Lymph Vessels and Lymph Nodes (Leaving Cert Biology): Revision Notes

Lymph Vessels and Lymph Nodes

Lymph Vessels

• Lymph is transported in lymph vessels in the same way that blood is transported in veins.
• Movement is aided by:
  • Muscular walls of the vessels.
  • Body movements pressing on the vessels.
• Lymph flows slowly through the lymph vessels and returns to the blood near the neck at the subclavian veins via:
  • The thoracic duct (left side of the body).
  • The right lymphatic duct (right side of the body).

Lymph Nodes

• Lymph vessels have many small swellings called lymph nodes**.**
• Clusters of these lymph nodes (glands) are found near the throat, armpits, chest, appendix and groyne.
• Lymph nodes contain white blood cells (lymphocytes)****.
• Lymph nodes fight infection in 2 ways:
  1. They filter out bacteria and other harmful substances from lymph as it flows through.
  2. They mature and store large numbers of lymphocytes.
  • When fighting disease, lymph nodes can become swollen. This indicates that the person has an infection.
  • If lymph vessels are blocked or if a person is inactive for several hours, swelling can occur.
  • Example: swollen ankles after sitting during a long flight.

Other Lymphatic Organs

The spleen, thymus, adenoids and tonsils are all part of the lymphatic system.

• Spleen: Philtres bacteria, recycles red blood cells and stores lymphocytes.
• Thymus: Aids in lymphocyte development.
• Adenoids and tonsils:
  • The adenoids are found at the back of the throat.
  • The tonsils are found towards the back of the mouth on either side.
  • They can become inflamed and enlarged, affecting breathing.
  • If tonsils become infected regularly, they may have to be removed.