Physiology ( // ; from Ancient Greek φύσις (physis), meaning 'nature, origin',and-λογία (-logia), meaning 'study of' ) is the scientific study of the functions and mechanisms which work within a living system.
In biology, function has been defined in many ways. In physiology, it is simply what an organ, tissue, cell or molecule does. In evolutionary biology, it is the reason some object or process occurred in a system that evolved through natural selection. That reason is typically that it achieves some result, such as that chlorophyll helps to capture the energy of sunlight in photosynthesis. Hence, the organism that contains it is more likely to survive and reproduce, in other words the function increases the organism's fitness. A characteristic that assists in evolution is called an adaptation; other characteristics may be non-functional spandrels, though these in turn may later be co-opted by evolution to serve new functions.
In the science of biology, a mechanism is a system of causally interacting parts and processes that produce one or more effects. Scientists explain phenomena by describing mechanisms that could produce the phenomena. For example, natural selection is a mechanism of biological evolution; other mechanisms of evolution include genetic drift, mutation, and gene flow. In ecology, mechanisms such as predation and host-parasite interactions produce change in ecological systems. In practice, no description of a mechanism is ever complete because not all details of the parts and processes of a mechanism are fully known. For example, natural selection is a mechanism of evolution that includes countless, inter-individual interactions with other individuals, components, and processes of the environment in which natural selection operates.
Life is a characteristic that distinguishes physical entities that have biological processes, such as signaling and self-sustaining processes, from those that do not, either because such functions have ceased, or because they never had such functions and are classified as inanimate. Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria. The criteria can at times be ambiguous and may or may not define viruses, viroids, or potential synthetic life as "living". Biology is the science concerned with the study of life.
As a sub-discipline of biology, the focus of physiology is on how organisms, organ systems, organs, cells, and biomolecules carry out the chemical and physical functions that exist in a living system.
The branches of science, also referred to as sciences, "scientific fields", or "scientific disciplines," are commonly divided into three major groups:
Biology is the natural science that studies life and living organisms, including their physical structure, chemical processes, molecular interactions, physiological mechanisms, development and evolution. Despite the complexity of the science, there are certain unifying concepts that consolidate it into a single, coherent field. Biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the creation and extinction of species. Living organisms are open systems that survive by transforming energy and decreasing their local entropy to maintain a stable and vital condition defined as homeostasis.
In biology, an organism is any individual entity that propagates the properties of life. It is a synonym for "life form".
Central to an understanding of physiological functioning is the investigation of the fundamental biophysical and biochemical phenomena, the coordinated homeostatic control mechanisms, and the continuous communication between cells.
In biology, homeostasis is the state of steady internal physical and chemical conditions maintained by living systems. This dynamic state of equilibrium is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set limits. Other variables include the pH of extracellular fluid, the concentrations of sodium, potassium and calcium ions, as well as that of the blood sugar level, and these need to be regulated despite changes in the environment, diet, or level of activity. Each of these variables is controlled by one or more regulators or homeostatic mechanisms, which together maintain life.
Cell signaling is part of any communication process that governs basic activities of cells and coordinates all cell actions. The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity, as well as normal tissue homeostasis. Errors in signaling interactions and cellular information processing are responsible for diseases such as cancer, autoimmunity, and diabetes. By understanding cell signaling, diseases may be treated more effectively and, theoretically, artificial tissues may be created.
The physiologic state is the condition occurring from normal body function, while the pathological state is centered on the abnormalities that occur in animal diseases, including humans.
Pathology is the study of the causes and effects of disease or injury. The word pathology also refers to the study of disease in general, incorporating a wide range of bioscience research fields and medical practices. However, when used in the context of modern medical treatment, the term is often used in a more narrow fashion to refer to processes and tests which fall within the contemporary medical field of "general pathology," an area which includes a number of distinct but inter-related medical specialties that diagnose disease, mostly through analysis of tissue, cell, and body fluid samples. Idiomatically, "a pathology" may also refer to the predicted or actual progression of particular diseases, and the affix path is sometimes used to indicate a state of disease in cases of both physical ailment and psychological conditions. A physician practicing pathology is called a pathologist.
According to the type of investigated organisms, the field can be divided into, animal physiology (including that of humans), plant physiology, cellular physiology and microbial physiology.
