The Lymphatic System

Question 1

Function of the lymphatic system

Answer 1

Tissue drainage of tissue fluid into EC spaces and then the venous system. Approximately 8L/day drained. It allows for the return of plasma and plasma proteins. Absorbed fat is transported from the gut, drains into the SVC and then the liver. It aids immunity.

Question 2

Composition of the lymphatic system

Answer 2

Fluid and plasma proteins. Lymphocytes (lymphatic capillaries and channels) and fats (small intestine).

Question 3

Lymph nodes

Answer 3

There are approx 450 lymph nodes in a young adult. They are isolated or grouped. Periodically lymphatic vessels traverse lymph nodes which are where immunological functions of lymph are located. They are small bean shaped glands throughout the body, which are major sites of B and T lymphocytes and other WBCs. They act as filters for foreign particles and cancer cells.

Question 4

Lymphatic drainage

Answer 4

Lymphatic drainage follows routes of arterial supply.

Question 5

Lymph ducts

Answer 5

Ultimately all lymph congregates into 2 large ducts; the right lymphatic duct and thoracic duct. These empty into the venous system at the jugular/subclavian junction.

Question 6

Lymphoid tissue

Answer 6

Where lymphocytes generate and mature. This includes the thymus and bone marrow (primary), spleen (secondary), lymph nodes (secondary), peyer’s patches (secondary) and tonsils.

Question 7

Flow of lymphatic fluid

Answer 7

Flow in lymphatic vessels relies upon muscle contractions, pressure changes and gravity. Due to the presence of valves, flow is unidirectional. Fluid flow into EC spaces increases during infection due to protein accumulation (osmosis), this drives increased lymph flow into ducts and therefore immune response in nodes as more antigens are presented so phagocytosis occurs.