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What is the immune system?
A physiological system composed of cells and organs that interact to protect the body from disease
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Where is the immune system NOT found?
- Brain
- Central nervous system
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What significance to CD markers have?
- They are differentially expressed on cells of the immune system
- Allow immunologists to determine the subpopulations of lymphocytes
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What is the normal CD4:CD8 ratio in humans? What happens during AIDS?
2:1. During an HIV infection, CD4 cells are destroyed, dropping it to 1:1 or below.
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What is a CD4+ cell?
T helper
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What is a CD8+ cell?
Cytotoxic T cell (CTL)
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What is a CD19+ cell?
B cell
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What is a CD14+ cell?
Macrophage
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What are the primary lymphoid tissues?
- Bone marrow
- Thymus
- Possibly some parts of the intestine
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What are the secondary lymphoid tissues?
- All other tissues that play a role in lymphoid development that are not the primary tissues
- Ie, spleen, blood, lymph nodes, tonsil, adenoids, appendix
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What is the MALT?
Mucosal-associated lymphoid tissue - a subclass of the peripheral immune system
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What subclasses make up the MALT?
- Oral mucosa
- NALT - nasopharyngeal-associated lymphoid tissue
- GALT - gut-associated lymphoid tissue
- Reproductive mucosa
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What is the difference in movement of cells thru blood versus lymph?
Blood is actively circulated by the heart, lymph is passively circulated by gravity and contractions due to movement
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What methods do lymphocytes use to enter and leave lymph nodes?
Afferent (approaching) and efferent (exiting) blood and lymph vessels
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How is the lymphatic system circulated back into the blood?
Thru the thoracic lymphatic duct near the heart
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How many lymph nodes are in the body?
~120
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What purpose does the lymph node serve?
To bring together the cells of the immune system to initiate an immune response
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What is hematopoesis?
The creation of new cells of the immune system
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What gives rise to the hematopoetic cells? What is the experimental proof?
The hematopeotic stem cell (a pluripotent cell). One of these is capable of reconsitituting an entire mouse's immune system
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During hematopoiesis, what does the bone marrow offer?
- Stromal cells - for support
- Growth factors - a microenvironment for development
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Where do all immune cells come from?
Bone marrow
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What cells are myeloid?
- Macrophage
- Neutrophil
- Basophil
- Eosinophil
- Mast Cell
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What can monocytes give rise to?
- Macrophages
- Dendritic cells
- Langerhan cells
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Are macrophages ever found in the blood?
NO
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Where does T-cell maturation begin?
Thymus
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Where does B-cell maturation begin?
Blood or lymph nodes
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What percent of leukocytes are neutrophils?
50-70%
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What percent of leukocytes are lymphocytes?
20-40%
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What percent of leukocytes are monocytes?
1-6%
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What percent of leukocytes are eosinophils?
1-3%
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What percent of leukocytes are basophils?
<1%
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What separates adaptive immunity from innate?
- Specificity - targets one antigen
- Memory - re-exposure to same antigen leads to stronger/quicker response
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What are the cells of adaptive immunity?
- T-cells
- B-cells
- Plasma cells
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What are the components of the innate immune system?
- Myeloid cells (phagocytic, releasors of inflammatory cytokines)
- Toll-like receptors
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What are the major barriers of the innate immune system?
- Physiological
- Anatomical
- Phagocytic/endocytic
- Inflammatory
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What are the physiological barriers of the innate immune system?
- Fever
- pH
- Oxygen tension
- Chemical factors
- Anti-microbial substances
- Interferons
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Name some chemical factors that serve as physiological barriers
- Fatty acids, lactic acid
- Pepsin (a digestive enzyme)
- Lysozyme and hydrolytic enzymes
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Name some anti-microbial substances that serve as physiological barriers
- Cryptidins/a-defensins in small intestine
- b-defensins in skin/respiratory tract
- Surfactant proteins in lungs
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What are interferons?
Anti-viral proteins; secreted by infected cell to protect surrounding cells
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Name some anatomical barriers that function in the innate immune system
- Skin
- Tight junctions
- Mucous membranes
- Saliva
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How is endocytosis used in the innate immune system as a barrier?
- Endosomes contain macromolecules
- These fuse with lysosomes
- The ingested material is degraded
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How is phagocytosis different from endocytosis?
- It is used to digest whole micro-organisms or extremely large particulate matter
- 10-20x larger than endosome
- Only specialized cells can phagocytose
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What are the professional phagocytic cells?
- Monocytes/macrophages
- Neutrophils
- Dendritic cells
- Langerhan cells
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What non-professional cells can be stimulated during intense inflammation to phagocytose?
- Epithelial cells
- Fibroblasts
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Name the inflammatory barriers of the innate immune system
- Serum proteins in tissues
- Phagocytic cells from the blood extravesating
- Complement system
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What is the main function of the neutrophil?
- Phagocytosis
- Production immunological mediators
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What is the main function of the monocyte?
- Phagocytosis
- Production of immunological mediators
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What is the main function of the macrophage?
- Phagocytosis
- Anitgen presentation
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What is the main function of the dendritic cell/langerhans?
Phagocytosis and antigen presentation
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