lymphatic system Flashcards
(17 cards)
What happens to blood as it enters capillaries?
High pressure forces fluid out of the capillary wall into surrounding tissue.
What does the lymphatic system do with leaked fluid from capillaries?
It collects the fluid and returns it to the circulatory system near the venous end.
Why is the lymphatic system important in immunity?
It helps fight against disease-causing organisms/pathogens.
What is lymph?
Lymph is the fluid collected by the lymphatic system.
What are lymph capillaries?
A network of one-way vessels that collect leaked fluid near the arterial end of capillaries.
Where does lymph return to the circulatory system?
Near the venous end before the heart via two lymphatic ducts in the thorax.
How do lymph capillaries originate?
As ‘blind-end’ tubes between cells, larger than regular blood capillaries.
What is special about the permeability of lymph vessels?
They are permeable to proteins and disease-causing organisms.
How is lymph pushed through lymph vessels?
By smooth muscle contractions and skeletal muscle movement.
What prevents lymph from flowing backward?
Valves in the lymph vessels.
Where are lymph nodes found?
Along some lymph vessels – especially in the neck, armpit, groin, and around the digestive system.
What do lymph nodes look like and how big are they?
Bean-shaped, 1–25 mm in length, made of lymphoid tissue enclosed in connective tissue.
What key immune cells are found in lymph nodes?
Lymphocytes, macrophages, and plasma cells.
How does lymph flow through a lymph node?
It enters on the convex side, is filtered, then exits on the other side.
What happens when pathogens penetrate the body’s external defences?
They may be trapped in lymph nodes and destroyed by immune cells.
How are large bacteria removed in lymph nodes?
Macrophages engulf them via phagocytosis, which can take 10–30 minutes.
Why do lymph nodes swell during infection?
More fluid enters and lymphocytes are actively produced to fight the infection.
