Term
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Definition
(nonspecific & general in action)
•First line of defense:
–Anatomical & physiological barriers that block invasion at the portals of entry
–Does not involve recognition of foreign substances
•Second line of defense:
–Internalized system of protective cells & chemicals
–Does involve recognition of foreign substances
–Inflammation, phagocytosis, fever, antimicrobial proteins |
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Term
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Definition
(specific & provides long-term immunity)
•Third line of defense:
–Acquired on an individual basis as each foreign substance is encountered by lymphocytes
–Reaction with each microbe produces unique protective substances and cells that can come into play if the microbe is encountered again |
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Term
Innate, first line of defense |
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Definition
- a surface protection composed of anatomical and physiological barriers that keep microbes from penetrating sterile body compartments
- physical barriers, chemical barriers, genetic components |
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Term
Innate, second line of defense |
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Definition
- a cellular and chemical system that comes immediately into play if infectious agents make it past the surface defenses
- phagocytosis, inflammation, fever, antimicrobial proteins |
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Term
Acquired, third line of defense |
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Definition
- includes specific host defenses that must be developed uniquely for each microbe through the action of specialized white blood cells
- active/infection; passive/maternal antibodies (B cells, T cells and their effects) |
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Term
Innate (nonspecific) Immunity |
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Definition
•Rapid response to a broad range of microbes
•Not selective
•1st & 2nd lines of defense
•Physical & chemical barriers
•Cellular defense |
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Term
Adaptive (specific) Immunity |
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Definition
- Slow response to specific microbes
- Highly selective
- 3rd line of defense
- Humoral response
- (B cell/antibody mediated)
- Cell-mediated responses
- (T cell mediated) |
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Term
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Definition
- First line of defense
• thick, tough layer that is highly impervious and waterproof (epithelial cells compacted, cemented together, and impregnated with keratin)
–Few pathogens can penetrate this unbroken layer
–Sebaceous secretions exert an antimicrobial effect
–Lactic acid and electrolyte concentrations in sweat
–Skin’s acidic pH & fatty acid content |
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Term
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Definition
- first line of defense
- Flushing effect helps remove microbes |
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Term
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Definition
• digestive, urinary, respiratory tracts, eye.
–Provide barrier protection without keratinized layer
–Mucous coat (moist & slippery) prevents the entry and attachment of bacteria
–Saliva carries microbes into harsh stomach conditions
–Lysozyme enzyme in tears, saliva, sweat: hydrolyzes PGs in the cell walls of bacteria |
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Term
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Definition
- Barriers: first line of defense
– Nasal hair traps larger particles
– Huge flow of mucus and fluids during allergies and colds exerts a flushing action (sneezing & coughing the same)
– Ciliary escalator: ciliated epithelium (trachea & bronchi) moves entrapped foreign particles in mucus toward the pharynx for removal |
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Term
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Definition
– Barriers: first line of defense
– Bladder emptying flushes the urethra
– Vaginal secretions provide cleansing of the lower reproductive tract in females
– Vagina has a protective acidic pH maintained by normal biota |
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Term
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Definition
- Barriers: first line of defense
– Provides microbial antagonism
– Commensal/mutualistic bacteria occupy the “tops” of gut epithelium (not the “crypts”) where there are no PRRs;
– Blocks access of pathogens to these epithelial surfaces by creating unfavorable environments for pathogens
•Competing for nutrients/space
•Altering local pH |
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Term
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Definition
- Barriers: first line of defense
– Hydrochloric acid in stomach
– Digestive juices and Bile in intestines
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Term
Genetic variation of the host |
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Definition
- Barriers: first line of defense
– Some hosts are unaffected by infectious diseases that affect other hosts
– Some pathogens have such specificity for one host that they cannot infect another species
– Viruses can only infect by attaching to a specific host receptor
• Those with a loss or lack of complete immune system are more susceptible to infection
–Victims of severe burns
–Blockages of tear ducts, salivary glands, intestine or urinary tract
• The first line of defense alone is not sufficient to protect against infection
–Many pathogens find a way to circumvent these barriers |
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Term
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Definition
• The study of all features of the body’s second and third lines of defense
–Central to the study of the fields of cancer and allergy
• A healthy, functioning immune system is responsible for:
–Surveillance of the body
–Recognition of foreign material
–Destruction of entities deemed to be foreign |
