Reality of National Tennis
Sunday, March 28, 2010
Thursday, March 4, 2010
Random Funny Spanish Words
Sentidos - La Vista
Vision Vision is a sense the sense of sight allows the brain first part of the visual system responsible for forming the optical image of the visual stimulus on the retina (optical system). This is the role of the cornea and lens of the eye.
retinal cells are the sensory system of the eye. The first step in the photoreceptors, which capture the light that strikes them. Its two types are the rods and cones. Other retinal cells that are responsible for transforming light into electrochemical impulses and transported to the optic nerve. From there, project important regions such as the lateral geniculate nucleus and visual cortex of the brain.
In the brain starts the process of rebuilding the distances, colors, movements and shapes of objects around us.
The World Sight Day is celebrated on 8 October.
The story began with the pre-Socratic vision saying that the eye is made of water and fire. After Aristotle gave the basis for scientific study.
The scientific study of visual perception begins in the nineteenth century, Hermann von Helmholtz, and the first psychophysical methods. In the early twentieth century becomes strong school of Gestalt proposes that vision is strongly guided by top-down processes.
mid twentieth century displayed the proponents of indirect perception, Constructivists, and the proponents of direct perception, environmentalists. Today
it difficult to talk of schools, since the study of vision is highly interdisciplinary.
The eye is the organ responsible for the reception of visual stimuli, has exquisite architecture and highly specialized product of millions of years of evolution in animals. The eyeball has three sheaths, which from the outside in are:
1. Outer fibrous tunic, which consists of two regions
- sclera, which is white and opaque, with type I collagen fibers interspersed with elastic fibers, avascular, which provides protection to internal structures, and stability. It covers most of the eyeball, in a small region eccept above.
- Cornea, is a former extension transparent, avascular but highly innervated of the sclera, which the eye bulges forward. It is slightly thicker than the sclera.
2. Media Vascular Tunic (Uvea) is composed by three regions, the choroid, ciliary body and iris.
- Choroid; is the posterior pigmented vascular tunic media, which is attached to the sclera loosely and is separated from the lens through Bruch's membrane.
- Ciliary Body, is a wedge-shaped extension, which is projected onto the lens and is located in the light of the eye between the iris (anterior) and the vitreous humor (posterior). The lens is a transparent biconvex lens located just behind the pupil, whose function is to regulate the focus of light rays to impinge on the retina properly.
- Iris, is the anterior extension of the choroid pigment, whose function is to regulate the light entering the eye by contraction or relaxation of the pupil.
3. Neural retina Tunic: consists of 10 layers, which from the outside inside the balloon is called:
- pigmented epithelium
- Layer of rods and cones (receiver)
-
outer limiting membrane - outer nuclear layer
-
outer plexiform layer - inner nuclear layer
-
inner plexiform layer - Layer
ganglion cells - nerve fiber layer optical
- internal limiting membrane
addition to these layers, the eye has cavities:
- vitreous cavity, which contains the vitreous humor, and is located behind the lens, forming the nucleus transparent, gelatinous the eyeball.
- Posterior chamber, located in front of the lens, and posterior to the iris contains aqueous humor.
- Camera above, located between the cornea (forward) and the iris and lens (back) also contains aqueous humor.
Retina
As already mentioned the retina has 10 layers, the light must pass through almost all these layers to get to where are located the rods and cones, which are specialized cells in the reception of visual stimuli, and the transformation of these signals into nerve impulses to build images, shapes, colors, tones, and movements in the brain. Besides retinal rods and cones have a complex network of neurons, the rods and cones next to the choroid cells synapse with bipolres and these with the ganglion (diffuse and dwarf), whose axons converge and leave the eye to form the optic nerve. Other neurons called horizontal cells connect receptor cells with each other, while another group of cells, amacrine, are also interneurons whose nuclei are located in the inner nuclear layer and throw their extensions to the inner plexiform layer.
