Chapter 13: The Human Immune System Flashcards
1
Q
first line of nonspecific defense
A
- barrier that prevents pathogens from entering the body
- skin
- mucous membranes, which release mucus with antimicrobial substances such as lysozymes
- cilia in the respiratory system to sweep out mucus with microbes
- stomach acid
2
Q
second line of nonspecific defense
A
- goal: limit spread of invaders
- inflammatory response, phagocytes, complement, interferons, natural killer cells
3
Q
inflammatory response
A
- histamine triggers vasodilation (enlargement of blood vessels) that brings more blood, and then phagocytes secreted by basophils (white blood cells) and mast cells
- pyrogens: released by leukocytes, increase body temperature
4
Q
phagocytes
A
- ingest invading fungal and bacterial microbes
- 2 types: neutrophils and macrophages (both migrate to infected site based on chemical attractants)
- neutrophils: engulf microbes and die after a few days
- macrophages: transform from monocytes, extend pseudopods, and engulf huge numbers of microbes over a long period of time with lysozymes and toxic oxygen
5
Q
complement
A
-group of proteins tat leads to lysis of invading cells
6
Q
interferons
A
-block cell-to-cell viral infections
7
Q
natural killer (NK) cells
A
-destroy virus-infected body cells (as well as cancerous cells) by attacking the cell membrane, causing it to lyse
8
Q
adaptive (specific) defense
A
- B lymphocyte and T lymphocytes arise from stem cells in the bone marrow
- B mature in bone marrow, T mature in the thymus gland
- travel in body recognizing specific antigens
9
Q
adaptive immune response
A
- recognition: antigen receptors on B and T lymphocytes recognize specific antigens or epitopes (accessible part of antigen that lymphocytes bind to) by binding to them
a. lymphocytes must be presented antigen on antigen-presenting cell (macrophages, dendritic cells, sometimes B cells)
b. B cells are specific to one epitope - activation phase: lymphocytes undergo rapid cell division, forming effector and memory cells (responsible for immunological memory)
- effector phase: B cells produce humoral response of producing antibodies and T-cells engage in cell-mediated response
10
Q
T lymphocytes
A
- recognize and bind to antigens that are displayed on APCs by MHC molecule
- once activated, T cell proliferates to form active T clones, some which become memory, some effector cells
- two types: helper T cells and cytotoxic T cells
11
Q
helper T cells
A
- activated by interaction with antigen-presenting cells
- activates cytotoxic T cells, other helper T cells, and B cells that rproduce antibodies
- trigger both humoral and cell-mediated responses
- AKA CD4 cells
12
Q
cytotoxic T cells
A
- attack and kill infected or cancerous body cells
- cell-mediate humoral response: release perforin and granzymes that cause cell to die
- AKA CD8 cells
13
Q
B lymphocytes
A
- has antigen receptors (Y-shaped molecule consisting of 4 polypeptide chains, 2 light and 2 heavy, 4 constant regions, 4 variable regions) on its surface
- antibodies: soluble forms of antigen receptors
- humoral immune response: produce antibodies (immunoglobins)
- activation
- APC presents antigen or epitope on its cell surface using class II MHC
- helper T recognizes epitope-MHC molecule complex and is actiavted by cytokines secreted from APC
- produces clone: some become effector cells (plasma cells) that secrete antibodies, others become memory cells
14
Q
self-tolerance
A
-immune system often doesnt attack its own body cells
15
Q
auto-immune disease
A
-does not exhibit self-tolerance, but rather lymphocytes have receptors for their own body cells
