The eye is an important sensory organ for vision which houses a sensitive optical apparatus in a relatively isolated tissue compartment. Eye is essentially made of three layers: (1) sclera, (2) uveal tract, and (3) retina with each of these layers performing intricate duties which ensure proper functioning of the eye.
Sclera is an outer fibrous layer which mainly provides the mechanical stability to protect the eye and its sensitive optical apparatus. Sclera is mainly composed of collagen and elastic fiber and their irregularity gives sclera an opaque appearance. The most important function of sclera is to offer resistance to internal and external forces and to provide attachment for the extraocular muscle insertions. The scleral surface area in humans is
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Each component of this ensemble has a specific function. For example, iris acts as a variable aperture to control the light that enters the eye and ciliary body secretes aqueous humor. The vascular layer is the choroid, which provides blood supply to the retina. The iris arises from the anterior face of the ciliary body and is a forward extension of the choroid. The central aperture in the iris is called the pupil and its size is controlled by the iris to regulate the amount of light that enters the eye. The iris is made up of two types of muscles dilator and sphincter muscles. Sympathetic nervous system innervates dilator muscles and parasympathetic nervous system innervates sphincter muscles. Mydriasis which is dilation of the pupil is a result of increase in dilator muscle activity. Miosis the constriction of the pupil is a result of increase in sphincter muscle activity. The ciliary body consists of smooth muscle, which is innervated by the parasympathetic nervous system. When ciliary muscle contracts, the lens become more convex to accommodate proper vision. The other important function of the ciliary body is the production of aqueous humor, which
Glaucoma is a disease of the eye and it is fluid pressure within the eye rises and if the eye is left untreated the patient might lose vision or maybe even blind. But this disease is generally affects both eyes but although one of their eyes may have more severe signs or symptoms then the other eye. When you have glaucoma there are small spaces in the front of the eye and they are called anterior chamber. There is clear liquid that flows in and out of the anterior chamber and the fluid nourishes and bathes nearby the tissues. And if the patient has glaucoma the fluid dose not drain like it should drain but the fluid drains out of the eye. And this may lead to fluid build up and pressure inside the rises of the eye. Unless the pressure is brought down and controlled and the optic nerves and some of the other parts of the eye might become damaged leading to ...
The facial nerve consists of mixed nerves with associated parasympathetic fibers (Marieb & Hoehn). It conveys motor impulses to skeletal muscles of the face: the muscles of facial expression (Marieb & Hoehn). It transmits parasympathetic motor impulses to the lacrimal glands for tear production, nasal and palatine glands for smell and mucous production, and submandibular and sublingual salivary glands to produce saliva (Mar...
Acquired prosopagnosia refers to when the onset of prosopagnosic symptoms occur after brain trauma, resulting in damage to the cortex of the brain from hitting the inside of the skull (Bodamer, 1947). It can also refer to the initiation of symptoms after brain tissue dies (ischemia) such as from loss of blood supply like from a stroke, or a neurodegenerative disease (Villa et al., 2013, pg. 375).
The iris acts to control the size of the pupil. In bright light, the iris is dilated in such a way as to reduce the size of the pupil and limit the amount of entering light. In dim light, the iris adjusts its size as to maximize the size of the pupil and increase the amount of incoming light.
It is made mostly of connective tissue (areolar and dense irregular). Connective tissue provides support to the epidermis because it consists of numerous collagen and elastin fibers. The dermis serves as a first line of protection so that pathogens (bacteria and/or microbes) that have made it through the epidermis cannot move any farther. The dermis produces a gel-like substance within the areolar connective tissue that slows down the movement of microbes. The dermis also supplies blood and nutrients to the epidermis (via blood vessels) and supports sensory reception (nerve fibers). Accessory structures found in the dermis include a portion of the hair follicle, secretory glands (sebaceous and sweat glands), touch receptors (nerve fibers) and blood vessels. There dermis has two layers: the papillary layer and reticular layer. The papillary layer is the outer top portion of the dermis that is below (deep to) the epidermis. It has a sub layer called dermal papillae. Dermal papillae has ridge-like projections that interlock with ridges in the lower portion of the epidermis (epidermal ridges). These ridge-like projections have sensory receptors and capillaries. The sensory receptors are called tactile corpuscles that detect light, delicate touch and capillaries supply blood and nutrients to the epidermis above. The reticular layer is the deeper portion of the dermis and consists mostly of dense irregular connective tissue (ground substance and randomly arranged collagen fibers). The lamellated corpusle is a large, leaflet like sensory receptor located in the reticular layer. This receptor detects pressure, rough touch and
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.
parts to it; the choroids, ciliary body, and the iris. The choroids is what provides
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...
In “The Bluest Eye” by Toni Morrison, the audience is shown the skewed idea of beauty and how whiteness in the 1940s was the standard of beauty. This idea of beauty is still prevalent today which is why the novel is powerful and relevant. Narrated by a nine year old girl, this novel illustrates that this standard of beauty distorts the lives of black people, more specifically, black women and children. Not only was it a time when being white was considered being superior, being a black woman was even worse because even women weren’t appreciated and treated as equal back then. Set in Lorain, Ohio, this novel has a plethora of elements that parallels Toni Morrison’s personal life. The population in Lorain back then was considered to be ethnically asymmetrical, where segregation was still legal but the community was mostly integrated. Black and white children could attend the same schools and neighborhoods by then would be inhabited by a mix of black and white families. The theme of race and beauty is portrayed through the lives of three different families and stories told by the characters: Claudia, Pecola, and Frieda. Through the exploration of the families’ and character’s struggles, Morrison demonstrates the horrid nature of racism as well as the caustic temperament of the suppressed idea of white beauty on the individual, and on the society.
In the world of bionics, the technologies such as the bionic eye sit between the realms of science fiction and reality. Bionic eyes are at this time limited by current technologies, and while they can bring a certain quality of life to people with sight impairments, the bionic eye at this point is falls way short of the organic eye. This essay will endeavour to persuade the reader that organic eyes, due to current technological limitations, are superior to bionic eyes. In order for people to benefit from bionic eyes, they need to have a functional visual pathway from the retina to the brain along the optic nerve as well as some intact retinal cells. This need for intact optical nerves \ intact retinal cells limits the potential recipients for treatment to people with retinitis pigmentosa and age-related macular degeneration and other genetic eye conditions that effect around 1.5 million people worldwide.
One sub-system under the sensory system is the visual system; the main sense organs of this are the eyes. The eye is the sensory organ that allows us to detect light from external stimuli. When a light ray is detected, the eye converts these rays into electrical signals that can be sent to the brain in order to process the information and giv...
Have you ever wondered why the sky is blue. Often times I find myself looking up on a clear day, pondering over that question? Why isn’t it green, or red or pink for even that matter. Every day, the human eye blinks more than 23,00 times. The human eye is a complicated organ that performs one of the most important tasks for our body. There are many questions about the eye however. What function do they perform? What happens if we don’t take care of them? How exactly do they work together to help us form images? Exactly how far can they human eye see?
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.
...the surrounding objects. They also assist humans to do their duties in an orderly way without crossing each other’s paths. It is eyes that ferry light to our brains, therefore triggering the learning and communication process; meaning without eyes, people would literally not be visionary.