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Immune System

Anatomy & Physiology

QuestionAnswer
immune system protects from infectious agents & harmful substances (typically w/o awareness), composed of numerous cellular and molecular substances that function together to provide us with immunity, and its function is dependent on specific types of infectious agents
infectious agents organisms that cause damage or death to host organism
pathogenic a term used to describe infectious agents that cause harm
five major categories of infectious agents bacteria, viruses, fungi, protozoans, and multicellular parasites
bacteria single-celled organism, 1-2 micrometers, enclosed by cell wall, come in multiple shapes (spherical [cocci], rodlike [bacilli], coiled [spirilla]), and there are good and bad types
examples of diseases caused by bacteria streptococcal infection (strep throat), tuberculosis, and Lyme disease
Viruses acellular organisms that are composed of DNA or RNA within a protein shell, and they are smaller than bacteria (one-hundredth of a micrometer), and are obligate intracellular parasites
obligate intracellular parasites must enter cell to reproduce, viral particles formed within infected cells, released from them to infect surrounding cells, and cell can be ultimately killed by virus or immune system
examples of diseases caused by a virus depends partly on type of infected cell (i.e. chicken pox, HIV, common cold)
fungi have cell wall external to plasma membrane, includes molds, yeasts, multicellular fungi, release proteolytic enxymes
proteolytic enzymes induce inflammation causing redness and swelling
fungal diseases in U.S. usually limited to superficial infections of skin, scalp, nails (i.e. ringworm and athlete's foot), others can infect mucosal linings or internal infection
protozoans lack cell walls, are intracellular and extracellular parasites, and have the ability to move (with cilia)
protozoan disease examples malaria, trichomoniasis
multicellular parasites nonmicroscopic organisms that reside in host from which they take nourishment
example of parasitic diseases parasitic worms such as tapeworms infect intestinal tract of humans and other mammals
leukocytes formed in the red bone marrow, include three types of granulocytes, include monocytes, and include lymphocytes
types of granulocytes neutrophils, eosinophils, and basophils
monocytes become macrophages when take up residence in the tissues
lymphocytes B-lymphocytes, T-lymphocytes, NK (natural killer) cells
structures that house immune system cells most found not in the blood but in lymphatic tissue, select organs, epithelial and mucosal membranes, and connective tissue
lymphatic tissue lymph nodes, spleen, tonsils, MALT, lymphatic nodules
lymphatic tissue where many T- and B-lymphocytes, macrophages, NK cells are housed
select organs macrophages also housed in other organs, some specifically named based on location (i.e. alveolar macrophages of lung, microglia of brain), may be permanent residents (fixed macrophages), and may migrate through tissues as wandering macrophages
epithelial layers of skin and mucosal membranes dendritic cells here that derived from monocytes engulf pathogens in skin and mucosal membranes and migrate to lymph node through lymph vessels
connective tissue mast cells located here, typically in close proximity to small blood vessels, abundant in dermis, and abundant in mucosa of respiratory, digestive, and urogenital tracts
two categories of the immune system innate immunity and adaptive immunity
the two types of immune systems are... organized based on type of immunity provided and work together to protect from harmful agents
how the two types of immune systems differ cells involved, specificity of cell response, mechanisms of eliminating harmful substances, and amount of time for response
innate immunity protects against numerous different substances, born with these defenses, does not require previous exposure to a foreign substance, and respond immediately to potentially harmful agent.
