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50-445: In physiology , medicine, and anatomy , muscle tone ( residual muscle tension or tonus ) is the continuous and passive partial contraction of the muscles , or the muscle's resistance to passive stretch during resting state. It helps to maintain posture and declines during REM sleep . Muscle tone is regulated by the activity of the motor neurons and can be affected by various factors, including age, disease, and nerve damage. If

100-649: 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

150-469: A different statin; however, they should not be ignored if they persist, as they can, in rare cases, develop into more serious problems. Coenzyme Q10 supplementation can be helpful to avoid some statin-related adverse effects, but currently there is not enough evidence to prove the effectiveness in avoiding myopathy or myalgia. Stretching, massage, and drinking plenty of liquids may be helpful in treating simple muscle cramps. The antimalarial drug quinine

200-497: 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

250-455: A medical field originates in classical Greece , at the time of Hippocrates (late 5th century BC). 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 the theory of humorism , which consisted of four basic substances: earth, water, air and fire. Each substance

300-452: A medication associated with a high incidence of leg cramps. Additional factors, which increase the probability for these side effects, are physical exercise, age, history of cramps, and hypothyroidism . Up to 80% of athletes using statins experience significant adverse muscular effects, including cramps; the rate appears to be approximately 10–25% in a typical statin-using population. In some cases, adverse effects disappear after switching to

350-565: A normal posture. Resting muscle tone varies along a bell-shaped curve . Low tone is perceived as "lax, flabby, floppy, mushy, dead weight" and high tone is perceived as "tight, light, strong". Muscles with high tone are not necessarily strong and muscles with low tone are not necessarily weak. In general, low tone does increase flexibility and decrease strength, and high tone does decrease flexibility and increase strength, but with many exceptions. A person with low tone will most likely not be able to engage in "explosive" movement such as needed in

400-474: A person is exercising or engaging in an activity where the heartbeat rises. Medical conditions associated with leg cramps are cardiovascular disease, hemodialysis, cirrhosis, pregnancy, and lumbar canal stenosis. Differential diagnoses include restless legs syndrome , claudication , myositis , and peripheral neuropathy . All of them can be differentiated through careful history and physical examination. Gentle stretching and massage , putting some pressure on

450-426: A sprinter or high jumper. These athletes usually have high tone that is within normal limits. A person with high tone will usually not be flexible in activities such as dance and yoga. Joint laxity contributes greatly to flexibility, especially with flexibility in one or a few areas, instead of overall flexibility. For example, a person can be high tone with normal to poor flexibility in most areas, but be able to put

500-441: A sudden pull or stretch occurs, the body responds by automatically increasing the muscle's tension, a reflex which helps guard against danger as well as helping maintain balance . Such near-continuous innervation can be thought of as a "default" or "steady state" condition for muscles. Both the extensor and flexor muscles are involved in the maintenance of a constant tone while at rest. In skeletal muscles, this helps maintain

550-483: A symptom or complication of pregnancy ; kidney disease; thyroid disease; hypokalemia , hypomagnesemia , or hypocalcaemia (as conditions); restless legs syndrome ; varicose veins ; and multiple sclerosis . As early as 1965, researchers observed that leg cramps and restless legs syndrome can result from excess insulin , sometimes called hyperinsulinemia . Under normal circumstances, skeletal muscles can be voluntarily controlled. Skeletal muscles that cramp

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600-430: 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

650-550: 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

700-420: Is a traditional treatment that may be slightly effective for reducing the number of cramps, the intensity of cramps, and the number of days a person experiences cramps. Quinine has not been shown to reduce the duration (length) of a muscle cramp. Quinine treatment may lead to haematologic and cardiac toxicity. Due to its low effectiveness and negative side effects, its use as a medication for treating muscle cramps

750-427: 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

800-400: Is essential for diagnosing and treating health conditions and promoting overall wellbeing. It 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

850-462: Is known for having a corresponding humor: black bile, phlegm, blood, and yellow bile, respectively. Hippocrates also noted some emotional connections to the four humors, on which Galen would later expand. 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

