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anatomy_of_the_human_eye [2023/01/30 07:41] – [The Sclera] andrewtaustinanatomy_of_the_human_eye [2023/03/06 09:11] (current) – Remove socialite tom
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 +{{tag>Anatomy}} 
 ======Anatomy of The Eye====== ======Anatomy of The Eye======
  
-The human eye is a complex and delicate structure responsible for capturing and processing visual information. It is made up of several key components, each of which plays an essential role in the process of seeing.+The human eye[(Humaneye>Human eye[[https://en.wikipedia.org/wiki/Human_eye|Wikipedia]])][(anatomy>Category:Human eye anatomy[[https://en.wikipedia.org/wiki/Category:Human_eye_anatomy|Wikipedia]])] 
 + is a complex and delicate structure responsible for capturing and processing visual information. It is made up of several key components, each of which plays an essential role in the process of seeing.
  
 **Cornea**: The clear, curved front surface of the eye that helps to refract light and focus it onto the retina. **Cornea**: The clear, curved front surface of the eye that helps to refract light and focus it onto the retina.
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 **Ciliary Body**: A ring-shaped structure that surrounds the lens and helps to change its shape, allowing the lens to focus on objects at different distances. **Ciliary Body**: A ring-shaped structure that surrounds the lens and helps to change its shape, allowing the lens to focus on objects at different distances.
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 +<WRAP RIGHT 400px>
 +<figure>{{https://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Schematic_diagram_of_the_human_eye_en.svg/832px-Schematic_diagram_of_the_human_eye_en.svg.png
 +  | Schematic diagram of the human eye}}<caption>[[https://commons.wikimedia.org/wiki/File:Schematic_diagram_of_the_human_eye_en.svg|Rhcastilhos. And Jmarchn]]  Diagram of the human eye in English. It shows the lower part of the right eye after a central and horizontal section. [[https://creativecommons.org/licenses/by-sa/3.0/deed.en| CC-BY-SA-3.0]]</caption>
 +</figure>
 +</WRAP>
 +
 +The evolution of the eye is a topic of much scientific inquiry, with multiple theories and hypotheses proposed to explain the intricate processes that led to the development of this complex organ. The eye is considered to be a remarkable adaptation for detecting and processing visual information, and its evolution represents one of the most fascinating examples of convergent evolution in the animal kingdom.
 +
 +One widely accepted hypothesis is that the eye evolved gradually from simpler light-sensitive structures over millions of years through the process of natural selection. This process involved the development of increasingly complex photoreceptor cells that were able to detect changes in light intensity and direction. This eventually led to the formation of cup-shaped photoreceptor structures in certain organisms, which could detect incoming light from multiple directions.
 +
 +Another hypothesis suggests that the eye evolved rapidly and independently in multiple lineages through convergent evolution. This theory posits that the eye evolved in response to similar selective pressures across a variety of different environments and taxa. This rapid evolution may have been driven by the need to avoid predators, locate prey, and navigate through the environment.
 +
 +Regardless of the exact mechanism, the evolution of the eye represents one of the most remarkable adaptations in the animal kingdom. The eye's complex and intricate structure and function are the result of millions of years of evolution, and it continues to be a topic of intense scientific research and investigation.
  
 =====Cornea===== =====Cornea=====
  
-The cornea is a clear, dome-shaped structure that covers the front of the eye and is one of the most important refractive elements of the eye. It is responsible for about two-thirds of the eye's total focusing power and helps to bend light to focus it onto the retina. The cornea is composed of several layers of cells and is extremely transparent, allowing light to pass through it with minimal scattering.+The cornea[(Cornea>Cornea[[https://en.wikipedia.org/wiki/Cornea|Wikipedia]])] is a clear, dome-shaped structure that covers the front of the eye and is one of the most important refractive elements of the eye. It is responsible for about two-thirds of the eye's total focusing power and helps to bend light to focus it onto the retina. The cornea is composed of several layers of cells and is extremely transparent, allowing light to pass through it with minimal scattering.
  
