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Lymphatic System
Study of the lymphatic system
91
Anatomy
Undergraduate 2
03/10/2008

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Term
What is a lacteal?
Definition
Specialized lymph capillaries in the villi of intestines: help to absorb digested fats from intestine.
Term
Why are lymph vessels permeable?
Definition
They have a porous endothelium with minivalves, collagen anchors the endothelial cells so that they open.
Term
What is a lymphatic collecting vessel?
Definition
Similar to a vein, but thinner walled and having more valves.
Term
What is a lymphatic trunk?
Definition
Formed by the union of the largest collecting vessels, drain large areas of the body.
Term
What are the major trunks of the body?
Definition
lumbar, bronchomediastinal, subclavian, jugular, intestinal (only one of these)
Term
Where do the trunk eventually deliver lymph?
Definition
To the two large ducts in the thoracic region.
Term
What are the two major lymphatic ducts?
Definition
The right lymphatic duct, and the thoracic duct.
Term
What is the right lymphatic duct?
Definition
Drains lymph from right upper arm and right side of the head and thorax.
Term
What is the thoracic duct?
Definition
Drains lymph from the rest of the body, leads to cisterna chyli.
Term
What is the cisterna chyli?
Definition
An enlarged sac leading from the thoracic duct, anterior to first two lumbar vertebrae, collects lymph from lumbar trunks.
Term
Where do the terminal ducts empty to?
Definition
Empty lymph into the venous circulation at junction of internal jugular vein and subclavian vein on its own side of the body.
Term
How many liters of lymph enter bloodstream each day?
Definition
About 3 liters of lymph.
Term
What do lymphoid cells do?
Definition
Protect body from invading bacteria and viruses, fought off by inflammation, phagocytes, and lymphocytes.
Term
Where do leukocytes arise from?
Definition
Arise from red bone marrow.
Term
What are T cells?
Definition
Type of lymphocyte, activated by foreign antigens in body, manage immune reponse, can directly attack and destroy foreign cells.
Term
What are B cells?
Definition
Type of lymphocyte, secrete plasma cells.
Term
What are plasma cells?
Definition
Secrete antibodies into blood and fluids that immobilize antigens.
Term
What are macrophages?
Definition
From monocytes, phagocytize foreign substances and help activate T cells.
Term
What are reticular cells?
Definition
Produce the reticular fiber network (STROMA) that supports all cells in lymphoid organs.
Term
What does lymphoid tissue do?
Definition
Houses and provides proliferation site for lymphocytes, ideal surveillance point for lymphocytes and macrophages.
Term
Which lymphoid organ does not contain reticular connective tissue?
Definition
The thymus does not contain it.
Term
What is a lymphatic follicle?
Definition
Solid spherical bodies that lack a capsule, have tightly packed reticular elements and cells.
Term
What is a germinal center?
Definition
Contains dendritic cells and B cells producing plasma cells - found in lymph nodes, intestinal wall, appendix.
Term
What are Peyer's patches?
Definition
Large isolated clusters of lymph nodules in the wall of the small intestine.
Term
What is the function of Peyer's patches?
Definition
Destroy bacteria, generate memory lymphocytes for long-term immunity.
Term
What is a lymph node?
Definition
100's of nodes are clustered along lymphatic vessels, esp. near axillary, inguinal, and cervical regions.
Term
What do lymph nodes do?
Definition
Filter lymph as transported to the bloodstream
Term
Describe lymph nodes.
Definition
Bean shaped less than 1 inch in length, have an outer capsule of CT, has cortex and medulla.
Term
What is the cortex of a lymph node?
Definition
The outer region of the node, densely packed follicles w/ germinal center filled with dividing B cells.
Term
What is the medulla of the lymph nodes?
Definition
The innermost region of the node, contains B and T lymphocytes and plasma cells.
Term
Describe circulation in lymph nodes.
Definition
Lymph enters convex side of node, subcapsular sinus, smaller sinuses in cortex, medulla, exits viw hilus.
Term
What are swollen lymph nodes referred to?
Definition
Buboes.
Term
Where is the spleen located?
Definition
On the left side of the abdominal cavity just beneath the diaphragm.
Term
How is blood supplied to the spleen?
Definition
Via the splenic artery and vein.
Term
What are the functions of the spleen?
Definition
Site of lymphocyte proliferation and immune surveillance and response, filters blood.
Term
What are the spleen's functions in blood?
Definition
Removes old RBC's, debris, bacteria, toxins, stores iron, blood platelets.
Term
What is the function of the spleen in a fetus?
Definition
Site of erythrocyte production in fetus.
Term
Describe the white pulp of the spleen.
Definition
Contains lymphocytes on reticular fibers surrounding central artery, involved in the immune functions of the spleen.
Term
What is the thymus and where is it located?
Definition
A bi-lobed organ found in the lower neck region, extends into mediastinum of superior thorax, contains thymocytes.
Term
What are thymocytes?
Definition
Produce thymosin and thymopoeitin, which help T lymphocytes to mature.
Term
Does the thymus directly fight antigens?
Definition
No, the blood-thymus barrier keeps antigens out while lymphocytes mature.
Term
Describe the structure of the thymus.
Definition
Divided into lobules, outer cortex is darker and contains dividing T lymphocytes, inner medulla is lighter.
