Lymphatic and Immune System Flashcards
What is the functional tissue of this system?
Parenchyma
Describe Innate immunity.
Response speed is sec or min. No specificity. Recognizes few dozen antigens. No memory. Cellular action: phagocytosis & intracellular distraction.
Describe Adaptive immunity.
Reaction time is days to years. High specificity. Can recognize infinite antigens. Second encounter results in faster response, memory is life long. Cellular action: B and T cells, phagocytosis, intracellular distraction killing.
Location and function of T helper cells.
Adaptive immunity. Originate in bone marrow and migrate to mature in thymus, end differentiation in paracortex of lymph node. They recognize and cause immune response to antigens.
Location and function of T-cytotoxic cells.
Adaptive immunity. Kill foreign, tumor and virally altered cells.
Location and function of B cells.
Adaptive immunity. Originate in bone marrow and become immunocompetent in bone marrow. Differentiates into plasma or memory B cell in lymph nodes. Finds an antigen which matches its receptor, once activated by T helper cell splits into plasma and memory cells.
What is the Thymus?
A primary lymphoid organ, where T cells mature. Prominent at birth, reduced in size replaced by fat after puberty. Cortex has macrophages and epithelial reticular cells. The Medulla stain lighter than the cortex because it has a smaller lymphocyte population.
Describe how T cells mature.
- Young T cells begin in the periphery of Thymic cortex, undergoing proliferation and instruction to become immunocompetent
- 98% of T cells die in cortex, and get phagocytosed
- The survivors enter the medulla of Thymus, and get distributed to secondary lymphoid organs in vascular system.
Location and function of Reticular cells.
Thymus. Separate the cortex from medulla. Can’t pass without them knowing.
Location and function of Hassall’s Copuscles.
Medulla of Thymus. Large, pale-staining cells that form whorl-shapes. Function unknown. They increase with age.
What are formative/ primary lymphoid organs?
Bone marrow and Thymus.
What are reactive/ secondary lymphoid organs?
External cavity organs (MALT, GALT, BALT) and fluid organs (lymph nodes, spleen).
What is a lymph node? What makes it up?
A secondary lymphoid organ. Supplied with blood and lymph vessels, filters to catch antigens/ microbes. Has cortex, paracortex and medulla. The final stage of T lymphocyte differentiation and B lymphocytes into Plasma cells.
Location and function of a Secondary follicle.
Cortical region of Lymph node. Outside is mantle, contains memory B and plasma cells. Inside is germinal center, contains activated B-cells. This is where the interaction between a pathogen and B cell occurs. The B cell them matures and becomes either a memory B cell or plasma cell.
What is the spleen?
A secondary lymphoid organ. Removes old blood cells, antigen presenting cells activate T lymphocytes, B lymphocytes exposed to antigens, a blood reserve. Has red a white pulp.