The optic nerve exits the eyeball near the back of the eye point along the retinal vessels at a point known as the optic disc, where there are no visual receptors, and thus constitutes a blind spot. By contrast there is also a point of greater visual acuity located near the back of the eye, called the macula lutea, yellow aspect, and which is the central fovea, which is a thin slice retina (there are very few cells on receivers) lacking rods but with higher density of cones. That is why the set of visual attention in a particular object, the object light is impinging on the fovea. Receptor cells
The receptor cells are the rods and cones. The cones are related to color vision daylight vision, and rods with night vision. there are over 100 million rods in the human eye, and about 4 million cones. Each rod is divided into external and internal segment, the which, in turn has a core region and a synaptic region. In the outer segment disks contain a disk called photosensitive compounds in their membranes, which respond to light a series of reactions leading to init action potentials.
cones also possess these segments, unlike the cones, the outer region has a different shape by the folding of membrane leads to the formation of the bags, which are also membrane photosensitive pigments. Photosensitive compounds
photosensitive compounds in most animals and in humans are composed of a protein called opsin and retineno-1 which is an aldehyde of vitamin A1. Rhodopsin is the photosensitive pigmanto of rod opsin which is called escotopsina. Rhodopsin captures light with a maximum sensitivity at 505 nm wavelength, the incident light causes rhodopsin changes its structural conformation, producing a cascade of reactions that amplifies the signal and create an action potential that moves through of nerve fibers and the brain interprets as light.
In humans there are three types of cones, which respond more strongly to light with wavelengths of 440, 535 and 565 nm. The three types of cones have retineno-1, and opsin which has a characteristic structure in each type of cone. Then through a process similar to nerve impulses rods from the stimulation of these receptors, reaching the visual cortex, where they are interpreted as a wide range of colors and shades, shapes and movement. Nerve pathways
The optic nerve is formed by the meeting of ganglion cell axons. The optic nerve exits near the back of the eye and goes back and medially to together in a structure called the optic chiasm, where fibers from the external hemirretinas remain in the optic tracts for the same side, while the fibers of the nasal hemirretinas, crossing to the opposite optic tract. Then the optic tracts are directed to medial geniculate bodies (located in the back of the thalamus), and meet again in geniculocalcarino beam, which is directed toward the occipital lobe of the cerebral cortex, to be distributed in the region surrounding the calcarine fissure, corresponding to Brodmann areas 17, 18 and 19 primary and associative visual area respectively. On your way these fibers provide small branches to the suprachiasmatic nucleus of the hypothalamus. 
Vision Vision is a sense the sense of sight allows the brain first part of the visual system responsible for forming the optical image of the visual stimulus on the retina (optical system). This is the role of the cornea and lens of the eye.
retinal cells are the sensory system of the eye. The first step in the photoreceptors, which capture the light that strikes them. Its two types are the rods and cones. Other retinal cells that are responsible for transforming light into electrochemical impulses and transported to the optic nerve. From there, project important regions such as the lateral geniculate nucleus and visual cortex of the brain.
In the brain starts the process of rebuilding the distances, colors, movements and shapes of objects around us.
The World Sight Day is celebrated on 8 October.
Resources
's vision draws on multiple sources of information to interpret the world around us. Thus, the use of two eyes allows binocular vision, which we can perceive the distance that an object is or the difference between the motion of a bird and movement in the bushes on which stands allows us to distinguish the animal carrying a twig (see perception of motion.) History and current
's vision draws on multiple sources of information to interpret the world around us. Thus, the use of two eyes allows binocular vision, which we can perceive the distance that an object is or the difference between the motion of a bird and movement in the bushes on which stands allows us to distinguish the animal carrying a twig (see perception of motion.) History and current
The story began with the pre-Socratic vision saying that the eye is made of water and fire. After Aristotle gave the basis for scientific study.
The scientific study of visual perception begins in the nineteenth century, Hermann von Helmholtz, and the first psychophysical methods. In the early twentieth century becomes strong school of Gestalt proposes that vision is strongly guided by top-down processes.
mid twentieth century displayed the proponents of indirect perception, Constructivists, and the proponents of direct perception, environmentalists. Today
it difficult to talk of schools, since the study of vision is highly interdisciplinary.
ocular anatomy
The eye is the organ responsible for the reception of visual stimuli, has exquisite architecture and highly specialized product of millions of years of evolution in animals. The eyeball has three sheaths, which from the outside in are:
1. Outer fibrous tunic, which consists of two regions
- sclera, which is white and opaque, with type I collagen fibers interspersed with elastic fibers, avascular, which provides protection to internal structures, and stability. It covers most of the eyeball, in a small region eccept above.
- Cornea, is a former extension transparent, avascular but highly innervated of the sclera, which the eye bulges forward. It is slightly thicker than the sclera.
2. Media Vascular Tunic (Uvea) is composed by three regions, the choroid, ciliary body and iris.
- Choroid; is the posterior pigmented vascular tunic media, which is attached to the sclera loosely and is separated from the lens through Bruch's membrane.
