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Death
Death is the end of life; the irreversible cessation of all biological functions that sustain a living organism. Death eventually and inevitably occurs in all organisms. The remains of a former organism normally begin to decompose shortly after death. Some organisms, such as '' Turritopsis dohrnii'', are biologically immortal; however, they can still die from means other than aging. Death is generally applied to whole organisms; the equivalent for individual components of an organism, such as cells or tissues, is necrosis. Something that is not considered an organism, such as a virus, can be physically destroyed but is not said ''to die'', as a virus is not considered alive in the first place. As of the early 21st century, 56 million people die per year. The most common reason is aging, followed by cardiovascular disease, which is a disease that affects the heart or blood vessels. As of 2022, an estimated total of almost 110 billion humans have died, or rou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain Death
Brain death is the permanent, irreversible, and complete loss of Electroencephalography, brain function, which may include cessation of involuntary activity (e.g., Control of ventilation#Control of respiratory rhythm, breathing) 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 Medical definition of death, defined inconsistently and often confused by the public. Various parts of the brain may keep functioning when others do not anymore, bringing questions about whether they should truly be considered dead. The term "brain death" has been used to refer to various combinations. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clinical Death
Clinical death is the medical term for cessation of blood circulation and breathing, the two criteria necessary to sustain the lives of human beings and of many other organisms. It occurs when the heart stops beating in a regular rhythm, a condition called cardiac arrest. The term is also sometimes used in resuscitation research. Stopped blood circulation has historically proven irreversible in most cases. Prior to the invention of cardiopulmonary resuscitation (CPR), defibrillation, epinephrine injection, and other treatments in the 20th century, the absence of blood circulation (and vital functions related to blood circulation) was historically considered the official definition of death. With the advent of these strategies, cardiac arrest came to be called ''clinical death'' rather than simply ''death'', to reflect the possibility of post-arrest resuscitation. At the onset of clinical death, consciousness is lost within several seconds, and in dogs, measurable brain activity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardiovascular Disease
Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumatic heart disease, cardiomyopathy, arrhythmia, congenital heart disease, valvular heart disease, carditis, aortic aneurysms, peripheral artery disease, thromboembolic disease, and venous thrombosis. The underlying mechanisms vary depending on the disease. It is estimated that dietary risk factors are associated with 53% of CVD deaths. Coronary artery disease, stroke, and peripheral artery disease involve atherosclerosis. This may be caused by high blood pressure, smoking, diabetes mellitus, lack of exercise, obesity, high blood cholesterol, poor diet, excessive alcohol consumption, and poor sleep, among other things. High blood pressure is estimated to account for approximately 13% of CVD deaths, while tobacco accounts for 9%, di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Necrosis
Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who is often regarded as one of the founders of modern pathology. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated digestion of cell components. In contrast, ''apoptosis'' is a naturally occurring programmed and targeted cause of cellular death. While apoptosis often provides beneficial effects to the organism, necrosis is almost always detrimental and can be fatal. Cellular death due to necrosis does not follow the apoptotic signal transduction pathway, but rather various receptors are activated and result in the loss of cell membrane integrity and an uncontrolled release of products of cell death into the extracellular space. This initiates an inflammatory response in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decomposition
Decomposition is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is essential for recycling the finite matter that occupies physical space in the biosphere. Bodies of living organisms begin to decompose shortly after death. Although no two organisms decompose in the same way, they all undergo the same sequential stages of decomposition. Decomposition can be a gradual process for organisms that have extended periods of dormancy. One can differentiate ''abiotic'' decomposition from ''biotic'' decomposition ( biodegradation); the former means "the degradation of a substance by chemical or physical processes", e.g., hydrolysis; the latter means "the metabolic breakdown of materials into simpler components by living organisms", typically by microorganisms. Animals, such as earthworms, also help decompose the organ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life
