lymph

Test Information

  • The upcoming test on circulation has been rescheduled.

  • Current Schedule:

    • Listed for Monday, the 8th (incorrect).

  • New Schedule:

    • Test will take place on Thursday, the 11th.

  • Content Covered:

    • Heart, blood vessels, blood pressure, and lymphatic system.

  • Note:

    • Previous quiz on blood is not included in test content.

The Lymphatic System

  • The lymphatic system operates as a drainage and filtration system for excess fluids.

  • It is often compared to a sewer system in the body, as it collects excess fluid that leaks from capillary beds.

Capillary Leakage and Edema

  • Blood circulates through capillary beds where plasma leaks into the extracellular space, forming interstitial fluid.

  • If excess fluid accumulates and is not drained, it leads to edema (swelling).

  • The lymphatic system collects this excess fluid and returns it to the bloodstream.

Lymph Capillaries

  • Lymph capillaries are found in areas where capillary beds exist and they help drain excess fluid back into circulation.

  • Fluid Transformation:

    • In the blood, fluid is called plasma.

    • When it enters the extracellular space, it becomes interstitial fluid or extracellular fluid.

    • In lymph vessels, it is referred to as lymph.

Lymph Nodes

  • Lymph nodes, also referred to as lymph glands, act as filtration stations for the lymph, trapping particles such as bacteria and noxious compounds to purify the lymph before it re-enters circulation.

  • They are strategically located throughout the body to filter lymph from various regions.

Flow of Lymph

  • Lymph flows through a series of progressively larger vessels.

  • Lymphatic vessels have valves (similar to veins) to ensure one-way flow toward the circulatory system.

  • Ultimately, lymph drains into the junction of the subclavian and jugular veins.

Differences Between Right and Left Lymphatic Ducts

  • Thoracic Duct: Largest lymphatic vessel, collecting lymph from below the diaphragm and the left side of the body, including the left side of the head and neck.

  • Right Lymphatic Duct: Smaller duct draining lymph from the right side of the chest, right arm, and right side of the head and neck.

Functions of Lymph Nodes and the Spleen

  • Lymph nodes filter lymph; they may swell when activated by infection or cancer.

  • The spleen filters blood, serves as a reservoir for blood, and helps in immune responses.

Spleen Functions

  • The spleen holds blood and can contract to release it back into circulation when needed, such as during emergencies (e.g., trauma).

  • It contains red pulp (for blood filtering) and white pulp (accumulation of lymphocytes for immune response).

Organ Survival After Splenectomy

  • People can live without their spleen, although they may have decreased ability to fight blood-borne infections.

Training of Immune Cells

  • Thymus:

    • This organ trains T cells, which play a crucial role in immune defense.

    • The thymus atrophies after age 30, replaced by fatty tissue.

  • B Cells:

    • Trained in the bone marrow, they produce antibodies to respond to antigens.

Tonsils

  • Tonsils provide surveillance against pathogens entering through the oral cavity.

  • Composed of lymphatic tissue, they activate the immune response to infections particularly in the throat region.

Types of Tonsils

  1. Lingual Tonsil: Located at the base of the tongue.

  2. Palatine Tonsils: Located at the sides of the pharynx.

  3. Pharyngeal Tonsil (Adenoids): Located in the nasopharynx.

Lymph Nodes in Various Regions

  • Lymph nodes (axillary, cervical, inguinal) are strategically placed to filter lymph from specific body areas.

  • Understanding their locations is vital, particularly in cancer examinations (e.g., breast cancer related lymphatic drainage).

Conclusion

  • The lymphatic system plays a critical role in maintaining fluid balance and immune function in the body while working closely with the circulatory system.