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Medicine is a branch of health science concerned with maintaining human health and restoring it by treating disease and injury; it is both an area of knowledge, a science of body systems and diseases and their treatment, and the applied practice of that knowledge.

The practice of medical care is shared between the medical profession—physicians or doctors—and other groups of professionals, such as nurses or pharmacists (sometimes called allied health professions). Historically, only members of the medical profession proper have been considered to actually practice medicine in the strictest sense, in contrast to the allied fields of health care professionals. The medical profession is the social and occupational structure of the group of people formally trained and authorized to apply medical knowledge. Many countries and legal jurisdictions have legal limitations on who may practice medicine or the allied medical fields.

Medicine is typically seen as composed of various specialized sub-branches, such as pediatrics, gynecology, neurology, dealing with particular body systems, diseases, or areas of health.

Systems of medical and healthcare practices have existed among human societies since at least the dawn of recorded history. These systems have developed in various ways in different cultures and regions. Medicine as understood in the modern period has historically been considered to be the mainstream tradition which developed in the Western world since the early modern age. Many other traditions of medicine and healthcare are still widely practiced throughout the world, most of which are still considered to be separate and distinct from Western medicine, also called biomedicine or the Hippocratic tradition. The most highly developed systems of medicine outside the Western system are the Ayurvedic tradition of India and traditional Chinese medicine. Various non-mainstream traditions of health care have also developed in the Western world distinct from mainstream medicine. The various other systems practiced among various cultures are sometimes practiced alongside or in cooperation with Western medicine, while sometimes being seen as competing traditions.

Veterinary medicine is the practice of health care specialized for other animal species.


History of medicine

Main article: History of medicine

Medicine as it is practiced now is rooted in various traditions, but developed mainly in the late 18th and early 19th century in Germany (Rudolf Virchow) and France (Jean-Martin Charcot, Claude Bernard and others). The new, "scientific" medicine replaced earlier Western traditions of medicine, mostly based on the "four humours" and other pre-modern theories. The focal points of development of clinical medicine shifted to the United Kingdom and the USA by the early 1900s (Sir William Osler, Harvey Cushing).

Evidence-based medicine is the recent movement to link the practice and the science of medicine more closely through the use of the scientific method and modern information science.

Genomics and knowledge of human genetics is already having a large influence on medicine, as the causative geness of most monogenic genetic disorders have now identified, and the development of techniques in molecular biology and genetics are influencing medical practice and decision-making.

Practice of medicine

The practice of medicine combines both science and art. Science and technology are the evidence base for many clinical problems for the general population at large. The art of medicine is the application of this medical knowledge in combination with intuition and clinical judgment to determine the proper diagnoses and treatment plan for this unique patient and to treat the patient accordingly.

Central to medicine is the patient-doctor relationship established when a person with a health concern or problem seeks the help of a physician (i.e. the medical encounter). Other health professionals similarly establish a relationship with a patient and may perform interventions from their perspective, e.g. nurses, radiographers and therapists.

As part of the medical encounter, the doctor needs to:

  • develop a relationship with the patient
  • gather data (medical history and physical examination combined with laboratory or imaging studies)
  • analyze and synthesize that data (assessment and/or differential diagnosis), and then
  • develop a treatment plan (further testing, therapy, watchful observation, referral and follow-up)
  • treat the patient accordingly
  • assess the progress of treatment and alter the plan as necessary.

The medical encounter is documented in a medical record, which is a legal document in many jurisdictions. One method that is used is called the problem-oriented medical record (POMR), which includes a problem list of diagnoses and a "SOAP" method of documentation for each visit:

  • S - Subjective, the medical history of the problem from the point-of-view of the patient.
  • O - Objective, the physical examination and any laboratory or imaging studies.
  • A - Assessment, is the medical decision-making process including the differential diagnoses and most probable diagnoses.
  • P - Plan, the way resolve the problem and monitor progress

Medical systems

Medicine is practiced within the medical system of a particular culture or government. Leaving aside tribal cultures, the most significant divide in developed countries is that between universal health care and the market based health care (such as practiced in the U.S.).

