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The visual analyzer, its structure and functions, the organ of vision. Author of the presentation: Pechenkina V.A. Teacher, Municipal Educational Institution “Gymnasium No. 10”, Pushkino
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Analyzers These are sensitive systems nerve formations, perceiving and analyzing various external and internal stimuli.
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Visual analyzer The visual analyzer consists of eyeball, accessory apparatus, pathways and visual cortex.
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1.Where is the eye located, what auxiliary organs protect our eyes? 2. How many muscles can the eyeball move? Organ vision - eye
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The eyeball and the auxiliary apparatus of the eye. The eyeball is located in the orbit of the skull. The auxiliary apparatus of the eye includes the eyelids, lacrimal apparatus, muscles of the eyeball, and eyebrows. Mobility of the eye is provided by six extrinsic muscles...
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Diagram of the structure of the eye Fig. 1. Scheme of the structure of the eye 1 - sclera, 2 - choroid, 3 - retina, 4 - cornea, 5 - iris, 6 - ciliary muscle, 7 - lens, 8 - vitreous body, 9 - optic disc, 10 - optic nerve, 11 - yellow spot.
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Sclera The sclera is the protein shell - the outer dense connective tissue membrane of the eye, which performs a protective and supporting function.
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The main substance of the cornea consists of a transparent connective tissue stroma and corneal bodies. In front, the cornea is covered with multilayered epithelium. The cornea (cornea) is the anterior most convex transparent part of the eyeball, one of the light-refracting media of the eye.
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The choroid of the eye is the middle layer of the eyeball. Plays an important role in metabolic processes, providing nutrition to the eye and removal of metabolic products. It is rich in blood vessels and eyeball pigment (in Fig. 2)
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The iris (iris) is the thin, movable diaphragm of the eye with a hole (pupil) in the center; located behind the cornea, in front of the lens. The iris contains varying amounts of pigment, which determines its color - “eye color”. The pupil is a round hole through which light rays penetrate inside and reach the retina (the size of the pupil changes [depending on the intensity of the light flux: in bright light it is narrower, in weak light and in the dark it is wider].
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Detect constriction and dilation of the pupil. - Look into the eyes of your desk neighbor and note the size of the pupil. -Close your eyes and shade them with your palm. -Count to 60 and open your eyes. -Observe changes in pupil size. How can we explain this phenomenon?
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The face of the eye is a transparent body located inside the eyeball opposite the pupil; Being a biological lens, the lens is an important part of the light-refracting apparatus of the eye. The lens is a transparent biconvex round elastic formation,
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The lens is strengthened inside the eye by special very thin ligaments. Replacing the lens of the eye.
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Retina of the eye Retina (lat. retina) - inner shell eyes, which is the peripheral part of the visual analyzer.
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Structure of the retina: Anatomically, the retina is a thin membrane adjacent along its entire length to inside to the vitreous body, and from the outside - to choroid eyeball. There are two parts in it: the visual part (receptive field - the area with photoreceptor cells (rods or cones) and the blind part (an area on the retina that is not sensitive to light). Light falls from the left and passes through all layers, reaching the photoreceptors (cones and rods), which transmit the signal through optic nerve into the brain.
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How does the eye see? The path of rays from an object and the construction of an image on the retina (a). Scheme of refraction in a normal (b), myopic (c) and farsighted (d) eye. The eye, like any converging lens, produces an inverted image on the retina, real and reduced.
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Ecology and visual hygiene it is better to use fluorescent lamps, it does not strain the eyesight so much
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Myopia Myopia (myopia) is a vision defect (refractive error) in which the image falls not on the retina, but in front of it. The most common cause is an enlarged (relative to normal) eyeball in length. A rarer option is when the refractive system of the eye focuses the rays more strongly than necessary (and, as a result, they again converge not on the retina, but in front of it). In any of the options, when viewing distant objects, a fuzzy, blurry image appears on the retina. Myopia most often develops during school years, as well as during studies in secondary and higher education. educational institutions and is associated with prolonged visual work at close range (reading, writing, drawing), especially in poor lighting and poor hygienic conditions. With the introduction of computer science in schools and the spread of personal computers, the situation became even more serious.
