Per Name Sheep Eye Dissection Lab Sheet Follow instruction sheet for procedures
ID: 3505363 • Letter: P
Question
Per Name Sheep Eye Dissection Lab Sheet Follow instruction sheet for procedures * You and your partner will sign off (initial) on the chart as you find the structures * You should be able to explain their functions, if asked by teacher. 1. Write three observations you made when you examined the surface of the eye: BAH BAHBAH Identify: Place your initials here * comea r sclera optic nerve * external eye muscle fatty tissue Questions fatty tissue? 1 Why dou' you have to worry about cutting into the sclera when you are removing the extrinsic muscles and 2. How does the fat tissue look different from the muscle tissue? 3. What is the choroid's function? 4. Why is the cornea so cloudy? 5. What is the tapetum lucidum? Do human have this structure? Why or why not- explain.Explanation / Answer
1. 3 observations are :
- The surface is soft and mushy.
- The surface is wet.
- The surface consists of enormous fat.
2. Cornea : Cornea is the transparent convex anterior portion of outer layer of the eyeball which covers the irish and the pupil. It transmits and refracts light.
Sclera : Sclera is the tough white fibrous outer layer of the eyeball that covers posterior 5/6th of the eye. Anteriorly it is continuous with cornea. It attaches muscles of the eyes.
Optic nerve : Optic nerve is formed by the nonmyelinated axon fibers of ganglionic cells. It is known as cranial nerve II and transmits sensory informations from the retina to the brain.
External eye muscle : External eye muscle are formed by skeletal muscle fibers and are controlled by the somatic nerves. It helps in movement of eyeballs within the orbit. There are 6 external muscles - superior rectus, inferior rectus, medial or internal rectus, lateral or external rectus, superior oblique and inferior oblique.
Fatty tissue : Fatty tissue is made up of adipocytes and it is a loose connective tissue. The tissue stores energy in the form of lipids.
1. Sclera is the tough outer layer of the eyeball which is formed by white fibrous tissues and elastic fibers. Therefore, you should not worry about sclera getting cut during the examination.
2. Fatty tissue is made up of adipocytes and it is bulky in nature. Fatty tissue is yellow in colour due to presence of carotene pigment. Muscle tissue is soft and the hybrid muscle is pink in colour. Fat tissue stores energy whereas muscle tissue helps in movement.
3. Choroid is composed of a rich capillary plexus, numerous small arteries and veins. The choroid plexus carries oxygen and nutrients to the eye.
4. Cornea is transparent convex anterior portion of outer layer of eyeball which transmits and refracts light. The cornea becomes cloudy due to disease, infection or injury. The common reasons are listed below :
- Inflammation.
- Non living tissue.
- sensitivity to non infectious bacteria.
- Keratitis.
- Infection.
- Corneal ulcer.
- Trachoma.
- River blindness.
- Swelling due to glaucoma
- Eye dryness due to autoimmune disorder like Sjogren's syndrome or by LASIK surgery or by vitamin A deficiency.
- Eye dystrophy.
- Scarring.
5. Tapetum lucidum is a retroreflector , seen in vertebrates and situated immediately behind the retina. The function of this shiny blue layer is to reflect back the visible light through the retina so that more light should be available to the photoreceptors which helps in the night vision of animals such as cats.
Humans are diurnal in nature but animals like cat, dog, deer are nocturnals. Some of them need to hunt at night and also they have to be cautious from outer dangers at night. But humans are mostly active during day time. So they didnot evolve this special characteristics as it of no use for humans.
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