The Lymphatic System Lecture Notes

Overview

• The lymphatic system is often overlooked and grouped with the immune system.
• It plays a crucial role in body fluid management and immune defense.

Key Components

Lymph

• Derived from interstitial fluid outside cells.
• Originates from blood plasma that leaks from blood capillaries.
• Contains proteins, lipids, and sometimes pathogens.

Lymphatic Pathway

• Lymph travels through a network of lymphatic capillaries, vessels, and ducts.
• Capillaries: Found in nearly all tissues; entry point for lymph.
• Vessels: Larger pathways; lymph moves due to body and smooth muscle movements.
• Ducts:
  • Right lymphatic duct: Drains lymph from the upper right body.
  • Thoracic duct: Drains lymph from the rest of the body, returning it to subclavian veins.

Functions

• Collects, filters, and returns lymph to the circulatory system.
• Supports immune function by filtering pathogens and debris.

Immune Functions

Lymph Nodes

• Act as filters for cellular debris and pathogens.
• Contain immune cells:
  • Lymphocytes: B and T cells.
  • Macrophages: Engulf pathogens.
• Swell in response to infection.

Other Lymphatic Organs

• Spleen:
  • Located behind the stomach.
  • Filters old red blood cells.
  • Contains red and white pulp for immune response.
• Tonsils:
  • Four sets (palatine, pharyngeal, lingual, tubal).
  • Act as a defense against pathogens in the respiratory and digestive tract.

Primary Lymphoid Organs

• Bone Marrow:
  • Origin and maturation site for B cells.
• Thymus:
  • Maturation site for T cells.
  • Active before puberty, diminishes with age.

Disorders and Conditions

• Lymphedema:
  • Caused by dysfunction in lymph traveling and draining.
  • Can lead to swelling in tissues due to lymph accumulation.
• Lymphatic Filariasis:
  • Caused by nematode parasites transmitted by mosquitoes.
  • Parasites can mature in lymphatic vessels, leading to lymphedema.
  • Treatments target parasites and vector control methods are being explored.

Recap

• Understanding of lymph and its movement.
• Importance of lymph nodes and lymphatic organs in filtering and immune response.
• The development of lymphocytes in primary lymphoid organs.
• Potential issues if the lymphatic system fails.

Reminder from the Amoeba Sisters: Stay curious!