The conjunctiva is a clear mucous membrane The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line various body cavities that are exposed to the external environment and internal organs. They are at several places continuous with skin: at the nostrils, the mouth, the lips, the eyelids, the ears, the consisting of cells and underlying basement membrane The basement membrane is a thin sheet of fibers that underlies the epithelium, which lines the cavities and surfaces of organs, or the endothelium, which lines the interior surface of blood vessels that covers the sclera The sclera, also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest. In children, it is thinner and shows some of the underlying pigment, appearing slightly blue. In the elderly, (white part of the eye Eyes are organs that detect light, and convert it to electro-chemical impulses in neurons. The simplest photoreceptors connect light to movement . In higher organisms complex neural pathways exist that connect the eye, via the optic nerve to the visual cortex and other areas of the brain. Complex optical systems with resolving power have come in) and lines the inside of the eyelids An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily. The human eyelid features a row of eyelashes. It is made up of the rare non-keratinizing squamous epithelium In anatomy, squamous epithelium is an epithelium characterised by its most superficial layer consisting of flat, scale-like cells called squamous cell. Epithelium may possess only one layer of these cells, in which case it is referred to as simple squamous epithelium; or it may possess multiple layers, referred to then as stratified squamous.

Contents

Function

It helps lubricate the eye Eyes are organs that detect light, and convert it to electro-chemical impulses in neurons. The simplest photoreceptors connect light to movement . In higher organisms complex neural pathways exist that connect the eye, via the optic nerve to the visual cortex and other areas of the brain. Complex optical systems with resolving power have come in by producing mucus In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. It is a viscous colloid containing antiseptic enzymes (such as lysozyme), proteins such as lactoferrin, glycoproteins known as mucins that are produced by goblet cells in the mucous membranes and submucosal glands, immunoglobulins, and inorganic salts. This and tears Tears are the liquid product of a process of crying to clean and lubricate the eyes. The word lacrimation (also spelled lachrymation) may also be used in a medical or literary sense to refer to crying. Strong emotions, such as sorrow or elation, may lead to crying. The process of yawning may also result in lacrimation, although a smaller volume of tears Tears are the liquid product of a process of crying to clean and lubricate the eyes. The word lacrimation (also spelled lachrymation) may also be used in a medical or literary sense to refer to crying. Strong emotions, such as sorrow or elation, may lead to crying. The process of yawning may also result in lacrimation than the lacrimal gland The lacrimal glands are paired almond-shaped glands, one for each eye, that secrete the aqueous layer of the tear film. They are situated in the upper, outer portion of each orbit. Inflammation of the lacrimal glands is called dacryoadenitis.[1] It also contributes to immune surveillance An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function and helps to prevent the entrance of microbes A microorganism or microbe is an organism that is microscopic (too small to be seen by the naked human eye). The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design into the eye.

Gross anatomy

The conjunctiva is typically divided into three parts:

Part Area
Palpebral or tarsal conjunctiva lines the eyelids
Fornix conjunctiva where the inner part of the eyelids and the eyeball meet, the palpebral conjunctiva is reflected at the superior fornix and the inferior fornix to become the bulbar conjunctiva. It is loose and flexible, allowing the free movement of the lids and eyeball. An ophthalmologist or optometrist can insert eye drops into the lower eyelid space. The substance works its way up the surface of the eyeball and diffuse into the internal eye. [2]
Bulbar or ocular conjunctiva covers the eyeball, over the sclera The sclera, also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest. In children, it is thinner and shows some of the underlying pigment, appearing slightly blue. In the elderly,. This region of the conjunctiva is bound tightly and moves with the eyeball movements.

Diseases and disorders

Main article: List of eye diseases and disorders The World Health Organisation publishes a classification of known diseases and injuries called the International Statistical Classification of Diseases and Related Health Problems or ICD-10. This list uses that classification

Disorders of the conjunctiva and cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is approximately 43 dioptres. While the cornea contributes most of the eye' are a common source of eye complaints.

The surface of the eye is exposed to various external influences and is especially suspectible to trauma Physical trauma refers to a physical injury, generally of a considerable degree. A trauma patient is someone who has suffered serious and life-threatening physical injury, with the potential for secondary complications such as shock, respiratory failure and death, infections An infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host's resources to multiply, usually at the expense of the host. The infecting organism, or pathogen, interferes with the normal functioning of the host and can lead to chronic wounds, gangrene, loss, chemical irritation, and allergic reactions Allergy is a disorder of the immune system often also referred to as atopy. Allergic reactions occur to normally harmless environmental substances known as allergens; these reactions are acquired, predictable, and rapid. Strictly, allergy is one of four forms of hypersensitivity and is called type I hypersensitivity. It is characterized by.

The conjunctiva is best known because of its inflamed Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process. Inflammation is not a synonym for infection. Even in cases where inflammation is state, conjunctivitis Conjunctivitis is an acute inflammation of the conjunctiva (the outermost layer of the eye and the inner surface of the eyelids), most commonly due to an allergic reaction or an infection (usually viral, but sometimes bacterial) (more commonly known as pinkeye).

Conjunctival irritation is one of the adverse health effects that can take place after overexposure to VOCs (Volatile organic compounds Volatile organic compounds are organic chemical compounds that have high enough vapor pressures under normal conditions to significantly vaporize and enter the earth's atmosphere. Volatile organic compounds are numerous and varied. Although ubiquitous in nature and modern industrial society, they may also be harmful or toxic. VOCs, or subsets of).

See also

Additional images

Sagittal section through the upper eyelid.

