special senses: olfaction, taste and vision pp. 264-293 in the lab book
TRANSCRIPT
Special Senses: Olfaction, Taste and Vision
Pp. 264-293 in the lab book
Types of Sensory Receptors
I. Chemoreceptors – detect chemical cuesEx: taste and smell
II. Mechanoreceptors – detect stimuli via a mechanical distortion of a cell membrane
EX: hearing and touch
III. Photoreceptors – detect lightEX: vision
Smell (Olfaction)
Chemoreceptors in the olfactory epithelium respond to chemicals in the air.
Olfactory Nerve
Olfactory Epithelium
Taste
The tongue’s 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
Taste Pore
Taste
Chemicals in food are detected by taste cells located in the taste buds
Taste Bud
Taste Cells
Taste Activities
Locate the papillae on your tongue – Pg. 290
Do Activity 3: Stimulating the taste buds
Can you taste the sugar?
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
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.
Taste Activities
Do Activity 5: The effect of smell on taste
Fill out the table on Pg. 292
Hearing
Inner EarOuter Ear Middle Ear
Auricle(Pinna)
External Acoustic Meatus
TympanumMiddle Ear BonesMalleus, Incus, and Stapes
Cochlea
Semicircular Canals
Auditory Tube(Eustacean Tube)
Hearing
The ear involves mechanoreceptors
Sound waves vibrate the tympanum (eardrum)
Ear Infection (Otis Media)
Inflammation of the mucosal membrane in the middle ear
Commonly caused by bacteria from a sore throat
middle ear & throat areconnected by the auditory tube
pupil
Pupil
IrisSclera
The pupil will change size with light condition
Cornea
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 highlight intensity
The Blind Spot
Do Activity 5: Demonstrating the Blind Spot
Why do you have a blind spot?
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
Cataract
Lens is hard and opaque
Causes problems for focusing light on the retina
Glaucoma
Vitreous humor is constantly being created and draining from the eye
Blockage stops drainage, putting pressure on theretina & optic nerve
Astigmatism
Irregular curvature to the cornea or lens causes focusing problems
Testing for Astigmatism
Do Activity 9: Testing for Astigmatism
Color Blindness
Normal Vision Color Blind
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 correctwavelengths of light
Occurs in 6% of men and 0.5% of women
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?