Barbiturate is the name given to a drug made from barbituric acid, a combination of urea (a compound found in urine and other body fluids) and malonic acid. Barbiturates work by depressing (slowing down) the activity of nerves, muscles, heart tissue, and the brain.


Pure barium is rarely used outside the laboratory. Barium compounds are found primarily in two ores (minerals from which valuable substances, like metal, can be removed).


Biotin is a member of the vitamin B family. It is water soluble (dissolvable) and an important coenzyme.

Birth Control

Birth control, also known as contraception, is the use of physical barriers, timing, chemicals, or a combination of the three to prevent pregnancy. The vast majority of contraceptive methods are designed for use by women.

Blood Clot Dissolving Agent

Blood clots are masses of blood cells that have clumped together because of disease or injury. In cases of damage, blood platelets (roundish disks associated with clotting found in mammal blood) mass (gather together) to stop bleeding.

Blood Pressure Measuring Devices

Modern health care experts know that a patient's blood pressure is a good indicator of how healthy a person is. A high blood pressure reading indicates stress and possible heart problems.

Blood Transfusion

Blood transfusion is the process of transferring blood from one person's body to another. A severely injured person or one undergoing surgery may need extra blood to replace that which has been lost.

Blue Baby Operation

Before 1944 babies who were born with cyanosis either died or lived with painful physical defects. Cyanosis is a condition of bluish skin caused by lack of oxygen in the blood.

Breast Implants

Breast implants are designed to either enlarge existing breasts, or to reconstruct breasts after surgery. Until very recently, the vast majority of implants were made of silicone (a generic term referring to organic, or living, compounds resistant to heat, water, and many other elements).


Calcium is a chemical element and member of the alkaline-earth metals group. In its pure form, calcium is a silvery-white substance.

Cataract Surgery

A cataract is an opacity, or clouding, of the lens in the eye. The opacity can cause blurred vision and eventual blindness.

Cathode Ray Tube (CRT)

In the mid to late 1800s, the world experienced a scientific revolution. Phenomena that had never before been truly understood, such as light, heat, and electricity, were systematically explored.


Gravity can eventually separate a sediment (material that settles to the bottom of a liquid) from a liquid or separate two liquids which do not mix. The heavier element within a container sinks to the bottom, while the lighter element rises to the surface.

Cesarean Section

Cesarean section is the removal of an unborn child from the uterus by means of surgical incision through the abdominal wall. Originally practiced only on dead women, cesarean section today is a common and relatively safe birth method.


Treating or preventing any disease or medical condition with chemicals or drugs is known as chemotherapy. Many people now connect the word chemotherapy with cancer treatment, but chemotherapy was first developed for other infectious diseases, such as syphilis (a sexually transmitted disease) and diphtheria (pronounced "dif-theer-iyah"; an infectious disease in which a membrane—or thin cover—forms, usually in the throat).


Chloroform is another name for the colorless, dense, liquid chemical compound trichloromethane. It is nonflammable and has a pleasant odor and a burning, sweet taste.


Chromatography works by separating the individual parts of a mixture so that each one can be analyzed and identified. In the decades since its invention, the chromatograph has become an essential piece of equipment in bio-chemical laboratories.


A clone is a group of genetically identical cells descended from a single common ancestor. Cloning is one method for producing identical twins.


Cocaine is a powerful drug of the stimulant-euphoriant class that is obtained from an alkaloid in the leaves of the coca plant, a shrub or tree that grows in the South American countries of Peru and Bolivia. The processed drug is a white, crystalline compound called benzoylmethylecgonine.


Like morphine, codeine is an alkaloid (a naturally occurring base) of opium, a drug made from the milky juice of unripe seed capsules of the opium poppy plant. The opium poppy was once native to Asia Minor (a large penninsula in western Asia between the Black Sea and the Mediterranean), but it is now grown legally and illegally in many parts of the world.