What is Lymph Nodes? Structure, Functions

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.

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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).