Summary Module 09 Lab Worksheet: Special Senses and Eyeball Dissection

MODULE 9 LAB WORKSHEET S - The Marketplace to Buy and Sell your Study Material Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material Module 09 Lab Worksheet: Special Senses and Eyeball Dissection Introduction This week’s lab will focus on the special senses of vision, hearing, balance, smell and taste. Objectives Objectives for this week’s lab include: 1) Identify the anatomical components of the special senses, 2) Identify the anatomical structures of the eye through dissection, and 3) Analyze the function of the special senses. Overview The special senses consist of vision, taste, smell, hearing and equilibrium. Compared to the general senses (touch sensation, pain, temperature, pressure) that are widespread throughout the body, the special senses are localized to the head region of the body and contain highly complex nerve receptors. Nearly 70% of our sensory receptors are found in the eye and just about half of our cerebral cortex is dedicate to visual processing. Technically, there are three layers to the eye: Fibrous layer (outer layer which includes the sclera), vascular layer (middle layer that includes the choroid and iris) and the inner layer (which includes the retina). The major components of the eye include the: Cornea, iris, pupil, vitreous humor and the retina. The retina contains two types of photoreceptor cells: Rods, which are responsible for dimly light/black & white vision and cones, which are responsible for color vision. In a very simplistic sense, incoming light is refracted (bent) by the cornea, lens and vitreous humor to be focused on a specific spot of the retina. The photoreceptor cells of the retina will convert light energy into an electrical impulse that is transmitted to the occipital lobe via the optic nerve. The eye can have imbalances with the refraction of the light on the retina, producing vision that is labeled ‘near-sightedness’ or ‘far-sightedness’ and leading to the need for corrective eyewear. Both the sense of taste and smell are classified as a chemical sense because they contain chemoreceptors, which are receptors that bind molecules to initiate their sense perception. For the sense of taste, mastication of food releases molecules that bind to sensory nerves found within our tastes buds. A human has roughly 10,000 taste buds that are housed within these tiny projections called papillae. Once the taste cell (gustatory epithelial cell) binds a molecule, it initiates an action potential that is sent to various locations of the cerebrum creating the sense of taste. The sense of smell utilizes the same method. Odor molecules, known as odorants, enter the nose and bind to the olfactory cells, which are connected to the olfactory bulb. Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material Upon binding an odorant, the olfactory cells will generate an action potential that is projected to various regions in the cerebrum and stimulates our sense of smell. The sense of hearing and equilibrium is housed within the inner ear. The cochlea, vestibule, and semicircular canals are the major structures involved. The cochlea is a small, spiral shaped boney chamber that houses the spiral organ, which ultimately allows for the sense of hearing. The spiral organ contains hair cells that move in accordance to air vibrations sensed by the tympanic membrane and generate an action potential that is sent to the temporal lobe for the sense of hearing. The vestibule contains the saccule and utricle while the semicircular canals contain the ampullas. These structures contain sensory hair cells that move in accordance to the movement of head creating the sense of acceleration, de-acceleration, head position and rotational movements of the head. Materials 1. Models of the eye and ear 2. Tuning fork 3. Starbursts™ candy 4. Eyeball specimen 5. Dissection tray and kit Pre-Lab Evaluation Questions The pre-lab evaluation questions must be answered prior to lab and demonstrated to your lab instructor. You must read through the assigned chapter readings, lab introduction, objectives, overview and procedure to answer these questions. Please cite your work for any reference source you utilize in answering these questions. 