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What is the mechanism behind an insects immune system?
Certain proteins bind to macromolecules specific to a certain pathogen and then activate the immune system leading to production of antimicrobial peptides.
What structures/cells in an insect protect it from pathogens?
Its exoskeleton protects it. It has digestive system protected by low pH and lysozymes. Hemocytes in hemolympth also protect.
How do white blood cells recognize pathogens?
Use toll-like receptors which recognize molecules characteristic of a set of pathogens. recognition of tlrs causes phagocytosis by certain white blood cells
What are the phagocytic cells?
neutrophils, macrophages, eosinophils, dendritic cells
engulf and destroy microbes. most abundant phagocytic cell
part of lymphatic system and found throughout body. found predominantly outside of body.
Found beneath mucosal surfaces, Discharge destructive enzymes, have low phagocytic activity. PRimarily defend against muticellular parasites and worms.
Stimulate development of aquired immunity. Populate tissues in contact with the environment. Mostly outside lymphatic system but once encounter pathogen enter lymph system to interact w/ other immune cells to create adaptive immunity
Natural killer cells
Detect abnormal protein arrays on the surfaces of vires-infected, malignant, or non-self cells and release chemicals that lead to cell death.
What do interferons do and what are they?
Interferons are proteins that fight viral infection. When a cell is infected by a virus, releases interferons to surrounding cells, these cells turn on genes for antiviral peptides, which thwarts the spread of the virus. Some white blood cells secrete interferons to activate macrophages.
Involves 30 differetn types of proteins. They circulate in inactive form in blood stream and activated by macromolecules on the surfaces of microbes. Once activated, trigger cascade which leads to the lysis of invading microbe. Also leads to inflammatory response. Involved in adaptive immunity.
When an area becomes injured, signaling molecules are released. Mast cells in connective tissues receive these signaling molecules and release histamine which causes vasodilation and increased leakiness of capillaries. Macrophages are also hit with the signaling molecules and they release chemicals that cause increased blood flow to the site. Increased blood flow brings more anti-microbial proteins and complement proteins. Complement proteins are activated and promote release of histamine and recruit more phagocytes. Endothelial cells secrete molecules that attract neutrophils and macrophages, which leave the blood and carry out phagocytosis at the site. Results in accumulation of pus.
Inflammation can be either ____ or ____
Local or systemic
Leads to a rapid increase of WBC in body. (many released from bone marrow)
What is fever?
Systemic inflammatory response when macrophages release pyrogens and when certain toxins of pathogens are detected. Leads to higher temp. May enhance phagocytosis and accelerate tissue repair.
What diseases arise from chronic immune response?
Crohn's disease and ulcerative colitis
Adaptive immunity and how lymphocytes work
Lymphocytes recognize and respond to antigens, which are foreign molecules, and inactivate the foreign cells. They also contribut to immunological memory. They originate from stem cells in the bone marrow. T cells migrate from the bone marrow and mature in the thymus. B cells mature in bone marrow. Recognition occurs when an antigen binds to an antigen receptor. All antigen receptors made by a particular B or T cell are identical and they recognize a small, accessible part of the antigen, called an epitope. Each lymphocyte has a specificity for only one epitope.
Antigen Recognition by B cells
When a B cell binds its receptor to a pathogen, it secretes a soluble form of the receptor, called an antibody or immunoglobulin, which have the same organization of an antigen receptor.
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