Glossary of Terms &
Listed Alphabetically - "L"
L-Arginine: L-Arginine is crystalline, free-form amino acid. It is a important factor in muscle metabolism and works to transport, store and excrete nitrogen and is involved in DNA synthesis. It is also a precursor of guanidophosphate, phosphoarginine, and creatine, three high-energy compounds found in muscles. Click here for more info on arginine.
Lactose intolerance: The inability to digest lactose because of the failure of the small intestinal mucosal cells to produce lactase.
Langerhans cells: Epidermal dendritic cell that functions as an antigen-presenting cell (APC) during an immune response.
Large intestine: The portion of the gastrointestinal tract extending from the ileum of the small intestine to the anus, divides structurally into the cecum, colon, rectum and anal canal.
LDL: Low density lipoprotein. Lipoproteins (particles composed of lipids and protein) are the form in which fats are transported throughout the body, in the bloodstream. LDL transport cholesterol from the liver to the tissues of the body. A high proportion of cholesterol carried in LDL (LDL-cholesterol) is associated with an increased likelihood of developing cardiovascular diseases (heart disease and stroke). Oxidized LDL appear to play an important role in the development of atherosclerosis.
Left ventricular hypertrophy (LVH): Abnormal thickening of the wall of the left ventricle (lower chamber) of the heart muscle. The ventricles have muscular walls in order to pump blood from the heart through the arteries, but LVH occurs when the ventricle must pump against abnormally high volume or pressure loads. LVH may accompany congestive heart failure (CHF).
Legumes: Members of the large family of plants known as leguminosae. In this context the term refers to the fruits or seeds of leguminous plants (e.g., peas and beans) that are used for food.
Lens: The transparent structure inside the eye that focuses light rays onto the retina (the nerve cells at the back of the eye).
Lethargy: A condition of drowsiness or indifference.
Leukemia: An acute or chronic form of cancer that involves the blood-forming organs. Leukemia is characterized by an abnormal increase in the number of white blood cells in the tissues of the body with or without a corresponding increase of those in the circulating blood, and is classified according to the type of white blood cell most prominently involved.
Lipase: An enzyme that splits fatty acids from triglycerides and phospholipids.
Lipid: An organic compound composed of carbon, hydrogen and oxygen that is usually insoluble in water, but soluble in alcohol, ether and chloroform; Different types of fat molecules. For example, phospholipids, cholesterol, triglycerides, steroids, eicosanoids.
Lipoic acid: A coenzyme, essential for the oxidation of alpha-keto acids, such as pyruvate, in metabolism.
Lipid profile: Blood test that measures total cholesterol, high-density lipoprotein, low-density lipoprotein and triglycerides, to assess risk of cardiovascular disease.
Lipolysis: The splitting of fatty acids from triglyceride (fat) or phospholipid molecules.
Lipoproteins: Particles composed of lipids and protein, that allows for transport of fat and cholesterol through the blood. A lipoprotein particle is composed of an outer shell of phospholipid, which renders the particle soluble in water; a core of fats called lipid, including cholesterol and a surface apoprotein molecule that allows tissues to recognize and take up the particle.
Lp(a) lipoprotein: A lipoprotein particle in which the protein (apolipoproteinB-100) is chemically linked to another protein apolipoprotein(a). Increased blood levels of Lp(a) are associated with an increased risk of cardiovascular diseases.
Lumbar spine: The portion of the spine, commonly referred to as the small of the back. The lumbar portion of the spine is located between the thorax (chest) and the pelvis.
Lupus: Also known as systemic lupus erythematosus (SLE). Lupus is a chronic inflammatory condition caused by an autoimmune disease. An autoimmune disease occurs when the body's tissues are attacked by its own immune system. Individuals with lupus have unusual antibodies in their blood that are targeted against their own body tissues.
Lymphocyte: A white blood cell that creates an immune response when activated by a foreign molecule (antigen). T lymphocytes or T-cells develop in an organ called the thymus and are responsible for cell-mediated immunity, while B-lymphocytes develop in the bone marrow and are responsible for the production of antibodies (immunoglobulins).