1 As light passes through the eye, describe the three major structures and their function that light passes through before reaching the retina -The cornea is a part of the outermost layer of the eye and allows for light to enter the eye. The light can pass though the pupil, the opening at the center of this iris where light enters the eye. The iris controls the amount of light that enters the eye by constricting the pupil in response to bright light or dilating the pupil in dim light. After light has passed through the iris, the lens that sits behind the iris then focuses the light on the retina. Muscle fibers allow the lens to bend shape to focus on light. The vitreous Body comprises a large portion of the eyeball. It is a clear gel-like substance that occupies the space behind the lens and in front of the retina at the back of the eye. Because the eye must process visual data, this liquid must be clear enough for light to easily pass through it. (Allen, n.d.). Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material 2 Compare and contrast the function of rods and cones. What role does the fovea centralis have in vision? Describe the blind spot of the eye and how we adjust for it? Both are photoreceptor cells found in the retina. -Rods: responsible for vision at low light levels (scotopic vision). They do not mediate color vision, and have a low spatial acuity -Cones: Active at higher light levels (photopic vision), are capable of color vision and are responsible for high special acuity. 3 types: S-cone, M-cone, and L-cones. (“Rods & Cones,” n.d.). -Central Fovea: populated exclusively by cones. “In the eye, a tiny pit located in the macula of the retina that provides the clearest vision of all. Only in the fovea are the layers of the retina spread aside to let light fall directly on the cones, the cells that give the sharpest image. Also called the central fovea or fovea centralis.” In the center of the macula and highest concentration of cone cells. (“Medical Definition of Fovea,” 2017) -Blind Spot: “The blind spot is the area on the retina without receptors that respond to light. Therefore an image that falls on this region will NOT be seen. It is in this region that the optic nerve exits the eye on its way to the brain” (“The Blind Spot,” n.d.). 3 Describe how our ability to taste is connected to our sense of smell. -Our ability to taste is connected to our sense of smell because “they both use the same types of receptors and are stimulated by molecules in solutions or air” Result of our body’s ability to smell. Both are classified as a chemical sense. (“Taste and Odors,” 2016) 4 In your own words, briefly describe how the tympanic membrane, ear ossicles and the spiral organ work together to create the sense of hearing. -Sound waves that are entering the ear from the external acoustic meatus strikes the tympanic membrane causing it to vibrate, which in return causes the ear ossicles to vibrate as well. The spinal organs contain hair cells that transmit sound vibrations to the nerve fibers (Ross, 2007) 5 Compare and contrast the two types of hearing loss. -Conductive Hearing Loss: “caused by any condition or disease that impedes the conveyance of sound in its mechanical form through the middle ear cavity to the inner ear. A conductive hearing loss can be the result of a blockage in the external ear canal or can be caused by any disorder that Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material unfavorably effects the middle ear's ability to transmit the mechanical energy to the stapes footplate. This results in reduction of one of the physical attributes of sound called intensity (loudness), so the energy reaching the inner ear is lower or less intense than that in the original stimulus. Therefore, more energy is needed for the individual with a conductive hearing loss to hear sound, but once it's loud enough and the mechanical impediment is overcome, that ear works in a normal way. Generally, the cause of conductive hearing loss can be identified and treated resulting in a complete or partial improvement in hearing. Following the completion of medical treatment for cause of the conductive hearing loss, hearing aids are effective in correcting the remaining hearing loss” Death or damage to the hair cells of the spinal organ. -Sensorineural Hearing Loss: “Sensorineural hearing loss results from inner ear or auditory nerve dysfunction. The sensory component may be from damage to the organ of Corti or an inability of the hair cells to stimulate the nerves of hearing or a metabolic problem in the fluids of the inner ear. The neural or retrocochlear component can be the result of severe damage to the organ of Corti that causes the nerves of hearing to degenerate or it can be an inability of the hearing nerves themselves to convey neurochemical information through the central auditory pathways” (“Hearing