 The cornea is responsible for many important functions, including: The cornea is responsible for many important functions, including:
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 ====Iris===== ====Iris=====
  
-The iris is the colored part of the eye and is located between the cornea and the lens. It plays a crucial role in controlling the amount of light entering the eye by adjusting the size of the pupil. The iris is composed of two main layers: the front stroma and the back pigmented epithelium.+The iris[(Iris>Iris[[https://en.wikipedia.org/wiki/Iris_(anatomy)|Wikipedia]])] is the colored part of the eye and is located between the cornea and the lens. It plays a crucial role in controlling the amount of light entering the eye by adjusting the size of the pupil. The iris is composed of two main layers: the front stroma and the back pigmented epithelium. 
 + 
 +<WRAP RIGHT 320px> 
 +<figure>{{https://upload.wikimedia.org/wikipedia/commons/thumb/4/4d/Iris_regions.jpg/320px-Iris_regions.jpg 
 +  |  Iris components }}<caption>[[https://commons.wikimedia.org/wiki/File:Iris_regions.jpg|Boyd, Aidan (2020).]]  Iris components [[https://creativecommons.org/licenses/by-sa/4.0/deed.en| CC-BY-SA-4.0]]</caption> 
 +</figure> 
 +</WRAP>
  
 The iris has several important functions, including: The iris has several important functions, including:
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 =====The Pupil===== =====The Pupil=====
  
-The pupil is the black circular opening in the center of the iris that allows light to enter the eye. It is surrounded by the iris and changes in size to regulate the amount of light entering the eye. The size of the pupil is controlled by the autonomic nervous system and is influenced by several factors, including the amount of light, the state of arousal, and the level of drug use.+The pupil[(Pupil>Pupil[[https://en.wikipedia.org/wiki/Pupil|Wikipedia]])] is the black circular opening in the center of the iris that allows light to enter the eye. It is surrounded by the iris and changes in size to regulate the amount of light entering the eye. The size of the pupil is controlled by the autonomic nervous system and is influenced by several factors, including the amount of light, the state of arousal, and the level of drug use.
  
 The pupil has several important functions, including: The pupil has several important functions, including:
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 ======The Lens===== ======The Lens=====
  
-The lens is a clear, flexible structure located behind the iris that helps to focus light onto the retina. It is one of the most important refractive elements of the eye, responsible for about one-third of the eye's total focusing power. The lens is composed of protein and water and is held in place by the ciliary body, which is responsible for adjusting the shape of the lens to fine-tune the focus of light.+The lens[(Lens>Lens (vertebrate anatomy)[[https://en.wikipedia.org/wiki/Lens_(vertebrate_anatomy)|Wikipedia]])] 
 + is a clear, flexible structure located behind the iris that helps to focus light onto the retina. It is one of the most important refractive elements of the eye, responsible for about one-third of the eye's total focusing power. The lens is composed of protein and water and is held in place by the ciliary body, which is responsible for adjusting the shape of the lens to fine-tune the focus of light.
  
 The lens has several important functions, including: The lens has several important functions, including:
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 ======Vitreous Humour===== ======Vitreous Humour=====
  
-Vitreous humor is a clear, gel-like substance located in the posterior cavity of the eye, behind the lens and in front of the retina. It makes up about 80% of the eye's volume and helps to maintain the shape of the eye. Vitreous humor is composed of water, salts, and proteins and is produced and maintained by the vitreous body, which is a structure located near the optic nerve.+Vitreous humor[(Vitreous>Vitreous body[[https://en.wikipedia.org/wiki/Vitreous_body|Wikipedia]])] is a clear, gel-like substance located in the posterior cavity of the eye, behind the lens and in front of the retina. It makes up about 80% of the eye's volume and helps to maintain the shape of the eye. Vitreous humor is composed of water, salts, and proteins and is produced and maintained by the vitreous body, which is a structure located near the optic nerve.
  
 Vitreous humor has several important functions, including: Vitreous humor has several important functions, including:
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 =====The Retina===== =====The Retina=====
  
-The retina is a thin layer of tissue located at the back of the eye, covering approximately 65% of its inner surface. It is responsible for converting light into electrical signals that are transmitted to the brain, allowing us to see the world around us. The retina contains photoreceptor cells, called rods and cones, which are responsible for detecting light and transmitting signals to the brain.+The retina[(Retina>Retina[[https://en.wikipedia.org/wiki/Retina|Wikipedia]])] is a thin layer of tissue located at the back of the eye, covering approximately 65% of its inner surface. It is responsible for converting light into electrical signals that are transmitted to the brain, allowing us to see the world around us. The retina contains photoreceptor cells, called rods and cones, which are responsible for detecting light and transmitting signals to the brain.
  
