Special Senses: Olfaction, Taste and Vision

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Special Senses Olfaction, Taste and Vision
Pp. 264-293 in the lab book
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Types of Sensory Receptors

• Chemoreceptors detect chemical cues
• Ex taste and smell
• Mechanoreceptors detect stimuli via a
• mechanical distortion of a cell membrane
• EX hearing and touch
• III. Photoreceptors detect light
• EX vision

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Smell (Olfaction)
Chemoreceptors in the olfactory epithelium
respond to chemicals in the air.
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Olfactory Nerve
Olfactory Epithelium
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Taste
The tongues surface is covered by small
projections called papillae Papillae contain
the taste buds There are 10,000 taste buds on
the human tongue Each taste bud has 100 taste
cells
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Taste Pore
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Taste
Chemicals in food are detected by taste cells
located in the taste buds
Taste Cells
Taste Bud
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Taste Activities
Locate the papillae on your tongue Pg. 290 Do
Activity 3 Stimulating the taste buds Can you
taste the sugar?
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The Distribution of Taste
Sweet, Sour, Salty, and Bitter There is now 5th
taste Umami is the distinctive taste found
in meat and cheese Led to the creation of MSG
as a seasoning/preservative
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Do Activity 4 Plotting Taste Bud
Distribution Does YOUR tongue match this pattern?
Hi, I am Kikunae Ikeda. I discovered Umami in
1907. You can blame MSG on me.
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Taste Activities
Do Activity 5 The effect of smell on taste Fill
out the table on Pg. 292
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Hearing
Outer Ear
Middle Ear
Inner Ear
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Middle Ear Bones Malleus, Incus, and Stapes
Semicircular Canals
Tympanum
Cochlea
Auricle (Pinna)
External Acoustic Meatus
Auditory Tube (Eustacean Tube)
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Hearing
The ear involves mechanoreceptors Sound waves
vibrate the tympanum (eardrum)
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Ear Infection (Otis Media)
Inflammation of the mucosal membrane in the
middle ear Commonly caused by bacteria from a
sore throat
middle ear throat are connected by the auditory
tube
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pupil
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Sclera
Iris
Pupil
Cornea
The pupil will change size with light condition
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The Rods and Cones
These are the photoreceptors of the eye They
occur in the retina of the eye 120 million rods
and 6 million cones in each retina Rods are
specialized for low light conditions Cones are
specialized for color vision under high light
intensity
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The Blind Spot
Do Activity 5 Demonstrating the Blind Spot Why
do you have a blind spot?
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The Causes of Near/Far Sightedness

1. Lens over or under compensates when focusing
2. Eyeball is too long or too short for proper
   focusing
3. Cornea or lens has improper curvature

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Cataract
Lens is hard and opaque Causes problems for
focusing light on the retina
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Glaucoma
Vitreous humor is constantly being created and
draining from the eye Blockage stops drainage,
putting pressure on the retina optic nerve
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Astigmatism
Irregular curvature to the cornea or lens causes
focusing problems
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Testing for Astigmatism
Do Activity 9 Testing for Astigmatism
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Color Blindness
Normal Vision
Color Blind
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What Causes Color Blindness?
There are 3 Types of Cones in the Human Eye
Red Cones for red wavelengths of light Blue
Cones for blue wavelengths of light Green
Cones for green wavelengths of light Color
Blindness occurs when one or all of these cone
types are not sensitive to the correct wavelength
s of light Occurs in 6 of men and 0.5 of women
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Testing for Color Blindness
Color Blindness Test
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Dissection of the Cow Eye Pg. 270-271
Find the parts listed in your handout What is
the tapetum lucidum? Do you have a tapetum
lucidum?