Lymphatic System

Lymphatic System Consists of: Lymphatic vessels Lymphatic tissues Lymphoid organs Lymph which consists of Interstitial fluid Lymphocytes Macrophages

Lymphatic System

Functions of the Lymphatic System Production, maintenance, distribution of lymphocytes Lymphocytes are infection fighting WBC Maintain normal blood volume Return of water and solutes that leak out into the interstitial fluid to the circulatory system Plasma protein recycling Alternate route for transport of hormones, nutrients, and waste products

Lymphoid Structures Primary lymphoid structures Structures that produces lymphocytes Bone marrow, thymus, spleen Secondary lymphoid structures Places where the immune response begins Lymph nodes, tonsils

Lymphatic capillaries

Lymphatic Vessels Carry lymph from peripheral tissue to venous system Like veins, they go from small to large and have valves System has no pump, and is unidirectional Vessel system goes as follows: Lymph capillaries Lymph collecting vessels Lymph nodes Lymph trunks Lymph ducts

Lymph Ducts Lymph trunks empty into the lymph ducts Lumbar trunk Intestinal trunk Bronchomediastinal trunk Subclavian trunk Jugular trunk Two major lymph ducts Thoracic duct Right lymphatic duct Ducts return lymph to venous circulation at the L and R subclavian veins

Lymph and Disease Any materials in the interstitial fluid can be picked up by the lymphatic system Pathogens in the tissues can get into the lymph and travel throughout the body Lymph nodes “inspect” the lymph for foreign material Swollen or tender nodes can indicate an immune response to pathogens in the lymph

This looks bad! Elephantiasis Blockage of the lymphatic return system by a worm Causes gross swelling(edema) of the tissue due to fluid build up Can be cured Don’t worry the worm doesn’t live in San Diego

Lymphocytes Lymphocytes are types of WBC Responsible for specific immunity to pathogens Two major types of lymphocytes B cells: produce antibody for humoral immune response T cells: cell-mediated immunity T helper cells, cytotoxic T cells, and suppressor T cells are the major types

Origin of B cells and T cells Both types of cells originate in the bone marrow B cells mature in the bone marrow hence the name B cells T cells originate in the bone marrow but move to the thymus gland to mature, hence the name T cells Both T cells and B cells are found in various lymphatic tissues

Lymphoid tissue and organs Tonsils Lymph nodes Spleen Thymus

Tonsils Lymphoid nodules found in the pharynx Aggregation of lymphocytes that remove pathogen from air or food Usually 5 tonsils Single pharyngeal tonsil (adenoids) Pair of palatine tonsils Pair of lingual tonsils

Lymph Node

Lymph Node

Spleen Soft, pulpy organ wedged between the stomach, diaphragm and left kidney The cellular component of the spleen is called the pulp Red pulp Mostly RBC White pulp Lymphatic nodules