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... ... middle of paper ... ...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
The eye is an extremely diverse organ, ranging in complexity across and within animal phyla. Here, a comparative approach is taken to outlining the diversity of the eye forms within vertebrates and invertebrates. The eye morphology of a variety of organisms was examined. Eye function, and placement on the body was also considered. Here, variation in eye form is discussed in relation to the environment the organism is adapted to. It is shown that an organisms eye morphology functions optimally for the ecological niche it occupies. Evolutionary analysis is used to account for the emergence of the different eyes. Convergent evolution is used to justify the similarities in eye types seen in organisms of different species. This analysis begins with the simplest of eye forms composes of single cells, present in the zooplankton larvae. Such primitive forms are identified in mollucs, annelids, cnidarians, and are then compared to more advanced eye forms contain lenses. This comparative approach provides a breadth of examples of vertebrates and invertebrates, making visible, the diversity of eye morphology within the animal kingdom.
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
The four main components of the eye that are responsible for producing an image are the cornea, lens, ciliary muscles and retina. Incoming light rays first encounter the cornea. The bulging shape of the cornea causes it to refract light similar to a convex lens. Because of the great difference in optical density between the air and the corneal material and because of the shape of the cornea, most of the refraction to incoming light rays takes place here. Light rays then pass through the pupil, and then onto the lens. A small amount of additional refraction takes place here as the light rays are "fine tuned" so that they focus on the retina.
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.
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.
the cornea and the sclera. The cornea is what covers the iris, and is the
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
Opthalamic: Apply a light touch to both eyeballs to instigate a blinking response, also known as the corneal reflex
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
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
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.
This reflected light passes through the lens and falls on to the retina of the eye. Here, the light induces nerve impulses that travel through the optic nerve to the brain, where it makes an image of the object, and then that image is passed on to muscles and glands.The eye is well protected. It lies within a bony socket of the skull. The eyelids guard it in front. They blink an average of once every six seconds. This washes the eye with the salty secretion from the tear, or lachrymal, glands.