Within medicine, there are a number of specialties and subspecialties one can concentrate in. Before a doctor decides on a focus, they must learn the basic sciences of medicine. Basic knowledge is essential when moving forward in one's studies, which is why doctors must attend four years of medical school before advancing to a specialty.



There are sixteen topics of introductory medical science. Anatomy, a subject often associated with doctors, is the study of the physical structures of humans. Histology is similar to anatomy, except with tissue instead of larger parts. Biochemistry and biostatistics are the applications of chemistry and statistics in a biological sense.

The study of individual cells is cytology, and genetics is studying the genes within cells. The nervous system has its own field called neuroscience, which comprises knowledge of the brain and spinal cord. Pharmacology and toxicology are both studies of drugs, except pharmacology focuses on the benefits of them while toxicology is about negative effects.

Other basic sciences include embryology, epidemiology, immunology, microbiology, nutrition, pathology, and physiology. General physicians need to have a background in all of these fields so they can appropriately refer patients to specialists.

Two broad categories exist in medicine; internal medicine and surgery. Internal medicine involves non-operative treatment of diseases and disorders through drugs and therapy. Surgery requires operative action, and is usually used in conjunction with some kind of internal medicine. Specialties branch out from both categories, while some are completely unrelated to either, such as radiology.

Cardiology is a specialty within internal medicine in which physicians concentrate on disorders related to the cardiovascular system. Subspecialties of cardiology focus on specific diseases, like coronary artery disease. In fact, most subspecialties of larger topics are dedicated to one disease.

Intensive care medicine is used with patients who are in immediate need of care or are in a life-threatening situation. Hepatology is concerned with the liver, and nephrology is concerned with the kidneys. Rheumatology involves treating joint problems, such as arthritis.

In addition to internal medicine specialties, several surgical specialties exist. Otolaryngology is surgery which comprises of head, neck, face, and certain cosmetic procedures. Surgical oncology is the use of surgery to combat cancer.

Vascular surgery involves peripheral blood vessels and the central nervous system, and cardiovascular surgery includes the heart and surrounding arteries. Transplantation is an important specialty, in which dysfunctional organs are replaced with optimal ones.

Besides the two main categories of internal medicine and surgery, a third class called diagnostic specialties exist. This type concerns itself not with curing diseases, but examining them. All laboratory sciences fall under diagnostic specialties. Cellular pathology is the study of diagnosing illnesses by utilizing samples of tissue or cells taken from patients.

Clinical microbiology involves in vitro diagnosis of diseases cause by fungi, viruses, parasites, and bacteria. Radiology is a widely known diagnostic specialty, which uses imaging technologies to diagnose and treat ailments.

Neurological disorders, which are not completely physical, require a different treatment approach than traditional diseases. Rehabilitation falls under neurology, as it is concerned with physical and mental healing after an injury or illness. Any disorder that involves the nervous system is neurological.

Therefore, all degenerative brain diseases, like Alzheimer's, are dealt with in neurology. Neurologists can specialize in specific conditions, like stroke or sleep problems, after they have completed general neurology training.