Loss Types,” 2017) References Allen, M. (n.d.). Basic Eye Anatomy. Retrieved from: American Optometric Association (2017). Astigmatism. Retrieved from: Bailey, G. (2017, January). Myopia Nearsightedness. Retrieved from: Bailey, G. (2016, October). Hyperopia Farsightedness. Retrieved from: Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material Diseases and Conditions: Hearing Loss. (n.d.). Retrieved from: Hearing Loss Types. (2017). Retrieved from: Medical Definition of Fovea. (2017). Retrieved from: National Eye Institute. (n.d.). Facts about Glaucoma. Retrieved from: National Eye Institute. (n.d.). Facts about Cataract. Retrieved from: Rods & Cones. (n.d.). Retrieved from: Ross, M. (2007, December 31). Ear Anatomy and Physiology. Retrieved from: Taste & Odors. (2016, September 20). Retrieved from: The Blind Spot. (n.d.). Retrieved from: Understanding Tinnitus: Diagnosis and Treatment. (2017). Retrieved from: Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material Vertigo. (2017). Retrieved from: Part 01 Procedure: Anatomy of Eye and Ear 1. Utilizing the eye and ear models set up in lab and the terms listed below, identify and label the anatomical structures of the eye and ear: (choroid, cochlea, cochlear nerve, cornea, ear ossicles, eustachian tube, iris, lens, optic disc, optic nerve, pupil, retina, sclera, semicircular canals, tympanic membrane, vestibular nerve, vestibule, vitreous humor) A) Vestibular Nerve B) Semicircular Canals C) Cochlea D) Lens E) Cornea F) Tympanic Membrane G) Optic Disc H) Pupil I) Choroid J) Cochlear Nerve K) Vitreous Humor L) Vestibule M) Sclera N) Optic Nerve O) Eustachian Tube P) Ear Ossicles Q) Retina R) Iris Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material Part 02 Procedure: Hearing Test- Rinne and Weber 1 The Rinne and Webber hearing tests are used to differentiate from sensorineural and conductive hearing loss. 2 Perform the Rinne hearing test first which compares air and bone conduction hearing for both ears: 1 Gently strike a 512 Hz tuning fork on the heel of your hand and place the tuning fork on the patient’s left mastoid process. Record the time when you start the test. 2 Have the patient inform you when sound is no longer heard. Quickly record the time. 3 Immediately move the tuning fork from the mastoid to a position right outside of the external auditory meatus and start recording the time. 4 Have the patient inform you when the sound is no longer heard. 5 Record your results below: LEFT EAR Bone Conduction (mastoid) Hearing Time: 9 Air Conduction Hearing Time: 15 RIGHT EAR Bone Conduction (mastoid) Hearing Time: 14 Air Conduction Hearing Time: 24 Possible Results: 1 Normal Hearing: Patient will hear air conduction sound about twice as long as bone conduction 2 Conductive Hearing Loss: Patient will have bone conduction hearing longer or just as equal to air conduction hearing in the affected ear 3 Sensorineural Hearing Loss: Patient will still hear air conduction hearing longer than bone conduction hearing in the affected ear but dramatically less than found in normal hearing. Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material 3 Perform the Weber hearing test which helps distinguish between conductive and sensorineural hearing loss: 1 Gently strike a 512 Hz tuning fork on the heel of your hand and place the tuning fork on the mid-sagittal suture on the top of the head. 2 Ask the patient if the sound is heard equally in both ears or if it is louder on one side. 3 Record your results below: Hearing the same in both hears *Hearing louder in the right ear* Hearing louder in the left ear Possible Results: 1 Normal Hearing: Patient will hear sound equally in both ears 2 Conductive Hearing Loss: Patient will hear sound louder in ear with conductive hearing loss. To demonstrate this, plug one of your ears (simulating conductive hearing loss) and repeat the test. 3 Sensorineural Hearing Loss: Patient will hear sound louder in ear without sensorineural hearing loss 4 Utilization of both tests will help differentiate between conductive and sensorineural hearing loss within the patient. Please be able to diagnose sensorineural and conductive hearing loss with results from these tests. Part 03 Procedure: Taste and Smell Test 1 The sense of taste is about 80% due to our sense of smell. This may not seem right but think about when you have been sick and congested in the nasal region. Your smell is obviously diminished and so is your taste; that’s why foods taste bland to someone who has nasal congestion. We are going to test this concept utilizing Starbursts™ candy. If you have any allergies, concerns or issues with consuming Starbursts™ candy, please refrain from completing this section. 