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farsightedness Farsightedness (hyperopia) is a feature of the refraction of the eye, consisting in the fact that images of distant objects at rest of accommodation are focused behind the retina. At a young age, if farsightedness is not too high, using accommodation voltage, you can focus the image on the retina. One of the causes of farsightedness may be a reduced size of the eyeball on the anterior-posterior axis. Almost all babies are farsighted. But with age, in most people this defect disappears due to the growth of the eyeball. The cause of age-related (senile) farsightedness (presbyopia) is a decrease in the ability of the lens to change curvature. This process begins at the age of about 25 years, but only by the age of 40-50 years it leads to a decrease in visual acuity when reading at the usual distance from the eyes (25-30 cm).
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What is the structure of the eye? Place signs. sclera Vitreous body retina lens pupil choroid oculomotor muscles iris cornea
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Screening test on the topic “Visual analyzer” Select the correct answer 1. The transparent part of the outer shell of the eye is: a) retina b) Cornea c) Iris 2. The cornea of the eye performs the function of: a) nutrition b) transmission sun rays c) protection 3. The pupil is located: a) in the lens b) in the vitreous c) in the iris 4. The membrane of the eye containing rods and cones is: a) tunica albuginea b) retina c) choroid 5. Rods are: a) twilight light receptors b) parts of the vitreous body c) color vision receptors 6. Cones are: a) twilight light receptors b) parts of the cornea c) receptors that perceive color 7. Night blindness is caused by dysfunction of: a) rods b) cones c) lens 8. In weak light, the pupil: a) reflexively narrows b) reflexively expands c) does not change 9. The retina of the eye: a) protects from mechanical damage b) supplies the eye with blood c) converts light rays into nerve impulses 10. If light rays are focused behind the retina, it causes: a) myopia b) farsightedness c) blindness
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Check yourself! 1. The transparent part of the outer shell of the eye is: a) retina b) Cornea c) Iris 2. The cornea of the eye performs the function of: a) nutrition b) transmission of sunlight c) protection 3. The pupil is located: a) in the lens b) in the vitreous body c) in the iris 4. The membrane of the eye containing rods and cones is: a) tunica albuginea b) retina c) choroid 5. Rods are: a) twilight light receptors b) parts of the vitreous c) color vision receptors 6 Cones are: a) receptors for twilight light b) parts of the cornea c) receptors that perceive color 7. Night blindness is caused by dysfunction of: a) rods b) cones c) lens 8. In low light the pupil: a) reflexively narrows b ) reflexively expands c) does not change 9. The retina of the eye: a) protects from mechanical damage b) supplies the eye with blood c) converts light rays into nerve impulses 10. If light rays are focused behind the retina, this causes: a) myopia b) farsightedness c ) blindness
The importance of vision Thanks to the eyes, you and I receive 85% of the information about the world around us; they are the same, according to calculations by I.M. Sechenov, give a person up to 1000 sensations per minute. The eye allows you to see objects, their shape, size, color, movements. The eye is able to distinguish a well-lit object with a diameter of one tenth of a millimeter at a distance of 25 centimeters. But if the object itself glows, it can be much smaller. Theoretically, a person could see a candle light at a distance of 200 km. The eye is capable of distinguishing between pure color tones and 5-10 million mixed shades. Complete adaptation of the eye to the dark takes minutes.
Diagram of the structure of the eye Fig. 1. Scheme of the structure of the eye 1 - sclera, 2 - choroid, 3 - retina, 4 - cornea, 5 - iris, 6 - ciliary muscle, 7 - lens, 8 - vitreous body, 9 - optic disc, 10 - optic nerve, 11 - yellow spot.
