The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinters, distinguishing them from the organism's own healthy tissue. Many species have two major subsystems of the immune system. The innate immune system provides a preconfigured response to broad groups of situations and stimuli.
Immunology is a branch of biology and medicine that covers the study of immune systems in all organisms. Immunology charts, measures, and contextualizes the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders (such as autoimmune diseases, hypersensitivities, immune deficiency, and transplant rejection); and the physical, chemical, and physiological characteristics of the components of the immune system in vitro, in situ, and in vivo.
In chemistry, a supramolecular assembly is a complex of molecules held together by noncovalent bonds. While a supramolecular assembly can be simply composed of two molecules (e.g., a DNA double helix or an inclusion compound), or a defined number of stoichiometrically interacting molecules within a quaternary complex, it is more often used to denote larger complexes composed of indefinite numbers of molecules that form sphere-, rod-, or sheet-like species.
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and molecule is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.
Adsorption (not to be mistaken for absorption) is the accumulation and adhesion of molecules, atoms, ions, or larger particles to a surface, but without surface penetration occurring. The adsorption of larger biomolecules such as proteins is of high physiological relevance, and as such they adsorb with different mechanisms than their molecular or atomic analogs. Some of the major driving forces behind protein adsorption include: surface energy, intermolecular forces, hydrophobicity, and ionic or electrostatic interaction.