Patient-doctor relationship

The doctor-patient relationship and interaction is a central process in the practice of medicine. There are many perspectives from which to understand and describe it.

An idealized physician's perspective, such as is taught in medical school, sees the core aspects of the process as the physician learning from the patient his symptoms, concerns and values; in response the physician examines the patient, interprets the symptoms, and formulates a diagnosis to explain the symptoms and their cause to the patient and to propose a treatment. In more detail, the patient presents a set of complaints or concerns about his health to the doctor, who then obtains further information about the patient's symptoms, previous state of health, living conditions, and so forth, and then formulates a diagnosis and enlists the patient's agreement to a treatment plan. Importantly, during this process the doctor educates the patient about the causes, progression, outcomes, and possible treatments of his ailments, as well as often providing advice for maintaining health. This teaching relationship is the basis of calling the physician doctor, which originally meant "teacher" in Latin. The patient-doctor relationship is additionally complicated by the patient's suffering (patient derives from the Latin patiens, "suffering") and limited ability to relieve it on his own. The doctor's expertise comes from his knowledge about, or experience with, other people who have suffered similar symptoms, and his presumed ability to relieve it with medicines or other therapies about which the patient may initially have little knowledge.

The doctor-patient relationship can be analyzed from the perspective of ethical concerns, in terms of how well the goals of non-maleficence, beneficence, autonomy, and justice are achieved. Many other values and ethical issues can be added to these. In different societies, periods, and cultures, different values may be assigned different priorities. For example, in the last 30 years medical care in the Western World has increasingly emphasized patient autonomy in decision making.

The relationship and process can also be analyzed in terms of social power relationships (e.g., by Michel Foucault), or economic transactions. Physicians have been accorded gradually higher status and respect over the last century, and they have been entrusted with control of access to prescription medicines as a public health measure. This represents a concentration of power and carries both advantages and disadvantages to particular kinds of patients with particular kinds of conditions. A further twist has occurred in the last 25 years as costs of medical care have risen, and a third party (an insurance company or government agency) now often insists upon a share of decision-making power for a variety of reasons, reducing freedom of choice of both doctors and patients in many ways.

The quality of the patient-doctor relationship is important to both parties. The better the relationship in terms of mutual respect, knowledge, trust, shared values and perspectives about disease and life, and time available, the better will be the amount and quality of information about the patient's disease transferred in both directions, enhancing accuracy of diagnosis and increasing the patient's knowledge about the disease.

In some settings, e.g. the hospital ward, the patient-doctor relationship is much more complex, and many other people are involved when somebody is ill: relatives, neighbors, rescue specialists, nurses, technical personnel, social workers and others.

Clinical skills

Main articles: Medical history, Physical examination.

A complete medical evaluation includes a medical history, a physical examination, appropriate laboratory or imaging studies, analysis of data and medical decision making to obtain diagnoses, and treatment plan.

The components of the medical history are:

  • Chief complaint (CC) - the reason for the current medical visit.
  • History of present illness (HPI) - the chronological order of events of symptoms. A mnemonic PQRST is sometimes helpful in obtaining the history:
    • Provocative-palliative factors - what makes a symptom worse or better.
    • Quality - description of the symptom
    • Region - which part of the body is affected
    • Severity - what is the intensity of the symptom; using a scale of 0-10 (10 worst)
    • Timing - what is the course of the symptom
  • Current activity - occupation, hobbies, what the patient actually does.
  • Medications - what drugs including OTCs, and home remedies, as well as herbal remedies such as St. John's Wort. Allergies are recorded.
  • Past medical history (PMH/PMHx) - other medical diagnoses, past hospitalizations and operations, injuries, past infectious diseases and/or vaccinations, history of known allergies.
  • Review of systems (ROS) - an outline of additional symptoms to ask which may be missed on HPI, generally following the body's main organ systems (heart, lungs, digestive tract, urinary tract, etc).
  • Social history (SH) - birthplace, residences, marital history, social and economic status, habits (including diet, drugs, tobacco, alcohol).
  • Family history (FH) - listing of diseases in the family that may impact the patient. A family tree is sometimes used.

