Skip to main content
Biology LibreTexts

16.6: Laboratory Activities and Assignment

  • Page ID
    53761
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    Laboratory Activities and Assignment

    Part 1: Review of Vision Anatomy

    1. Label the diagram of the eye below with the following structures:

    • anterior cavity
    • aqueous humor
    • choroid
    • ciliary body
    • cornea
    • fovea centralis
    • iris
    • lens
    • optic disc
    • optic nerve
    • ora serrata
    • posterior cavity
    • pupil
    • retina
    • sclera
    • suspensory ligaments
    • vitreous humor

    eye diagram for labeling

    2. Below is a image of a microscopic section of the eye, magnified by 10x. Label the following structures:

    • anterior cavity
    • aqueous humor
    • choroid
    • ciliary body
    • C.N. II optic nerve
    • cornea
    • lens
    • optic disc
    • posterior cavity
    • retina
    • sclera
    • suspensory ligaments
    • vitreous humor

    microscopic image of an eye for labeling

    3. Label the following structures of the eye on the diagram below (superior view of the right eye).

    • cornea
    • C.N. II optic nerve
    • C.N. III oculomotor nerve
    • C.N. IV trochlear nerve
    • iris
    • lateral rectus
    • levator palpebrae superioris
    • medial rectus
    • optic canal
    • pupil
    • sclera
    • superior oblique
    • superior rectus
    • trochlea of superior oblique

    superior view of eye and extrinsic eye muscles for labeling

    4. Below is a diagram of the cells in the retina. Label the following:

    • bipolar cells
    • choroid
    • cone cells
    • ganglion cells
    • posterior cavity of the eye
    • retina
    • rod cells

    cells of the retina diagram for labeling

    5. On the diagram above, number the structures light information is processed through beginning with the photoreceptors and ending with the cells carrying light sensory information to the thalamus in the optic nerve.

    6. On the diagram of the lacrimal apparatus below, label the following structures:

    • inferior palpebra
    • lacrimal canaliculi
    • lacrimal caruncle
    • lacrimal ducts
    • lacrimal gland
    • lacrimal puncta
    • lacrimal sac
    • nasolacrimal duct
    • superior palpebra

    lacrimal apparatus diagram for labeling

    7. On the diagram above, number the sequential path of lacrimal fluid.

    8. In the boxes of the diagram below, place the appropriate letters with each labeled structure of the vision neural pathway.

    A. Conscious visual sensation

    B. Beginning of axons of retinal ganglion cells

    C. Third order neuron

    D. Synapse between second and third order neuron in (in thalamus)

    E. Half of nerve fibers decussate here

    F. First region with axons from only the left side of both eyes

    Diagram of vision neural pathways for labeling

    Part 2: Review of Auditory and Equilibrium Anatomy

    1. Match the following items to their proper location.

    • auricle
    • cochlea
    • cochlear duct
    • endolymph
    • external auditory canal
    • hair cells
    • incus
    • malleus
    • organ of Corti
    • oval window
    • round window
    • semicircular canals
    • stapes
    • tympanic membrane
    • vestibule
    • vestibulocochlear nerve

    Outer ear

    Middle ear

    Inner ear

    2. Label the following diagram with the structures listed below.

    • auricle
    • cochlea
    • Eustachian tube
    • external acoustic meatus
    • external auditory canal
    • incus
    • inner ear
    • malleus
    • middle ear
    • osseous labyrinth
    • outer ear
    • semicircular canals
    • stapes
    • temporal bone
    • tympanic membrane
    • vestibule
    • vestibulocochlear nerve

    Diagram of ear for labeling

    3. Label the following diagram showing a section of the cochlea with the structures listed.

    • basilar membrane
    • cochlea (uncoiled)
    • cochlear nerve
    • endolymph
    • hair cells
    • organ of Corti
    • perilymph (2 places)
    • round window
    • scala media (cochlear duct)
    • scala tympani
    • scala vestibuli
    • stapes
    • tectorial membrane
    • vestibular membrane

    Diagram of cochlear structures for labeling

    Part 3: Review of Olfactory Anatomy

    1. Label the figure below with the following microstructures of olfaction:

    • axon of olfactory sensory neuron
    • C.N. I olfactory nerve
    • cribriform plate
    • mitral cell
    • nasal cavity
    • olfactory bulb
    • olfactory cilia
    • olfactory epithelium
    • olfactory foramina
    • olfactory sensory neuron

