Lab 4_ SPECIAL SENSES SUBMIT LAB REPORT-1

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PHYSIOLOGY NAME: Diana Phan LAB 4: SPECIAL SENSES Experiment 1: Accommodation Experiment 1a: Accommodation with wire mesh Was your focus on the object through the mesh or the mesh itself when you initially focused on the far object? Object through the mesh Number of individuals who focused through the mesh Number of individuals who focused on the mesh 5 1 Was your focus on the object through the mesh or the mesh itself when you initially focused on the mesh? Object through the mesh Number of individuals who focused through the mesh Number of individuals who focused on the mesh 5 1 Experiment 1b: Accommodation with pointer (OPTIONAL) Age Right eye’s nearest point before blurred (cm) Left eye’s nearest point before blurred (cm) 23 28 cm 28 cm 19 26 cm 26 cm 27 24 cm 27 cm 18 40 cm 25 cm 34 9 cm 9 cm 33 13 cm 11 cm Experiment 2: Visual Acuity Experiment 2a: Visual Acuity with Snellen Chart Individual Visual Acuity of the Right Eye Visual Acuity of the Left Eye 1 20/10 20/13 2 20/25 -3 20/20 3 20/40 -3 20/40 -3 4 20/13 20/15 5 20/50 20/13 6 20/100 20/50 Experiment 2b: Visual Acuity with Astigmatism Chart Individual Does your Right Eye have Does your Left Eye have 1

Astigmatism? Astigmatism? 1 No No 2 No No 3 Yes Yes 4 Yes No 5 Yes Yes 6 No No If you wear glasses, do they correct for astigmatism? - Yes Experiment 3: Pupillary Reflex What happened/will happen when you shined light to the right eye? - The pupil constricted and then the left pupil also constricted. What happened/will happen when you shined light to the left eye? - The pupil constricted and then the right pupil also constricted. Experiment 4: Observing the Retina using an Ophthalmoscope What is the purpose of using ophthalmoscope? What did you see? What would you expect to see? - The purpose of using a ophthalmoscope is to see a healthy retina and to ensure red reflexes work. We saw red. I expected to see more of the retina – like the macula lutea with the fovea centralis. Experiment 5: Finding the Optic Disc Individua l Left eye distance of index card for blind spot (cm) Right eye distance of index card for blind spot (cm) 1 38 cm 38 cm 2 32 cm 36 cm 3 20 cm 25 cm 4 15 cm 9 cm 5 30 cm 31 cm 6 45 cm 50 cm Experiment 6: Red-Green Color Blindness Can you read the numbers in the Ishihara test (at the end of the page)? - Yes Is there anyone in your group that was colorblind? - No 2

Experiment 7: Bleaching Reaction and Afterimage Look at the white spot on the flag (at the end of the report) with colors black, green and yellow for 45 seconds to a minute without blinking and then quickly move to a blank white screen. What did you observe? Was there an after image? Explain the physiological phenomenon at work as you see the after image. - When staring at the red square, a blue square with a white center dot appeared on the white screen. When staring at the blue square, a red square appeared on the white screen. When staring at the yellow square, a dark purple/blue appeared on the white screen. - If we stare at something long enough, all the photoreceptors that are stimulated become all- trans. After shifting our focus, we end up seeing the inverse of the thing that we were staring at (afterimage). Post-Lab Questions: Background for Vision 1. List the structures and their functions as light enters the eye, include the retinal cells that light passes through. - The light first passes the cornea, which is the anterior and transparent part of the sclera, also known as the white of the eye. - It then passes the aqueous humor, which is clear liquid that nourishes the lens and cornea. - It passes through the pupil. The pupil is the space in the middle of the iris. The iris controls the amount of light that enters the pupil with 2 types of smooth muscles. The smooth muscles control the diameter of the pupil and they are the radial and circular smooth muscles. The radial smooth muscles contract to cause dilation, which is innervated by the sympathetic nervous system and allows more light to enter the eye. The circular smooth muscles contract to cause constriction and is innervated by the parasympathetic nervous system to decrease the amount of light entering the eye. - The lens helps focus the light rays onto the retina which has the suspensory ligaments that are connected to the ciliary body. Ciliary body is the smooth muscles that help focus on things that are far away (by making the lens thinner) and close up (by making the lens thicker). The suspensory ligaments connect the lens to the ciliary body. When the ciliary body contracts, the suspensory ligaments loosen. When the ciliary body relaxes, the suspensory ligaments tighten. - The vitreous humor is fluid that helps maintain the shape of the eye and pushes the retina towards the choroid. The space between the lens and the retina is known as the posterior cavity. - The retina contains the neurons that detects light. Within the retina is the ganglion cells, bipolar cells, and photoreceptors. Light will pass through these cells in that specific order. - Choroid is vascularized and pigmented to support the retina and sclera. The vascularization helps receive nutrients and oxygen and removes the wastes and carbon dioxide. The pigmentation absorbs light so that it doesn’t scatter. 3