The physical examination is the examination of the patient looking for signs of disease. The doctor uses his senses of sight, hearing, touch, and sometimes smell (taste has been made redundant by the availability of modern lab tests). Four chief methods are used: inspection, palpation, percussion, and auscultation; smelling may be useful (e.g. infection, uremia, diabetic ketoacidosis). The clinical examination involves study of:

  • Vital signs include height, weight, body temperature, blood pressure, pulse, respiration rate, hemoglobin oxygen saturation
  • General appearance of the patient
  • Skin
  • Head, eye, ear, nose, and throat (HEENT)
  • Cardiovascular - heart and blood vessels
  • Respiratory - lungs
  • Abdomen and rectosigmoid
  • Genitalia
  • Spine and extremities - musculoskeletal
  • Neurological and psychiatric

Laboratory and imaging studies results may be obtained, if necessary.

The medical decision-making (MDM) process involves analysis and synthesis of all the above data to come up with a list of possible diagnoses (the differential diagnoses), along with an idea of what needs to be done to obtain a definitive diagnosis that would explain the patient's problem.

The treatment plan may include ordering additional laboratory tests and studies, starting therapy, referral to a specialist, or watchful observation. Follow-up may be advised.

This process is used by primary care providers as well as specialists. It may take only a few minutes if the problem is simple and straightforward. On the other hand, it may take weeks in a patient who has been hospitalized with multi-system problems, with involvement by several specialists.

On subsequent visits, the process may be repeated in an abbreviated manner to obtain any new history, symptoms, physical findings, and lab or imaging results or specialist consultations.

Settings where medical care is delivered

See also clinic, hospital, and hospice

Medicine is a diverse field and the provision of medical care is therefore provided in a variety of locations.

Primary care medical services are provided by physicians or other health professionals who has first contact with a patient seeking medical treatment or care. These occur in physician's office, clinics, nursing homes, schools, home visits and other places close to patients. About 90% of medical visits can be treated by the primary care provider. These include treatment of acute and chronic illnesses, preventive care and health education for all ages and both sex.

Secondary care medical services are provided by medical specialists in their offices or clinics or at local community hospitals for a patient referred by a primary care provider who first diagnosed or treated the patient. Referrals are made for those patients who required the expertise or procedures performed by specialists. These include both ambulatory care and inpatient services, emergency rooms, intensive care medicine, surgery services, physical therapy, labor and delivery, endoscopy units, diagnostic laboratory and medical imaging services, hospice centers, etc. Some primary care providers may also take care of hospitalized patients and deliver babies in a secondary care setting.

Tertiary care medical services are provided by specialist hospitals or regional centers equipped with diagnostic and treatment facilities not generally available at local hospitals. These include trauma centers, burn treatment centers, advanced neonatology unit services, organ transplants, high-risk pregnancy, radiation oncology, etc.

Modern medical care also depends on information - still delivered in many health care settings on paper records, but increasingly nowadays by electronic means.

Branches of medicine

Working together as an interdisciplinary team, many highly trained health professionals besides medical practitioners are involved in the delivery of modern health care. Some examples include: nurses, laboratory scientists, pharmacists, physiotherapists, speech therapists, occupational therapists, dietitians and bioengineers.

The scope and sciences underpinning human medicine overlap many other fields. Dentistry and psychology, while separate disciplines from medicine, are sometimes also considered medical fields. Physician assistants, nurse practitioners and midwives treat patients and prescribe medication in many legal jurisdictions. Veterinary medicine applies similar techniques to the care of animals.

Medical doctors have many specializations and subspecializations which are listed below.

