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Hypoxic-ischemic Brain Injury
Cerebral hypoxia is a form of hypoxia (reduced supply of oxygen), specifically involving the brain; when the brain is completely deprived of oxygen, it is called ''cerebral anoxia''. There are four categories of cerebral hypoxia; they are, in order of increasing severity: diffuse cerebral hypoxia (DCH), focal cerebral ischemia, cerebral infarction, and global cerebral ischemia. Prolonged hypoxia induces neuronal cell death via apoptosis, resulting in a hypoxic brain injury. Cases of total oxygen deprivation are termed "anoxia", which can be hypoxic in origin (reduced oxygen availability) or ischemic in origin (oxygen deprivation due to a disruption in blood flow). Brain injury as a result of oxygen deprivation either due to hypoxic or anoxic mechanisms are generally termed hypoxic/anoxic injuries (HAI). Hypoxic ischemic encephalopathy (HIE) is a condition that occurs when the entire brain is deprived of an adequate oxygen supply, but the deprivation is not total. While HIE i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circle Of Willis
The circle of Willis (also called Willis' circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures in reptiles, birds and mammals, including humans. It is named after Thomas Willis (1621–1675), an English physician. Structure The circle of Willis is a part of the cerebral circulation and is composed of the following arteries: * Anterior cerebral artery (left and right) * Anterior communicating artery * Internal carotid artery (left and right) * Posterior cerebral artery (left and right) * Posterior communicating artery (left and right) The middle cerebral arteries, supplying the brain, are not considered part of the circle of Willis. Origin of arteries The left and right internal carotid arteries arise from the left and right common carotid arteries. The posterior communicating artery is given off as a branch of the internal carotid artery just before it divides into its termi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Short-term Memory
Short-term memory (or "primary" or "active memory") is the capacity for holding a small amount of information in an active, readily available state for a short interval. For example, short-term memory holds a phone number that has just been recited. The duration of short-term memory (absent rehearsal or active maintenance) is estimated to be on the order of seconds. The commonly cited capacity of 7 items, found in Miller's Law, has been superseded by 4±1 items. In contrast, long-term memory holds information indefinitely. Short-term memory is not the same as working memory, which refers to structures and processes used for temporarily storing and manipulating information. Stores The idea of separate memories for short-term and long-term storage originated in the 19th century. A model of memory developed in the 1960s assumed that all memories are formed in one store and transfer to others store after a small period of time. This model is referred to as the "modal model", most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colorless and odorless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins), in the nucleic acids ( DNA and RNA) and in the energy transfer molecule adenosine triphosphate. The human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes the movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere. Many indus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Status Epilepticus
Status epilepticus (SE), or status seizure, is a single seizure lasting more than 5 minutes or 2 or more seizures within a 5-minute period without the person returning to normal between them. Previous definitions used a 30-minute time limit. The seizures can be of the tonic–clonic type, with a regular pattern of contraction and extension of the arms and legs, or of types that do not involve contractions, such as absence seizures or complex partial seizures. Status epilepticus is a life-threatening medical emergency, particularly if treatment is delayed. Status epilepticus may occur in those with a history of epilepsy as well as those with an underlying problem of the brain. These underlying brain problems may include trauma, infections, or strokes, among others. Diagnosis often involves checking the blood sugar, imaging of the head, a number of blood tests, and an electroencephalogram. Psychogenic nonepileptic seizures may present similarly to status epilepticus. Other conditio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anemia
Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, the symptoms are often vague, such as tiredness, weakness, shortness of breath, headaches, and a reduced ability to exercise. When anemia is acute, symptoms may include confusion, feeling like one is going to pass out, loss of consciousness, and increased thirst. Anemia must be significant before a person becomes noticeably pale. Symptoms of anemia depend on how quickly hemoglobin decreases. Additional symptoms may occur depending on the underlying cause. Preoperative anemia can increase the risk of needing a blood transfusion following surgery. Anemia can be temporary or long term and can range from mild to severe. Anemia can be caused by blood loss, decreased red blood cell production, and increased red blood cell breakdown. Causes o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, coughing, chest tightness, and shortness of breath. These may occur a few times a day or a few times per week. Depending on the person, asthma symptoms may become worse at night or with exercise. Asthma is thought to be caused by a combination of genetic and environmental factors. Environmental factors include exposure to air pollution and allergens. Other potential triggers include medications such as aspirin and beta blockers. Diagnosis is usually based on the pattern of symptoms, response to therapy over time, and spirometry lung function testing. Asthma is classified according to the frequency of symptoms, forced expiratory volume in one second (FEV1), and peak expiratory flow rate. It may also be classified as atopic or non-atopic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mebibyte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as The Internet Protocol () refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness. The first bit is number 0, making the eighth bit number 7. The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxic Hypoxia
