Organs
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A new policy for matching lung transplant candidates with organs from deceased donors is projected to decrease deaths among waitlisted patients and provide more lung transplants for the most medically urgent candidatesThe issues at stake in organ transportationA look at the intersecting challenges in organ transportation and the need for national-level solutions to ensure donor organs get safely to patients in needThe best outcome for patientsMatthew Cooper, M.D., discussed equity, outreach and patient engagement at recent ASTS conference
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function.[1] In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue and smooth muscle tissue.[2] Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system.
An organ's tissues can be broadly categorized as parenchyma, the functional tissue, and stroma, the structural tissue with supportive, connective, or ancillary functions. For example, the gland's tissue that makes the hormones is the parenchyma, whereas the stroma includes the nerves that innervate the parenchyma, the blood vessels that oxygenate and nourish it and carry away its metabolic wastes, and the connective tissues that provide a suitable place for it to be situated and anchored. The main tissues that make up an organ tend to have common embryologic origins, such as arising from the same germ layer. Organs exist in most multicellular organisms. In single-celled organisms such as bacteria, the functional analogue of an organ is known as an organelle. In plants, there are three main organs.[3]
In the study of anatomy, viscera (singular viscus) refers to the internal organs of the abdominal, thoracic, and pelvic cavities.[4] The abdominal organs may be classified as solid organs, or hollow organs. The solid organs are the liver, pancreas, spleen, kidneys, and adrenal glands. The hollow organs of the abdomen are the stomach, intestines, gallbladder, bladder, and rectum.[5] In the thoracic cavity the heart is a hollow, muscular organ.[6]
In the study of anatomy, viscera (singular viscus) refers to the internal organs of the abdominal, thoracic, and pelvic cavities.[4] The abdominal organs may be classed as solid organs, or hollow organs. The solid organs include the liver, pancreas, spleen, kidneys, and adrenal glands. The hollow organs include the stomach, intestines, gallbladder, bladder, and rectum.[5] In the thoracic cavity the heart is a hollow, muscular organ.[6] Splanchnology is the study of the viscera.[8] The term \"visceral\" is contrasted with the term \"parietal\", meaning \"of or relating to the wall of a body part, organ or cavity\"[9] The two terms are often used in describing a membrane or piece of connective tissue, referring to the opposing sides.[10]
The organ level of organisation in animals can be first detected in flatworms and the more derived phyla, i.e. the bilaterians. The less-advanced taxa (i.e. Placozoa, Porifera, Ctenophora and Cnidaria) do not show consolidation of their tissues into organs.
More complex animals are composed of different organs, which have evolved over time. For example, the liver and heart evolved in the chordates about 550-500 million years ago, while the gut and brain are even more ancient, arising in the ancestor of vertebrates, insects, molluscs, and worms about 700-650 million years ago.
Given the ancient origin of most vertebrate organs, researchers have looked for model systems, where organs have evolved more recently, and ideally have evolved multiple times independently. An outstanding model for this kind of research is the placenta, which has evolved more than 100 times independently in vertebrates, has evolved relatively recently in some lineages, and exists in intermediate forms in extant taxa.[11] Studies on the evolution of the placenta have identified a variety of genetic and physiological processes that contribute to the origin and evolution of organs, these include the re-purposing of existing animal tissues, the acquisition of new functional properties by these tissues, and novel interactions of distinct tissue types.[11]
The study of plant organs is covered in plant morphology. Organs of plants can be divided into vegetative and reproductive. Vegetative plant organs include roots, stems, and leaves. The reproductive organs are variable. In flowering plants, they are represented by the flower, seed and fruit.[citation needed] In conifers, the organ that bears the reproductive structures is called a cone. In other divisions (phyla) of plants, the reproductive organs are called strobili, in Lycopodiophyta, or simply gametophores in mosses. Common organ system designations in plants include the differentiation of shoot and root. All parts of the plant above ground (in non-epiphytes), including the functionally distinct leaf and flower organs, may be classified together as the shoot organ system.[12]
The vegetative organs are essential for maintaining the life of a plant. While there can be 11 organ systems in animals, there are far fewer in plants, where some perform the vital functions, such as photosynthesis, while the reproductive organs are essential in reproduction. However, if there is asexual vegetative reproduction, the vegetative organs are those that create the new generation of plants (see clonal colony).
