Hematology Blood lymph system 1 st Physiology Lecture

Hematology Blood & lymph system ----------------------------1 st Physiology Lecture LYMPHATIC SYSTEM By Dr. Eman Elbassuoni Professor of Physiology ---------

Lymphatic system formed of: 1 - Lymphatic vessels 2 - Lymph 3 - Lymph nodes 4 - Lymphatic organs such as: I - Thymus gland II - Tonsils III - Spleen

1 - Lymphatic vessels: Lymphatic collecting vessels. Collecting lymph from lymphatic capillaries. Carries lymph to and away from lymph nodes, finally reenter the blood vessels of the cardiovascular system.

2 - Lymph: Fluid formed in the tissue spaces. Transported by way of lymphatic vessels to finally reenter the bloodstream carried by the cardiovascular system.

Lymph formation: - At the arterial end of the capillaries, blood plasma filters out into the spaces between tissue cells because of the pressure generated by the pumping action of the heart. There, the liquid is called interstitial fluid (IF). - Much of the interstitial fluid goes back into the blood by entering the venous end of the capillaries, through the capillary membrane. - The remainder excess interstitial fluid and larger molecules, including proteins and other substances forming the lymph that enters the lymphatic vessels before it returns to the blood. - So, lymphatic vessels, permit excess tissue fluid to leave the tissue spaces.

Lymph function: - Cardiovascular system plays a key role in bringing many needed substances to cells and then removing the waste products that accumulate as a result of metabolism. - This exchange of substances between blood and tissue fluid occurs in capillary beds. - Many additional substances that cannot enter or return through the capillary walls, including excess fluid and protein molecules, are returned to the blood as lymph. - So, LYMPH maintain the constancy of the fluid around each body cell.

3 - Lymph nodes: - These are the smallest but most numerous encapsulated lymphoid organs. Lie in groups along lymphatic vessels

Function of the lymph nodes: 1 Filtration of lymph before it return to blood. 2 Defensive function by: Macrophages that engulf and destroy foreign substances. Lymphocyte production (lymphopoiesis). Immunoglobulin production.

4 - Lymphatic organs: It help to filter the body’s fluids, remov ing harmful particles before they can cause significant damage to other parts of the body. Lymphatic organs such as: I Thymus gland II Tonsil III Spleen

I - Thymus gland The thymus is a small lym phoid tissue organ located in the mediastinum. It is composed of lymphocytes in a mesh like framework.

Function of the thymus gland: Although small in size, the thymus plays a central and critical role in the body’s vital immunity mecha nism. First, it is a source of lymphocytes before birth. Then it is important in the maturation or development of T lymphocytes that then leaves the thymus and circulates to the spleen, tonsils, lymph nodes, and other lymphoid tissues.

II – Tonsils: Masses of lymphoid tissue located in the mouth and back of the throat. Types: 1 The palatine tonsils: on each side of the throat. 2 The pharyngeal tonsils: near the posterior open ing of the nasal cavity. 3 The lingual tonsils: is near the base of the tongue.

Function of the tonsils: - They help protect us against bacteria that may invade tissues in the area around the openings between the nasal and oral cavities. The ton sils serve as the first line of defense from theexterior.

III – Spleen: Spleen is the largest lymphoid organ in the body. Located in the left side of the abdomen. Has a very rich blood supply, may contain more than 500 ml blood.

Function of the spleen: After entering the spleen, blood flows through lymphoid tissue inside it to remove many bacteria and other foreign substances by filtration and phagocytosis. The spleen also serves as a reservoir for monocytes, which can quickly leave the spleen to help repair damaged tissue anywhere in the body dur ing an emergency. The spleen also destroys old and damaged RBCs and saving the iron found in hemoglobin for future use. Act as a reservoir for blood that can be returned to the cardiovascular system when needed.

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