The main substance of the cornea consists of a transparent connective tissue stroma and corneal bodies. In front, the cornea is covered with multilayered epithelium. The cornea (cornea) is the anterior most convex transparent part of the eyeball, one of the light-refracting media of the eye.
The iris (iris) is the thin, movable diaphragm of the eye with a hole (pupil) in the center; located behind the cornea, in front of the lens. The iris contains varying amounts of pigment, which determines its color “eye color”. The pupil is a round hole through which light rays penetrate inside and reach the retina (the size of the pupil changes [depending on the intensity of the light flux: in bright light it is narrower, in weak light and in the dark it is wider].
The lens is a transparent body located inside the eyeball opposite the pupil; Being a biological lens, the lens is an important part of the light-refracting apparatus of the eye. The lens is a transparent biconvex round elastic formation,
Photoreceptors signs rods cones Length 0.06 mm 0.035 mm Diameter 0.002 mm 0.006 mm Number 125 – 130 million 6 – 7 million Image Black and white Colored Substance Rhodopsin (visual purple) iodopsin location Prevail in the periphery Prevail in the central part of the retina Yellow spot– a cluster of cones, the blind spot – the exit point of the optic nerve (no receptors)
Structure of the retina: Anatomically, the retina is a thin membrane, adjacent along its entire length from the inside to the vitreous body, and from the outside to the choroid of the eyeball. There are two parts in it: the visual part (the receptive field - the area with photoreceptor cells (rods or cones) and the blind part (the area on the retina that is not sensitive to light). Light falls from the left and passes through all the layers, reaching the photoreceptors (cones and rods) Which transmit the signal along the optic nerve to the brain.
Myopia Myopia (myopia) is a vision defect (refractive error) in which the image falls not on the retina, but in front of it. The most common cause is an enlarged (relative to normal) eyeball in length. A rarer option is when the refractive system of the eye focuses the rays more strongly than necessary (and, as a result, they again converge not on the retina, but in front of it). In any of the options, when viewing distant objects, a fuzzy, blurry image appears on the retina. Myopia most often develops during school years, as well as during studies in secondary and higher educational institutions, and is associated with prolonged visual work at close range (reading, writing, drawing), especially in poor lighting and poor hygienic conditions. With the introduction of computer science in schools and the spread of personal computers, the situation has become even more serious.
Farsightedness (hyperopia) is a feature of the refraction of the eye, consisting in the fact that images of distant objects at rest of accommodation are focused behind the retina. At a young age, if farsightedness is not too high, using accommodation voltage, you can focus the image on the retina. One of the causes of farsightedness may be a reduced size of the eyeball on the anterior-posterior axis. Almost all babies are farsighted. But with age, in most people this defect disappears due to the growth of the eyeball. The cause of age-related (senile) farsightedness (presbyopia) is a decrease in the ability of the lens to change curvature. This process begins at about 25 years of age, but only by 4050 years of age leads to a decrease in visual acuity when reading at the usual distance from the eyes (2530 cm). Colorblindness Up to 14 months in newborn girls and up to 16 months in boys, there is a period of complete color blindness. The formation of color perception ends by the age of 7.5 years in girls and by 8 years in boys. About 10% of men and less than 1% of women have the defect color vision(inability to distinguish between red and green colors or, less commonly, blue; there may be complete indistinction between colors)
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Structure and functions of the eye
A person sees not with his eyes, but through his eyes, from where information is transmitted through the optic nerve, chiasm, visual tracts to certain areas of the occipital lobes of the cerebral cortex, where the picture of the external world that we see is formed. All these organs make up our visual analyzer or visual system. Having two eyes allows us to make our vision stereoscopic (that is, form a three-dimensional image). The right side of the retina of each eye transmits the “right side” of the image to the optic nerve. right side brain, acts similarly left-hand side retina. Then the brain connects two parts of the image - right and left - together. Since each eye perceives “its own” picture, if the joint movement of the right and left eyes is disrupted, binocular vision may be disrupted. Simply put, you will begin to see double or see two completely different pictures at the same time.
