Lymph nodes are the oval or bean shaped organ that lie often in groups along the length of the lymph vessels . the lymph drains through a number of nodes usually 8 to 10 before returning to the venous circulation. These nodes vary considerably in size some are the small as a pin head and the largest are about the size of an almond.
Lymph Node
Structure of Lymph nodes
Lymph nodes have an outer capsule of fibrous tissue which dips down into the nodes substances forming partition or trebculae. The main substance of the consists of reticular lymphatic tissue containing many lymphocytes and macrophages.
As many as four or five different lymph vessels May enter a lymph nodes while only one efferent vessels lymph away from the nodes , Each node has a concave surface called hilum where an artery and a vein and the efferent lymph vessels leave.
The large numbers of lymph nodes situated in strategic throughout the body are arranged in deep and superficial groups.
Lymph from the head and the neck passes through deep and superficial cervical nodes. Lymph from the upper limbs passes through the deep and superficial axillaries nodes.Lymph from organ and tissue in the thoracic cavity drains through groups of nodes that are situated close to the mediastinum. Large always oesophagus and chest wall . Most of the lymph from the breast passes through the axillaries nodes lymph from the pelvic and abdominal cavities passes though the the lymph modes before entering cisterns chuki . Tbe abdominal and pelvic nodes are situated mainly in association with the blood vessels supplying the organs and close the main arteries I.e. the aorta and the external and internal iliac arteries. The lymph from the power limb drains through the deep superficial nodes including groups of nodes behind the knee and in the groin .
Functions of Lymph Nodes
Filtering and phagocytosis — Lymph is filtered by reticular and lymphoid tissue as ut passes through lymph nodes. Particulate matter May include microbes, dead and alive phagocytes containing ingested microbes cells from malignant tumours ‚worn out and damaged tissue cells and inhaled particles .Organic material is destroyed in lymph nodes by macrophages and antibodies . Some inorganic inhaled particles cannot be destroyed by. Phagocytosis. These remain inside the macrophages either causing no damage or killing the cells
Material not filtered off and dealt with in one lymph nodes passes on to successive nodes and by the time lymph enters the blood it has usually been cleared of foreign matter abd cell debris . in some cases where phagocytosis of microbes is incomplete they May stimulate inflammations and enlargement of the node (lymphadenopathy).