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Greyout
A greyout is a transient loss of vision characterized by a perceived dimming of light and color, sometimes accompanied by a loss of peripheral vision. It is a precursor to fainting or a blackout and is caused by hypoxia (low brain oxygen level), often due to a loss of blood pressure. Greyouts have a variety of possible causes: * Shock, such as hypovolemia, even in mild form such as when drawing blood. * Standing up suddenly (see orthostatic hypotension), especially if sick, hungover, or experiencing low blood pressure. * Fatigue * Hyperventilation, paradoxically: self-induced hypocapnia, such as in the fainting game or in shallow water blackout. * Overexertion * Severe episodes of coughing or sneezing * Panic attack Possible symptoms include: * blurred vision * tunnel vision * dizziness * loss of balance * lightheadedness * sudden feeling of exhaustion * breathing accelerates into short quick breaths * respiratory acidosis (“hot breath”) * heart rate spi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-LOC
g-force induced loss of consciousness (abbreviated as G-LOC, pronounced "JEE-lock") is a term generally used in aerospace physiology to describe a loss of consciousness occurring from excessive and sustained g-forces draining blood away from the brain causing cerebral hypoxia. The condition is most likely to affect pilots of high performance fighter and aerobatic aircraft or astronauts, but is possible on some extreme amusement park rides. G-LOC incidents have caused fatal accidents in high performance aircraft capable of sustaining high ''g'' for extended periods. High-g training for pilots of high performance aircraft or spacecraft often includes ground training for G-LOC in special centrifuges, with some profiles exposing pilots to 9 ''g''s for a sustained length of time. Effects of ''g''-forces Under increasing positive ''g''-force, blood in the body will tend to move from the head toward the feet. For higher intensity or longer duration, this can manifest progress ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redout
A redout occurs when the body experiences a negative g-force sufficient to cause a blood flow from the lower parts of the body to the head. It is the inverse effect of a greyout, where blood flows away from the head to the lower parts of the body. Usually, a redout will only ever be experienced by pilots, as planes are the most common devices that allow such negative g-forces to be exerted. Redouts are potentially dangerous and can cause retinal damage and hemorrhagic stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor .... According to the predominant theory, the redness appearing in the visual field is not caused by an actual blood flow to the eye, but it is most likely caused by the blood-laden lower eyelid coming into the visual field because of the pull of negative-Gs. Se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-force
The g-force or gravitational force equivalent is a Specific force, mass-specific force (force per unit mass), expressed in Unit of measurement, units of standard gravity (symbol ''g'' or ''g''0, not to be confused with "g", the symbol for grams). It is used for sustained accelerations that cause a perception of weight. For example, an object at rest on Earth's surface is subject to 1 ''g'', equaling the conventional value of gravitational acceleration on Earth, about . More transient acceleration, accompanied with significant jerk (physics), jerk, is called Shock (mechanics), ''shock''. When the g-force is produced by the surface of one object being pushed by the surface of another object, the reaction force to this push produces an equal and opposite force for every unit of each object's mass. The types of forces involved are transmitted through objects by interior Stress (mechanics), mechanical stresses. Gravitational acceleration is one cause of an object's accelera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freediving Blackout
Freediving blackout, breath-hold blackout, or apnea blackout is a class of hypoxic blackout, a Unconsciousness, loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold (freedive or dynamic apnea) dive, when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have caused it. It can be provoked by hyperventilation, hyperventilating just before a dive, or as a consequence of the pressure reduction on ascent, or a combination of these. Victims are often established practitioners of breath-hold diving, are fit, strong swimmers and have not experienced problems before. Blackout may also be referred to as a syncope (medicine), syncope or fainting. Divers and swimmers who black out or Greyout (medical), grey out underwater during a dive will usually Drowning, drown unless rescued and resuscitated within a short time. Freediving blackout has a high fatality rate, and mostly involves males younge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightheadedness
Lightheadedness is a common and typically unpleasant sensation of dizziness or a feeling that one may faint. The sensation of lightheadedness can be short-lived, prolonged, or, rarely, recurring. In addition to dizziness, the individual may feel as though their head is weightless. The individual may also feel as though the room is "spinning" or moving (vertigo). Most causes of lightheadedness are not serious and either cure themselves quickly or are easily treated. Keeping a sense of balance requires the brain to process a variety of information received from the eyes, the nervous system, and the inner ears. If the brain is unable to process these signals, such as when the messages are contradictory, or if the sensory systems are improperly functioning, an individual may experience lightheadedness or dizziness. Lightheadedness is very similar to pre-syncope. Pre-syncope is the immediate stage before syncope (fainting), particularly in cases of temporary visual field loss (i.e. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grey Out Illustration