innate immunity includes barriers of the skin and mucosal membranes, nonspecific cellular and molecular internal defenses
adaptive immunity involves specific T-lymphocytes and B-lymphocytes, provides powerful means of eliminating foreign substances, and takes several days to be effective
T-lymphocytes and B-lymphocytes respond differently to different foreign substances (i.e. particular lymphocytes responds to chickenpox virus
structures of innate immunity prevent entry of potentially harmful substances, respond nonspecifically to wide range of harmful substances and include the first two lines of defense
first line of defense skin and mucosal membrane
second line of defense internal processes of innate immunity, activities of neutrophils, macrophages, NK cells, chemicals such as interferon and complement, and physiological processes such as inflammation and fever
physical barrier of skin formed by epidermis and dermis, few microbes able to penetrate, has natural flora (nonpathogenic microorganisms residing here, help prevent growth of pathogenic microorganisms)
mucosal membrane barrier membranes lining openings of the body, produce mucin (when hydrated, forms mucus), lined by harmless bacteria
barrier defenses mechanisms usually successful, but infectious agents may enter if the barrier is compromised or there are too many microbes (this activates the innate immunity and adaptive immunity)
neutrophils and macrophages cells of innate immunity
neutrophils most prevalent leukocyte in blood, first to arrive during inflammatory response, and fights off bacteria
macrophages reside in tissues throughout the body, arrive later and stay longer than the neutrophils, engulf unwanted substances through phagocytosis
basophils and mast cells proinflammatory chemical-secreting cells that release substances to increase fluid movement from blood to injured tissue and are chemotactic
basophils circulating in blood
mast cells reside in connective tissue, mucosa, and internal organs
chemotactic describes attracting immune cells as part of inflammatory response
granules released by basophils and mast cells during inflammatory response... contain histamine and heparin
histamine increases vasodilation and capillary permeability
heparin anticoagulant
eicosanoids released from the plasma membrane of basophils and mast cells and increase inflammation
natural killer cells destroy wide variety of unwanted cells (i.e. virus/bacteria-infected cells, tumor cells, transplanted tissue cells), formed in bone marrow & circulate in blood, accumulate in secondary lymphatic structures, and patrol the body detecting unhealthy cells
immune surveillance the patrolling of the body detecting unhealthy cells that is conducted by the natural killer cells
natural killer cells destroy unhealthy cells by releasing cytotoxic chemicals (include perforin and granzymes)
perforin forms transmembrane pore in unwanted cells
granzymes initiate apoptosis
apoptosis form of cellular death
eosinophils target parasites, degranulation and release of enzymes and other substances, participate in immune response of allergy and asthma, and engage in phagocytosis of antigen-antibody complexes
inflammation immediate, local, nonspecific response, occurs in vascularized tissue against variety of stimuli, major effector of innate immunity, and helps eliminate infectious agents from body
stimuli that ellicit inflammation scratch of skin, bee sting, overuse of body structure
first event of inflammation numerous chemicals are released from injured tissue, basophils, mast cells, and infectious organisms (including histamine, leukotrienes, prostaglandins, chemotactic factors)
second event of inflammation released chemicals causing responses in local blood vessels, vasodilation (increased capillary permeability)
third event of inflammation leukocytes recruited to the area
effects of inflammation increased fluid, protein, immune cells leaving capillaries, delivers substances needed to eliminate pathogens and promote healing, raises hydrostatic pressure
effects of inflammation continued... net movement of fluid from blood through infected area exudates additional fluid uptake by lymphatic capillaries, carries away infectious agents, dead cell, cellular debris, and lymph monitored as passes through lymph nodes
effects of inflammation within 72 hours (inflammatory response slowing down) monocytes exit blood, become macrophages, & begin cleaning up affected area, bacteria, damaged host cells, dying neutrophils destroyed by macrophages, fibroblasts multiplying & synthesizing collagen, starts tissue repair, may lead to scar tissue formation
cardinal signs of inflammation redness, heat, swelling, pain, and loss of function
redness results from... increased blood flow
heat results from... increased blood flow and increased metabolic activity within the area
swelling results from... increase in fluid loss from capillaries to interstitial space
