Human Growth Hormone

Human growth hormone (GH), also called somatotropin, is a protein that stimulates growth. GH must be secreted (released) in just the right amount in a child for normal growth to take place.

Hydrogen Peroxide

Hydrogen peroxide is a chemical compound of hydrogen and oxygen. (It can be thought of as water with an extra oxygen atom.) Pure anhydrous hydrogen peroxide is a colorless, syrupy liquid that it rapidly decomposes into oxygen and water.


Ibuprofen is a non-steroid drug often used to treat arthritis and relieve pain, fever, and swelling. Its development resulted from a search to find a drug more potent (powerful) and better tolerated than aspirin.


An incubator is an enclosed chamber used for maintaining a living organism in a controlled environment. The ancient Egyptians and Chinese both devised incubators to hatch chicks from eggs without having the mother hen sit on them.


Inoculation is the injection of dead or weakened disease-causing bacteria or viruses into the human body in order to produce immunity against (prevent infection by) that disease. Because the organisms injected into the body are dead or weakened, they can create immunity without causing the disease.


Insulin is a hormone produced by the pancreas (a gland that releases a digestive juice into the intestine). The pancreas is composed of acinar cells, which produce digestive enzymes, and the islet cells of Langerhans, which produce hormones.


Interferon is a protein produced by animals in response to viral infections. It is a defensive mechanism by the body to prevent multiplication of the virus.

In Vitro Fertilization

In vitro fertilization (IVF) is the term used to describe the combination of egg cells and sperm in a glass petri dish in order to fertilize the eggs. "In vitro" comes from the Latin word meaning "in glass." The procedure is used to treat infertility, a condition in which, for various reasons, a woman cannot become pregnant.


Iodine is the heaviest member in a family of chemical elements called halogens. The halogen group includes fluorine, chlorine, bromine, astatine, and iodine.

Iron Lung and Other Respirators

The iron lung was invented in 1929 by Philip Drinker (1893-1977), a professor at the School of Public Health at Harvard University. The device performs the function of the muscles that control breathing.

Kidney Transplant

Replacing a kidney is a difficult process because the kidney acts as a filter for the body. Its functions are to excrete (get rid of) urine which contains the end products of metabolism and help regulate the water, electrolyte level, and the acid base content of blood.

Laparoscopic Surgery

Laparoscopic surgery has become a common method for treating a variety of abdominal medical problems. To insert the laparoscopic version of the endoscope (an endoscope is an optical instrument that allows doctors to see inside the human body; also referred to as a fiberscope), doctors make tiny incisions instead of the usual large cuts across the surgical area.

Laser Surgery

The term "laser" is an acronym for Light Amplification by the Stimulated Emission of Radiation. The elements necessary for the invention of the first laser have been around for quite some time.


Lithium is an alkali metal. It is silvery white in color.

Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging (MRI) is a tool of medical diagnosis used to examine tissues and organs inside a patient's body. MRI assembles a detailed, readable image based on the response of atoms placed within a strong magnetic field.

Magnifying Glass

The magnifying glass is one of the most ancient optical (related to the eye) devices known to science. Thousands of years ago Egyptians used chips of crystal or obsidian (a type of shiny stone) to better view small objects.


Breast cancer is one of the leading causes of death among women, but it can also affect men. Approximately one out of every nine women will develop breast cancer in their lifetime.


Methadone is used as a substitute for heroin and morphine to treat opiate addiction. To understand what methadone does, it is first necessary to understand how opiates act on the body.

Microscope, Compound

Microscopes have been in use in various forms for more than 3,000 years. The first microscopes were extremely simple magnifiers made of globes of water-filled glass or chips of transparent crystal.


Morphine is the most effective naturally-occurring compound used to relieve pain. It also induces sleep and produces euphoria (a feeling of well-being).