In taxonomy, Homo sapiens is the only extant human species. The name is Latin for "wise man" and was introduced in 1758 by Carl Linnaeus.
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology, plant ecology, phytochemistry, cell biology, genetics, biophysics and molecular biology.
Cell physiology is the biological study about the activities that take place in a cell to keep it alive. This includes, among animal cells, plant cells and microorganisms. The term "physiology" refers to all the normal functions that take place in a living organism. All of these activities in the cell could be counted as following ; nutrition, environmental response, cell growth, cell division, reproduction and differentiation. The differences among the animal cell, plant cell and microorganisms shows the essential functional similarity even though those cells have different structures. Absorption of water by roots, production of food in the leaves, and growth of shoots towards light are examples of plant physiology. The heterotrophic metabolism of food derived from plants and animals and the use of movement to obtain nutrients are characteristic of animal physiology.
The Nobel Prize in Physiology or Medicine is awarded to those who make significant achievements in this discipline by the Royal Swedish Academy of Sciences.
The Nobel Prize in Physiology or Medicine, administered by the Nobel Foundation, is awarded yearly for outstanding discoveries in the fields of life sciences and medicine. It is one of five Nobel Prizes established in his will in 1895 by Swedish chemist Alfred Nobel, the inventor of dynamite. Nobel was interested in experimental physiology and wanted to establish a prize for scientific progress through laboratory discoveries. The Nobel Prize is presented at an annual ceremony on 10 December, the anniversary of Nobel's death, along with a diploma and a certificate for the monetary award. The front side of the medal displays the same profile of Alfred Nobel depicted on the medals for Physics, Chemistry, and Literature. The reverse side is unique to this medal. The most recent Nobel prize was announced by Karolinska Institute on 1 October 2018, and has been awarded to American James P. Allison and Japanese Tasuku Honjo – for their discovery of cancer therapy by inhibition of negative immune regulation.
The Royal Swedish Academy of Sciences is one of the royal academies of Sweden. Founded on June 2, 1739, it is an independent, non-governmental scientific organization which takes special responsibility for promoting the natural sciences and mathematics and strengthen their influence in society, whilst endeavouring to promote the exchange of ideas between various disciplines.
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Human physiology seeks to understand the mechanisms that work to keep the human body alive and functioning,through scientific enquiry into the nature of mechanical, physical, and biochemical functions of humans, their organs, and the cells of which they are composed. The principal level of focus of physiology is at the level of organs and systems within systems. The endocrine and nervous systems play major roles in the reception and transmission of signals that integrate function in animals. Homeostasis is a major aspect with regard to such interactions within plants as well as animals. The biological basis of the study of physiology, integration refers to the overlap of many functions of the systems of the human body, as well as its accompanied form. It is achieved through communication that occurs in a variety of ways, both electrical and chemical.
Changes in physiology can impact the mental functions of individuals. Examples of this would be the effects of certain medications or toxic levels of substances.Change in behavior as a result of these substances is often used to assess the health of individuals.
Much of the foundation of knowledge in human physiology was provided by animal experimentation. Due to the frequent connection between form and function, physiology and anatomy are intrinsically linked and are studied in tandem as part of a medical curriculum.
Plant physiology is a subdiscipline of botany concerned with the functioning of plants. Closely related fields include plant morphology, plant ecology, phytochemistry, cell biology, genetics, biophysics, and molecular biology. Fundamental processes of plant physiology include photosynthesis, respiration, plant nutrition, tropisms, nastic movements, photoperiodism, photomorphogenesis, circadian rhythms, seed germination, dormancy, and stomata function and transpiration. Absorption of water by roots, production of food in the leaves, and growth of shoots towards light are examples of plant physiology.
Although there are differences between animal, plant, and microbial cells, the basic physiological functions of cells can be divided into the processes of cell division, cell signaling, cell growth, and cell metabolism.