Basic sciences

  • Anatomy is the study of the physical structure of organisms. In contrast to macroscopic or gross anatomy, cytology and histology are concerned with microscopic structures.
  • Biochemistry is the study of the chemistry taking place in living organisms, especially the structure and function of their chemical components.
  • Biostatistics is the application of statistics to biological fields in the broadest sense. A knowledge of biostatistics is essential in the planning, evaluation, and interpretation of medical research. It is also fundamental to epidemiology and evidence-based medicine.
  • Cytology is the microscopic study of individual cells.
  • Embryology is the study of the early development of organisms.
  • Epidemiology is the study of the demographics of disease processes, and includes, but is not limited to, the study of epidemics.
  • Genetics is the study of genes, and their role in biological inheritance.
  • Histology is the study of the structures of biological tissues by light microscopy, electron microscopy and immunohistochemistry.
  • Immunology is the study of the immune system, which includes the innate and adaptive immune system in human, for example.
  • Microbiology is the study of microorganisms, including protozoa, bacteria, fungi, and viruses.
  • Neuroscience is a comprehensive term for those disciplines of science that are related to the study of the nervous system. A main focus of neuroscience is the biology and physiology of the human brain.
  • Nutrition is the study of the relationship of food and drink to health and disease, especially in determining an optimal diet. Medical nutrition therapy is done by dietitians and is prescribed for diabetes, cardiovascular diseases, weight and eating disorders, allergies, malnutrition and neoplastic diseases.
  • Pathology is the study of disease - the causes, course, progression and resolution thereof.
  • Pharmacology is the study of drugs and their actions.
  • Physiology is the study of the normal functioning of the body and the underlying regulatory mechanisms.
  • Toxicology is the study of hazardous effects of drugs and poisons.

Diagnostic specialties

Clinical disciplines

  • Anesthesiology (AE), Anaesthesia (BE), is the clinical discipline concerned with providing anesthesia. Pain medicine is often practiced by specialised anesthesiologists.
  • Emergency medicine is concerned with the diagnosis and treatment of acute or life-threatening conditions, including trauma, surgical, medical, pediatric, and psychiatric emergencies.
  • General practice or family medicine or primary care is, in many countries, the first port-of-call for patients with non-emergency medical problems. Family doctors are usually able to treat over 90% of all complaints without referring to specialists.
  • Hospital medicine is the general medical care of hospitalized patients. Doctors whose primary professional focus is hospital medicine are called hospitalists.
  • Intensive care medicine is concerned with the therapy of patients with serious and life-threatening disease or injury. Intensive care medicine employs invasive diagnostic techniques and (temporary) replacement of organ functions by technical means.
  • Internal medicine is concerned with systemic diseases of adults, i.e. those diseases that affect the body as a whole , (restrictive ,current meaning) or with all adult non-operative somatic medicine (traditional , inclisive meaning) , thus excluding pediatrics , surgery , gynaecology & obstetrics and psychiatry. There are several subdisciplines of internal medicine:
  • Obstetrics and Gynecology (often abbreviated as Ob/Gyn) are concerned respectively with childbirth and the female reproductive and associated organs. Reproductive medicine and fertility medicine are generally practiced by gynecological specialists.
  • Palliative care is a relatively modern branch of clinical medicine that deals with pain and symptom relief and emotional support in patients with terminal diseases (cancer, heart failure).
  • Pediatrics (or paediatrics) is devoted to the care of infants, children, and adolescents. Like internal medicine, there are many pediatric subspecialities for specific age ranges, organ systems, disease classes and sites of care delivery. Most subspecialities of adult medicine have a pediatric equivalent such as pediatric cardiology, pediatric endocrinology, pediatric gastroenterology, pediatric hematology, and pediatric oncology, pediatric ophthalmology, and neonatology.
  • Physical medicine and rehabilitation (or physiatry) is concerned with functional improvement after injury, illness, or congenital abnormality.
  • Preventive medicine is the branch of medicine concerned with preventing disease.
    • Community health care or public health is an aspect of health services concerned with threats to the overall health of a community based on population health analysis.
    • Occupational medicine's principal role is the provision of health advice to organisations and individuals to ensure that the highest standards of health and safety at work can be achieved and maintained.
  • Psychiatry is a branch of medicine that studies and treats mental disorders. Related non-medical fields are psychotherapy and clinical psychology. There are several subdisciplines of Psychiatry:
  • Radiation therapy is concerned with the therapeutic use of ionizing radiation and high energy elementary particle beams in patient treatment.
  • Surgical specialties - there are many medical disciplines that employ operative treatment. Some of these are highly specialized and are often not considered subdisciplines of surgery, although their naming might suggest so.
    • General surgery is traditionally defined as the specialty of surgery of the skin, endocrine glands, and abdomen (and, sometimes, the mammary glands). In some countries, it is still deemed a pre-requisite training prior to progression to training in certain sub-specialties, but lately has evolved into its own sub-specialty.
    • Cardiovascular surgery is the surgical specialty that is concerned with the heart and major blood vessels of the chest.
    • Neurosurgery is concerned with the operative treatment of diseases of the nervous system.
    • Maxillofacial surgery (technically a subspeciality of dentistry)
    • Ophthalmology deals with the diseases of the eyes and their treatment.
    • Orthopedic surgery consists on surgery of the locomotor system.
    • Otolaryngology (or otorhinolaryngology or ENT/ear-nose-throat) is concerned with treatment of ear, nose and throat disorders. The term head and neck surgery defines a closely related specialty which is concerned mainly with the surgical management of cancer of the same anatomical structures.
    • Pediatric surgery treats a wide variety of thoracic and abdominal (and sometimes urologic) diseases of childhood.
    • Plastic surgery includes aesthetic surgery (operations that are done for other than medical purposes) as well as reconstructive surgery (operations to restore function and/or appearance after traumatic or operative mutilation).
    • Surgical oncology is concerned with curative and palliative surgical approaches to cancer treatment.
    • Urology focuses on the urinary tracts of males and females, and on the male reproductive system. It is often practiced together with andrology ("men's health").
    • Vascular surgery is surgery of "peripheral" blood vessels, i.e. those outside of the chest (usually operated on by cardiovascular surgeons) and of the central nervous system (treated by neurosurgery).
  • Urgent Care focuses on delivery of unscheduled, walk-in care outside of the hospital emergency department for injuries and illnesses that are not severe enough to require care in an emergency department.

