ancestor: A predecessor. It could be a family forebear, such as a parent, grandparent or great-great-great grandparent.
blood vessel: A tubular structure that carries blood through the tissues and organs.
cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells.
develop: To emerge or to make come into being, either naturally or through human intervention, such as by manufacturing. (in biology) To grow as an organism from conception through adulthood, often undergoing changes in chemistry, size, mental maturity or sometimes even shape.
disorder: (in medicine) A condition where the body does not work appropriately, leading to what might be viewed as an illness. This term can sometimes be used interchangeably with disease.
gene: (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.
hemoglobin: A molecule that binds to oxygen in the blood, carrying it around to tissues.
literally: A term that the phrase that it modifies is precisely true. For instance, to say: “It’s so cold that I’m literally dying,” means that this person actually expects to soon be dead, the result of getting too cold.
malaria: A disease caused by a parasite that invades the red blood cells. The parasite is transmitted by mosquitoes, largely in tropical and subtropical regions.
marrow: (in physiology and medicine) Spongy tissue that develops inside of bones. Most red blood cells, infection-fighting white blood cells and blood platelets form within the marrow.
molecule: An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).
mutant: Adjective that describes some altered gene in an organism’s DNA. Such changes, known as mutations, may occur naturally. Others may be triggered by outside factors, such as pollution, radiation, medicines or something in the diet.
organ: (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that makes sense of nerve signals and a plant’s roots are organs that take in nutrients and moisture.
oxygen: A gas that makes up about 21 percent of Earth’s atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).
parasite: An organism that gets benefits from another species, called a host, but doesn’t provide that host any benefits. Classic examples of parasites include ticks, fleas and tapeworms.
pediatrician: A doctor who works in the field of medicine that has to do with children and especially child health.
protein: A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Among the better-known, stand-alone proteins are the hemoglobin (in blood) and the antibodies (also in blood) that attempt to fight infections. Medicines frequently work by latching onto proteins.
red blood cell: Colored red by hemoglobin, these cells move oxygen from the lungs to all tissues of the body. Red blood cells are too small to be seen by the unaided eye.
stroke: (in biology and medicine) A condition where blood stops flowing to part of the brain or leaks in the brain.
therapy: (adj. therapeutic) Treatment intended to relieve or heal a disorder.
transplant: (in medicine) The replacement of organs, tissues or cells with those from another organism. It is also a term for the material that will be moved.