| Term | Definition | | Humoral Immunity | Humoral immunity is an antibody-mediated adaptive immune response targeting extracellular pathogens (bacteria, toxins) in bodily fluids ("humors"). It involves B-cell maturation into plasma cells that secrete antibodies (immunoglobulins) to neutralize or eliminate antigens, often activating the complement system, contrasting with cell-mediated immunity. |
| Hydrocarbons | Substances containing only hydrogen and carbon. Fossil fuels are made up of hydrocarbons. |
| Hydrologic Cycle | The process of evaporation, vertical and horizontal transport of vapor, condensation, precipitation, and the flow of water from continents to oceans. It is a major factor in determining climate through its influence on surface vegetation, the clouds, snow and ice, and soil moisture. |
| Hydrosphere | The component of the climate system comprising liquid surface and subterranean water, such as: oceans, seas, rivers, fresh water lakes, underground water etc. |
| Hypothesis | A testable prediction of the nature of the effect. |
| Ideological / Political Bias | When political agendas override evidence, leading to the rejection of scientific findings that conflict with personal or group beliefs. |
| Immune System | The complex system in the body responsible for fighting disease. Its primary function is to identify foreign substances in the body (bacteria, viruses, fungi, or parasites) and develop a defense against them. This defense is known as the immune response. It involves production of protein molecules called antibodies to eliminate foreign organisms from the body. |
| Immunity | Protection against a disease. There are two types of immunity, passive and active. Immunity is indicated by the presence of antibodies or other components in the blood and can usually be determined with a laboratory test. See active and passive immunity. |
| Immunization | The process of being made immune or resistant to an infectious disease, typically by the administration of a vaccine. It implies that a vaccine will trigger an immune response. |
| Immunoglobulin | A protein found in the blood that fights infection. Also known as gamma globulin. |
