special senses: olfaction, taste and vision pp. 264-293 in the lab book

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

Testing for Color Blindness

Color Blindness Test

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?