Grey (more frequent in British English) or gray (more frequent in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning that it has no chroma. It is the color of a cloud-covered sky, of ash, and of lead. The first recorded use of ''grey'' as a color name in the English language was in 700 CE.Maerz and Paul ''A Dictionary of Color'' New York:1930 McGraw-Hill Page 196 ''Grey'' is the dominant spelling in European and Commonwealth English, while ''gray'' is more common in American English; however, both spellings are valid in both varieties of English. In Europe and North America, surveys show that gray is the color most commonly associated with neutrality, conformity, boredom, uncertainty, old age, indifference, and modesty. Only one percent of respondents chose it as their favorite color. Etymology ''Grey'' comes from the Middle English or , from the Old English , and is related to the Dutch and Germa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equilibrioception
The sense of balance or equilibrioception is the perception of balance and spatial orientation. It helps prevent humans and nonhuman animals from falling over when standing or moving. Equilibrioception is the result of a number of sensory systems working together; the eyes (visual system), the inner ears ( vestibular system), and the body's sense of where it is in space (proprioception) ideally need to be intact. The vestibular system, the region of the inner ear where three semicircular canals converge, works with the visual system to keep objects in focus when the head is moving. This is called the vestibulo-ocular reflex (VOR). The balance system works with the visual and skeletal systems (the muscles and joints and their sensors) to maintain orientation or balance. Visual signals sent to the brain about the body's position in relation to its surroundings are processed by the brain and compared to information from the vestibular and skeletal systems. Vestibular system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix
A helix (; ) is a shape like a cylindrical coil spring or the thread of a machine screw. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word ''helix'' comes from the Greek word , "twisted, curved". A "filled-in" helix – for example, a "spiral" (helical) ramp – is a surface called a '' helicoid''. Properties and types The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruent) helices with the same axis, differing by a translation along the axis. A circular helix (i.e. one with constant radius) has constant band curvature and constant torsion. The slope of a circular helix is commonly defined as the ratio of the circumference of the circular cylinder that it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Loop
The generic roller coaster vertical loop, also known as a Loop-the-loop, or a Loop-de-loop, where a section of track causes the riders to complete a 360 degree turn, is the most basic of roller coaster inversions. At the top of the loop, riders are completely inverted. History The vertical loop is not a recent roller coaster innovation. Its origins can be traced back to the 1850s when ''centrifugal railways'' were built in France and Great Britain. The rides relied on centripetal forces to hold the car in the loop. One early looping coaster was shut down after an accident. Later attempts to build a looping roller coaster were carried out during the late 19th century with the ''Flip Flap Railway'' at Sea Lion Park, designed by Roller coaster engineer Lina Beecher. The ride was designed with a completely circular loop (rather than the teardrop shape used by many modern looping roller coasters), and caused neck injuries due to the intense G-forces pulled with the tight radius ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roller Coaster
A roller coaster is a type of list of amusement rides, amusement ride employing a form of elevated Railway track, railroad track that carries passengers on a roller coaster train, train through tight turns, steep slopes, and other elements, usually designed to produce a thrilling experience, though some roller coasters aim to provide a more gentle experience. Trains consist of open cars connected in a single line, and the rides are often found in theme parks around the world. Roller coasters originate from "Russian Mountains" which first appeared in the 17th century. Invented and mostly found in Russia, these were slides made of ice that upper-class Russians would slide down. LaMarcus Adna Thompson obtained one of the first known patents for a roller coaster design in 1885, based on the Switchback Railway which opened a year earlier at Coney Island. Tracks are typically built and designed as a complete circuit in which trains depart from and return to the same Station (roller coa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-suit
A g-suit, or anti-''g'' suit, is a flight suit worn by aviators and astronauts who are subject to high levels of acceleration force ( g). It is designed to prevent a black-out and g-LOC (g-induced loss of consciousness) caused by the blood pooling in the lower part of the body when under acceleration, thus depriving the brain of blood. Black-out and g-LOC have caused a number of fatal aircraft accidents. Operation If blood is allowed to pool in the lower areas of the body, the brain will be deprived of blood. This lack of blood flow to the brain first causes a greyout (a dimming of the vision also called brownout), followed by tunnel vision and ultimately complete loss of vision 'blackout' followed by g-induced Loss Of Consciousness or 'g-LOC'. The danger of g-LOC to aircraft pilots is magnified because on relaxation of g-force there is a period of disorientation before full sensation is re-gained. A g-suit does not so much increase the g-threshold, but makes it possible to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stroke
Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemorrhagic, due to bleeding. Both cause parts of the brain to stop functioning properly. Signs and symptoms of stroke may include an hemiplegia, inability to move or feel on one side of the body, receptive aphasia, problems understanding or expressive aphasia, speaking, dizziness, or homonymous hemianopsia, loss of vision to one side. Signs and symptoms often appear soon after the stroke has occurred. If symptoms last less than 24 hours, the stroke is a transient ischemic attack (TIA), also called a mini-stroke. subarachnoid hemorrhage, Hemorrhagic stroke may also be associated with a thunderclap headache, severe headache. The symptoms of stroke can be permanent. Long-term complications may include pneumonia and Urinary incontinence, loss of b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