2 Locate the three bags labeled 1, 2, and 3. Each bag contains a specific flavor of Starbursts™ candy; lemon, orange or strawberry. You will test your lab partner’s ability to taste with his/her nose open and closed. 3 Test your lab partner’s taste ability: With your lab partner’s EYES CLOSED, randomly chose one of the three flavors of Starbursts™ candy, unwrap it and hand it to him/her. Do not inform him/her of the flavor. Have your lab partner chew the Starbursts™ candy and determine the flavor. Record the Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material flavor they think they are eating and record the results in the chart below in the appropriate row and column. Once finished, complete the same procedure for the other two Starbursts™ candy flavors. 4 Next, you will complete the same procedure as above but with your lab partner’s EYES CLOSED and NOSE PLUGGED. Record the results below: Flavor Type Flavor Guessed w/Eyes Closed Flavor Guessed w/Eyes Closed & Nose Plugged Flavor: Lemon Could Identify Could Identify Flavor: Orange Could Identify Could Not Identify Flavor: Strawberry Could Identify Could Not Identify Part 04 Procedure: Eyeball Specimen Dissection 1 Utilizing the “Rasmussen Dissection Guide – Eye Unit”, follow the instructions, protocol and diagrams under: Eyeball Specimen Dissection. 2 When completed with the dissection, dispose of the eyeball specimen in the appropriate location as instructed by your lab instructor along with clean your lab dissection materials and disinfect your lab workstation. Part 05 Procedure: Mini Case Studies 1. Utilizing the case studies handed out in the lab session, please determine and describe the type of hearing loss presented in each case: Case Study A: Sensorineural Hearing Loss in left ear because for the Weber Test she heard it louder in the right ear. Older age contributes to this. He is 67 years old. Case Study B: Patient has sensorineural hearing loss in both ears because they have significantly less hearing loss. It is not double. Also because he has a military background and has been around loud noises continuously. Case Study C: Conductive Hearing Loss in right ear because he is hearing the Rinne test in his affected ear. He doesn’t clear his ears and has a buildup of Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material earwax. Post-Lab Evaluation Questions The post lab evaluation questions must be completed prior to your submission of the lab. Answers for these questions will be derived from the lab protocol, the weekly concepts associated with the lab and possibly research content from the book and/or online resources. Please cite your work for any reference source you utilize in answering these questions. 1 Describe two specific features that you found interesting with the eyeball dissection. What was beneficial for you with this dissection? -One feature that I found the most interesting was actually seeing the vitreous body. It was neat to see the gel like substance first hand. -I also enjoyed being able to see the actual eyeball of the sheep and I really enjoyed seeing the sclera and lens. I found those two features to be super interesting. -Our group first decided to do all of the labeling before the dissection. We used the models that were given to us in class. After we did the dissection and it was awesome to see an actual eye and see firsthand all of the labels that we just done. 2 Compare and contrast the cause, treatments and complication of myopia and hyperopia. How does an astigmatism influence these conditions? What is the importance of the light being refracted on the retina? Myopia: occurs when the eyeball is too long, relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface. Nearsightedness also can be caused by the cornea and/or lens being too curved for the length of the eyeball. In some cases, myopia is due to a combination of these factors. Typically begins in childhood and you may have a higher risk of developing it if your parents are both nearsighted. Treatments include glasses, contact lenses, or refractive surgery. The surgeries can include PRK in which the laser removes a layer of corneal tissue, which flattens the cornea and allows light rays to focus more accurately on the retina. Also, LASIK is another option and is the most common refractive procedure. (Bailey, 2017) -Hyeropia: Farsightedness. Hyperopia is a “vision condition in which distant objects