Ch. 20 Lymphatic System Flashcards
What are the three components of the lymphatic system?
Lymphatic vessels, Lymph, Lymph Nodes
Which of the above components (Lymphatic vessels, Lymph, Lymph Nodes) are considered to be lymphoid organs?
Lymph nodes
Explanation: they function to cleanse and filter the lymph
What are the major functions of the lymphatic vessels?
Carry/collect excess fluid and return it to blood
What is lymph?
Colorless watery fluid that flows ONLY toward the heart (one-way system)
Trace the flow of lymph through the lymphatic vessels, beginning with the lymphatic capillaries and
ending at the point where the lymphatic system empties into the venous circulation. Include the following
structures: lymphatic ducts, lymphatic capillaries, lymphatic trunks, and lymphatic collecting vessels
Lymphatic capillaries –> lymphatic collecting vessels -> lymph node –> lymphatic trunk –> lymphatic duct –> Heart –> Arterial system
Describe how mini valves work to promote the movement of lymph into a lymphatic capillary
- Mini valves open when there’s an increase in interstitial fluid, allowing fluid to enter. However, they are closed shut by increased fluid pressure inside the capillary
- Prevent backflow, ensuring lymph moves one way
What body regions are drained by the:
a) Right lymphatic duct?
b) Thoracic Duct?
A) right upper limb and right side of head & thorax
b) Thoracic duct: drains rest of body
Where does the lymph go after it leaves the lymphatic ducts?
Ducts will empty lymph into venous circulation
List the major types of lymphoid cells:
- Immune system cells: Lymphocytes, Macrophages & Dendritic cells
- Supporting cells: reticular cells (in reticular connective tissue)
Lymphoid tissue is made up of what specific type of connective tissue?
Reticular Connective Tissue
What distinguishes the primary lymphoid organs from the secondary lymphoid organs?
Primary lymphoid organs are where lymphocytes mature
Secondary lymphoid organs: where mature lymphocytes encounter antigen & become activated
List the two primary lymphoid organs:
Thymus and Red bone marrow
List the secondary lymphoid organs:
Lymph nodes, Spleen, MALT (mucosa-associated lymphoid tissue)
What are the only lymphoid organs that cleanse the lymph?
lymph nodes
What are the two functions of lymph nodes
- Cleanse lymph; lymph “filters” - macrophages remove debris & microorganisms (prevent from entering blood)
- Immune system activation: provide site where lymphocytes can be activated & mount attack against antigen
What vessels carry lymph:
A) INTO a lymph node?
B) OUT of a lymph node
A) Afferent lymphatic vessels
B) Efferent lymphatic vessels
What is the advantage of having fewer efferent than afferent lymphatic vessels serving a lymph node?
slows lymph flow
Where is the spleen located?
left side of abdominal cavity (largest lymphoid organ)
What are two major functions of the spleen, as discussed in class?
- Immune: site of lymphocyte activation & immune surveillance
- Blood-cleansing: macrophages remove aged RBCs and debris
What does “MALT” stand for?
Mucosa-associated lymphoid tissue (MALT)
Where are the large collections of MALT found?
Tonsils, Peyer’s patches, Appendix
Tonsils:
A) Locations
B) examples
A) form ring around pharynx (throat)
B) Include: palatine tonsil, pharyngeal tonsil, lingual tonsil
Tonsil functions
- trap and destroy bacteria in food or air that enter tonsillar crypts
- generates “memory” lymphocytes
Peyer’s Patches
A) Location
A) (clusters of lymphoid follicles) found in wall of distal small intestine
Appendix
A) Location
B) Function
A) offshoot of first part of large intestine
B) Has same function as peyer’s patches
Which structures function to remove pathogens from entering food or air?
Tonsils
What are two functions of the Peyer’s patches & appendix?
a) destroy bacteria
b) generate memory lymphocytes
Where is the thymus located?
mediastinum; partially overlies the heart
What is the major function of the thymus?
Site where T lymphocytes mature
How would you expect the relative size of the thymus to differ in a two-year-old girl as compared to a 60-
year-old woman?
A two year old girl will have a larger thymus (the thymus is the most active & largest in size during childhood) while a 60 year old woman would have an atrophying (shriveling) thymus
Unlike the other lymphoid organs, the thymus is composed of
Epithelial cells
True or False: The thymus directly fights antigens.
FALSE - Unlike other lymphoid organs, the thymus DOES NOT directly fight antigens
When does the thymus stop growing?
During adolescence, will start to gradually atrophy or shrivel up