Interdisciplinary fields

Interdisciplinary sub-specialties of medicine are:

Medical education

See also Medical doctor (BE), Physician (AE), and Medical school.

Medical training involves several years of university study followed by several more years of residential practice at a hospital. Entry to a medical degree in some countries (such as the United States) requires the completion of another degree first, while in other countries (such as the United Kingdom, Australia and New Zealand) medical training can be commenced as an undergraduate degree immediately after secondary education.

The name of the medical degree gained at the end varies: some countries (e.g. the US) call it "Doctor of Medicine" (abbreviated 'M.D.'), while other countries (mostly following the British Oxbridge system) call it "Medicinæ Baccalaureus & Baccalaureus Chirurgiæ" (Latin for "Bachelor of Medicine/Bachelor of Surgery", Old English: "Chirurgie"); this is technically a double degree, frequently abbreviated 'MB BChir', 'MB ChB', 'MB BS' (or variations thereof), dependent on the medical school. In either case, graduates of a medical degree may call themselves physician. In the US and some other countries there is a parallel system of medicine which is equal in all aspects of education, legality, and practice to M.D.'s. It is called Osteopathic medicine (generic term: "osteopathy") which awards the degree of "Doctor of Osteopathic Medicine" (abbreviated 'D.O.'). In many countries, a doctorate of medicine does not require original research as does, in distinction, a Ph.D..

Once graduated from medical school most physicians (both M.D.'s and D.O.'s) begin their residency/house post training, where skills in a speciality of medicine are learned, supervised by more experienced doctors. The first year of residency is known as the "intern" year (USA) or "junior/pre-registration house officer" year (UK). The duration of residency training depends on the speciality.

A medical graduate can then enter general practice and become a general practitioner (or primary care internist in the USA); training for these is generally shorter, while specialist training is typically longer.

Medical education is a never ending endeavor. In addition to continually reading relevant medical journals, physicians require a number of continuing medical education (CME)credits annually to be recertified. These can be acquired by attending conferences, lectures, online, and through other sources.