 The retina has several important functions, including: The retina has several important functions, including:
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 =====The Optic Nerve===== =====The Optic Nerve=====
  
-The optic nerve is a bundle of over 1 million nerve fibers that connects the retina to the brain, transmitting visual signals from the eye to the brain. The optic nerve is responsible for transmitting the electrical signals generated by the photoreceptor cells in the retina to the brain, allowing us to see the world around us.+The optic nerve[(Optic_nerve>Optic nerve[[https://en.wikipedia.org/wiki/Optic_nerve|Wikipedia]])] is a bundle of over 1 million nerve fibers that connects the retina to the brain, transmitting visual signals from the eye to the brain. The optic nerve is responsible for transmitting the electrical signals generated by the photoreceptor cells in the retina to the brain, allowing us to see the world around us.
  
 The blind spot is a small area of the retina where the optic nerve and blood vessels enter and exit the eye, creating a gap in the photoreceptor cell layer. There are no photoreceptor cells in the blind spot, so the brain does not receive any signals from this area. However, our brain compensates for the blind spot by automatically filling in the missing information with surrounding visual information, so we are not typically aware of it. The blind spot is a small area of the retina where the optic nerve and blood vessels enter and exit the eye, creating a gap in the photoreceptor cell layer. There are no photoreceptor cells in the blind spot, so the brain does not receive any signals from this area. However, our brain compensates for the blind spot by automatically filling in the missing information with surrounding visual information, so we are not typically aware of it.
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 =====The Sclera===== =====The Sclera=====
  
-The sclera is the white, tough, outer layer of the eye that covers most of the eye's surface and helps to protect the inner structures of the eye. The sclera is composed of fibrous connective tissue and is the strongest and most protective layer of the eye.+The sclera[(Sclera>Sclera[[https://en.wikipedia.org/wiki/Sclera|Wikipedia]])] is the white, tough, outer layer of the eye that covers most of the eye's surface and helps to protect the inner structures of the eye. The sclera is composed of fibrous connective tissue and is the strongest and most protective layer of the eye.
  
 The sclera has several important functions, including: The sclera has several important functions, including:
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 =====The Choroid===== =====The Choroid=====
  
-The choroid is a layer of tissue located between the retina and the sclera, in the middle of the eye. It is composed of blood vessels and pigmented cells and helps to provide oxygen and nutrients to the retina and other parts of the eye.+The choroid[(Choroid>Choroid[[https://en.wikipedia.org/wiki/Choroid|Wikipedia]])] is a layer of tissue located between the retina and the sclera, in the middle of the eye. It is composed of blood vessels and pigmented cells and helps to provide oxygen and nutrients to the retina and other parts of the eye.
  
 The choroid has several important functions, including: The choroid has several important functions, including:
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   * **Maintaining Eye Pressure**: The choroid helps to regulate the pressure inside the eye, which is important for maintaining good vision.   * **Maintaining Eye Pressure**: The choroid helps to regulate the pressure inside the eye, which is important for maintaining good vision.
 +
 +=====The Ciliary Body=====
 +
 +The ciliary body[(Ciliary>Ciliary body[[https://en.wikipedia.org/wiki/Ciliary_body|Wikipedia]])] is a ring-shaped muscular structure located behind the iris in the eye. It has several important functions in the eye, including:
 +
 +  * **Controlling the Shape of the Lens**: The ciliary body is composed of smooth muscle fibers that control the shape of the lens, allowing us to focus on objects at different distances. When the ciliary muscle contracts, it changes the shape of the lens, making it more rounded and allowing us to focus on close objects. When the ciliary muscle relaxes, the lens becomes flatter, allowing us to focus on distant objects.
 +
 +  * **Producing the Aqueous Humor**: The ciliary body is responsible for producing the aqueous humor, a clear fluid that fills the anterior chamber of the eye. The aqueous humor helps to nourish the lens and the cornea and provides the pressure needed to maintain the shape of the eye.
 +
 +  * **Maintaining Eye Pressure**: The ciliary body also helps to regulate the pressure inside the eye, which is important for maintaining good vision.
 +
 + 
  • Last modified: 2023/01/30 07:41
  • by andrewtaustin