Microorganisms can be found almost everywhere on Earth.Types of microorganisms include archaea, bacteria, eukaryotes, protists, fungi, and micro-plants. Microbes are important in human culture and health in many ways, serving to ferment foods, treat sewage, produce fuel, enzymes and other bioactive compounds. They are essential tools in biology as model organisms and have been put to use in biological warfare and bioterrorism. They are a vital component of fertile soils. In the human body microorganisms make up the human microbiota including the essential gut flora. They are the pathogens responsible for many infectious diseases and as such are the target of hygiene measures. Most microorganisms can reproduce rapidly, and bacteria are also able to freely exchange genes through conjugation, transformation and transduction, even between widely divergent species.
The study of human physiology as a medical field originates in classical Greece, at the time of Hippocrates (late 5th century BC). AD), known as Galen of Pergamum, was the first to use experiments to probe the functions of the body. Unlike Hippocrates, Galen argued that humoral imbalances can be located in specific organs, including the entire body. His modification of this theory better equipped doctors to make more precise diagnoses. Galen also played off of Hippocrates idea that emotions were also tied to the humours, and added the notion of temperaments: sanguine corresponds with blood; phlegmatic is tied to phlegm; yellow bile is connected to choleric; and black bile corresponds with melancholy. Galen also saw the human body consisting of three connected systems: the brain and nerves, which are responsible for thoughts and sensations; the heart and arteries, which give life; and the liver and veins, which can be attributed to nutrition and growth. Galen was also the founder of experimental physiology. And for the next 1,400 years, Galenic physiology was a powerful and influential tool in medicine.Outside of Western tradition, early forms of physiology or anatomy can be reconstructed as having been present at around the same time in China, India and elsewhere. Hippocrates incorporated his belief system called the theory of humours, which consisted of four basic substance: earth, water, air and fire. Each substance is known for having a corresponding humour: black bile, phlegm, blood and yellow bile, respectively. Hippocrates also noted some emotional connections to the four humours, which Claudius Galenus would later expand on. The critical thinking of Aristotle and his emphasis on the relationship between structure and function marked the beginning of physiology in Ancient Greece. Like Hippocrates, Aristotle took to the humoral theory of disease, which also consisted of four primary qualities in life: hot, cold, wet and dry. Claudius Galenus (c. 130–200
Jean Fernel (1497–1558), a French physician, introduced the term "physiology".Galen, Ibn al-Nafis, Michael Servetus, Realdo Colombo, Amato Lusitano and William Harvey, are credited as making important discoveries in the circulation of the blood. Santorio Santorio in 1610s was the first to use a device to measure the pulse rate (the pulsilogium), and a thermoscope to measure temperature.
In 1791 Luigi Galvani described the role of electricity in nerves of dissected frogs. In 1811, César Julien Jean Legallois studied respiration in animal dissection and lesions and found the center of respiration in the medulla oblongata. In the same year, Charles Bell finished work on what would later become known as the Bell-Magendie law, which compared functional differences between dorsal and ventral roots of the spinal cord. In 1824, François Magendie described the sensory roots and produced the first evidence of the cerebellum’s role in equilibration to complete the Bell-Magendie law.
In the 1820s, the French physiologist Henri Milne-Edwards introduced the notion of physiological division of labor, which allowed to "compare and study living things as if they were machines created by the industry of man." Inspired in the work of Adam Smith, Milne-Edwards wrote that the "body of all living beings, whether animal or plant, resembles a factory ... where the organs, comparable to workers, work incessantly to produce the phenomena that constitute the life of the individual." In more differentiated organisms, the functional labor could be apportioned between different instruments or systems (called by him as appareils).
In 1858, Joseph Lister studied the cause of blood coagulation and inflammation that resulted after previous injuries and surgical wounds. He later discovered and implemented antiseptics in the operating room, and as a result decreased death rate from surgery by a substantial amount.
The Physiological Society was founded in London in 1876 as a dining club.The American Physiological Society (APS) is a nonprofit organization that was founded in 1887. The Society is, "devoted to fostering education, scientific research, and dissemination of information in the physiological sciences."
In 1891, Ivan Pavlov performed research on "conditional responses" that involved dogs' saliva production in response to a bell and visual stimuli.
In the 19th century, physiological knowledge began to accumulate at a rapid rate, in particular with the 1838 appearance of the Cell theory of Matthias Schleiden and Theodor Schwann. It radically stated that organisms are made up of units called cells. Claude Bernard's (1813–1878) further discoveries ultimately led to his concept of milieu interieur (internal environment),which would later be taken up and championed as "homeostasis" by American physiologist Walter B. Cannon in 1929. By homeostasis, Cannon meant "the maintenance of steady states in the body and the physiological processes through which they are regulated." In other words, the body's ability to regulate its internal environment. William Beaumont was the first American to utilize the practical application of physiology.