Medical devices

See also the main articles: implant, artificial limbs, corrective lenses, cochlear implants, ocular prosthetics, facial prosthetics, somato prosthetics, surgical prosthetics, maxillo-facial prosthetics and dental implants

Medical devices are devices used by health professionals as tools in diagnosis, treatment, or other aspects of patient care.

Legal restrictions

In most countries, it is a legal requirement for medical doctors to be licensed or registered. In general, this entails a medical degree from a university and accreditation by a medical board or an equivalent national organization, which may ask the applicant to pass exams. This restricts the considerable legal authority of the medical profession to doctors that are trained and qualified by national standards. It is also intended as an assurance to patients and as a safeguard against charlatans that practice inadequate medicine for personal gain. While the laws generally require medical doctors to be trained in "evidence based", Western, or Hippocratic Medicine, they are not intended to discourage different paradigms of health and healing, such as alternative medicine or faith healing.


Criticism of medicine has a long history. In the Middle Ages, it was not considered a profession suitable for Christians, as disease was considered Godsent, and interfering with the process a form of blasphemy. Barber-surgeons generally had a bad reputation that was not to improve until the development of academic surgery as a speciality of medicine, rather than an accessory field.

Through the course of the twentieth century, doctors focused increasingly on the technology that was enabling them to make dramatic improvements in patients' health. The ensuing development of a more mechanistic, detached practice, with the perception of an attendent loss of patient-focused care led to further criticisms. This issue started to reach collective professional consciousness in the 1970s and the profession had begun to respond by the 1980s and 1990s.

Perhaps the most devastating criticism of modern medicine came from Ivan Illich, in his 1976 work Medical Nemesis. In his view, modern medicine only medicalises disease, causing loss of health and wellness, while generally failing to restore health by eliminating disease. The human being thus becomes a lifelong patient. Other less radical philosophers have voiced similar views, but none were as virulent as Illich. (Another example can be found in Technopoly: The Surrender of Culture to Technology by Neil Postman, 1992, which criticises overreliance on technological means in medicine.)

Criticism of modern medicine has led to some improvements in the curricula of medical schools, which now teach students systematically on medical ethics, holistic approaches to medicine, the biopsychosocial model and similar concepts.

The inability of modern medicine to properly address many common complaints continues to prompt many people to seek support from alternative medicine. Although most alternative approaches lack scientific validation, some report improvement of symptoms after obtaining alternative therapies. The bioscience medical paradigm and the alternative / complementary healthcare paradigms may differ to such an extent that what constitutes scientific evidence is contested. Many medical doctors also practice alternative medicine alongside the orthodox.

Medical errors are also the focus of many complaints and negative coverage. Practitioners of human factors engineering believe that there is much that medicine may usefully gain by emulating concepts in aviation safety, where it was long ago realized that it is dangerous to place too much responsibility on one "superhuman" individual and expect him or her not to make errors. Reporting systems and checking mechanisms are becoming more common in identifying sources of error and improving practice.

Radical critics of certain medical traditions may hold that whole fields or traditions of medicine are intrinsically harmful or ineffective. They would reject any use or support of practices belonging to that tradition. However, generally, there is spectrum of efficacy on which all traditions lie; some are more effective, some are less effective, but nearly all contain some harmful practices and some effective ones. Naturally, though, most individuals or groups seeking a healthcare practice to improve their own health would seek a tradition with the maximum degree of efficacy.

See also

External links

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Health science - Medicine
Anesthesiology - Dermatology - Emergency Medicine - General practice - Intensive care medicine - Internal medicine - Neurology - Obstetrics & Gynecology - Pediatrics - Podiatry - Public Health & Occupational Medicine - Psychiatry - Radiology - Surgery
Branches of Internal medicine
Cardiology - Endocrinology - Gastroenterology - Hematology - Infectious diseases - Nephrology - Oncology - Pulmonology - Rheumatology
Branches of Surgery
General surgery - Cardiothoracic surgery - Neurosurgery - Ophthalmology - Organ Transplantation - Orthopedic surgery - Otolaryngology (ENT) - Pediatric surgery - Plastic surgery - Podiatric surgery - Urology - Vascular surgery
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