LYMPHATIC SYSTEM

LYMPH

Tissue fluid, when enters to the lymph capillaries, from the tissue spaces is called as the lymph.

Lymph is clear, colorless body fluid derived from & closely resembling to the blood.

The fluid within the lymph capillaries & vessels is known as lymph.

LYMPHATIC CAPILLARY

Special lymph capillaries — Lacteals
Lacteals-lymphatic vessels of the small intestine which absorb digested food.
collect digested fats( in chylomicrons)

Chylomicrons-

chlyomicrons are lipoprotein particles that consist of Triglycerides, phospholipids, cholesterol & proteins. They transport dietary lipid from the intestine to other locations of the body.

LYMPHATIC DUCT

Tissue fluid, when enters the lymph capillaries is known as lymph. The lymph capillaries unite to form larger vessels which eventually converted into two large ducts
1.Thoracic duct
2.Right lymphatic duct.
These ducts drain their lymph or fluid into the left & right innominate veins respectively.

COMPONENTS OF LYMPHATIC SYSTEM

1.Lymph vessels

2.Lymph nodes & other lymphatic tissue

3.Spleen

4.Thymus gland

5.Tonsils

LYMPHATIC VESSELS

Larger ones composed of 3 layers

tunica interna: endothelium and valves

tunica media: elastic fibers, smooth muscle

tunica externa: thin outer layer

Valves are present to prevent backflow.

LYMPH NODES

The lymph nodes are the oval or bean or kidney shaped bodies.
They are located in the passage of lymphatic vessels.
They usually occurs in groups.
The concave border of the gland is called as hilum.
Efferent lymphatic vessels carries lymph from the lymph node.
Afferent lymphatic vessels enters lymph into the gland.
After entering the lymph gets filtered in lymph node by trapping of foreign particles & micro-organism.
Lymph reaches to blood only after passing through lymph node.
There are many groups of lymph nodes in the body such as, neck, axilla, thorax, abdomen & grain.

FUNCTIONS
1.Production of lymphocytes and antibodies.
2.They acts as a filter & prevents spread of organism.

SPLEEN

Largest lymphatic organ
Located to the left of the stomach below the diaphragm under 9th,10th & 11th ribs.
It is 12 cm long, 8 cm broad & 3 cm in thick, weighing 150 gm in adult.
It is surrounded by kidney, colon, & pancreas.

Histology

Red pulp contains all the components of circulating blood

White pulp is similar to lymphatic nodules

Spleen is covered with persitonium. Below this,is the layer of connective tissue capsules, fibroelastic capsules, that dips into organ,forming trabeculae.

The cellular element, consisting of lymphocytes & macrophages, is called splenic pulp. It lies between trabeculae.

It consists of spleen artery, spleen vein, lymph vessels & nerves.

Blood passing through the spleen passes through sinusoids, instead of capillaries, allowing it to come in contact with splenic pulp.

FUNCTIONS OF SPLEEN

1.Phagocytosis
Erythrocytes are destroyed in spleen, other cellular materials such as leukocyte, platelets and microbes are also phagocytosed in the spleen.
2.Haemopoietic organ
Erythrocytes are formed by spleen in fetal as well as in adult.
3.Red cell storage
During stress, it can liberate 150 ml of blood, since it acts as reservoir of red blood cells.
4.Antibodies formation
The spleen provides defense against infection by tubercle bacillus.

THYMUS

Location – behind the sternum in the mediastinum

The capsule divides it into 2 lobes

Development

Infant – conspicuous

Puberty – maximum size

Maturity – decreases in size

At birth, gland is small increases in size  till puberty and shrinks again the thymus is concerned with antibodies production.

Function

secretes hormones (thymopoietin, thymulin and thymosins)

It also controls the lymphocyte production by spleen & other spleen glands.

In elderly mostly fatty and fibrous tissue

TONSILS

Multiple groups of large lymphatic nodules

Location – mucous membrane of the oral and pharyngeal cavities

Palatine tonsils – Posterior-lateral walls of the oropharynx

Pharyngeal tonsil-Posterior wall of nasopharynx

Lingual tonsils-Base of tongue

FUNCTIONS OF LYMPHATIC SYSTEM

To return the tissue fluid to the general circulation

Transportation of lymphocytes from lymph glands to the circulation

The lymph nodes filter & destroy the microorganisms thereby preventing the spread of the infection.

Antibody formation by the lymph glands for protection of the body.

APPLIED ANATOMY

Lymphangitis – Inflammation of the lymph vessels

Lymphedema— Occurs due to accumulation of lymphatic fluid in the interstitial tissue.

Lymphadenopathy— Means a disease of the lymph nodes Lymph nodes become swollen/ enlarged and may be painful to touch

Lymphomas— Cancers originating either from the lymphocytes in the lymph nodes or the lymphatic tissue in organs Risk factors — HIV, Hepatitis.

Tonsillitis—Infection of the pharyngeal tonsils

Tonsils are swollen, Fever and pain during swallowing usually present. Treatment – surgical removal of tonsils (Tonsillectomy)

SPLENOMAGALY-enlarged spleen.

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