Lymphatic System Flashcards
Platelets (thrombocytes) are formed in ___ and by ___
In red bone marrow and by megakaryocytes
The Spleen:
Filters and destroyed pathogens and other foreign materials from the blood.
The Spleen contains:
B-lymphocytes (produce antibodies against foreign antigens)
T-lymphocytes (attach to invading viruses or foreign entities)
Both these lymphocytes have an active role in the immune system.
Monocytes (leukocytes/WBC) in the spleen:
Become macrophages, which fight infection by phagocytosis.
Macrophages are phagocytes.
Macrophages are leukocytes/WBCs.
Interior of spleen contains:
Splenic pulp consisting of red pulp, blood-filled sinusoids that fill the interspaces of the spleen’s sinuses.
Interior of spleen contains:
Splenic pulp consisting of red pulp, blood-filled sinusoids that fill the interspaces of the spleen’s sinuses.
Sinusoids of red pulp:
Are surrounded by reticular fibers, mononuclear phagocytes (WBCs), lymphocytes, plasma cells, and monocytes.
Also within the red pulp is white pulp, sheaths of lymphatic tissue surrounding the arteries of the spleen, particularly the splenic artery.
Spleen functions in fetus:
Spleen (along with the liver) has a role in blood cell formation. (A role later assumed by bone marrow).
Spleen functions in adult:
Spleen destroys old RBCs and forms bilirubin from hemoglobin. It acts as a reservoir for blood, which can be released quickly in an emergency, such as hemorrhage. 20%-30% of body’s platelets are stored here.
The spleen:
Filters and destroys pathogens and other foreign materials from the blood.
The spleen contains:
20%-30% of the body’s platelets.
B-lymphocytes (produce antibodies against antigens)
T-lymphocytes (attach to invading viruses or foreign entities)
Both of these lymphocytes have an active role in the immune system
Adult without a spleen:
More susceptible to some bacterial infections, such as pneumonia and meningitis.
After spleen removal, liver, bone marrow and lymph nodes assume some of the spleens functions,
Thymus:
Ductless gland in the upper chest, under the sternum. Important in the immune response, although its function declines with age.
Thymus during fetal and early neonatal life:
Thymus entraps immature stem cells in its reticular structure. it sensitizes these cells so they are able to mature into a specific type of lymphocyte (eventually becoming T-cells).
If Thymus fails:
Persons cell-mediated immunity is non functioning.