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Functions of the eye
optical system that projects the image; a system that perceives and “encodes” the received information for the brain; "serving" life support system.
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The structure of the eye The eye can be called a complex optical device. Its main task is to “transmit” the correct image to the optic nerve. The cornea is the transparent membrane that covers the front of the eye. It lacks blood vessels and has great refractive power. Part of the optical system of the eye. The cornea borders the opaque outer layer of the eye - the sclera. The anterior chamber of the eye is the space between the cornea and the iris. It is filled with intraocular fluid. The iris is shaped like a circle with a hole inside (the pupil). The iris consists of muscles that, when contracted and relaxed, change the size of the pupil. It enters the choroid of the eye. The iris is responsible for the color of the eyes (if it is blue, it means there are few pigment cells in it, if it is brown, it means a lot). Performs the same function as the aperture in a camera, regulating the light flow. The pupil is a hole in the iris. Its size usually depends on the light level. How more light, the smaller the pupil. The lens is the “natural lens” of the eye. It is transparent, elastic - it can change its shape, almost instantly “focusing”, due to which a person sees well both near and far. Located in the capsule, held in place by the ciliary band. The lens, like the cornea, is part of the optical system of the eye. The vitreous is a gel-like transparent substance located in the back of the eye. The vitreous body maintains the shape of the eyeball and is involved in intraocular metabolism. Part of the optical system of the eye. Retina - consists of photoreceptors (they are sensitive to light) and nerve cells. Receptor cells located in the retina are divided into two types: cones and rods. In these cells, which produce the enzyme rhodopsin, the energy of light (photons) is converted into electrical energy of the nervous tissue, i.e. photochemical reaction.
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The rods are highly photosensitivity and allow you to see in poor lighting; they are also responsible for peripheral vision. Cones, on the contrary, require more light for their work, but they are the ones that allow you to see small details (responsible for central vision), make it possible to distinguish colors. The largest concentration of cones is located in the central fossa (macula), which is responsible for the highest visual acuity. The retina is adjacent to the choroid, but in many areas it is loose. This is where it tends to flake off when various diseases retina. The sclera is the opaque outer layer of the eyeball that merges at the front of the eyeball into the transparent cornea. 6 are attached to the sclera oculomotor muscles. It contains a small number of nerve endings and blood vessels.
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Structure of the eye
The choroid - lines the posterior part of the sclera; the retina is adjacent to it, with which it is closely connected. The choroid is responsible for the blood supply to intraocular structures. In diseases of the retina, it is very often involved in pathological process. There are no nerve endings in the choroid, so when it is diseased, there is no pain, which usually signals some kind of problem. Optic nerve - with the help of the optic nerve, signals from nerve endings are transmitted to the brain.
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Visual analyzer and its parts
The visual analyzer is a paired organ of vision, represented by the eyeball, the muscular system of the eye and the auxiliary apparatus. With the help of the ability to see, a person can distinguish the color, shape, size of an object, its illumination and the distance at which it is located. So the human eye is able to distinguish the direction of movement of objects or their immobility. A person receives 90% of information through the ability to see. The organ of vision is the most important of all the senses. The visual analyzer includes the eyeball with muscles and an auxiliary apparatus. The human eye is capable of distinguishing small objects and the slightest shades, while seeing not only during the day, but also at night. Experts say that with the help of vision we learn from 70 to 90 percent of all information. Many works of art would not be possible without eyes.