    Diagram of olfactory structures for labeling

    Part 4: Review of Taste Anatomy

    1. On the figure below, label the following structures:

    • circumvallate papillae
    • dorsal median sulcus
    • epiglottis
    • foliate papillae
    • fungiform papillae
    • lingual tonsil

    diagram of tongue for labeling

    2. Explain the role of the following structures in gustation:

    a. papillae:

    b. gustatory cells

    c. taste pore

    d. taste bud:

    3. Give the three cranial nerves that transmit taste sensory signals.

    Part 5: Cow Eye Dissection

    Instructions

    1. Collect a dissection tray, scalpel, scissors, probes, and gloves.
    2. Obtain a preserved cow eye and place it on your dissection tray.
    3. Examine the outside of the eye. You should be able to find the sclera, or the whites of the eye. This tough, outer covering of the eyeball has fat and muscle attached to it.
    4. Locate the covering over the front of the eye, the cornea. When the cow was alive, the cornea was clear. In your cow’s eye, the cornea may be cloudy or blue in color.
    5. Illustrate the outer eye in the space below. Label the following structures on your illustration (alternatively, you may take a photo and label it on the computer).
    • adipose tissue (fat)
    • cornea
    • sclera

    6. Cut the fat around the eye and remove it.

    7. Identify the optic nerve. It can be seen on the back of the eye. The nerve is usually buried in fat, so it will take some work to expose it.

    Image of cow eye showing optic nerve

    Above: Posterior view of a cow eye with adipose tissue cut away to reveal the optic nerve.

    8. Puncture the cornea (pinned in the image below) with scissors or scalpel. Liquid should leak out.

    What is the name of the fluid that leaked out when the cornea was punctured? _____________________ (Hint: Which cavity of the eye did you open?)

    Image of cow eye showing the cornea

    Above: Cow eye with the cornea pinned

    9. Cut the eye in a frontal section (separating anterior and posterior). See image below. This cut will open another cavity of the eye.

    Name the cavity of the eye that was opened when making the frontal section: ___________________

    What is the name of the gelatinous fluid inside this cavity of the eye? ______________________

    Images of slicing open a cow eye

    Above: Making a frontal section of a cow eye.

    10.Open the eye (as shown in the image above).

    11.Separate the parts of the eye. The lens is the hard, sphere-shaped structure sitting in or on the liquid in this cavity.

    12.Find the cornea (which you punctured in step 8) and then the disk-shaped iris behind it.

    13.The iris will be dark in color and contain a center opening, the pupil.

    14.On the back of the eye, the thin layer of cells of the retina can be seen. It is very thin and easy to pull away. The spot where they remain attached is the optic disk which connects the retina to the optic nerve.

    15.The tapetum (a layer of the choroid that is highly reflective in animals) is clearly visible when the retina is removed. It is blue and shiny and will reflect light. This helps the cow to see in the dark

    tapetum and retina of a cow eye

    Above: Cow eye showing the tapetum and a small portion of retina remaining at the optic disc.

    16.The image below shows how each part of the eye appears when it has been separated.

    cornea, iris, lens, tapetum, and retina of cow eye

    Above: Isolated structures of a dissected cow eye.

    17.Illustrate the structures of your dissected cow eye and label the following structures in the space below. Alternatively, you can take a photo and label the image.

    • cornea
    • iris
    • lens
    • pupil
    • retina
    • tapetum

    18.[Optional] Take a photo of your dissected cow eye and share it on social media. #coweyedissection

    Part 6: Sound Localization Activity

    Materials Required

    • tuning forks (1 per group)

    Instructions

    1. Have a subject sit with their eyes closed.
    2. Using a tuning fork, strike the fork so it makes a sound and move it to the front, back, side and top of head at a constant distance.
    3. The subject will use their figure to continue pointing out the location they believe the sound is coming from as the tuning fork moves.
    4. Note the accuracy at each position of their pointing, and determine the most and least accurate positions for localization.
    5. Repeat with another subject.

