PREPARED BY : EN. MUHD FAZLI DOLLAH BIOLOGY FORM 5

LYMPHATIC SYSTEM

LEARNING OUTCOMES 1.Describe the formation of interstitial fluid 2.State the composition of interstitial fluid 3.State the importance of interstitial fluid 4.Describe the fate of interstitial fluid 5.Describe the structure of the lymphatic system

THE LYMPHATIC SYSTEM Part of the circulatory system & immune system. A closed system  consist of a network of lymphatic vessels, ducts & nodes. No pump, the fluid (lymph) id squeeze along the lymphatic vessels by pressure associated with movements of skeletal muscles, intestinal movements & breathing. Thymus & spleen are important organs of lymphatic system.

FORMATION OF INTERSTITIAL FLUID Blood flows from arteries  capillaries, there is a higher hydrostatic pressure at the arterial end of the capillaries

LYMPHATIC FLUID Oxygenated arterial end of the capillaries  high pressure  force water & dissolved substances out  capillary wall  interstitial spaces (spaces between cells)  interstitial fluid/ tissue fluid/ extracellular fluid. Erythrocytes & plasma protein are too large to pass through  remain in the capillary.

COMPOSITION OF INTERSTITIAL FLUID Contains water + dissolved oxygen + amino acids + glucose + fatty acids + glycerol + vitamins + minerals + hormones. An adult has ~11 litres of interstitial fluid providing the cells of the body with nutrients & a means of waste removal. At the venous end of the capillary  90% absorbs by blood consists of water, minerals & waste products. The rest  passes back into the BCS as lymph via the LYMPHATIC SYSTEM.

The Importance of Interstitial Fluid Carries dissolved substances (O2, amino acids, glucose, fatty acids, glycerol, vitamins, minerals & hormones) to cells for exchange. Carries waste products (CO2, urea, etc.) into BCS.

THE FATE OF INTERSTITIAL FLUID 10% of interstitial fluid  drains into the lymphatic capillaries forming lymph. Move due to the contraction & relaxation of skeletal muscles  backflow is prevented by semilunar valves. Lymph in the right lymphatic duct & the thoracic duct  flows into the right & left subclavian veins of the BCS, respectively.

THE STRUCTURE OF THE LYMPHATIC SYSTEM Starts from the minute blind-ended tubes including lacteals (in the ileum) & lymphatic capillaries in other tissues. Lymphatic capillaries  form larger lymphatic vessels  lymphatics. Semilunar valves are present along the lymphatics. Lymphatics from all parts of the body  two large ducts  the right lymphatic duct, the thoracic duct.

THE STRUCTURE OF THE LYMPHATIC SYSTEM Situated at intervals along the lymphatics are the oval-shaped structures  lymph nodes (neck, armpits & groin). Lymphocytes are found in the lymph nodes  produce antibodies & play an important role in the body’s immune system. Phagocytes in the lymph nodes help to remove bacteria.