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Components of vision and their functions
Let's start by considering the structure of the visual analyzer, consisting of: the eyeball; conducting pathways - through them the picture recorded by the eye is fed to the subcortical centers, and then to the cerebral cortex. Therefore, in general, three sections of the visual analyzer are distinguished: peripheral – eyes; conduction – optic nerve; central – visual and subcortical zones of the cerebral cortex. The visual analyzer is also called the visual secretory system. The eye includes the orbit as well as the ancillary apparatus. The central part is located mainly in the occipital part of the cerebral cortex. The accessory apparatus of the eye is a system of protection and movement. In the latter case, the inside of the eyelids has a mucous membrane called the conjunctiva. The protective system includes the lower and upper eyelid with eyelashes. The sweat from the head goes down, but does not get into the eyes due to the existence of the eyebrows. Tears contain lysozyme, which kills harmful microorganisms, getting into the eyes. Blinking the eyelids helps to regularly moisten the apple, after which the tears descend closer to the nose, where they enter the lacrimal sac. Then they move into the nasal cavity.
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Outdoor
The outer shell contains the cornea and sclera. The first one doesn't blood vessels, however, it has many nerve endings. Nutrition is provided by intercellular fluid. The cornea allows light to pass through and also has a protective function, preventing damage to the inside of the eye. It has nerve endings: when even a little dust gets on it, cutting pain appears. The sclera is either white or bluish in color. The oculomotor muscles are attached to it.
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Average
The tunica media can be divided into three parts: the choroid, located under the sclera, has many vessels and supplies blood to the retina; the ciliary body is in contact with the lens; iris - the pupil reacts to the intensity of light that hits the retina (dilates in low light, contracts in strong light).
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Internal
The retina is a brain tissue that allows the function of vision to be realized. She looks like thin shell, adjacent over the entire surface to the choroid. The eye has two chambers filled with transparent liquid: the anterior one; rear As a result, we can identify factors that ensure the performance of all functions of the visual analyzer: a sufficient amount of light; focusing the image on the retina; accommodation reflex.
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Binocular vision
To get one picture formed by two eyes, the picture is focused at one point. Such lines of vision diverge when looking at distant objects, and converge when looking at close objects. Thanks to binocular vision, you can determine the location of objects in space in relation to each other, evaluate their distance, etc.
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Rods and cones of the retina
Rods and cones are sensitive receptors in the retina of the eye that transform light stimulation into nervous stimulation, i.e. they convert light into electrical impulses that travel along the optic nerve to the brain. Rods are responsible for perception in low light conditions (responsible for night vision), cones - for visual acuity and color perception (day vision). Let's consider each type of photoreceptor separately.
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Retinal rods
The sticks have the shape of a cylinder with an uneven, but approximately equal diameter of the circumference along the length. In addition, the length (equal to 0.000006 m or 0.06 mm) is 30 times greater than their diameter (0.000002 m or 0.002 mm), which is why the elongated cylinder really looks very much like a stick. In the eye healthy person there are about 115-120 million sticks. The human eye rod consists of 4 segments: 1 - Outer segment (contains membrane disks), 2 - Connecting segment (cilium), 3 - Inner segment (contains mitochondria), 4 - Basal segment (nerve junction)
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Cones of the retina
Cones get their name due to their shape, similar to laboratory flasks. The length of a cone is 0.00005 meters, or 0.05 mm. Its diameter at its narrowest point is about 0.000001 meters, or 0.001 mm, and 0.004 mm at its widest. There are about 7 million cones in the retina of a healthy adult. Cones are less sensitive to light; in other words, to excite them, a light flux that is tens of times more intense will be required than to excite rods. However, cones are able to process light more intensely than rods, which is why they better perceive changes in light flux (for example, they are better than rods at distinguishing light in dynamics when objects move relative to the eye), and also determine a clearer image. Cone human eye consists of 4 segments: 1 - Outer segment (contains membrane disks with iodopsin), 2 - Connecting segment (constriction), 3 - Inner segment (contains mitochondria), 4 - Area of synaptic connection (basal segment).
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Optical system of the eye
Optical system- a set of optical elements (refractive, reflective, diffractive, etc.) created to transform light beams (in geometric optics), radio waves (in radio optics), charged particles (in electronic and ion optics) Optical design - graphical representation the process of changing light in an optical system. Optical instrument (eng. optical instrument) - structurally designed to perform specific task an optical system consisting of at least one of the basic optical elements. An optical device may include light sources and radiation receivers. In another formulation, a device is called optical if at least one of its main functions is performed by an optical system.