Term
What accumulates in the adult thymus?
Definition
Adipose tissue.
Term
What are tonsils?
Definition
Ring of lymphatic tissue around the entrance to the throat, gather and remove many pathogens from air and food.
Term
What are the 4 types of tonsils?
Definition
Palatine, lingual, pharyngeal, and tubal.
Term
Where are palatine tonsils?
Definition
On the posterior sides of the oral cavity.
Term
Where are lingual tonsils?
Definition
At the base of the tongue.
Term
Where are pharyngeal tonsils?
Definition
Adenoids, in posterior wall of naspharynx.
Term
Where are tubal tonsils?
Definition
Surround the opening of auditory tubes.
Term
What is the typical structure of tonsils?
Definition
Nodules with germinal centers, have deep invaginations that trap bacteria.
Term
What are the two defense systems of the body?
Definition
The innate (nonspecific) system, and the adaptive (specific) defense system.
Term
What is the first line of defense in the innate immune system?
Definition
Intact skin and mucosa prevent the entry of microorganisms.
Term
What is the second line of defense in the innate immune system?
Definition
Antimicrobial proteins, phagocytes, and other cells.
Term
What enzyme is contained in saliva and lacrimal fluid?
Definition
Lysozyme, which digest bacteria.
Term
What are the chief phagocytic cells?
Definition
Macrophages, wandering in search of debris.
Term
What are some examples of macrophages in specific places having specific names?
Definition
Kupffer cells (liver), microglia (brain), Langerhans cells (skin).
Term
What are the three phagocytes?
Definition
Neutrophils, eosinophils, and mast cells.
Term
What are mast cells?
Definition
Basophils wandering through tissue, binding and digesting a wide range of bacteria.
Term
What do eosinophils do?
Definition
Weakly phagocytic against parasitic worms.
Term
What is the purpose of inflammation?
Definition
Prevents spread of damagin agents to nearby tissues, diposes of cell debris and pathogens, sets stage for repair process.
Term
What are the four cardinal signs of acute inflammation?
Definition
Redness, heat, swelling, and pain.
Term
Why does hotness occur in inflammation?
Definition
Heat promotes phagocytosis of infectious material and cellular debris.
Term
What occurs in the redness of swelling?
Definition
Chemical mediators cause vasodilation, increase of blood pressure, and increased leukocytes.
Term
What occurs in swelling?
Definition
Vasodilation and increased interstitial fluid.
Term
What part of the brain is stimulated in a fever response?
Definition
The hypothalamus which is reset in response to pyrogens released by leukocytes and macrophages.
Term
What chemicals are released by leukocytes and macrophages to stimulate fever?
Definition
Pyrogens.
Term
What occurs in the liver during a fever?
Definition
It uses excess Zn and Fe, making them less available for bacteria.
Term
What do natural killer cells do?
Definition
Lyse tumor and virus infected cells.
Term
What do eosinophils do?
Definition
Inhibits inflammatory response, defense against parasitic worms.
Term
What is typically the first WBC to enter infected tissue?
Definition
The most abundant, that is, neutrophils.
Term
What are the functions of mast cells?
Definition
Found in CT, promote inflammation via release of histamine - they're basophils!
Term
What are the two overlapping arms of the adaptive immune system?
Definition
The humoral and cellular branches.
Term
What is the humoral arms of the immune system?
Definition
Antibody mediated immunity.
Term
What is the cellular arm of the immune system?
Definition
Cell mediated immunity - non antibody mediated.
Term
What are some types of antigens that are found?
Definition
Foreign proteins, nucleic acids, certain lipds, and large sugars.
Term
What is the main function of MHC?
Definition
Major histocompatibility complex marks a cell as "self".
Term
What are class I MHC proteins?
Definition
Found on all cells.
Term
What are Class II MHC proteins?
Definition
Found only on immune cells?
Term
Where do T lymphocytes mature?
Definition
In the thymus.
Term
What are APC's?
Definition
Antigen presenting cells - engulf foreign particles and present fragments of antigens to be recognized by T cells.
Term
What are the major APC's?
Definition
Dendritic cells, macrophages, and activated B cells.
Term
After meeting an antigen, where do APC's go?
Definition
Migrate to lymph nodes and secondary lymph organs to present antigens to T and B cells.
Term
What do T cells do?
Definition
Recognize and respond to processed fragments of antigens displayed on surface cells.
Term
Antibodies are useless against what?
Definition
Intracellular antigens, here cell mediated immunity is needed.
Term
What are the two major populations of T cells?
Definition
CD4 cells and CD8 cells.
Term
What are CD4 cells?
Definition
Primarily helper T cells (Th)
Term
What are CD8 cells?
Definition
Cytotoxic T cells that destroy cells harboring foreign antigens.
Term
How do Tc cells kill other cells?
Definition
Injecting perforin granules into a cells, which eventually target nucleus and cause apoptosis.
Term
What are cytokines?
Definition
Mediators involved in cellular immunity
Term
What are the functions of perforin and lymphotoxin?
Definition
Perforin lyses cells while lymphotoxin leads to necrosis.
Term
What do antibodies do?
Definition
Tag antigen, making antigen-antibody complex, inactivate it and tag it for destruction.
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