Lymphatic System Flashcards
What is the lymph?
Interstitial fluid that returns lost plasma proteins to bloodstream in lymphatic vessels
What are lymphatic vessels?
Structures and organs that contain lymphatic tissue
What is lymphatic tissue?
A specialised connective tissue that contains large numbers of lymphocytes
What is red bone marrow?
Stem cells that develop into RBC and WBC
What is the first function of the lymphatic system?
Drain tissue spaces of excess interstitial fluid and return it to the cardiovascular system
What is the second function of the lymphatic system?
Transport dietary lipids and lipid soluble vitamins from the GI tract to the blood
What is the third function of the lymphatic system?
Protect the body from foreign cells, microbes and cancer cells through immune responses
What is the smallest lymphatic vessel?
Lymphatic capillaries
What forces fluid into lymphatic capillaries?
Pressure in tissues
What makes sure fluid does not flow out of lymphatic capillaries?
Overlapping endothelial cells that act like a one way valve
Where are lymphatic capillaries found?
Throughout body except in CNS, bone marrow, portions of spleen and avascular tissues
What do lymphatic capillaries merge to form?
Lymphatic ducts- thinned walled structures like veins but with more valves
Apart from valves what can be found periodically along lymphatic duct?
Lymph nodes that are lymphocytes in capsular structure
Lymph flows through system due to….
Muscle contractions, 1-way valves, respiratory pressure and smooth muscle contractions in lymph vessel wall
What are primary lymphatic organs?
Thymus and red bone marrow
What are secondary lymphatic organs?
Sites where most immune responses occur and made of lymph nodes, spleen and lymphatic nodules
Where is thymus found?
Between lungs and above heart
What happens to immature T cells?
They migrate from bone marrow to cortex of thymus where they multiply and mature
What happens to mature T-cells?
They enter blood and populate lymph nodes, spleen and other lymphatic tissues
Where are lymph nodes found?
Scattered throughout the body and concentrated near mammary glands, axillae and groin
What do lymph nodes contain?
Mature B-cells, T-cells, dendritic cells and macrophages
What do lymph nodes do?
Filter lymph, trap foreign substances which macrophages and lymphocytes mostly destroy
What happens at germinal centres of lymph nodes?
Aggregation of B lymphocytes which are rapidly proliferating and differentiating upon stimulation with antigen
What percentage of volume removed from blood goes to lymphatic and what percentage is returned to blood?
10% to lymphatic, 90% returns