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The optical system of the eye can be considered as a system of lenses formed by various transparent tissues and fibers. The difference in the “material” of these natural lenses causes a difference in their optical characteristics and primarily in the refractive index. The optical system of the eye creates a real image of the observed object on the retina. The shape of a normal eye is close to a sphere. For an adult, the diameter of the eyeball sphere is approximately 25 mm. Its mass is about 78 g. With ametropia, the spherical shape is usually disrupted. The anteroposterior dimension of the axis, also called sagittal, with myopia usually exceeds the vertical and horizontal (or transverse). In this case, the eye no longer has a spherical, but an elliptical shape. With hypermetropia, on the contrary, the eye, as a rule, is somewhat flattened in the longitudinal direction; the sagittal size is smaller than the vertical and transverse ones.
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Intravital measurement of the anteroposterior axis of the eye does not currently cause difficulties. For this purpose, echobiometry (a method based on the use of ultrasound) or an x-ray method is used. Determining this quantity is important for solving the series diagnostic tasks. It is also necessary to determine the true scale of the image of fundus elements.
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Visual acuity
Visual acuity is the ability of the eye to distinguish two points separately with a minimum distance between them. A measure of visual acuity is the angle formed by the rays coming to the eye from these points. The smaller this angle, the higher the visual acuity. The visual acuity of the eye with the smallest visual angle, equal to 1 minute, is taken as one. The highest visual acuity is provided only by the area of the macula of the retina, and on both sides of it it quickly decreases and already at an angular distance of about 10° it is approximately 5 times less. Seeing with one eye makes it difficult to judge the depth of space. Combined vision with two eyes provides a clear three-dimensional perception of the object in question and allows you to correctly determine its location in space. With one eye, without turning the head, a person can cover about 150o of space, with two eyes - about 180o.
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Doltonism
Doltonism, color blindness, is a hereditary, less commonly acquired feature of vision in humans and primates, expressed in the inability to distinguish between green and red colors to a greater extent. Named after John Dalton, who first described a type of color blindness based on his own sensations in 1794. The inheritance of color blindness is associated with the X chromosome and is almost always transmitted from a mother who carries the gene to her son, as a result of which it is twenty times more likely to occur in men who have a set of XY sex chromosomes. In men, the defect in the only X chromosome is not compensated for, since there is no “spare” X chromosome. To varying degrees Colorblindness affects 2-8% of men, and only 0.4% of women. Some types of color blindness should not be considered " hereditary disease", but rather - a feature of vision. According to research by British scientists, people who find it difficult to distinguish between red and green colors can distinguish many other shades. In particular, khaki shades that appear the same to people with normal vision.
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Myopia
With myopia (myopia), only objects located at a certain short distance can be clearly perceived by the eye, since their image is focused strictly on the retina. A person with myopia sees everything that is further away fuzzy and blurry. This happens because rays from more distant objects, refracted in the structures of the eye, form an image not on the retina, it is formed in front of the retina, and a person cannot see clear outlines. Causes of myopia: 1. The refractive power of the ocular media is too high,2. Elongated eyeball, 3. Inadequate change in lens curvature4. Changes in corneal curvature, 5. Injuries with displacement of the lens. Where do the causes of myopia come from? Of course, no one is immune from injury; it is most often an accident. But all other problems leading to myopia can be caused by heredity, too much visual stress, improper vision correction process or lack thereof.
