the senses sight hearing taste smell touching general sense organs widely distributed throughout the...
TRANSCRIPT
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.