Nineteenth century physiologists such as Michael Foster, Max Verworn, and Alfred Binet, based on Haeckel's ideas, elaborated what came to be called "general physiology", a unified science of life based on the cell actions,later renamed in the 20th century as cell biology.
In the 20th century, biologists became interested in how organisms other than human beings function, eventually spawning the fields of comparative physiology and ecophysiology.Major figures in these fields include Knut Schmidt-Nielsen and George Bartholomew. Most recently, evolutionary physiology has become a distinct subdiscipline.
In 1920, August Krogh won the Nobel Prize for discovering how, in capillaries, blood flow is regulated.
In 1954, Andrew Huxley and Hugh Huxley, alongside their research team, discovered the sliding filaments in skeletal muscle, known today as the sliding filament theory.
Recently, there have been intense debates about the vitality of physiology as a discipline (Is it dead or alive?).If physiology is perhaps less visible nowadays than during the golden age of the 19th century, it is in large part because the field has given birth to some of the most active domains of today's biological sciences, such as neuroscience, endocrinology, and immunology. Furthermore, physiology is still often seen as an integrative discipline, which can put together into a coherent framework data coming from various different domains.
Initially, women were largely excluded from official involvement in any physiological society. The American Physiological Society, for example, was founded in 1887 and included only men in its ranks.In 1902, the American Physiological Society elected Ida Hyde as the first female member of the society. Hyde, a representative of the American Association of University Women and a global advocate for gender equality in education, attempted to promote gender equality in every aspect of science and medicine.
Soon thereafter, in 1913, J.S. Haldane proposed that women be allowed to formally join The Physiological Society, which had been founded in 1876. 978-0-9933410-0-7)On 3 July 1915, six women were officially admitted: Florence Buchanan, Winifred Cullis, Ruth C. Skelton, Sarah C. M. Sowton, Constance Leetham Terry, and Enid M. Tribe. The centenary of the election of women was celebrated in 2015 with the publication of the book "Women Physiologists: Centenary Celebrations And Beyond For The Physiological Society." ( ISBN
Prominent women physiologists include:
There are many ways to categorize the subdiscplines of physiology:
Anatomy is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science which deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology, embryology, comparative anatomy, evolutionary biology, and phylogeny, as these are the processes by which anatomy is generated over immediate (embryology) and long (evolution) timescales. Anatomy and physiology, which study (respectively) the structure and function of organisms and their parts, make a natural pair of related disciplines, and they are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine.
Biology – The natural science that involves the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy.
Aelius Galenus or Claudius Galenus, often Anglicized as Galen and better known as Galen of Pergamon, was a Greek physician, surgeon and philosopher in the Roman Empire. Arguably the most accomplished of all medical researchers of antiquity, Galen influenced the development of various scientific disciplines, including anatomy, physiology, pathology, pharmacology, and neurology, as well as philosophy and logic.
Neuroscience is the scientific study of the nervous system. It is a multidisciplinary branch of biology that combines physiology, anatomy, molecular biology, developmental biology, cytology, mathematical modeling and psychology to understand the fundamental and emergent properties of neurons and neural circuits. The understanding of the biological basis of learning, memory, behavior, perception, and consciousness has been described by Eric Kandel as the "ultimate challenge" of the biological sciences.
Zoology is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. The term is derived from Ancient Greek ζῷον, zōion, i.e. "animal" and λόγος, logos, i.e. "knowledge, study".
The history of anatomy extends from the earliest examinations of sacrificial victims to the sophisticated analyses of the body performed by modern scientists. The study of human anatomy can be traced back thousands of years, at least to the Egyptians, but the science of anatomy, as we know it today, did not develop until far later. The development of the study of anatomy gradually built upon concepts that were understood during the time of Galen and slowly became a part of the traditional medical curriculum. It has been characterized, over time, by a continually developing understanding of the functions of organs and structures in the body.
The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body.
Organs are groups of tissues with similar functions. Plant and animal life relies on many organs that coexist in organ systems.