- Ciliary Body, is a wedge-shaped extension, which is projected onto the lens and is located in the light of the eye between the iris (anterior) and the vitreous humor (posterior). The lens is a transparent biconvex lens located just behind the pupil, whose function is to regulate the focus of light rays to impinge on the retina properly.
- Iris, is the anterior extension of the choroid pigment, whose function is to regulate the light entering the eye by contraction or relaxation of the pupil.
3. Neural retina Tunic: consists of 10 layers, which from the outside inside the balloon is called:
- pigmented epithelium
- Layer of rods and cones (receiver)
-
outer limiting membrane - outer nuclear layer
-
outer plexiform layer - inner nuclear layer
-
inner plexiform layer - Layer
ganglion cells - nerve fiber layer optical
- internal limiting membrane
addition to these layers, the eye has cavities:
- vitreous cavity, which contains the vitreous humor, and is located behind the lens, forming the nucleus transparent, gelatinous the eyeball.
- Posterior chamber, located in front of the lens, and posterior to the iris contains aqueous humor.
- Camera above, located between the cornea (forward) and the iris and lens (back) also contains aqueous humor.
histological and physiological aspects
Retina
As already mentioned the retina has 10 layers, the light must pass through almost all these layers to get to where are located the rods and cones, which are specialized cells in the reception of visual stimuli, and the transformation of these signals into nerve impulses to build images, shapes, colors, tones, and movements in the brain. Besides retinal rods and cones have a complex network of neurons, the rods and cones next to the choroid cells synapse with bipolres and these with the ganglion (diffuse and dwarf), whose axons converge and leave the eye to form the optic nerve. Other neurons called horizontal cells connect receptor cells with each other, while another group of cells, amacrine, are also interneurons whose nuclei are located in the inner nuclear layer and throw their extensions to the inner plexiform layer.
The optic nerve exits the eyeball near the back of the eye point along the retinal vessels at a point known as the optic disc, where there are no visual receptors, and thus constitutes a blind spot. By contrast there is also a point of greater visual acuity located near the back of the eye, called the macula lutea, yellow aspect, and which is the central fovea, which is a thin slice retina (there are very few cells on receivers) lacking rods but with higher density of cones. That is why the set of visual attention in a particular object, the object light is impinging on the fovea. Receptor cells
The receptor cells are the rods and cones. The cones are related to color vision daylight vision, and rods with night vision. there are over 100 million rods in the human eye, and about 4 million cones. Each rod is divided into external and internal segment, the which, in turn has a core region and a synaptic region. In the outer segment disks contain a disk called photosensitive compounds in their membranes, which respond to light a series of reactions leading to init action potentials.
cones also possess these segments, unlike the cones, the outer region has a different shape by the folding of membrane leads to the formation of the bags, which are also membrane photosensitive pigments. Photosensitive compounds
photosensitive compounds in most animals and in humans are composed of a protein called opsin and retineno-1 which is an aldehyde of vitamin A1. Rhodopsin is the photosensitive pigmanto of rod opsin which is called escotopsina. Rhodopsin captures light with a maximum sensitivity at 505 nm wavelength, the incident light causes rhodopsin changes its structural conformation, producing a cascade of reactions that amplifies the signal and create an action potential that moves through of nerve fibers and the brain interprets as light.
In humans there are three types of cones, which respond more strongly to light with wavelengths of 440, 535 and 565 nm. The three types of cones have retineno-1, and opsin which has a characteristic structure in each type of cone. Then through a process similar to nerve impulses rods from the stimulation of these receptors, reaching the visual cortex, where they are interpreted as a wide range of colors and shades, shapes and movement. Nerve pathways
The optic nerve is formed by the meeting of ganglion cell axons. The optic nerve exits near the back of the eye and goes back and medially to together in a structure called the optic chiasm, where fibers from the external hemirretinas remain in the optic tracts for the same side, while the fibers of the nasal hemirretinas, crossing to the opposite optic tract. Then the optic tracts are directed to medial geniculate bodies (located in the back of the thalamus), and meet again in geniculocalcarino beam, which is directed toward the occipital lobe of the cerebral cortex, to be distributed in the region surrounding the calcarine fissure, corresponding to Brodmann areas 17, 18 and 19 primary and associative visual area respectively. On your way these fibers provide small branches to the suprachiasmatic nucleus of the hypothalamus.
Subscribe to:
Posts (Atom)