lymphatic system.docx

1-the lymphatic system is formed of ? \- lymph vessels. \- lymph nodes. \- lymphatic tissues as:spleen,tonsilis and, thymus gland. 2-Formation of lymph vessels ? -Starts network of lymph capillaries in the intercellular spaces collecting the excess fluid. -The lymph capillaries collect into ly...

1-the lymphatic system is formed of ? \- lymph vessels. \- lymph nodes. \- lymphatic tissues as:spleen,tonsilis and, thymus gland. 2-Formation of lymph vessels ? -Starts network of lymph capillaries in the intercellular spaces collecting the excess fluid. -The lymph capillaries collect into lymph vessels. -The lymph vessels interrupted by lymph nodes. -then lymph vessels unit to form 2main lymph trunks. -The two lymph trunks open in the venous system at the root of the neck. 3-There are no lymphatics in certain tissues such as ? -Nervous system. -bone marrow. -spleen. -Eye. 4-Function of lymph vessels ? -Absorption of colloid from tissue space. 5-Characteristics of lymph vessels ? -Superficial lymphatic follow veins. -deep veins follow arteries. -thin wall and wide pores to absorb substances of high molecular weight. -have constrictions opposite site of valves from inside valves increase in; head and neck-upper limb-near lower nodes. -drain lymph which is a colorless fluid except intestinal lymph rich in fat and is known as lacteals. 6-Factors helping lymphatic return ? -Contraction of surrounding muscles. -valves prevent passage of lymph to peripheries. -Pulsation of nearby artery. -Intrathoracic negativity. -Smooth muscles in the wall of lymph trunk. -Peristaltic movement of the intestine. 7-shape of lymph nodes ? -oval or kidney shape. 8-Structure of lymph nodes ? -formed of Cortex receives lymph through afferent vessels medulla (hilum) lymph leaves the hilum through efferent vessels. 9-Function of lymph nodes ? -filtration of lymph from bacteria and foreign bodies. -formation of lymphocytes. -defense mechanism site of interaction between antigens and lymphocyte. 10-Site of lymph nodes ? -At the root of the limbs (axillary and inguinal LNS). -Neck on both sides & its junction with the head. -Chest close to the trachea and bronchi. -Close abdominal and pelvic organs. -Around abdominal aorta and B.V.s of the pelvis. 11-Site of spleen(hemolymphatic organ) ? -left upper part of the abdomen below the dome of the diaphragm, protected by 9th, 10th, 11th, ribs. 12-Surfaces of spleen(hemolymphatic organ) ? -Diaphragmatic; smooth -Visceral related to stomach, left kidney, pancreas and left colic flexure contain the hilum. 13-Size of spleen(hemolymphatic organ) ? -it is not palpable, unless if it is enlarged at least three times. 14-Function of the spleen(hemolymphatic organ) ? -In the fetus, the spleen has a role in the formation of the blood cells. -In the adult:the spleen stores and concentrates blood cells so in case of hemorrhage it pours the concentrated blood into circulation. -It destroys the old expired red cells. -It filter the blood from organisms or any harmful substances.