Lymphatic and Immune Systems Flashcards
What is the Lymphatic system?
The system of vessels, cells, and organs that carries excess fluids to the bloodstream and filters pathogens form the blood.
Functions of the lymphatic system:
-Returns body fluids to the bloodstream that leaked out from the bloodstream due to blood pressure
-Transports cells of the immune system
-Transports dietary lipids and fat-soluble vitamins
-Lymph nodes are major staging areas for development of critical immune responses
Structure of the lymphatic system:
-Lymphatic vessels begin as open-ended capillaries that feed into larger vessels
-Lymph travels through the lymph nodes
How does lymph flow?
Not actively pumped by the heart, relies on the contraction of skeletal muscles and breathing
Which part(s) of the body drain into the right lymphatic duct?
Right side of the body, right sides of the head, thorax, and right upper limb
Which part(s) of the body drain into the thoracic duct?
The left side of the body and any remaining portion of the body not included in the right lymphatic duct (much larger portion of the body than the right lymphatic duct)
How does lymph reenter the bloodstream?
The right and thoracic lymphatic ducts empty into the right and left subclavian veins
What are lymphocytes?
-Primary cells of adaptive immune responses
-Two types: B & T cells
How do lymphoid organs get their name?
They are sites of B & T cell maturation
Where do B & T cells mature?
B cells mature in red bone marrow
T cells mature in the thymus
What are B cells?
-Immune cells that produce antibodies
-When activated by binding to an antigen, they differentiate into cells that secrete a soluble form of their surface antibodies
-Activated B cells are known as plasma cells
What are antibodies?
Any of the group of proteins that binds specifically to pathogen-associated molecules known as antigens
What are antigens?
Chemical structures on the surface of a pathogen that binds to T or B lymphocyte antigen receptors
What are plasma cells?
-B cells that have differentiated in response to antigen binding
-Gained the ability to secrete soluble antibodies
-Differ from B & T cells due to containing a large amount of cytoplasm packed with rough endoplasmic reticulum
What are T cells?
-Do no secrete antibodies
-Function in the adaptive immune response
-Can either secrete soluble factors that communicate with other immune cells or destroy infected cells
-Form immunological synapse with APCs
-Release cytokines
What are natural killer cells?
-Circulating blood cell that contains cytotoxic granules in its cytoplasm
-Among the body’s first lines of defence against viruses and certain cancers
Red bone marrow as a primary lymphoid organ:
-Takes over most hematopoietic functions
-B cells undergo most of its development
-Immature T cells (thymocyte) leaves bone marrow to mature in the thymus
The thymus as a primary lymphoid organ:
-Bilobed organ found in the space between the sternum and the aorta
-Connective tissue holds the lobes closely together but separates them and forms a capsule
-Location of T lymphocyte maturation (self vs non-self processes)
What are secondary lymphoid organs?
-Location of immune responses
-Receives naive lymphocytes
-Includes lymph nodes, spleen, lymphoid nodules
What is a naive lymphocyte?
-lymphocyte that has left the primary organ and entered a secondary lymphoid organ
-Fully immunologically functional
-Yet to encounter an antigen
-Concentrate themselves in secondary lymphoid organs
What are lymph nodes?
-Filter lymph
-Receive bacteria Fromm infected interstitial fluid
-Contain dendritic cells and macrophages to kill pathogens
-Sites of adaptive immune responses
-Surrounded by connective tissue and compartmentalized by trabeculae
-Contain germinal centres filled with rapidly dividing B cells surrounded by T cells
What is the spleen?
-Major secondary lymphoid organ
-Filters blood using dendritic cells and macrophages
-Nodules containing areas of red and white pulp
-Blood enters via splenic artery
-Blood leaves via splenic vein
What are lymphoid nodules?
-Simpler architecture than spleen/lymph nodes
-Dense cluster of lymphocytes
-Located in respiratory and digestive tracts
What are tonsils?
-Lymphoid nodules on the inner surface of the pharynx
-Swell as an active immune response to infection
-Epithelial layer invaginates deeply to form crypts
-Crypts accumulate pathogens introduced by eating and breathing
What is MALT?
-Mucosa-Associated Lymphoid Tissue
-Aggregate of lymphoid follicles associated with the mucous membrane epithelia
-Dome-shaped structures found underlying the mucosa of GI tract, breast tissue, lungs, eyes
-Peyer’s patches are MALT in the small intestine
What is being indicated by the two arrows in this image of a lymph node?
Black: dense connective tissue capsule
Green: germinal center
What is the purpose of staining this lymph node with silver?
To show the reticular fibres that form a network to hold the lymphocytes as they filter the lymph
