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Biol273 Immune System Unit Review.docx

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BIOL 273
Vivian Dayeh

Immune System Unit 6 Unit Review Unit 6 Overview of the Immune System -There are two types of lymphoid organs/tissues: 1. Primary Lymphoid Organ – where the lymphocytes develop (bone marrow and the thymus) 2. Secondary Lymphoid Organ – organs where the lymphocytes interact and initiate responses -The lymphoid tissues can be encapsulated or diffuse. - Encapsulated – includes the spleen and lymph nodes surrounded by a fibrous structure that limits their size - Diffuse – includes the tonsils and gal, which are not surrounded by a capsule -The lymphoid organs are connected to the blood vessels and the lymph vessels. The primary lymphoid organs create the lymphocytes in the bone marrow and the thymus. They the secondary lymphoid organs interact and initiate responses. These involve locations such as the spleen, lymph nodes, tonsils and the Gt Associated Lymphoid Tissue (GALT) which filter for pathogens and pathogen containing lymphocytes. There are a lot of functions associated with this practice: - Afferent lymph vessel brings in lymphocytes from periphery - Efferent lymph vessel allows circulation to continue - The gap in between (Pulp) allows mixing of lymphocytes and leukocytes - These occur while the arteries and veins are supplying nutrients and O(2) and non-lymphocytic leukocytes -Lymph nodes are garrisons of B, T, and immunity cells that include leukocytes (white blood cells) and they are also connected with the lymphatic vessels at the knee, groin, elbow, shoulder and neck. Multiple afferent lymph vessels bring lymph into the node. -Phagocytes are leukocytes that engulf and ingest pathogens. These include the eosinophil, neutrophils and macrophages. Neutrophils and macrophages are professional phagocytes. -Cytotoxicity is usually associated with the granulocytes. When an Eosinophil binds to an antibody-coated parasite, it degranulates and spews granule contents. These contents include toxic enzymes and oxidative chemicals that damage and kill parasites. -Antigen Presenting Cells include the Monocytes, the precursor to macrophages (monocytes in tissue). Macrophages scavenge and engulf old red blood cells as well as dead neutrophils. After engulfing them, the fragments of the pathogen are placed on the cell surface. -Neutrophils are granulocytes that are phagocytic. They are the most abundant leukocytes and can leave the circulatory system to attack pathogens in tissues. They contain cytokines that cause fever and start other inflammatory responses. -Monocyte/macrophages are monocytes in the blood and macrophages in the tissue. They are amoeboid cells that engulf and function as scavenger to eat red blood cells and dead neutrophils. They present parts of the pathogens they engulf after engulfing and become APC’s. -Lymphocytes are key players in the acquired immune response. Most are found in lymphoid tissues and have fundamental differences in function. Lymphocytes include the B cells (or B lymphocytes), natural killer cells and T cells (or T lymphocytes) which includes Tc cells and Th cells. Innate Immunity Acquired Immunity -Majority are phagocytes which destroy or -Mainly uses lymphocytes (NK, B and T suppress the invader by ingesting it cells) -Attract other cells by chemotaxins -Are specific to one pathogen (chemicals that attract other immune cells) -Have two responses after exposure -Has phagosomes formed after a phagocyte engulfs pathogen -Involves memory cells -Found in all organisms -Includes 5 classes of antibodies -Includes physical and chemical barriers -Uses MHC proteins types I or II -Includes natural killers cells that are lymphocytes and release Interferons that -Happens only specifically combat the viruses -Only in vertebrates -Creates inflammatory response -Happens after the innate immune -Uses Interleukin to mediate capillary and response permeability -Opsonizes and uses opsonin JUST LIKE -Complement proteins do innate response OPSONIN but this opsonization comes with MAC attack from B cells, which also activates the complement -Opsonins from Blood Proteins Humoral Immunity Cellular Immunity -B cells using antibodies to attack in the -T cells produce the immunity but does not blood stream with the help of macrophages use antibodies. An antigen causes a response to release various cytokines that stimulates the cytotoxic T cell and other phagocytes. Innate Immunity -The professional phagocytes they have receptors on their membrane that can detect harmful substances and that are not regul
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