Lymphatic System Flashcards
How does the lymphatic system maintain homeostasis?
By eventually returning most of the fluid that has been diverted back into the blood
What is lymph?
Watery solution that flows through the lymphatic system
What does most lymph start out as?
Blood plasma that is forced out of capillaries, where leakage helps exchange of nutrients and gases between blood in capillaries and cells in tissues
What do the lymph nodes do?
Monitor and cleanse lymph as it filters through
Give four examples of lymphoid organs
Spleen
Thymus
Adenoids
Tonsils
What are the lymphatic capillaries made of?
Loosely overlapping endothelial cells that has flap-like mini valve that ensures lymph fluid won’t leak back into the interstitial space
What does the right lymphatic duct drain?
Lymph collected from the upper right area of the torso, arm and right side of the head and thorax
What can blockage of the lymph system lead to?
Lymphedema
What does MALT stand for?
Mucosa-associated lymphoid tissues
Where are MALTs found?
In mucous membranes around the body eg. Tonsils, Peyer’s patches and the appendix
What three things help propel lymph along?
Skeletal muscle movement
Pressure change in the thorax
Pulsations of adjacent arteries
What does GALT stand for?
Gut associated lymphatic tissue
What does BALT stand for?
Bronchus associated lymphatic tissue
What is the hilum?
Indentation in the surface of a kidney, spleen or other organ where blood vessels, ducts, nerve fibres etc enter or leave it
Where are follicular dendritic cells found?
Germinal centres
What do follicular dendritic cells cause?
Proliferation of B cells, in particular memory B cells
What is the term given for enlarged lymph nodes?
Lymphadenopathy
What causes lymphadenopathy?
As nodes fight infection, germinal centres fill with increasing numbers of lymphocytes, causing lymph nodes to swell
What are the immune functions of the spleen?
Antigen presentation by APCs
Activation and proliferation of B and T lymphocytes, production of antibodies
Removal of macromolecular antigen from blood
What are the haemopoietic functions of the spleen?
Removal and destruction of old, damaged and abnormal erythrocytes
Retrieval of iron from erythrocyte Hb
How can a ruptured spleen lead to death?
Through exsanguination (severe blood loss)
Where is the thymus located?
In the superior mediastinum
What is the role of the thymus?
Maturation of bone marrow derived stem cells into T cells (this is called thymic cell education)
When might the spleen enlarge?
In response to systemic infection (glandular fever, malaria and septicaemia)