Carl Ferdinand Cori, ForMemRS was a Czech-American biochemist and pharmacologist born in Prague who, together with his wife Gerty Cori and Argentine physiologist Bernardo Houssay, received a Nobel Prize in 1947 for their discovery of how glycogen – a derivative of glucose – is broken down and resynthesized in the body, for use as a store and source of energy. In 2004, both were designated a National Historic Chemical Landmark in recognition of their work that elucidated carbohydrate metabolism.
George Emil Palade ForMemRS HonFRMS was a Romanian-American cell biologist. Described as "the most influential cell biologist ever", in 1974 he was awarded the Nobel Prize in Physiology and Medicine along with Albert Claude and Christian de Duve. The prize was granted for his innovations in electron microscopy and cell fractionation which together laid the foundations of modern molecular cell biology, the most notable discovery being the ribosomes of the endoplasmic reticulum – which he first described in 1955.
Schack August Steenberg Krogh was a Danish professor at the department of zoophysiology at the University of Copenhagen from 1916 to 1945. He contributed a number of fundamental discoveries within several fields of physiology, and is famous for developing the Krogh Principle.
Bert Sakmann is a German cell physiologist. He shared the Nobel Prize in Physiology or Medicine with Erwin Neher in 1991 for their work on "the function of single ion channels in cells," and invention of the patch clamp. Bert Sakmann was Professor at Heidelberg University and is an Emeritus Scientific Member of the Max Planck Institute for Medical Research in Heidelberg, Germany. Since 2008 he leads an emeritus research group at the Max Planck Institute of Neurobiology.
Martin Rodbell was an American biochemist and molecular endocrinologist who is best known for his discovery of G-proteins. He shared the 1994 Nobel Prize in Physiology or Medicine with Alfred G. Gilman for "their discovery of G-proteins and the role of these proteins in signal transduction in cells." According to a Plaque posted in Silver Spring Maryland, Dr. Martin Rodbell was a "Nobel Laureate in medicine for discovering that cells were like computer chips."
A biologist is a scientist who has specialized knowledge in the field of biology, the scientific study of life. Biologists involved in fundamental research attempt to explore and further explain the underlying mechanisms that govern the functioning of living matter. Biologists involved in applied research attempt to develop or improve more specific processes and understanding, in fields such as medicine and industry.
A biological system is a complex network of biologically relevant entities. Biological organization spans several scales and are determined based different structures depending on what the system is. Examples of biological systems at the macro scale are populations of organisms. On the organ and tissue scale in mammals and other animals, examples include the circulatory system, the respiratory system, and the nervous system. On the micro to the nanoscopic scale, examples of biological systems are cells, organelles, macromolecular complexes and regulatory pathways. A biological system is not to be confused with a living system, such as a living organism.
The history of biochemistry can be said to have started with the ancient Greeks who were interested in the composition and processes of life, although biochemistry as a specific scientific discipline has its beginning around the early 19th century. Some argued that the beginning of biochemistry may have been the discovery of the first enzyme, diastase, in 1833 by Anselme Payen, while others considered Eduard Buchner's first demonstration of a complex biochemical process alcoholic fermentation in cell-free extracts to be the birth of biochemistry. Some might also point to the influential work of Justus von Liebig from 1842, Animal chemistry, or, Organic chemistry in its applications to physiology and pathology, which presented a chemical theory of metabolism, or even earlier to the 18th century studies on fermentation and respiration by Antoine Lavoisier.
The Department of Physiology, Development and Neuroscience, (PDN) is a part of the School of Biological Sciences at the University of Cambridge. Research in PDN focuses on three main areas: Cellular and Systems Physiology, Developmental and Reproductive Biology, and Neuroscience and is currently headed by Sarah Bray and William Colledge. The department was formed on 1 January 2006, within the School of Biological Sciences at the University of Cambridge from the merger of the Departments of Anatomy and Physiology. The department hosts the Centre for Trophoblast Research and has links with the Cambridge Centre for Brain Repair, the Cambridge Stem Cell Institute, and the Gurdon Institute.
The following outline is provided as an overview of and topical guide to physiology:
Together with physiology and biochemistry, anatomy is one of the basic sciences that are to be taught in the medical curriculum.
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