Many societies have a system for organ donation, in which a living or deceased donor's organ are transplanted into a person with a failing organ. The transplantation of larger solid organs often requires immunosuppression to prevent organ rejection or graft-versus-host disease.
Beginning in the 20th century[13] organ transplants began to take place as scientists knew more about the anatomy of organs. These came later in time as procedures were often dangerous and difficult.[14] Both the source and method of obtaining the organ to transplant are major ethical issues to consider, and because organs as resources for transplant are always more limited than demand for them, various notions of justice, including distributive justice, are developed in the ethical analysis. This situation continues as long as transplantation relies upon organ donors rather than technological innovation, testing, and industrial manufacturing.[citation needed]
Plant organs are made from tissue composed of different types of tissue. The three tissue types are ground, vascular, and dermal.[16] When three or more organs are present, it is called an organ system.[17]
The adjective visceral, also splanchnic, is used for anything pertaining to the internal organs. Historically, viscera of animals were examined by Roman pagan priests like the haruspices or the augurs in order to divine the future by their shape, dimensions or other factors.[18] This practice remains an important ritual in some remote, tribal societies.
Aristotle used the word frequently in his philosophy, both to describe the organs of plants or animals (e.g. the roots of a tree, the heart or liver of an animal), and to describe more abstract \"parts\" of an interconnected whole (e.g. his logical works, taken as a whole, are referred to as the Organon).[20]
The Repertory covers the practice of United Nations organs from 1946 onwards. For the period 1946 to 31 August 1954, it consists of five volumes published in English, French and Spanish in 1955 and 1956. In the following years, the publication has been updated by means of Supplements, each covering a period of two to ten years. With a few variations, each study of individual Articles is sub-divided into a General Survey and an Analytical Summary. The General Survey captures the trend in the application and interpretation of the given Article as reflected in the legislative materials of the period. The Analytical Summary identifies or highlights relevant debates within the organization, mainly by the principal organs, on specific questions related to the application and interpretation of the given Article.
Photoacoustic tomography (PAT) can create multiscale multicontrast images of living biological structures ranging from organelles to organs. This emerging technology overcomes the high degree of scattering of optical photons in biological tissue by making use of the photoacoustic effect. Light absorption by molecules creates a thermally induced pressure jump that launches ultrasonic waves, which are received by acoustic detectors to form images. Different implementations of PAT allow the spatial resolution to be scaled with the desired imaging depth in tissue while a high depth-to-resolution ratio is maintained. As a rule of thumb, the achievable spatial resolution is on the order of 1/200 of the desired imaging depth, which can reach up to 7 centimeters. PAT provides anatomical, functional, metabolic, molecular, and genetic contrasts of vasculature, hemodynamics, oxygen metabolism, biomarkers, and gene expression. We review the state of the art of PAT for both biological and clinical studies and discuss future prospects.
A severe injury to one of your organs may cause acute organ failure. If your organ recovers, but it sustains permanent damage from the injury, that may cause chronic organ failure. Your organ may not be able to do its job as well as before. A severe injury that affects your whole body may provoke a state of shock, which stops blood flow to all of your organs. This can cause acute multiple-organ failure.
Toxins can cause both acute and chronic organ injury. They can affect any or all of your vital organs. You can get toxic poisoning from substances in your environment, from bacterial infections that produce toxins in your body or from substances that you take. Your liver and kidneys filter low levels of toxins from your blood every day. If they fail, these toxins may build up and injure your other organs. 59ce067264