The Lymphatic System

Background and Context

• Ambiguity in the numbers of body systems (11 major systems).
• Systems can be grouped or named differently (e.g., musculoskeletal, urinary within excretory).
• Systems do not work in isolation.

The Lymphatic System

• Often combined with the immune system but deserves individual attention.
• Lymph: Derived from blood plasma and contains proteins and lipids.

Understanding Lymph

1. Interstitial Fluid: Fluid between cells, originating from blood capillaries.

   • Most reabsorbed by capillaries; some become lymph.

2. Lymphatic Capillaries and Vessels: Present in almost all body tissues.

   • Lymph travels via body movements and smooth muscle contractions.

3. Lymphatic Ducts: Two main ducts: Right Lymphatic Duct and Thoracic Duct.

   • Right duct: Upper right body.
   • Thoracic duct: Rest of the body.
   • Drain into subclavian veins (links to circulatory system).

Lymph Nodes and Immune Function

• Nodes filter lymph for debris and pathogens (bacteria, viruses).

• Contain lymphocytes (B and T cells) and macrophages.

• Lymphocyte Types:

  • B Cells: Develop/mature in red bone marrow.
  • T Cells: Start in bone marrow, mature in the thymus.

• Common Symptoms: Swollen lymph nodes during illness (immune response).

Other Lymphoid Organs

1. Spleen:

   • Located behind the stomach.
   • High blood flow; holds a lot of blood.
   • Red Pulp: Filters damaged/old red blood cells.
   • White Pulp: B and T cell activity.

2. Tonsils: Four sets of tonsils (e.g., palatine, pharyngeal/adenoids, lingual, tubal).

   • Location aids in tackling inhaled/ingested pathogens.

3. Thymus:

   • Active before puberty; shrinks with age.
   • Maturation site for T cells.

Summary

• Pathway of Lymph: Interstitial fluid → Lymphatic capillaries → Vessels → Ducts → Circulatory system.
• Immune Function: Nodes filter lymph (macrophages, lymphocytes).
• Primary vs Secondary Lymphoid Organs:
  • Primary: Bone marrow, thymus (development/maturation of lymphocytes).
  • Secondary: Nodes, spleen, tonsils (site of immune responses).

Lymphatic System Disorders

• Lymphedema: Swelling due to poor lymph drainage.
• Lymphatic Filariasis: Caused by nematodes transmitted by mosquitoes.
  • Nematodes mature in lymphatic vessels, causing damage.
  • Treatments focus on parasites and vector control.

End of notes for The Lymphatic System