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2. What type of photopigment is in rods and what is it made of? What about the cones? - Rods contain rhodopsin which has 2 molecules, retinaldehyde and opsin. Cones contain retinaldehyde and photopsin. 3. What is the optic nerve and what is its function? - The optic nerve is one of the cranial nerves and it sends visual information to the brain. 4. What is the superior colliculi and its function? - The superior colliculi is part of the brain, specifically part of the corpora quadrigemina, and it is where visual reflexes occur. Experiment 1: Accommodation 5. How do we correct presbyopia? - By using bifocals 6. An elderly patient with 20/20 vision and doesn’t suffer from hyperopia, is having trouble reading, seeing their smartphone. What might this patient from and what may be a treatment for it? - The patient may be suffering from presbyopia. This happens as you get older, and the lens becomes less flexible, causing it to be harder to focus on things that are close. A treatment would be to wear bifocals. Experiment 2: Visual Acuity 7. What chart is used to test visual acuity? - The Snellen Chart 8. What is myopia? Why does this occur? How do you correct myopia? - Myopia is nearsightedness, which means they can’t see far away. This occurs because the eyes are too elongated, and it makes the focal point of the image to be in front of the retina. To fix this, you would need concave lenses. 9. What is hyperopia? Why does this occur? How do you correct hyperopia? - Hyperopia is farsightedness, which means they can’t see close up. This occurs because the eyes are too short which causes the focal point of the image to be behind the retina. To fix this, you would need convex lenses. 10. What is astigmatism? - Astigmatism is when the cornea is deformed so light rays on different planes are unable to be focused on the retina. 11. What is your visual acuity? What type of vision do you have? 4

- My visual acuity is 20/100 in my right eye and 20/50 in my left eye. I have myopia and astigmatism. 12. If a person has 20/50, what type of vision does this person have? What does it mean? - The person has myopia. It means that they have worse vision than normal. Experiment 3: Pupillary Reflex 13. What two muscles are found in the iris and what do they do, and which cranial nerve are they innervated by? - The 2 smooth muscles control the diameter of the pupil. They are the radial and circular smooth muscles. The radial smooth muscles contract to cause dilation, which is innervated by the sympathetic nervous system and allows more light to enter the eye. The circular smooth muscles contract to cause constriction and is innervated by parasympathetic nervous system to decrease the amount of light entering the eye. They are innervated by CNII – the optic nerve. 14. Which part of the autonomic nervous system controls which smooth muscle of the iris? - The sympathetic nervous system controls the radial smooth muscle. The parasympathetic nervous system controls the circular smooth muscle. Experiment 6: Red-Green Color Blindness 15. What types of cones are there and what are they sensitive to? - Short-wavelength (S) cones are sensitive to 420 nm of light, medium-wavelength (M) cones are sensitive to 531 nm, and long-wavelength (L) cones are sensitive to 558 nm. 16. What is red-green color blindness? What are they lacking? - Red-green color blindness is when a person cannot distinguish between red and green. They are lacking L or M cones. 17. What type of trait is red-green color blindness? Who is more susceptible in getting red-green color blindness? Why? - It is a sex-linked recessive trait. Males are more susceptible since the gene is on the X chromosome. Males only have one X and females have XX. For a female to be colorblind, both XX chromosomes would need to have the colorblind gene. Since males only have one X, the red-green color blindness only needs to be on that one X. 18. What is used to test red-green color blindness? - The Ishihara test is used. Experiment 8: Extrinsic Eye Muscles 5