References

  1. ^ London Place Eye Center (2003). Conjunctivitis. Retrieved July 25, 2004.
  2. ^ Eye, human Encyclopaedia Britannica

External links

Head and neck anatomy Head and neck anatomy focuses on the structures of the head and neck of the human body, including the brain, bones, muscles, blood vessels, nerves, glands, nose, mouth, teeth, tongue, and throat. It is an area frequently studied in depth by surgeons, dentists, dental technicians, and speech language pathologists – accessory organs of the eye Eyes are organs that detect light, and convert it to electro-chemical impulses in neurons. The simplest photoreceptors connect light to movement . In higher organisms complex neural pathways exist that connect the eye, via the optic nerve to the visual cortex and other areas of the brain. Complex optical systems with resolving power have come in / adnexa (TA 15.2.7 Terminologia Anatomica is the international standard on human anatomic terminology. It was developed by the Federative Committee on Anatomical Terminology (FCAT) and the International Federation of Associations of Anatomists (IFAA) and was released in 1998. It supersedes the previous standard, Nomina Anatomica. Terminologia Anatomica contains, GA 10.1021 medulla: Solitary tract · Solitary nucleus (Gustatory nucleus))
Eyelid An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily. The human eyelid features a row of eyelashes Palpebral fissure Palpebral fissure is the anatomic name for the separation between the upper and lower eyelids. In the adult this measures about 10mm vertically and 30 mm horizontally/Canthus • Eyelash An eyelash or simply lash is one of the hairs that grow at the edge of the eyelid. Eyelashes protect the eye from debris and perform some of the same function as whiskers do on a cat or a mouse in the sense that they are sensitive to being touched, thus providing a warning that an object is near the eye (which is then closed reflexively) • Tarsus • Medial palpebral ligament • Epicanthic fold An epicanthic fold, epicanthal fold, or epicanthus is a skin fold of the upper eyelid, from the nose to the inner side of the eyebrow, covering the inner corner of the eye. This is a normal trait for a large percentage of humans. The fold gives the eyes of some East Asians a characteristic appearance which is narrower and almond-like in comparison • Meibomian gland The meibomian glands are a special kind of sebaceous glands at the rim of the eyelids, responsible for the supply of sebum, an oily substance that prevents evaporation of the eye's tear film, prevents tear spillage onto the cheek, and makes the closed lids airtight. There are approximately 50 glands on the upper eyelids and 25 glands on the lower • Ciliary glands
Lacrimal apparatus This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated Lacrimal lake The lacrimal lake is the pool of tears in the lower conjunctival cul-de-sac, which drains into the opening of the tear drainage system . The volume of the lacrimal lake has been estimated to be between 7 and 10 µL • Lacrimal gland The lacrimal glands are paired almond-shaped glands, one for each eye, that secrete the aqueous layer of the tear film. They are situated in the upper, outer portion of each orbit. Inflammation of the lacrimal glands is called dacryoadenitis • Lacrimal canaliculi The lacrimal canaliculi, also known as the lacrimal canals or lacrimal ducts, are the small channels in each eyelid that commence at minute orifices, termed puncta lacrimalia, on the summits of the papillae lacrimales, seen on the margins of the lids at the lateral extremity of the lacus lacrimalis • Lacrimal punctum • Lacrimal papilla • Nasolacrimal duct The nasolacrimal duct carries tears from the lacrimal sac into the nasal cavity. Excess tears flow through nasolacrimal duct which opens in the nose. This is the reason the nose starts to run when a person is crying or has watery eyes from an allergy, and why one can sometimes taste eye drops • Lacrimal sac The lacrimal sac is the upper dilated end of the nasolacrimal duct, and is lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla. It connects the lacrimal canaliculi, which drain tears from the eye's surface, and the nasolacrimal duct, which conveys this fluid into the nasal cavity • Lacrimal caruncle • Krause's glands Krause's glands are small, mucous accessory lacrimal glands that are found underneath the eyelid where the upper and lower conjuctivae meet. Their ducts unite into a rather long sinus which open into the fornix conjunctiva. There are approximately forty Krause glands in the region of the upper eyelid, and around 6 to 8 in the region of the lower
Other

Periorbita The periorbita is a layer of tissue surrounding the orbit. It consists of periosteum • Orbital septum In the upper eyelid it blends with the tendon of the Levator palpebræ superioris, and in the lower eyelid with the tarsal plate • Tenon's capsule The fascia bulbi is a thin membrane which envelops the eyeball from the optic nerve to the limbus, separating it from the orbital fat and forming a socket in which it plays • Suspensory ligament of eyeball

Eyebrow The eyebrow is an area of thick, delicate hairs above the eye that follows the shape of the lower margin of the brow ridges of some[which?] mammals. Their main function is to protect the eye,[citation needed] but they are also important to human communication and facial expression. It is not uncommon for people – women in particular – to

Conjunctiva (Plica semilunaris)

Extraocular muscles The extraocular muscles are the six muscles that control the movements of the eye. The actions of the extraocular muscles depend on the position of the eye at the time of muscle contraction (Trochlea of superior oblique The Trochlea of superior oblique is a pulley structure in the eye. The tendon of the superior oblique muscle passes through it. Situated on the superior nasal aspect of the frontal bone, it is the only cartilage found in the normal orbit)
eye Eyes are organs that detect light, and convert it to electro-chemical impulses in neurons. The simplest photoreceptors connect light to movement . In higher organisms complex neural pathways exist that connect the eye, via the optic nerve to the visual cortex and other areas of the brain. Complex optical systems with resolving power have come in navs: ////, //, ,
This eye Eyes are organs that detect light, and convert it to electro-chemical impulses in neurons. The simplest photoreceptors connect light to movement . In higher organisms complex neural pathways exist that connect the eye, via the optic nerve to the visual cortex and other areas of the brain. Complex optical systems with resolving power have come in article is a stub. You can help Wikipedia by expanding it.

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