Lymphatic System

• Introduction:

The Lymphatic System consists of a fluid called Lymph that flows in lymph vessels. Lymphatic tissue is a part of reticular connective tissue that contains a large number of lymphocytes.

Lymph flows in lymph vessels and drains into lymph nodes and mixes with blood.

Lymphatic System includes the following

lymph, lymph vessels, lymph nodes, lymph organs (spleen, thyms gland), lymphoid tissue (tonsils), bone marrow.

• Functions of lymphatic system

drains interstitial fluid. which absorbs tissue fluid and mixes with blood. Dietary lipids and fat soluble vitamins like A, D, E, K are G.I. Absorbed from the track and mixed with the blood. Provides protection against invasion of the body by micro-organisms. Certain lymphocytes prevent invasion of the body by microorganisms and maintain antibodies in the plasma thus playing an important role in maintaining immunity.

Acts as a mediator between body cell tissue and blood.

• lymph

Lymph is a fluid with a clear watery appearance. which flows into the lymph vessels. Its composition resembles blood plasma. It has isotonic property. The contraction of the muffles surrounding the lymph vessels and the valves in the lymph vessels moves the lymph into further circulation. As the lactic acid in the small intestine absorbs the fat, it has a white milky appearance.

• Lymph vessels

The thickness of the lymph vessels resembles the structure of the vein and the structure of its wall also has layers similar to those found in the wall of the vein.

Outer layer – fibrous tissue

Middle layer – smooth muscles

Inner layer – endo thallium

These above lymph vessels contain valves. It is useful for carrying lymph in one direction. Smaller lymph vessels join to form larger lymph vessels and finally they form right lymphatic duct and thoracic lymphatic duct.

1. Thoracic Duct (Left Lymphatic Duct) : It is 38-45 cm long. It collects all the lymph from the left side of the body and then drains it into the left subclavian vein.
2. Right Lymphatic Duct: It is 1.25 cm long. It collects lymph from the upper right side of the body. which drains lymph into the right subclavian vein.

Lymph Capillaries:

Small branches of lymph vessels are called lymph capillaries. Its diameter is larger than the diameter of the blood capillary. There is a network of lymph capillaries throughout the body. The structure of lymph capillaries resembles blood capillaries except that the layer above the central nervous system and the skin. which is closely attached to the cell.

Lymph Nodes:

Lymph nodes are small oval or non-sap structures. Which lies in the way of lymph vessels. Which does the job of filtering lymph and lymphocytes are formed in it. Mainly the lymph nodes are located in the joint and axilla, THORAX, ABDOMEN and groin

.Structure of lymph nodes:

Each lymph node has an outer covering made of dense connective tissue called a capsule and an inward extension called a trabeculae. which divides the lymph node into some parts. The lymph node part is divided into two parts. The part towards the outer surface is called the cortex and the inner part is called the medulla. In the lymph node, the lymph is carried in one direction, the vessels entering the lymph node are called afferent vessels and the vessels leaving the lymph node are called efferent vessels. The depressed part of the entering and exiting vessels is called the hilum. Blood vessels also go in and out from here.

Functions of lymph nodes:

Filtering and phagocytosis: Lymph node filters lymph in which lymph enters from one side and comes out after filtering from the other side. The macrophages in this destroy the foreign substances in it by the action of phagocytosis and the lymph gets mixed with the blood. Proliferation of lymphocytes: Plasma cells and T cells can increase in number in the lymph node and they can also circulate in other body parts from the lymph node so that the immune The response is sustained. Hematopoiesis: Some lymphocytes and monocytes from the bone marrow enter the lymph nodes and undergo their final maturation there.

• SPLEEN:

It is oval drop. SPLEEN is the largest lymphatic tissue in the body. Length: 12 cm Width: 7 cm Thickness: 22.5 cm It is located in the left hypochondriac region between the stomach and the diaphragm lateral to the liver. Its weight is approximately 200 gm.

Organs Associated with the Spleen:

Around the Spleen are Diaphragm, Intestines, Stomuch, Pancreas, Left Kidney, etc… Organs.

Structure:

The spleen has a network of connective tissue on the inside called the splenic pulp. It contains lymphoid tissue and some blood cells. A capsule made of smooth muscle fibers and elastic tissue surrounds it. Its tissues are divided into two parts inside the spleen. White pulp and Red pulp. Wight pulp is for immunity where B-cell count increases to help make antibody plasma. Which is useful against infection. Red pulp is vascular. Bacteria are phagocytosed there and RBCs and platelets also act to segregate and phagocytose damaged cells.

• Functions of Spleen:

Phagocytosis: Helps to destroy bacteria and RBCs that are damaged are removed from circulation by phagocytosis.

Storage of blood: Spleen stores approximately 350 ml of blood. Which sends this blood back into the circulation as soon as sympathetic stimulation is received in a situation like hemorrhage.

Immue response: T and B lymphocytes that are activated by antigens to maintain immunity.

Erythropoiesis: Spleen and liver are important for the production of cells during fetal life. Even in adults, Spleen produces cells when needed.

• Thymus gland:

It is an organ of the lymphatic system with two lobes. It is located in the mediastinum space. It is larger in size in infants and reaches a maximum of 40 gr by the age of 10-12 years. Its weight at birth is 10 to 15 gr. As much as

Organ Associated with the Thymus gland.

Around it are organs like sternum, aortic arch, trachea, lungs, heart etc.

Structure : It has two lobes. It has a capsule. The outside of each lobe is divided into lobules with the outer part called the cortex and the inner part called the medulla.

Functions:

Bone marrow-derived B-lymphocytes are activated as T-lymphocytes after entering the thymus gland.

Thymosin stimulates maturation of the thymus gland and other lymphoid tissues. Which hormone is secreted through the epithelial cells of the gland.