pain results from... stimulation of pain receptors from compression from interstitial fluid
loss of function results from... may occur in severe cases
fever abnormal elevation of body temperature (at least 1 degree Celsius from normal 37 degrees Celsius), may accompany inflammatory response, requires increased fluid intake to prevent dehydration (due to excess fluid loss)
events of fever onset, stadium, and defervescence
onset period during which temperature begins to rise, hypothalamus stimulating dermis blood vessels to vasoconstrict, may occur with chills and shivering
stadium period when elevated temperature maintained, increased metabolic rate, promotes physiologic processes involved in eliminating harmful substance
defervescence period when temperature returning to normal set point, hypothalamus stimulating mechanisms to release heat (i.e. increased vasodialtion of skin blood vessels, sweating
benefits of fever inhibits reproduction of bacteria and viruses, increases activity of adaptive immunity, accelerates tissue repair, and recommended to leave a low fever untreated
risks of high fever high fevers are potentially dangerous, change in metabolic pathways and denaturation of proteins, possible seizures, irreversible brain damage if over 106 F and death likely if over 109 F
adaptive immunity initiated upon entry of foreign substance, takes longer to respond than innate immunity, contact with antigen (causes lymphocyte to proliferate and form specialized "army"), lymphocytes and products released, considered third line of body's defense
immune response lymphocytes and products released with adaptive immunity
two branches of immunity cell-mediated immunity and humoral immunity
cell-mediated immunity immune response involving T-lymphocytes
humoral immunity immune response involving B-lymphocytes, develop into plasma cells to release antibodies
foreign antigens different in structure from human body's molecules and bind body's immune components
self-antigens body's molecules, typically do not bind immune components
immune system is generally able to distinguish between foreign and self-antigens
autoimmune disorder when the body reacts to self-antigens as if foreign
T- and B-lymphocytes have unique receptor complexes, about 100,000 per cell, each complex binding specific antigen
B-lymphocytes make direct contact with antigen
T-lymphocytes must have antigen processed, antigen presented in plasma membrane of another cell type, and have additional receptor molecules (coreceptors)
coreceptors facilitate T-lymphocyte interaction with cell presenting antigen
two types of T-lymphocytes helper T-lymphocytes and cytotoxic T-lymphocytes
Helper T-lymphocytes help activate B-lymphocytes and other immune cells, contain CD4 in plasma membrane, and classified as CD4 cells and bind to MHC II complex
cytotoxic T-lymphocytes release chemicals toxic to cells, contain CD8 in plasma membrane, classified as CD8 cells that bind to MHC I complex
antigen presentation display of an antigen on a cell's plasma membrane, process performed by other cells (help T-lymphocytes "see" the antigen), and two types of cells presenting antigen to T-lymphocytes
two types of cells presenting T-lymphocytes all nucleated cells of the body and antigen-presenting cells (APCs)
antigen-presenting cells any immune cell communicating antigen presence to T-lymphocytes (dendritic cells, macrophages, and B-lymphocytes
antigen presentation requires physical attachment of antigen to transmembrane protein (termed major histocompatibility complex [MHC] and a group of genes codes for MHC molecules in plasma membrane)
two major MHC groups MHC I and MHC II
MHC I found in all nucleated cells
MHC II found in APCs (in addition to MCH I)
three events in life of lymphocytes formation and maturation, activation of lymphocytes, and effector response
formation and maturation of lymphocytes occurs within primary lymphatic structures (red bone marrow and thymus), become able to recognize one specific foreign antigen
activation of lymphocytes migrate to secondary lymphatic structures, usually where they are first exposed to antigen they bind, and become activated and replicate to form identical lymphocytes
effector response action of T-lymphocytes and B-lymphocytes to eliminate antigen (T-lymphocytes migrate to site of infection and B-lymphocytes remain within secondary lymphatic structures)
B-lymphoctyes remaining within secondary lymphatic structures synthesize and release large quantities of antibodies against antigen, enter blood and lymph and are transported to infection site
mechanisms activated lymphocytes use to help eliminate antigen Helper T-lymphocytes (release IL-2 and other cytokines, regulate cells of adaptive and innate immunity), cytotoxic T-lymphocytes (destroy unhealthy cells by apoptosis), and plasma cells (produce antibodies)
Created by: Nicolekr