900-546: Is narrower than the definition of muscle spasm : spasms include any involuntary abnormal muscle contractions, while cramps are sustained and painful. True cramps can be distinguished from other cramp-like conditions. Cramps are different from muscle contracture , which is also painful and involuntary, but which is electrically silent. The main distinguishing features of cramps from dystonia are suddenness with acute onset of pain, involvement of only one muscle and spontaneous resolution of cramps or their resolution after stretching

950-401: Is no longer recommended for treatment of nocturnal leg cramps due to potential fatal hypersensitivity reactions and thrombocytopenia . Arrhythmias , cinchonism , and hemolytic uremic syndrome can also occur at higher dosages. Various medications may cause nocturnal leg cramps: Statins may sometimes cause myalgia and cramps among other possible side effects. Raloxifene (Evista) is

1000-580: 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,

1050-649: Is the scientific study of functions and mechanisms in a living system . As a subdiscipline of biology , physiology focuses on how organisms , organ systems , individual organs , cells , and biomolecules carry out chemical and physical functions in a living system. According to the classes of organisms , the field can be divided into medical physiology , animal physiology , plant physiology , cell physiology , and comparative physiology . Central to physiological functioning are biophysical and biochemical processes, homeostatic control mechanisms, and communication between cells. Physiological state

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1100-540: Is the condition of normal function. In contrast, pathological state refers to abnormal conditions , including human diseases . The Nobel Prize in Physiology or Medicine is awarded by the Royal Swedish Academy of Sciences for exceptional scientific achievements in physiology related to the field of medicine . Because physiology focuses on the functions and mechanisms of living organisms at all levels, from

1150-550: Is variable, with cramps lasting anywhere from a few seconds to several minutes. Muscle soreness may remain after the cramp itself ends. These cramps are more common in older people. They happen quite frequently in teenagers and in some people while exercising at night. Besides being painful, a nocturnal leg cramp can cause much distress and anxiety . The precise cause of these cramps is unclear. Potential contributing factors include dehydration , low levels of certain minerals ( magnesium , potassium , calcium , and sodium , although

1200-442: Is velocity-independent resistance to passive stretch (i.e. there is uniform increased tone whether the elbow is passively moved quickly or slowly). Spasticity can be in the form of the clasp-knife response , in which there is increased resistance only at the beginning or at the end of the movement. Rigidity can be of the leadpipe type, in which there is resistance throughout to passive movement, or it may be of cogwheel type, in which

1250-398: The affected leg by walking or standing, or taking a warm bath or shower may help to end the cramp. If the cramp is in the calf muscle, dorsiflexing the foot (lifting the toes back toward the shins) will stretch the muscle and provide almost immediate relief. There is limited evidence supporting the use of magnesium, calcium channel blockers , carisoprodol , and vitamin B 12 . Quinine

1300-799: The affected muscle. Restless leg syndrome is not considered the same as muscle cramps and should not be confused with rest cramps. Skeletal muscle cramps may be caused by muscle fatigue or a lack of electrolytes such as sodium (a condition called hyponatremia ), potassium (called hypokalemia ), or magnesium (called hypomagnesemia ). Some skeletal muscle cramps do not have a known cause. Motor neuron disorders (e.g., amyotrophic lateral sclerosis ), metabolic disorders (e.g., liver failure ), some medications (e.g., diuretics and inhaled beta‐agonists ), and haemodialysis may also cause muscle cramps. Causes of cramping include hyperflexion , hypoxia , exposure to large changes in temperature, dehydration, or low blood salt . Muscle cramps can also be

1350-418: 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 the 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

1400-421: 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",

1450-433: The cause of cramps is unknown. The stimulus for muscle cramps may originate in the cerebral cortex, the spinal cord, or the muscle itself. This could indicate developing pathology or other problems in the future. Physiology Physiology ( / ˌ f ɪ z i ˈ ɒ l ə dʒ i / ; from Ancient Greek φύσις ( phúsis )  'nature, origin' and -λογία ( -logía )  'study of')

1500-538: The 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

1550-417: The description of "dead weight". Physical disorders can result in abnormally low ( hypotonia ) or high ( hypertonia ) muscle tone. Another form of hypertonia is paratonia , which is associated with dementia . Hypotonia is seen in lower motor neuron disease like poliomyelitis . Hypotonia can present clinically as muscle flaccidity , where the limbs appear floppy, stretch reflex responses are decreased, and

