17. Lymphatic system Flashcards
(15 cards)
What is the main function of the lymphatic system?
Acts as a secondary circulatory system by transporting and filtering interstitial fluid (lymph); returns tissue fluid to the blood and monitors the body for pathogens (immunity).
What is lymph?
Fluid that starts as blood plasma forced out of capillaries; known as interstitial fluid before it is absorbed into lymphatic vessels.
What are lymphatic capillaries?
Thin-walled vessels that collect excess interstitial fluid and transport it to lymphatic vessels.
What tissues are part of the central lymphoid system?
Thymus (site of T-cell maturation) and bone marrow (produces lymphocytes); these replenish lymphocytes.
What tissues are part of the peripheral lymphoid system?
Lymph nodes, spleen, adenoids, appendix, Peyer’s patches; these do not replenish lymphocytes.
What do lymph nodes do?
Contain leukocytes that filter lymph and can initiate an immune response.
What does the spleen do?
Filters blood as it passes through.
What do adenoids do?
Inspect incoming food and air for pathogens.
What does the appendix do?
Contains lymphoid tissue that helps destroy bacteria before it breaches the intestinal wall.
What are Peyer’s patches?
Large aggregates of lymphoid tissue in the small intestine.
How does lymph fluid move?
Interstitial fluid is absorbed by lymphatic capillaries, becoming lymph; movement is assisted by one-way valves, skeletal muscle contraction, and smooth muscle lining.
Where do lymphatic capillaries drain lymph?
Throughout the body except bones, bone marrow, teeth, and CNS; lymph is ultimately returned to the blood.
What can cause lymph system blockage?
Obstruction (e.g., tumor) can cause swelling and edema because fluid pools in tissue instead of returning to circulation.
What is edema?
Swelling due to fluid pooling in tissues, which can constrain blood flow.
What is a lymph node biopsy used for?
Detects cancer and determines where cancer cells have traveled.