    In the table below, write a check mark when the subject accurately pointed out the position of the tuning fork. Write an X when the subject inaccurately pointed out the position of the tuning fork.

    Subject #

    Anterior to head

    Posterior to head

    Lateral (right) to head

    Lateral (left) to head

    Superior to head

    1

    2

    3

    4

    5

    6

    6. Were there any positions of the tuning fork where sound localization was most accurate? If so, which ones?

    7. Were there any positions of the tuning fork where sound localization was least accurate? If so, which ones?

    8. Consider the anatomy of the auditory sense (macroscopic and microscopic). What features of the anatomy might account for the observations you made in 6. and 7.?

    Part 7: Olfaction Threshold

    Material Required

    • Serial dilutions of odorant oils in sealed containers (lowest concentration should be less than micromolar concentrations) - may use spearmint, orange, anise, etc.

    Instructions

    Humans consistently recognize certain odorants when their olfactory epithelium detects inhaled chemicals. In this activity, you will test your olfactory sensitivity for each by starting with a series at the low end of the concentrations.

    1. Unseal the lowest concentration solution and smell it. If you smell an odor from the solution, put a check mark in the table below for "concentration 1." If you do not smell an odor, write an X.
    2. Repeat this procedure for all five solutions, each with an increasing concentration of odorant.

    Concentration 1

    Concentration 2

    Concentration 3

    Concentration 4

    Concentration 5

    Result

    3. Inform your instructor of the lowest concentration that you first smelled the odorant. They will compile class results.

    4. Record the class results shared by your instructor below.

    Number of Students at this Detection Level

    Percentage of the Class

    Concentration 1

    Concentration 2

    Concentration 3

    Concentration 4

    Concentration 5

    Total

    5. Discuss the macroanatomy and microanatomy of olfaction with your lab group and how chemical molecules are detected through olfaction. What individual anatomical differences might account for the ability to detect smells at lower concentrations than others?

    Part 8: Are You a Super-Taster?

    Materials Required

    • dark-colored food coloring liquid or power
    • clean spoons (1 per student)
    • paper squares with 1 cm diameter holes in them (1 per student)
    • camera phones

    Instructions

    1. Use a spoon to put a small amount of dark food coloring liquid or powder on the surface of the tongue. Your goal is to stain the surface of your tongue.
    2. Align your paper square with a hole above the stained part of your tongue.
    3. Have another student take a clear, close-up image of your tongue in the circle.
    4. The papillae on the surface of your tongue will be obvious since their color will contrast the color of the food coloring. Count the number of papillae on your tongue using the image taken.
    5. Record the number of papillae in the circle on your tongue in the table and share this number with your instructor who will compile all of the data from the rest of the class.

    Data Collection and Analysis

    1. Number of papillae on my tongue in a 1 cm diameter circle: ___________

    The number of papilla in the circle indicates whether you are an "average-taster," a "hypo-taster" with fewer papilla than average, or a "hyper-taster" with more papilla than average.

    • 0 - 5 papillae = "hypo-taster"
    • 6 - 15 papillae = "average taster"
    • 16+ papillae = "hyper-taster"

    A "hypo-taster" is more tolerant of bitter tastes. A hyper-taster is more sensitive to bitter tastes.

    2. What type of taster are you based on your data? ________________

    3. Collect class data below and calculate the percentages of the class that are "hypo-tasters," "average tasters," and "hyper-tasters."

    Taster type

    Number of students

    Percentage of Students

    hypo

    average

    hyper

    Total

    Activity Questions

    1. Explain how the number of papillae on your tongue relates to your taste sensitivity. Relate the anatomy of taste (including the microscopic anatomy of taste) with your answer.

    2. Does your experience validate the data collected in this experiment? For example, if you are a "hypo-taster" do you notice that bitter tasting foods seem to bother you less than other people?

    Attributions

    Part 1: Review of Vision Anatomy

    Part 2: Review of Auditory and Equilibrium Anatomy

    Part 3: Review of Olfactory Anatomy

    Part 4: Review of Taste Anatomy

    Part 5: Cow Eye Dissection

    Part 6: Sound Localization Activity

    Part 7: Olfaction Threshold


    This page titled 16.6: Laboratory Activities and Assignment is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Rosanna Hartline.

    • Was this article helpful?