can be seen clearly, but close ones do not come into proper focus. Cause: Farsightedness occurs if your eyeball is too short or the cornea has too little curvature. In these cases, your eye can't correctly focus the light that enters it” Also occurs when light rays entering the eye focus behind the retina, rather than directly on it. Complications include difficulty concentrating and maintaining a clear focus on near objects, eye strain, fatigue, headaches, aching or burning eyes, irritability or Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material nervousness. (Bailey, 2016) -An astigmatism can associate with either hyperopia or myopia. An astigmatism is where there is an imperfection in the cornea causing it to misshape preventing it from focusing light into the retina. It causes blurred vision (American Optometric Association, 2017) -Light must be refracted on the retina in order for a person to focus and see an object clearly 3 Compare and contrast how glaucoma and cataracts disrupt vision. -Glaucoma: is a “group of diseases that damage the eye’s optic nerve and can result in vision loss and blindness” This can cause misty and patchy vision which if left unchecked could ultimately result in blindness. Cannot be cured, but may be treated with eyedrops amongst other aids to lower the pressure in the eye (National Eye Institute, n.d.). -Cataracts: “is a clouding of the lens in the eye that affects vision. Most cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.” It cannot spread from eye to the other. It occurs in either or both eyes. Vision is disrupted by the clouding of your eyes natural lens. (National Eye Institute, n.d.). 4 Vertigo and tinnitus are both conditions of the inner ear. How do they differ from symptoms, causation (what is causing the condition) and treatments? -Vertigo: a feeling of being off balance. You have dizzy spells, you might feel like you are spinning or that the world around you is spinning. Symptoms include: spinning, tilting, swaying, unbalanced, pulled to one direction, sweating, headache, ringing in the ears or hearing loss, feeling nauseated, etc. The cause is by an inner ear infection. Other causes include: BPPV which stands for Benign Paroxysmal Positional Vertigo and occurs when tiny calcium particles clump up in the canals of the inner ear, Meniere’s Disease which is thought to be a build up of fluid and changing pressure in the ear, head or neck injury, brain problems such as stroke or tumor, certain medications that cause ear damage, migraine headaches. Treatments depend on what is causing it. In many cases, it goes away on its own without any treatment. If treatment is needed, vestibular rehabilitation is an option along with medicines or surgery. (“Vertigo”, 2017) -Tinnitus: Ringing in the ears. Symptoms include noise in the ears such as ringing, roaring, buzzing, hissing, whistling; the noise may be intermittent or continuous. To determine what is causing this, the doctor may give a general physical exam. Some causes are damage to the auditory system, drug use, and damage to your head, neck, or jaw amongst other things. Treatments can be Downloaded by: Taiyiai | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material determined if a specific cause has been figured out. To attempt to treat tinnitus, one can change their diet, add medications prescribed by the doctor or use a device in an attempt to mask the sound. (“Understanding Tinnitus: Diagnosis and Treatment,” 2017). 5 As we age, hearing loss progresses but not equally in all individuals. What are some factors that can cause or lead to an accelerated rate of hearing loss? Why is permanent hearing loss permanent? What treatments are available for individuals with hearing loss? Are there any pros and cons to them? -Exposure to excessive noise is the most common cause of hearing loss. Heredity, aging, some medications, some illnesses can cause hearing loss. Also damage to the inner ear, a buildup of earwax, infections, and ruptured ear drums can cause accelerated hearing loss. Treatments available for people with hearing loss include surgical procedures, removing wax blockage, hearing aids, cochlear implants. The pros are greater self confidence, closer relationships with loved ones, improved outlook on life, and less depression. There may be some cons such as hearing aids not working properly or they are expensive, surgery could be unsuccessful and expensive as well. (“Diseases and Conditions: Hearing Loss,” n.d.). Powered by TCPDF () Downloaded by: Taiyiai | Distribution of this document is illegal