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Farsightedness
Farsightedness (hyperopia) is a condition in which the focusing of the image of distant objects (but only up to a certain distance) occurs on the retina, and a person sees them well. Images of other objects are focused behind the retina, so a person sees them blurry and unclear. Farsightedness is observed in all newborns; as the child and the eyeball grow, it goes away and vision becomes normal. Causes of farsightedness: Age-related changes in the structures of the eye, for example, loss of elasticity by the lens or a decrease in the contractility of the ciliary muscle, Shortening of the eyeball. How does myopia differ from farsightedness? Firstly, by the peculiarities of vision: farsighted people see well only in the distance, myopic people only see close up. Secondly, these two conditions differ in the age of development, which, in turn, depends on the reasons. Myopia is most often caused genetically and fully develops by age 12. Farsightedness in most cases is the result age-related changes, occurring in the organs of vision. It begins to appear at the age of 35-50 or more years.
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Eye diseases
AmblyopiaFunctional disorder visual system, in which it is noted that it cannot be corrected with glasses or contact lenses decreased vision, impaired contrast sensitivity and accommodative abilities of one or less often both eyes in the absence of any pathological changes organ of vision. Symptoms: deterioration of vision in one or both eyes, difficulty perceiving three-dimensional objects, estimating the distance to them, difficulties in learning.
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Eye diseases
Anisocoria is a condition in which the pupils of the eyes differ in size. This phenomenon is quite common in the practice of doctors and does not always mean the presence of any pathology in the body. About 20% of the population has physiological anisocoria. Symptoms: the pupils of the right and left eyes differ in size.
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Eye diseases
Astigmatism A type of ametropia in which light rays cannot focus on the retina of the eye. In cases where the cause of astigmatism is irregular shape cornea, it is called corneal, with an abnormal shape of the lens - lenticular, or lenticular. Their sum is total astigmatism. Symptoms: distortion, blurriness, double image, rapid eye fatigue, constant eye strain, headache, the need to squint in order to better see an object.
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Lesson topic: “The organ of vision and the visual analyzer”
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Organ of vision
The organ of vision (eye) is the perceptive section of the visual analyzer, which serves to perceive light stimuli.
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External structure of the eye
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Internal structure of the eye
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Accommodation of the lens
Accommodation is the ability of the eye to clearly see objects located at different distances from us. If we look into the distance, the lens becomes flatter; if we look at objects close up, it becomes more convex. Thanks to this, the lens directs rays strictly to the retina. He focuses the image on her.
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The structure of the retina
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Retinal image and visual image
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Structure of the visual analyzer
Peripheral section 1 - retina Conductor section 2 - optic nerves Central section 3 - visual cortex cerebral hemispheres
The visual analyzer provides the perception of the size, shape, color of objects, their relative position and the distance between them.
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Binocular vision
Binocular or stereoscopic vision is vision with two eyes, which provides a clear three-dimensional perception of an object and its location in space.
Differences binocular vision from peripheral
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Consolidation
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Identify the structures that make up external structure eyes
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Consolidation
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Identify the structures that make up internal structure eyes
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Consolidation
Solving biological problems
Task No. 1. At night, a man walked out of the illuminated room onto the street, into pitch darkness, where nothing was visible. However, after a while he began to distinguish the outlines of houses, trees and bushes, and then he saw a path. Give an explanation for this phenomenon.
Correct answer: In conditions of good lighting, a person perceives a light image with cones; in the dark, color perception fades, and rods act - cells of “night” vision, which are highly sensitive. Adaptation (adaptation) to darkness does not occur immediately, and time is needed to restore the visual pigment (rhodopsin), since during daytime vision it is not present in the rods.
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Consolidation
Solving biological problems.
Problem No. 2. There are people who claim that they have observed “visions”, however modern science proves that no “visions” exist. Explain from a scientific point of view whether such phenomena are possible.
Correct answer: The appearance of visions is associated with a certain mental state a person, when, under the influence of mental stress (in the evening in an abandoned park, a dark street), or suggestion (a story about a terrible thing), or the action of substances (poisons), strong excitement arises in the visual zones of the cerebral cortex. This leads to the appearance of visual images (visions). The rods and cones of the retina are not excited, since in reality the object does not exist.
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Homework
§ 46; answer the questions. Creative task: compose 1 – 2 puzzles on the topic “The organ of vision and the visual analyzer.”
