Protections of the eye:
The human eye is one of the most important things to a person and thus has many forms of protection.
The eyelid protects the eye in three different ways: the eyelashes, the glands, and the movement of the eyelids.
The eyelashes are beneficial in keeping dust and debris out of the eye. Touching the lashes will trigger the reflexive blinking mechanism.
There are many different glands that are located in the eye. The Zeis gland is a gland that secretes oil. An infection in this gland results in a stye. A second gland, the Meibomian gland, are large oil secreting glands located in the lid of the eye and play a part in producing the oily outer layer of tears. This oily layer prevents the evaporation of tears. Also contributing to the make up of tears are the aqueous and mucous producing glands.
Eyelids protect the eye mainly by their rapid rate at which they cover the eye. Even though blinking interrupts the line of vision, the illusion of sight continues while the eye is briefly closed.
The Cornea:
The cornea is the front part of the eye and is a transparent tissue that lacks blood vessels and covers the iris and pupil. The cornea allows light rays to permeate and bends the light enough to allow for focusing of the eye.
The cornea contains five different layers:
* the epithelium
This is the outermost layer of the cornea. The cells of the layer offer a smooth surface that serves the tear layer well.
* Bowman's membrane
This is the main part of the cornea. It is a tough layer of transparent tissue that has no cells. It is made up of mostly collagen material.
* the stroma
This layer has other layers in it of tissue called lamellae which go through the e...
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...is focused on the retina. The image is actually seen on the retina upside down, and is reversed when it is sent to the brain. Recall that the left side of the brain controls the right side of the body, and in remembering this, the fact that the left half of the visual field in each eye is sent to the right half of the brain.
Although an eye is likened to a camera, "[t]he one major difference is that the focus of the eye is altered by changing the focal length (or power, P=1/f) of the lens, rather than by changing the distance between the lens and the retina." (www.dur.ac.uk/r.g.bower/OpticsI/optlec/node34.html)
Works Cited:
Cassel, Gary, et al. The Eye Book: A Complete Guide to Eye Disorders and Health. The John Hopkins University Press: Baltimore & London. 1998. (pp. 3-15)
D'Alonzo, Dr. T.L. Your Eyes! Avanti Publishing: Pennsylvania. 1991. (pp. 15-54)
The endothelium is a cell layer that is lined on the interior surface of lymphatic vessels and blood vessels, which are made up of endothelial cells (Dorland, 2012).
After the skin, there is a layer called the dermis. The dermis is a broad layer of fibrous and elastic tissue (made mostly of fibrillin, elastin, and collagen) which gives the skin its flexibility and strength. The dermis incorporates nerve endings, sweat glands and oil glands, hair follicles, and blood
Life revolves around being able to see things. Although individuals who are blind can lead a full and happy life, someone with excellent vision who suddenly loses theirs or notices a decrease in their visual acuity over time may find it difficult to adapt. Thankfully, with the help of an optometrist, individuals can actively work to preserve their vision for as long as possible. Phoenix Eye Care must be a priority for all, as advanced technology allows threats to the eyes to be detected as the earliest stage. The right treatment can help to slow or stop the progression before major issues develop. For this reason, every individual needs to undergo routine eye exams.
the eyes had densely packed lenses and may have served merely as a light sensitive
Then I realized that it was so tough because it was used for the protection of the brain. The rest of the brain underneath the thick covering was squishy, and slippery. Cow eye: The first thing I noticed about the cow eye is that it wasn’t as big as I thought it would be, considering the size of their heads versus our heads. I also noticed that the pupil of the cow eye is more oval shaped than the circular shape of a human’s pupil. Finally, I expected the eye to feel rubbery but instead it felt firm.
This is a representation of the eye's lens system. This eye has no eye condition, such as nearsightedness or farsightedness, and the lens is drawn in its relaxed position. The light rays are focused appropriately on the retina. The thickness of the cornea is 0.449 mm, the distance from the cornea to the lens is 2.
Opthalamic: Apply a light touch to both eyeballs to instigate a blinking response, also known as the corneal reflex
Fluid circulating inside the front portion of the eye is produced by a structure called the ciliary body, which is located behind the iris. This fluid moves through the opening of the pupil, passes into the space between the iris and the cornea, and drains out of the eye through a tissue called the angle. With glaucoma, the passing of fluid through the angle is either reduced or suddenly stops, and amounts of fluid inside the eye increase. This high fluid pressure hurts the nerve fibers and the eye's optic nerve and causes blind spots. It may lead to blindness in some cases.
of the eye, this is what gives form to the eyeball. The vascular tunic has three
The epithelium tissue helps protect the body. It lines the surface. Epithelial tissue has an apical surface which means it is lined with microvilli above tight junctions. There are four main types of epithelium tissues; squamous epithelial cells, Cuboidal epithelial cells, columnar epithelial cells and ciliated columnar cells. The squamous epithelium protects the linings in the body such as blood vessels and air sacs in the lungs. The cuboidal epithelium protects things such as the kidneys and glands as they can
An inspection of the modern animal phyla will reveal that eyes are just as diverse as they are complex. Some organisms like the rag worm have pigmented cup eyes while other like he box jellyfish have two lens eyes and two pairs of pigment pit eyes. To account for the diversity in eye structure, we must first examine the eye ‘prototype’, the original structure that was acted upon by evolution. The simplest organ that can be considered an eye is composed of a single photoreceptor cell and a single pigment cell, without any lens or other refractive body (Arendt, 2003). Such organs are know as eyespots, and...
Regarding to the ocular examination, the patient's visual acuity without optical correction (spectacle) was good 20/20 in both eyes. IOP measurements was 18 mmHg on the right eye and 16 mmHg in the left eye. The pupil was equal, round and reactive to light with no afferent pupillary defect in both eyes. In extarocular movement test, there was limited downward gaze with
Although this R3 was a bit gross, I found it interesting and it made it easier for me to understand different parts of the eye. I think the main purpose of this R3 was to use hands on experience to make it easier for us to label parts of the eye on a diagram. One of the first observations I made when I saw the eye was how much bigger a cow’s eye is than a human’s. After I saw how big the cornea looked, I was surprised with how much meat surrounded the eye that I would have to cut off. Then I had to decide where and how I was going to cut off the excess.
There are three simple tissues namely, parenchyma, collenchyma, and sclerenchyma. Parenchyma is thought of as the ground tissue of an axis since it occurs in greatest abundance and is the tissue in which the vascular tissues are embedded. Parenchyma cells may be isodiametric in both the pith and the cortex, but are more mostly longitudinally elongated in the cortex. They have comparatively thin walls. Wall layers are continuously shaped regions. These simple pits usually occur opposite each other, forming pit-pairs in the walls of contiguous cells. Plasmodesmata (specialized strands of endoplasmic reticulum) form interconnections with the protoplasts of adjacent living cells through simple
As further protection, the eyelids automatically close when an object suddenly moves close to the eye.Parts Of the EyeThe eye is made of 3 coats, or tunics. The outermost coat consists of the cornea and the sclera. The middle coat contains the main blood supply to the eye and consists of the choroid, the ciliary body, and the Iris. The innermost layer is the retina.Cornea and ScleraThe Sclera, or the white of the eye, is composed of tough fibrous tissue. On the exposed area of the eye the scleral surface is covered with a mucous membrane called the conjunctiva.