Lab 12
Special Senses: Vision
Special Senses: Hearing and Equilibrium
Exercise 24
Exercise 25
Vision
Some of the activities below can be done at home.
Activity 1:Identifying Accessory Eye Structures
Activity 2: Identifying Internal Structures of the Eye
Dissection: The Cow Eye
Activity 5: Demonstrating the Blind Spot
Activity 6: Determining Near Point Accommodation
Activity 7: Testing Visual Acuity
There is a white line on the lab floor 20 feet from the chart.
Activity 8: Testing for Astigmatism
Activity 9: Testing for Color Blindness
Activity 10: Testing for Binocular Vision
Demonstrating Afterimages
Negative afterimage
(www.biology-online.org/dictionary/Negative_afterimage)
An afterimage in which the lightness relationship is reversed; if
chromatic, it appears in complementary color, for example a green
image that is looked at for a while when gaze is turned to a white
sheet of paper it would have a red afterimage. Afterimages usually
last from about a few seconds to a minute. most nerve cells
quickly readjust.
Use the picture of the American flag at the front of the lab. Stare at the
image for one minute and then look at the white area below the flag
until an image appears. It can take several seconds.
Hearing
Activity 1: Identifying the Structures of the Ear
Activity 4: Conducting Laboratory Tests on Hearing
Acuity Test
Sound Localization
Weber Test
Microscopic Anatomy of the Cochlea - from Figures in Lab Manual
Viewing the slide is optional.
Name____________________________
Lab Section ________________
Pre-lab Activity - Turn in at the beginning of the lab.
1. The mucous membrane that lines the eyelids and covers the surface of the eye is the
___________________.
Inflammation of this membrane is called ___________________ .
2. What are the three basic layers of the eyeball?
___________________,
______________________, and ___________________.
3. The transparent part of the outer layer of the eyeball is called the ____________ .
4. The hole in the center of the iris is called the _____________ .
5. Put the following terms in the correct order for the pathway of light into the eyeball.
______ Cornea
______ Retina
______ Lens aqueous humor
______ Vitreous humor
______ Pupil
6. Photoreceptors for color vision are called __________________ and are located in
the ___________________ .
7. The optic nerves become the optic tracts after the __________________________.
8. The axons of the ganglion cells of the retina form the _______________________.
9. Define optic disc.
10. Define fovea.
11. The three parts of the ear are the ?
___________________,
______________________, and ___________________.
12. What is the name of the organ of hearing?
13. Other than hearing, what is another role for the inner ear.
14. Trace the pathway of sound waves into the ear.
______ Auditory canal
______ Perilymph of scala vestibuli
______ Incus
______ Stapes
______ Malleus
______ Tympanic membrane
______ Oval window
Name____________________________
Lab Section ________________
Data and Review Sheets - Special Senses
Data Sheet
1. Record the results of the Snellen Test for Visual Acuity
Right eye unaided ________ Right eye with correction _________
Left eye unaided
________ Left eye with correction _________
Why is it important to check each eye separately?
2. Record the results of the test for Near Point of Accommodation
Right eye ________
Left eye ________
Is your near point within normal range?
3. a. Describe what happened when you stared at the flag figure and then
looked at a white background.
b. What is this called?
Cow Eye Dissection
Questions
1. What is the name of the place where the retina attached to the eyeball?
2. What is the relationship between the location of the optic disc and the optic
nerve?
3. Compare the shape of the cow pupil to the pupil of the human eye.
4. What is tapetum lucidum?
What is its role?
Is it present in the human eye?
5. In what two ways are the cornea and lens affected by the preservative? 2
points.
__________________________________ and ______________________________
6. What is the normal condition of the lens and cornea in an unpreserved eye?
2 points.
__________________________________ and ______________________________
Review Sheet
1. What does 20/20 vision mean?
2. What does 20/40 vision mean?
3. What does 20/15 vision mean?
4. a. What is astigmatism?
b. What is the test for astigmatism?
5. a. What is another name for the part of the retina called the blind spot?
b. Why is vision lost when light passes over this area?
c. What receptors are responsible for color vision?
d. What receptors are responsible for vision in shades of gray?
6. a. Where are the extrinsic or external eye muscles attached to the
eyeball?
b. Which branch of the nervous system controls these muscles?
Somatic motor
Autonomic (circle one)
c. Where are the internal muscles of the eye located? (2 places)
_______________________
_______________________
d. Which branch of the nervous system controls these muscles?
Somatic motor
Autonomic (circle one)
7. Use the figure in the lab manual to trace an impulse from the retina to
the visual cortex.
Axons of ganglion cells of the retina ⇒ _____________________ ⇒
_____________________ ⇒_____________________⇒ synapse in the
thalamus ⇒_____________________ ⇒visual cortex
A
N
B
C
D
M
E
L
F
G
H
I
J
K
8. Match the letters on the figure with the terms below:
____ Aqueous humor
____ Optic nerve
____ Choroid
____ Pupil
____ Ciliary body
____ Retina
____ Cornea
____ Sclera
____ Iris
____ Scleral venous sinus
____ Lens
____ Suspensory ligaments
____ Optic disc
____ Vitreous body
The Ear
F
A
G
B
H
C
I
D
J
E
K
L
9. Label on the figure:
____ Auditory tube
____ Middle ear cavity
____ Cochlea
____ Semicircular canals
____ External auditory canal
____ Stapes
____ Incus
____ Tympanic membrane
____ Inner ear
____ Vestibule
____ Malleus
____ Vestibulocochlear nerve
10. What is the role of the hair cells of the cochlea in hearing sounds of
different pitches, and why should you wear ear plugs at loud concerts?
11. Label: Print the labels in the margins.
basilar membrane
outer hair cells
cochlear nerve
tectorial membrane
inner hair cells
12. Label: Print the letters at the end of the
correct leader lines.
A basilar membrane
B cochlear nerve
C stapes
D oval window
13. Record threshold of audibility. Right ear _______ cm. Left ear ________ cm.
14. Sound localization.
Can sound be localized equally well from all positions? _____________
If not, at which positions was sound less easily located?