lymphatic system

what is the lymphatic system composed of?

•One-way vessels

•Begins with initial lymphatics which are close to capillaries

•Carries interstitial fluid (called lymph once it enters the lymph vessel) back toward veins near the heart.

how does interstitial fluid become lymph?

Fluid pressure on the outside of the vessel pushes the endothelial cell’s free edge inward, permitting entrance of interstitial fluid (now lymph).

how does lymph not escape?

Fluid pressure on the inside of the vessel forces the overlapping edges together

how does lymph get back into the heart?

•No pressure gradient from the heart

•Larger lymph vessels contain a layer of smooth muscle which is myogenic

•Rhythmic contractions push lymph toward veins in the thoracic cavity

•One-way valves prevent back flow

•Neighboring skeletal muscle contractions help to pump the lymph 

what is in lymph?

•Excess interstitial fluid (too much interstitial fluid causes edema)

•Plasma proteins which have leaked from the capillaries

•Fats absorbed from the digestive tract

•Bacteria from the interstitial fluid which are destroyed by special white blood cells in the lymph nodes

what lymphatic structures assist the cardiovascular system?

• lymphatic trunk and ducts

• spleen

• lymphatic vessels

  • lacteals

  • lymphatic capillaries

what are the lymphatic structures that assist the immune system?

• red bone marrow

• thymus

• lymph nodes

• spleen

• tonsils

• lymph nodules/mucosal linings

what are the primary lymphatic structures?

• red bone marrow

• thymus

what are the secondary lymphatic structures?

• lymph nodes

• spleen: white pulp

• tonsils

• lymph nodules/ mucosal linings

what does the lymphatic trunks and ducts do?

Lymph is transported through progressively larger lymph vessels Lymphatic ducts drain lymph into the venous circulation.

what do lymphatic vessels do?

transport lymph

what are lacteals?

Lymphatic Capillaries in the small intestine Absorb Fats from GI tract.

what is lymphatic capillary?

interstitial fluid is absorbed into lymphatic capillaries

what is the spleen?

Phagocytizes old or defective erythrocytes and platelets from circulating blood; serves as a reservoir for platelets

what is red bone marrow?

produces formed elements; including lymphocytes

what is the thymus?

site of T-lymphocyte maturation and differention

what are lymph nodes and spleen: white pulp?

monitor lymph for foreign materials (bacteria and viruses)

what are tonsils?

provides defense against pathogens in air and ingested food

what are lymph nodules/mucosal linings?

protects body organs (lymphatic nodules) and mucosal linings against potentially harmful substances