Skip to main content



Anatomy: A branch of morphology that deals with the structure of organisms.

Autosome (Autosomal): A chromosome other than a sex chromosome.

Bacteria: A domain in the system of classification dividing all organisms into three major domains of life that includes the prokaryotes that are bacteria but not those that are archaebacteria or archaea.

Carbohydrate: Any of various neutral compounds of carbon, hydrogen, and oxygen (as sugars, starches, and celluloses) most of which are formed by green plants and which constitute a major class of animal foods.

Cells: A small usually microscopic mass of protoplasm bounded externally by a semipermeable membrane, usually including one or more nuclei and various nonliving products, capable alone or interacting with other cells of performing all the fundamental functions of life, and forming the smallest structural unit of living matter capable of functioning independently.

Digestive System: The bodily system concerned with the ingestion, digestion, and absorption of food.

Disease: An impairment of the normal state of the living animal or plant body or one of its parts that interrupts or modifies the performance of the vital functions, is typically manifested by distinguishing signs and symptoms, and is a response to environmental factors (as malnutrition, industrial hazards, or climate), to specific infective agents (as worms, bacteria, or viruses), to inherent defects of the organism (as genetic anomalies), or to combinations of these factors. 

Hereditary: Genetically transmitted or transmittable from parent to offspring.

Homeostasis: The  maintenance of relatively stable internal physiological conditions (as body temperature or the pH of blood) in higher animals under fluctuating environmental conditions; also :  the process of maintaining a stable psychological state in the individual under varying psychological pressures or stable social conditions in a group under varying social, environmental, or political factors.

Immune System:  The bodily system that protects the body from foreign substances, cells, and tissues by producing the immune response and that includes especially the thymus, spleen, lymph nodes, special deposits of lymphoid tissue (as in the gastrointestinal tract and bone marrow), lymphocytes including the B cells and T cells, and antibodies.

Lipid: Any of various substances that are soluble in nonpolar organic solvents (as chloroform and ether), that with proteins and carbohydrates constitute the principal structural components of living cells, and that include fats, waxes, phospholipids, cerebrosides, and related and derived compounds.

Lymphatic System: The part of the circulatory system that is concerned especially with scavenging fluids and proteins that have escaped from cells and tissues and returning them to the blood, with the phagocytic removal of cellular debris and foreign material, and with immune responses, that overlaps and parallels the system of blood vessels in function and shares some constituents with it, and that consists especially of the thymus, spleen, tonsils, lymph, lymph nodes, lymphatic vessels, lymphocytes, and bone marrow where stem cells differentiate into precursors of B cells and T cells.

Macromolecule: A very large molecule (as of a protein, nucleic acid, or rubber) built up from smaller chemical structures.

Membrane: A thin soft pliable sheet or layer especially of animal or plant origin.

Mycotic: Infection with or disease caused by a fungus.

Nucleic Acids: Any of various acids (as an RNA or a DNA) composed of nucleotide chains.

Parasite (Parasitic): An organism living in, with, or on another organism in parasitism.

Physiology: A branch of biology that deals with the functions and activities of life or of living matter (as organs, tissues, or cells) and of the physical and chemical phenomena involved.

Protein: Any of numerous naturally occurring extremely complex substances (as an enzyme or antibody) that consist of amino acid residues joined by peptide bonds, contain the elements carbon, hydrogen, nitrogen, oxygen, usually sulfur, and occasionally other elements (as phosphorus or iron), that are essential constituents of all living cells, that are synthesized from raw materials by plants but assimilated as separate amino acids by animals, that are both acidic and basic and usually colloidal in nature although many have been crystallized, and that are hydrolyzable by acids, alkalies, proteolytic enzymes, and putrefactive bacteria to polypeptides, to simpler peptides, and ultimately to alpha-amino acids. 

Protozoa (Protozoan): Any protist of the phylum or subkingdom Protozoa. 

Rickettsia: Any of a family (Rickettsiaceae) of rod-shaped, coccoid, or diplococcus-shaped, often pleomorphic gram-negative bacteria that are intracellular parasites of arthropods (as lice or ticks) and when transmitted to humans cause various diseases (as typhus).

Tissue: An aggregate of cells usually of a particular kind together with their intercellular substance that form one of the structural materials of a plant or an animal and that in animals include connective tissue, epithelium, muscle tissue, and nerve tissue. 

Virus: Any of a large group of submicroscopic infective agents that are regarded either as extremely simple microorganisms or as extremely complex molecules, that typically contain a protein coat surrounding an RNA or DNA core of genetic material but no semipermeable membrane, that are capable of growth and multiplication only in living cells, and that cause various important diseases in humans, animals, or plant.

(All terms came from Merriam- Webster)