AMA 180 - Anatomy & Physiology/Medical Terminology/Pathology 11 Blood & Lymphatic System
Function of the Blood: • Maintains a constant environment for living tissues in the body. • Transports nutrients, gases (e.g. oxygen and carbon dioxide) and wastes to and from the cells. • Transports hormones from glands to distant sites to regulate growth, reproduction and energy production. • Contains proteins, white blood cells and antibodies to fight infection, and platelets (thrombocytes) to help with clotting.
Composition and Formation of Blood: • Cells: formed elements; blood cells originate in the bone marrow (hematopoietic stem cells) and change size and shape to become specialized (differentiated). • Plasma: liquid portion of the blood when circulating in the body; carries blood cells through the circulatory system. Composed of water, dissolved proteins, sugar, wastes, salts, hormones, etc. • Erythrocytes: red blood cells that contain hemoglobin (protein) that enable them to carry oxygen. • Leukocytes: white blood cells come in 5 differentiations (granulocytes, basophils, eosinophils, neutrophils and phagocytes) to help fight off infection through the body’s immune response and the creation of antibodies. • Thrombocytes: platelets; clotting cells that are formed in bone marrow from giant cells called megakaryocytes.
Lymphatic SystemFunction: • Acts as a drainage system to transport, via the bloodstream, proteins and fluid that have leaked into the interstitial fluid surrounding body cells. • Absorbs lipids from the small intestine. • Creates antibodies. • Lymph is clear watery fluid that surrounds cells.
Structure of the Lymphatic System: • Lymph capillaries: tiny vessels that surround cells and carry lymph from tissues. • Lymph vessels: larger vessels that transport lymph to the thoracic cavity. • Lymph nodes: collections of stationary lymph tissue that produce lymphocytes and act as filters; contain macrophages, B cells and T cells that destroy foreign substances. • Right lymphatic duct: large duct in the upper chest that the lymph vessels empty into; drains the right side of the head and the chest. • Thoracic duct: large duct in the upper chest that the lymph vessels empty into; drains the lower body and the left side of the head. • Large veins in the neck: lymph is carried here from the ducts where it then enters the bloodstream. • Spleen: composed of lymph tissue; destroys old blood cells, filters foreign substances from the blood, activates lymphocytes that produce antibodies and stores blood. • Thymus gland: composed of lymph tissue; especially important during childhood and helps with the creation of antibodies and immune cells.