19. What are the different extrinsic eye muscles, their functions, and which nerve are they innervated by? Extrinsic Eye Muscle Function Innervated by Lateral rectus Moves eye laterally CNVI – abducens nerve Medial rectus Moves eye medially CNIII – oculomotor nerve Superior rectus Elevates eye upward CNIII – oculomotor nerve Inferior rectus Moves eye downward CNIII – oculomotor nerve Superior oblique Moves eye laterally and inferiorly CNIV – trochlear nerve Inferior oblique Moves eye laterally and superiorly CNIII – oculomotor nerve 20. What is nystagmus? Why does it occur? - Nystagmus occurs when the eyes drift and then quickly moves back to the object. It occurs when the muscles or cranial nerves in the eyes are not functioning correctly. Background for Hearing 21. List the structures, in order, and their function for the pathway for sound - Pinna/auricle moves the sound waves into the - Auditory canal/external acoustic meatus which allows the sound waves to move to the - Tympanic membrane, causing the auditory ossicles to vibrate - Malleus is the first to receive the vibrations - Incus is the second - Stapes is the third, which is attached to the - Oval window which is the opening of the cochlea. The vibrations are converted into fluid vibrations which are moved to the - Perilymph of the scala vestibuli which is fluid located in the superior area of the cochlea. The vibrations then pass to the - Vestibular membrane which separates the scala vestibuli and scala media which contains - Endolymph which is fluid that vibrates to the - Basilar membrane which separates the scala media and scala tympani. It also contains the 6

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- Spiral organ/organ of corti that contains hair cells that convert the vibrational signals into electrical signals to be sent to the brain. Not all the hair cells are converted so the remaining are sent to the perilymph. The hair cells are also within the o Tectorial membrane which is not technically part of the pathway of sound but when the basilar membrane bends from the fluid vibrations, the stereocilia of the hair cell also bends - Perilymph of the scala tympani allows the remaining fluid vibration to leave the ear through the cochlea by the - Round window which is where the rest of the vibrations exits 22. What is perilymph? Where is it found? - Perilymph is extracellular fluid and is located in the scala vestibuli and scala tympani 23. What is endolymph? Where is it found? - Endolymph is intracellular fluid and is located in the scala media 24. What is the spiral organ/Organ of Corti? What is its function? - The spiral organ is the receptor organ for hearing. Its function is to convert vibrational signals into electrical signals. Experiment 10: Testing for Hearing Loss 25. What is conductive hearing loss? Explain - Conductive hearing loss is when there is a decrease in the ability of sounds to move from the ear to the oval window. This can occur due to too much ear wax, a ruptured tympanic membrane, or the damage of the malleus/incus/stapes. 26. What is sensorineural/perception hearing loss? What may help sensorineural/perception hearing loss? - Sensorineural hearing loss is when either the hair cells, cochlear branch, inferior colliculi, thalamus, primary auditory cortex, or auditory association area is damaged. Cochlear implants may help by sending electrical signals through existing neurons. 27. What is the Rinne’s test and what does it test for? - Rinne’s test compares sound waves through air conduction versus bone conduction. It tests for conductive hearing loss. 28. What is Weber’s test and what does it test for? - Weber’s test uses a tuning fork at the midline of the patient’s head. It tests for conductive and sensorineural hearing loss. 7

Lab 4_ SPECIAL SENSES SUBMIT LAB REPORT-1

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