Lymphatics Flashcards
What is the main function of the lymphatic system?
To prevent swelling due to edema.
How much plasma does the lymphatic system collect per day?
Collects about 3 liters a day; Returns it to the general circulation near the base of the neck.
Aside from phagocytosis, what is a leukocytes special function?
Diapedesis; Requires selectins and adhesins
What are the primary lymphoid tissues?
Fetal liver, Red marrow, and Thymus; Sites of hematopoiesis
Why is the fetal liver large in comparison to the body?
Due to the demands of hemopoisis and to make formed elements of the fetal blood.
What are the secondary lymphoid organs?
Spleen, lymph nodes, MALT, SALT; MALT contains tonsils, peyer’s patches, appendix and BALT.
When is a lymphocyte naive?
Lymphocytes are considered naive until they’re activated by antigens.
Where can red bone marrow be found in fetuses and infants?Adults?
All fetal and infant bone marrow is red. Adults have red bone marrow in the hips, sternum, scapula, skull, vertebra and the heads of femur and humerus
Where does most of B lymphocyte producion occur?
In red bone marrow; Once produced, they migrate away from endosteum and towards an artery and mature in periphery.
Where is the thymus?
Superior mediastinum; Anterior to great vessels; Recieves blood from internal thoracic, and superior thyroid arteries
Describe thymic involution
Adipocytes slowly infiltrate the thymic cortex and medulla replacing functional cells.
Histologically describe the outer capsule of the thymus
Eosinophilic, thin, dense CT; Partially penetrates the thymus as septa
Histologically describe the outer cortex of the thymus.
Highly Basophilic, outer cellular region due to high cell density; Contains T cells in earliest stage of development.
Histologically describe the medulla of the thymus.
Less basophilic, No septa; Contains T cells in later stages of development; No follicles in the thymus.
Where can Epithelioreticular cells be found in the thymus?
Both the cortex and medulla.