JOINT GLOSSARY   ARTICULATIONS: Places where bones come together; joints ARTICULAR CARTILAGE: Connective tissue that covers the end surfaces of the bones ATHEROSCLEROSIS: A chronic degenerative disease in which the walls of the large arteries become coated with fat-based deposits that eventually decrease the elasticity of the arteries and can block blood flow CATALASE (CAT): An enzyme present in nearly all cells that catalyze the decomposition of hydrogen peroxide to water and molecular oxygen COLLAGEN SYNTHESIS: Production of the main structural protein of the connective tissue. Collagen is the most abundant protein in the body. CYTOKINE: Protein hormones produced by immune cells that act as immune system messengers and help regulate inflammatory processes EXTRACELLULAR MATRIX (ECM): A unique feature of connective tissue composed primarily of ground substance, fibers and fluids that enables the connective tissue to support weight and withstand tension and physical force FIBROBLAST CELLS: Young, highly active cells that form the fibers of the connective tissue GALACTOSAMINE: A key hexosamine found in the connective tissue of the joints GLUCOSAMINE: A key hexosamine found in the connective tissue of the joints HYALURONIC ACID (HA): The primary glycosaminoglycan (GAG) in the connective tissue which forms the articular surface that covers the ends of the bones HYPOXIA: An oxygen deficiency HYPOXIC REPERFUSION INJURY: Tissue damage caused by temporary interruption of oxygen supply followed by reestablishment of oxygen availability INFLAMMATORY CASCADE: A series of biochemical steps that includes synthesis of arachidonic acid and conversion of this fatty acid into prostaglandins, leukotrienes and thromboxanes that activate the immune system an elicit inflammatory response INFLAMMATORY MESSENGER MOLECULES: Molecules that are synthesized by the immune system and carried through the bloodstream to regulate inflammatory responses throughout the body INTERLEUKIN-1 (IL-1): A cytokine (immune messenging) molecule, composed of protein, produced by the mononuclear and phagocytic cells of the immune system, and involved in the regulation of inflammatory response OSTEOARTHRITIS: Type of arthritis characterized by progressive cartilage deterioration in synovial joints and vertebrae and often called "wear and tear arthritis" OXIDATIVE STRESS: Any circumstance in which oxygen-based processes in the body are not adequately supported or balanced OXYGEN-PROCESSING ENZYMES: Proteins that act as catalysts in helping to stimulated oxygen-based reactions in the body REACTIVE MOLECULES: Molecules that are unstable because of their molecular structure and are highly likely to interact with other molecules REACTIVE OXYGEN SPECIES (ROS): Oxygen containing molecules that are highly unstable and highly interactive with other molecules RHEUMATOID ARTHRITIS: Arthritis characterized by inflammatory changes in joints and related structures ROS-NEUTRALIZING MOLECULES: Substances that help stabilize reactive oxygen molecules and make them less interactive SYNOVIAL JOINT: A joint where fluid separates the bones from each other SYSTEMIC LUPUS ERYTHEMATOSUS (SLE): A chronic inflammatory autoimmune disease that primarily affects connective tissue and occurs predominantly in women TUMOR NECROSIS FACTOR (TNF): A protein mediator or cytokine released primarily by macrophages and T-lymphocytes that helps regulate the immune response