smallest bones in body
tympanicmembrane
http://www.youtube.com/watch?v=0jyxhozq89g
Normal Swimmer’s ear (Otitis Media)
Tympanic membrane
sound waves travelthrough the canal, strike the eardrum, and cause it to vibrate.
Eustachian Tube: connects middle ear to the throat
- contains hairs that respond to ear fluid set in
motion by sound waves
http://www.blackwellpublishing.com/matthews/ear.html
http://www.youtube.com/watch?v=ahCbGjasm_E (function)
Papillae – contain tastebuds
Taste buds – chemoreceptors for taste
TASTE (chemoreceptors)http://www.youtube.com/watch?v=0hwOL91cjwM
http://www.bbc.co.uk/science/humanbody/body/factfiles/taste/taste_ani_f5.swf
“Primary” taste sensations:
1. Sweet2. Sour3. Bitter4. Salty
5th Taste: UMAMI ??
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
SMELL (chemoreceptors)http://education-portal.com/academy/lesson/the-sense-of-smell-olfactory-bulb-and-the-nose.html#lesson
Concept Check #11. What are 3 types of receptors that yourspecial sense organs detect. State the organ thatdetects each stimuli.Photoreceptors – eye Chemoreceptors–tongue/noseMechanoreceptors - 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.
Concept Check #25. How does the lens change to view distant and near
objects?Distant – lens flattens Near – lens curves6. 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.
Concept Check #39. 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.