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1600-432: 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   978-0-9933410-0-7 ) Prominent women physiologists include: Human physiology Animal physiology Plant physiology Fungal physiology Protistan physiology Algal physiology Bacterial physiology Cramp Cramp definition

1650-432: The entire limb that contains the "locked-up" muscle group. It may take up to a week for the muscle to return to a pain-free state, depending on the person's fitness level, age, and several other factors. Nocturnal leg cramps are involuntary muscle contractions that occur in the calves , soles of the feet, or other muscles in the body during the night or (less commonly) while resting. The duration of nocturnal leg cramps

1700-417: The evidence has been mixed), and reduced blood flow through muscles attendant in prolonged sitting or lying down. Nocturnal leg cramps (almost exclusively calf cramps) are considered "normal" during the late stages of pregnancy. They can, however, vary in intensity from mild to extremely painful. A lactic acid buildup around muscles can trigger cramps; however, they happen during anaerobic respiration when

1750-502: The humoral theory of disease, which also consisted of four primary qualities in life: hot, cold, wet and dry. Galen ( c.  130 –200 AD) 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

1800-458: The humors, 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

1850-410: 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

1900-402: The leaves, and growth of shoots towards light are examples of plant physiology. Human physiology is the study of how the human body's systems and functions work together to maintain a stable internal environment. It includes the study of the nervous, endocrine, cardiovascular, respiratory, digestive, and urinary systems, as well as cellular and exercise physiology. Understanding human physiology

1950-449: 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

2000-470: The limb's resistance to passive movement is also decreased. Hypertonia is seen in upper motor neuron diseases like lesions in pyramidal tract and extrapyramidal tract. Hypertonia can present clinically as either spasticity or rigidity . While spasticity is velocity-dependent resistance to passive stretch (e.g., passively moving an elbow quickly will elicit increased muscle tone, but passively moving elbow slowly may not elicit increased muscle tone), rigidity

2050-455: The molecular and cellular level to the level of whole organisms and populations, its foundations span a range of key disciplines: There are many ways to categorize the subdisciplines of 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 . Plant physiology

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2100-467: The most often are the calves , thighs , and arches of the foot , and in North America are sometimes called a " Charley horse " or a "corky". Such cramping is associated with strenuous physical activity and can be intensely painful; however, they can even occur while inactive and relaxed. Around 40% of people who experience skeletal cramps are likely to endure extreme muscle pain, and may be unable to use

2150-409: 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

2200-400: The palms of the hands on the floor with straight knees due to hypermobile sacroiliac joints. It is important to assess several areas before deciding if a person has high, low, or normal muscle tone. A fairly reliable assessment item is how the person feels when picked up. For example, small children with low tone can feel heavy while larger, high tone children feel light, which corresponds with

2250-413: The resistance to passive movement is in a jerky manner. In ophthalmology , tonus may be a central consideration in eye surgery , as in the manipulation of extraocular muscles to repair strabismus . Tonicity aberrations are associated with many diseases of the eye (e.g. Adie syndrome ). Normally, people are unaware of their muscle tone in their daily activities. The body maintains the balance between

2300-598: 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

2350-594: The tone of flexor and extensor muscle groups. Sometimes, in normal, healthy people, that tone is lost either in flexors or extensor muscle groups in isolation, temporarily and intermittently resulting in muscle cramps . Treating these extensor or flexor group of muscles in isolation can be difficult. Generally, muscle relaxants or quinine can help with cramps and is warranted when they become troublesome. But these medication cause their relaxing effect in both groups by moderating their tone. The cause of disproportionate intermittent contractions of either flexors or extensors or

2400-402: Was also the founder of experimental physiology. And for the next 1,400 years, Galenic physiology was a powerful and influential tool in medicine . 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

2450-923: 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. On 3 July 1915, six women were officially admitted: Florence Buchanan , Winifred Cullis , Ruth Skelton , Sarah C. M. Sowton , Constance Leetham Terry , and Enid M. Tribe . The centenary of

2500-410: 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. Involving evolutionary physiology and environmental physiology , comparative physiology considers the diversity of functional characteristics across organisms. The study of human physiology as

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