Physiology

thumb|300px|Left: A hormone feedback loop in a female adult human Right: Auxin transport from leaves to roots in [[Arabidopsis thaliana]]

thumb|upright=1.35|Simplified view of cellular metabolism

thumb|upright=1.5|Oil painting depicting Claude Bernard, the father of modern physiology, with his pupils

thumb|thumbtime=0:12|360px|Shadowgraph visualization of the airflow during a sneeze, comparing an unmasked sneeze with several different methods of covering one's mouth and nose: sneezing into a fist, a cupped hand, a tissue, a "coughcatcher" device, a [[surgical mask, and an N95 mask]] A sneeze (also known as sternutation) is a semi-autonomous, convulsive expulsion of air from the lungs through the nose and mouth, usually caused by foreign particles irritating the nasal mucosa. A sneeze expels air forcibly from the mouth and nose in an explosive, spasmodic involuntary action. This action allo

thumb|288px|Amandines de Provence, poster by Leonetto Cappiello, 1900, which shows a woman eating almond cookies

In biology, homeostasis (British also homoeostasis; ) is the state of steady internal physical and chemical conditions maintained by living organisms. This 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 (homeostatic range). Other variables include the pH of extracellular fluid, the concentrations of sodium, potassium, and calcium ions, as well as the blood sugar level, and these need to be regulated despite changes in the environment, diet, or level of activity. Each of t

thumb|class=skin-invert-image|Structure of the antioxidant glutathione

thumb|Mammals excrete urine through the urinary system. Excretion is elimination of metabolic waste, which is an essential process in all organisms. In vertebrates, this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the cell. For example, placental mammals expel urine from the bladder through the urethra, which is part of the excretory system. Unicellular organisms discharge waste products directly through the surface of the cell. Another example would be how mammals release solid waste (f

Hyperthermia, also known as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. According to the International Emergency Medicine Education Project, severe hyperthermia (body temperature elevation of beyond ) "becomes a medical emergency requiring immediate treatment to prevent disability or death". Almost half a million deaths are recorded every year from hyperthermia.

thumb|Statue drinking from a traditional waterskin|alt=Statue of a man drinking|upright=1.2 thumb|upright|A person drinking a glass of milk

thumb|right|240px|The field of ergonomics employs anthropometry to optimize human interaction with equipment and workplaces.

thumb|250px|Structure of a chylomicron (the largest lipoprotein). ApoA, ApoB, ApoC, ApoE are [[apolipoproteins; green particles are phospholipids; T is triglyceride; C is cholesterol ester.]]

Swallowing, also called deglutition or inglutition in scientific and medical contexts, is a physical process of an animal's digestive tract (e.g. that of a human body) that allows for an ingested substance (typically food) to pass from the mouth to the pharynx and then into the esophagus. In colloquial English, the term "swallowing" is also used to describe the action of gulping, i.e. taking in a large mouthful of food without any biting.

Acclimatization or acclimatisation (also called acclimation or acclimatation) is the process in which an individual organism adjusts to a change in its environment (such as a change in altitude, temperature, humidity, photoperiod, or pH), allowing it to maintain fitness across a range of environmental conditions. Acclimatization occurs in a short period of time (hours to weeks), and within the organism's lifetime (compared to adaptation, which is evolution, taking place over many generations). This may be a discrete occurrence (for example, when mountaineers acclimate to high altitude over hou

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thumb|400 px|Dose response curves of a full agonist, partial agonist, neutral antagonist, and inverse agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agonist, while an inverse agonist causes an action opposite to that of the agonist.

Pathophysiology (or physiopathology) is a branch of study, at the intersection of pathology and physiology, concerning disordered physiological processes that cause, result from, or are otherwise associated with a disease or injury. Pathology is the medical discipline that describes conditions typically observed during a disease state, whereas physiology is the biological discipline that describes processes or mechanisms operating within an organism. Pathology describes the abnormal or undesired condition (symptoms of a disease), whereas pathophysiology seeks to explain the functional changes

thumb|An anesthetized pig used for training a surgeon Vivisection () is surgery conducted for experimental purposes on a living organism, typically animals with a central nervous system, to view living internal structure. The word is, more broadly, used as a pejorative catch-all term for experimentation on live animals by organizations opposed to animal experimentation, but the term is rarely used by practicing scientists. Human vivisection, such as live organ harvesting, has been perpetrated as a form of torture.

chemical element whose concentration (or other measure of amount) is very low

In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions. It is a physiological state with very specific initiating and inhibiting conditions. The mechanism is a means of surviving predictable, unfavorable environmental conditions, such as temperature extremes, drought, or reduced food availability. Diapause is observed in all the life stages of arthropods, especially insects.

Acidophiles or acidophilic organisms are those that thrive under highly acidic conditions (usually at pH 5.0 or below). These organisms can be found in different branches of the tree of life, including Archaea, Bacteria, and Eukarya.

diagnostic medical tool designed to classify the form of human faeces into seven categories

biological rule that warm-blooded animals from colder climates usually have shorter limbs

thumb|250px|During winter dormancy, plant [[metabolism comes to a virtual standstill, due in part to low temperatures that slow chemical activity.]]