Life, also known as biota, refers to matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes. It is defined descriptively by the capacity for homeostasis, Structure#Biological, organisation, metabolism, Cell growth, growth, adaptation, response to stimulus (physiology), stimuli, and reproduction. All life over time eventually reaches a state of death, and none is Immortality, immortal. Many philosophical definitions of living systems have been proposed, such as self-organizing systems. Viruses in particular make definition difficult as they replicate only in Host (biology), host cells. Life exists all over the Earth in air, water, and soil, with many ecosystems forming the biosphere. Some of these are harsh environments occupied only by extremophiles. Life has been studied since ancient times, with theories such as Empedocles's materialism asserting that it was composed of Classical element, four eternal elements, and Aristotle's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart
The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the thorax, chest, called the mediastinum. In humans, the heart is divided into four chambers: upper left and right Atrium (heart), atria and lower left and right Ventricle (heart), ventricles. Commonly, the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. In a healthy heart, blood flows one way through the heart due to heart valves, which prevent cardiac regurgitation, backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a sma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aging
Ageing (or aging in American English) is the process of becoming Old age, older until death. The term refers mainly to humans, many other animals, and fungi; whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In a broader sense, ageing can refer to single cells within an organism which have Cellular senescence, ceased dividing, or to the Population ageing, population of a species. In humans, ageing represents the accumulation of changes in a human being over time and can encompass physical, psychological, and social changes. Reaction time, for example, may slow with age, while memories and general knowledge typically increase. Of the roughly 150,000 people who die each day across the globe, about two-thirds die from age-related causes. Current Theory of aging, ageing theories are assigned to the damage concept, whereby the accumulation of damage (such as DNA oxidation) may cause biological systems to fail, or to the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disease
A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical conditions that are associated with specific signs and symptoms. A disease may be caused by external factors such as pathogens or by internal dysfunctions. For example, internal dysfunctions of the immune system can produce a variety of different diseases, including various forms of immunodeficiency, hypersensitivity, allergy, allergies, and autoimmune disorders. In humans, ''disease'' is often used more broadly to refer to any condition that causes pain, Abnormality (behavior), dysfunction, distress (medicine), distress, social problems, or death to the person affected, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injury in humans, injuries, disability, disabilities, Disorder (medicine) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lifespan Extension
Life extension is the concept of extending the human lifespan, either modestly through improvements in medicine or dramatically by increasing the maximum lifespan beyond its generally-settled biological limit of around 125 years. Several researchers in the area, along with "life extensionists", " immortalists", or " longevists" (those who wish to achieve longer lives themselves), postulate that future breakthroughs in tissue rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement (such as with artificial organs or xenotransplantations) will eventually enable humans to have indefinite lifespans through complete rejuvenation to a healthy youthful condition (agerasia). The ethical ramifications, if life extension becomes a possibility, are debated by bioethicists. The sale of purported anti-aging products such as supplements and hormone replacement is a lucrative global industry. For example, the industry tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus
A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, more than 16,000 of the millions of List of virus species, virus species have been described in detail. The study of viruses is known as virology, a subspeciality of microbiology. When infected, a host cell is often forced to rapidly produce thousands of copies of the original virus. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent viral particles, or ''virions'', consisting of (i) genetic material, i.e., long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maximum Lifespan
Maximum life span (or, for humans, maximum reported age at death) is a measure of the maximum amount of time one or more members of a population have been observed to survive between birth and death. The term can also denote an estimate of the maximum amount of time that a member of a given species could survive between birth and death, provided circumstances that are optimal to that member's longevity. Most living species have an upper limit on the number of times somatic cells not expressing telomerase can divide. This is called the Hayflick limit, although this number of cell divisions does not strictly control lifespan. Definition In animal studies, maximum span is often taken to be the mean life span of the most long-lived 10% of a given cohort. By another definition, however, maximum life span corresponds to the age at which the oldest known member of a species or experimental group has died. Calculation of the maximum life span in the latter sense depends upon the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
