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Micro Chap 16
Terms in this set (42)
Immunity that is present before exposure and effective from birth. Responds to a broad range of pathogens.
First and Second lines of defense
immunity or resistance to a specific pathogen; slower to respond, has memory component
Third Line of defense
Toll-like receptors (TLRs)
transmembrane protein of immune cells that recognizes pathogens and activates an immune response directed against those pathogens
Pathogen-associated molecular patterns (PAMPs)
help the innate immune system recognize pathogens
proteins that regulate the intensity and duration of immune responses.
Three roles of cytokines
1. recruit other macrophages and dendritic cells, as well as other defensive cells, to isolate and destroy the microbes as part of the inflammatory response. Cytokines can also activate the T cells and B cells involved in adaptive immunity.
2. regulate immune response
3. directly or indirectly induce fever, pain, or T cell proliferation
First line of defense against pathogens and physical factors
skin-keratin and epidermis of tightly packed cells. mucous membranes-traps microbes, ciliary escalator
vaginal secretions-flows out
Chemical factors of first line of defense
sebum and ear wax-fatty acids
lysozyme-perspiration, tears and saliva
Low pH-gastric juices, skin, vaginal secretions, urine
compete with pathogens via microbial antagonism
-produce substances harmful to pathogens
-alter conditions that affect pathogen survival
The microbes that reside within our bodies, that benefit from us, without harming us. may be opportunistic
process in which extensions of cytoplasm surround and engulf large particles and take them into the cell
coating antigen with antibody enhances phagocytosis
Abnormal accumulation of fluid in interstitial spaces of tissues.
the sticking of phagocytes to blood vessels in response to cytokines at the site of inflammation
the passage of blood cells through the intact walls of the capillaries, typically accompanying inflammation.
complement system--second line of defense--innate immunity
A group of about 30 blood proteins from the liver that may amplify the inflammatory response, enhance phagocytosis, or directly lyse extracellular pathogens.(assist antibodies)
Activated in a cascade by▪ Antigen-antibody reaction▪ Proteins C3, B, D, P and a pathogen
results in cytolysis, opsonization, and inflammation.
second line of defense
protective cells and fluids; inflammation and phagocytosis - nonspecific
highly phagocytic and motile, are active in the initial stages of an infection. They have the ability to leave the blood, enter an infected tissue, and destroy microbes and foreign particles.
dominate during the initial phase of bacterial infection, at which time they are actively phagocytic
release substances, such as histamine, that are important in inflammation and allergic responses.
somewhat phagocytic and also have the ability to leave the blood. Their major function is to kill certain parasites, such as helminths. Although eosinophils are physically too small to ingest and destroy helminths, they can attach to the outer surface of the parasites and discharge peroxide ions that destroy them. Their number increases significantly during certain parasitic worm infections and hypersensitivity (allergy) reactions.
leave the bloodstream and enter the tissues as mature macrophages
responsible for the swelling of lymph nodes during an infection. As blood and lymph that contain microorganisms pass through organs with macrophages, the microorganisms are removed by phagocytosis. Macrophages also dispose of worn out blood cells.
as the infection progresses, the macrophages dominate; they scavenge and phagocytize remaining living bacteria and dead or dying bacteria
abundant in the epidermis of the skin, mucous membranes, the thymus, and lymph nodes. Dendritic cells destroy microbes by phagocytosis and initiate adaptive immune responses
include natural killer cells, T cells, and B cells. Natural killer (NK) cells are found in blood and in the spleen, lymph nodes, and red bone marrow. NK cells have the ability to kill a wide variety of infected body cells and certain tumor cells. NK cells attack any body cells that display abnormal or unusual plasma membrane proteins. The binding of NK cells to a target cell, such as an infected human cell, causes the release of toxic substances from lytic granules in NK cells
Intracellular storage granules of cytotoxic T cells and NK cells that contain perforin and granzymes results in cytolysis
nk cell granules release Cytotoxic enzymes that initiate apoptosis
One of the proteins released by cytotoxic T cells on contact with their target cells. It forms pores in the target cell membrane that contribute to cytolysis
path of lymph
Lymphatic Collecting Vessels
Right Lymphatic Duct or Thoracic Duct
blood plasma moves through the cardiovascular system and ultimately becomes interstitial fluid between tissue cells, and another cycle begins.
4. Phagosome formation
6. Digestion and destruction
how do microbes evade phagocytosis
1. induce chronic inflammatory response resulting in significant tissue damage
2. This causes accumulation of macrophages in the infected area
3. macrophages release cytokines with induce fibroblast to synthesize collagen fibers to form scar tissue--fibrosis
4. fibrosis can interfere with normal function of tissue
Signs of inflammation
pain, redness, immobility, swelling, heat
purpose of inflammation
contain site of damage, localize response, eliminate invader, and restore tissue function
stages of inflammation
vasodilation and increased permeability of blood vessels, phagocyte migration and phagocytosis, tissue repair
Chemical stored in mast cells that triggers vasodilation and increased permeability of capillaries.
vasodilation, increased permeability of blood vessels
Intensify histamine and kinin effect
Increased permeability of blood vessels, phagocytic attachment
a rise in the temperature of the body
causes of fever
Hypothalamus normally set at 37°C▪ Gram-negative endotoxin cause phagocytes to release interleukin-1 (IL-1)▪ Hypothalamus releases prostaglandins that reset the hypothalamus to a high temperature▪ Body increases rate of metabolism and shivering which raise temperature
advantages of fever
-increases T cell activity
-increases iron-binding activity of transferrins
-increases effect of antiviral interferons
-may speed up tissue repair reactions
disadvantages of fever
Method of Phagocytosis
A specific group of cytokines. Alpha- and beta-IFNs are antiviral proteins produced by certain animal cells in response to a viral infection. Gamma-IFN stimulates macrophage activity.
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