Hypoxemia (also spelled hypoxaemia) is an abnormally low level of oxygen in the blood. More specifically, it is oxygen deficiency in arterial blood. Hypoxemia is usually caused by pulmonary disease. Sometimes the concentration of oxygen in the air is decreased leading to hypoxemia.

thumb|300px|Diagram featuring stages of tissue healing Regarding physical trauma or disease suffered by an organism, healing involves the repairing of damaged tissue(s), organs and the biological system as a whole and resumption of (normal) functioning. Medicine includes the process by which the cells in the body regenerate and repair to reduce the size of a damaged or necrotic area and replace it with new living tissue. The replacement can happen in two ways: by regeneration in which the necrotic cells are replaced by new cells that form "like" tissue as was originally there; or by repair in

thumb|upright=1.35|When dried, terrestrial tardigrades draw in their legs and go into a cryptobiotic 'tun' state. They revive quickly when re-wetted.

Allometry (Ancient Greek "other", "measurement") is the study of the relationship of body size to shape, anatomy, physiology and behaviour, first outlined by Otto Snell in 1892, by D'Arcy Thompson in 1917 in On Growth and Form and by Julian Huxley in 1932.

Myology is the study of the muscular system, including the study of the structure, function and diseases of muscle. The muscular system consists of skeletal muscle, which contracts to move or position parts of the body (e.g., the bones that articulate at joints), smooth and cardiac muscle that propels, expels or controls the flow of fluids and contained substance.

thumb|250px|right|In the Occupational Safety and Health Administration|OSHA universe, the Exclamation Mark signifies an immediate skin, eye or respiratory tract irritant, or narcotic.

membrane transport that occurs down an electrochemical gradient and does not require energy

thumb|Cytokinesis|Cell division. All cells can be considered motile for having the ability to divide into two new daughter cells.

series of events that restore integrity to a damaged tissue, following an injury

non-directional responses to stimuli

thumb|Biofeedback device for treating posttraumatic stress disorder

study devoted to understanding the acute and chronic responses to physical activity

Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fields in a number of species. The name cryptochrome was proposed as a portmanteau combining the chromatic nature of the photoreceptor, and the cryptogamic organisms on which many blue-light studies were carried out.

Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens.

process that is characterized by a decrease in protein content, fiber diameter, force production and fatigue resistance.

Bioelectromagnetics, also known as bioelectromagnetism, is a branch of science studying the interaction between electromagnetic fields and biological entities. Areas of study include electromagnetic fields produced by living cells, tissues or organisms, the effects of man-made sources of electromagnetic fields like mobile phones, and the application of electromagnetic radiation toward therapies for the treatment of various conditions.

A stressor is a chemical or biological agent, environmental condition, external stimulus or an event seen as causing stress to an organism. Psychologically speaking, a stressor can be events or environments that individuals might consider demanding, challenging, and/or threatening individual safety.

enlargement or overgrowth of a muscle organ

thumb|A crabeater seal injured by a predator

the conversion of a stimulus sensed by a receptor cell into an electrical impulse, which is then transmitted by the nervous system – it is the absorption of energy from a stimulus and the conversion of that energy into electrical energy

describing pressure difference over an interface in fluid mechanics

Thermogenesis is the process of heat production in the metabolism of organisms. It occurs in all warm-blooded animals, and also in a few species of thermogenic plants such as the Eastern skunk cabbage, the Voodoo lily (Sauromatum venosum), and the giant water lilies of the genus Victoria. The lodgepole pine dwarf mistletoe, Arceuthobium americanum, disperses its seeds explosively through thermogenesis. Thermoregulation is an important component of a homeothermic animal's resting metabolic rate (RMR) and serves to defend body temperature within narrow limits at low or high ambient temperature.

detection of weak electric fields, via specialized sense organs and brain structures

chemical compound

in physiology

thumb|upright=1.2|Fossil skeletal parts from extinct Belemnitida|belemnite cephalopods of the [[Jurassic – these contain mineralized calcite and aragonite.]]

term for extra-cellular interstitial fluid surrounding bodily organs

shrinking or return of an organ to a former size

group of organisms, divided in relation to the nutrition mode according to the sources of energy and carbon, needed for living, growth and reproduction

Ecophysiology (from Greek , oikos, "house(hold)"; , physis, "nature, origin"; and , -logia), environmental physiology or physiological ecology is a biological discipline that studies the response of an organism's physiology to environmental conditions. It is closely related to comparative physiology and evolutionary physiology. Ernst Haeckel's coinage bionomy is sometimes employed as a synonym.

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 hi

temporary new bony tissue that forms at the ends of a fractured bone

the process of development of sex differences in humans

thumb|Migration of cranes Overwintering is the process by which some organisms pass through or wait out the winter season, or pass through that period of the year when "winter" conditions (cold or sub-zero temperatures, ice, snow, limited food supplies) make normal activity or even survival difficult or near impossible. In some cases "winter" is characterized not necessarily by cold but by dry conditions; passing through such periods could likewise be called overwintering.