Generalized hypoxia is a medical condition in which the tissues of the body are deprived of the necessary levels of oxygen due to an insufficient supply of oxygen, which may be due to the composition or pressure of the breathing gas, decreased lung ventilation, or respiratory disease, any of which may cause a lower than normal oxygen content in the arterial blood, and consequently a reduced supply of oxygen to all tissues perfused by the arterial blood. This usage is in contradistinction to localized hypoxia, in which only an associated group of tissues, usually with a common blood supply, are affected, usually due to an insufficient or reduced blood supply to those tissues. Genralized hypoxia is also used as a synonym for hypoxic hypoxia This is not to be confused with hypoxemia, which refers to low levels of oxygen in the blood, although the two conditions often occur simultaneously, since a decrease in blood oxygen typically corresponds to a decrease in oxygen in the surroundi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Library Of Medicine
The United States National Library of Medicine (NLM), operated by the United States federal government, is the world's largest medical library. Located in Bethesda, Maryland, the NLM is an institute within the National Institutes of Health. Its collections include more than seven million books, journals, technical reports, manuscripts, microfilms, photographs, and images on medicine and related sciences, including some of the world's oldest and rarest works. The current director of the NLM is Patricia Flatley Brennan.National Library of Medicine Welcomes New Director Dr. Patricia Flatley Brennan . ''National Library of Medicine''. August 15, 2016. History The precursor o ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MedlinePlus
MedlinePlus is an online information service produced by the United States National Library of Medicine. The service provides curated consumer health information in English and Spanish with select content in additional languages. The site brings together information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), other U.S. government agencies, and health-related organizations. There is also a site optimized for display on mobile devices, in both English and Spanish. In 2015, about 400 million people from around the world used MedlinePlus. The service is funded by the NLM and is free to users. MedlinePlus provides encyclopedic information on health and drug issues, and provides a directory of medical services. MedlinePlus Connect links patients or providers in electronic health record (EHR) systems to related MedlinePlus information on conditions or medications. PubMed Health was another NLM site that offered consumer health information, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain Death
Brain death is the permanent, irreversible, and complete loss of brain function which may include cessation of involuntary activity necessary to sustain life. It differs from persistent vegetative state, in which the person is alive and some autonomic functions remain. It is also distinct from comas as long as some brain and bodily activity and function remain, and it is also not the same as the condition locked-in syndrome. A differential diagnosis can medically distinguish these differing conditions. Brain death is used as an indicator of legal death in many jurisdictions, but it is defined inconsistently and often confused by the public. Various parts of the brain may keep functioning when others do not anymore, and the term "brain death" has been used to refer to various combinations. For example, although one major medical dictionary considers "brain death" to be synonymous with "cerebral death" (death of the cerebrum), the US National Library of Medicine Medical Subject ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brainstem Death
Brainstem death is a clinical syndrome defined by the absence of reflexes with pathways through the brainstem – the "stalk" of the brain, which connects the spinal cord to the mid-brain, cerebellum and cerebral hemispheres – in a deeply comatose, ventilator-dependent patient. Identification of this state carries a very grave prognosis for survival; cessation of heartbeat often occurs within a few days, although it may continue for weeks if intensive support is maintained.A Code of Practice for the Diagnosis and Confirmation of Death. Academy of Medical Royal Colleges, London, 2008 In the United Kingdom, death can be certified on the basis of a formal diagnosis of brainstem death, so long as this is done in accordance with a procedure established in "A Code of Practice for the Diagnosis and Confirmation of Death", published in 2008 by the Academy of Medical Royal Colleges. The premise of this is that a person is dead when consciousness and the ability to breathe are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
