Distribution of Lymph Nodes

Distribution of Lymph Nodes

Lymph nodes are present along the course of lymphatic vessels in elbow, axilla, knee and groin. Lymph nodes are also present in certain points in abdomen, thorax and neck, where many lymph vessels join.

FUNCTIONS OF LYMPH NODES

Lymph nodes serve as filters which filter bacteria and toxic substances from the lymph.

Functions of the lymph nodes are:

1. When lymph passes through the lymph nodes, it is filtered, i.e. the water and electrolytes are removed.

But, the proteins and lipids are retained in the lymph.

2. Bacteria and other toxic substances are destroyed by macrophages of lymph nodes. Because of this,

lymph nodes are called defense barriers.

SWELLING OF LYMPH NODES

During infection or any other processes in a particular region of the body, activities of the lymph nodes in that region increase. This causes swelling of the lymph nodes. Sometimes, the swollen lymph nodes cause pain. Most common cause of swollen lymph nodes is infection. Lymph nodes situated near an infected area swell immediately. When the body recovers from infection, the lymph nodes restore their original size gradually, in one or two weeks.

Causes for Lymph Node Swelling

1. Skin infection of arm causes swelling of lymph nodes in armpit.

2. Tonsillitis or throat infection causes swelling of lymph nodes in neck.

3. Infection of genital organs or leg results in swelling of lymph nodes in groin.

4. Viral infections such as glandular fever which affect the whole body cause swelling of lymph nodes in

various parts of the body.

5. Cancer in a particular region may spread into the nearby lymph nodes causing the swelling.

Examples:

i. Throat cancer may spread into lymph nodes in neck

ii. Lung cancer may spread into lymph nodes in chest.

iii. Breast cancer may spread into lymph nodes in armpit.

iv. Intestinal cancer may spread into lymph nodes in abdomen.

v.. Lymphomas (cancer of lymphatic system) and leukemia cause swelling of lymph nodes in many

parts of the body.

LYMPH

FORMATION OF LYMPH

Lymph is formed from interstitial fluid, due to the permeability of lymph capillaries. When blood passes

via blood capillaries in the tissues, 9/10th of fluid passes into venous end of capillaries from the arterial end. And, the remaining 1/10th of the fluid passes into lymph capillaries, which have more permeability than blood capillaries. So, when lymph passes through lymph capillaries, the composition of lymph is more or less similar to that of interstitial fluid including protein content. Proteins present in the interstitial fluid cannot enter the blood capillaries because of their larger size. So, these proteins enter lymph vessels, which are permeable to large particles also.

Addition of Proteins and Fats

Tissue fluid in liver and gastrointestinal tract contains more protein and lipid substances. So, proteins and lipids enter the lymph vessels of liver and gastrointestinal tract in large quantities. Thus, lymph in larger vessels has more proteins and lipids.

Concentration of Lymph

When the lymph passes through the lymph nodes, it is concentrated because of absorption of water and the electrolytes. However, the proteins and lipids are not absorbed.

RATE OF LYMPH FLOW

About 120 mL of lymph flows into blood per hour. Out of this, about 100 mL/hour flows through thoracic duct and 20 mL/ hour flows through the right lymphatic duct.

Factors Increasing the Flow of Lymph

Flow of lymph is promoted by the increase in:

1. Interstitial fluid pressure.

2. Blood capillary pressure.

3. Surface area of lymph capillary by means of dilatation.

4. Permeability of lymph capillaries.

5. Functional activities of tissues.

COMPOSITION OF LYMPH

Usually, lymph is a clear and colorless fluid. It is formed by 96% water and 4% solids. Some blood cells are also present in lymph .

FUNCTIONS OF LYMPH

1. Important function of lymph is to return the proteins from tissue spaces into blood.

2. It is responsible for redistribution of fluid in the body.

3. Bacteria, toxins and other foreign bodies are removed from tissues via lymph.

4. Lymph flow is responsible for the maintenance of structural and functional integrity of tissue. Obstruction to lymph flow affects various tissues, particularly myocardium, nephrons and hepatic cells.

5. Lymph flow serves as an important route for intestinal fat absorption. This is why lymph appears milky after a fatty meal.

6. It plays an important role in immunity by transport of lymphocytes

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