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Term
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Definition
- Phagocytes in blood; active engulfers and killers of bacteria
- 45% of white blood cells |
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Term
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Definition
- function in inflammatory events
- 0.5% of white blood cells |
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Term
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Definition
- active in worm and fungal infections, allergy, and inflammatory reactions
- 4% of white blood cells |
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Term
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Definition
- blood phagocytes that rapidly leave the circulation; mature into macrophages and dendritic cells
- 7% of white blood cells |
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Term
Lymphocytes (T cell and B cell) |
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Definition
- primary cells involved in specific immune reactions to foreign matter
- 20-35% of white blood cells
- T cells: perform a number of specific cellular immune responses such as assisting B cells and killing foreign cells (cell-mediated immunity)
- B cells: differentiate into plasma cells and form antibodies (humoral immunity) |
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Term
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Definition
- largest phagocytes that ingest and kill foreign cells
- strategic participants in certain specific immune reactions |
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Term
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Definition
- relatives of macrophages that reside throughout the tissues and mononuclear phagocyte system
- responsible for processing foreign matter and presenting it to lymphocytes |
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Term
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Definition
- specialized tissue cells similar to basophils that trigger local inflammatory reactions and are responsible for many allergic symptoms |
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Term
Natural Killer (NK) cells |
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Definition
- relating to T cells but displaying no antigen specificity, these cells are active against cancerous and virally infected cells |
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Term
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Definition
• move throughout the body, searching for potential pathogens.
–Trained to recognize self, or body cells and non-self, bacterial cells or other invading pathogens
–Commensal microbes and food we ingest recognized as non-harmful |
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Term
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Definition
- molecules on the surface of cells
- composed of proteins and/or sugars
- evaluated by cells of the immune system |
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Term
The Mononuclear Phagocyte System (MPS) |
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Definition
- collection of connective tissues of the extracellular space & phagocytic cells scattered throughout
- is a part of the immune system w. function to engulf and degrade foreign molecules
- spreads throughout tissues of all organs as framework
– Spaces surrounding tissue cells that contain extracellular fluid (ECF)
–The bloodstream*
–The lymphatic system
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Term
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Definition
- plasma-like fluid (escaped from cardiovascular system) carried by the lymphatic system
- made up of water, dissolved, and 2-5% protein
- Transports numerous white blood cells (especially lymphocytes), fats, cellular debris, and infectious agents that have gained access to tissue spaces
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Term
Major functions of the lymphatic system |
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Definition
- provide an auxiliary route for return of extracellular fluid to the circulatory system
– Act as a “drain-off” system for the inflammatory response
– Provide surveillance, recognition and protection against foreign materials, through a system of lymphocytes, phagocytes, and antibodies
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Term
Lymphoid organs and tissues |
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Definition
- a loose connective tissue framework that house aggregations of lymphocytes
– Thymus
– Lymph nodes
– Spleen
– GALT (Gut-associated lymphoid tissue), MALT (Mucosa), SALT (Skin), BALT (Bronchial)
Two differences between blood and lymphatic vessels:
--Lymph moves in one direction only: from the extremities to the heart
--Lymph is only transported through the contraction of skeletal muscles (like blood in veins)
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Term
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Definition
- site of T-cell maturation
– Triangular structure in the pharyngeal region–Exhibits high rates of growth and activity and growth until puberty
– Shrinks gradually through adulthood
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Term
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Definition
− small, encapsulated, bean-shaped glands
− Stationed in clusters along lymphatic channels and large blood vessels
− Major aggregations:
−In armpit (Axillary)
−Groin (Inguinal)
−Neck (Cervical)
− Ideal for filtering out materials that have entered the lymph since they house resident lymphocytes
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Term
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Definition
- lymphoid organ in the upper left portion of the abdominal cavity
−Serves as a filter for blood instead of lymph
−Primary function: Removes worn-out red blood cells from circulation
−Immunologic function: Filters pathogens from the blood for phagocytosis by resident macrophages
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Term
Miscellaneous Lymphoid Tissue |
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Definition
- bundles of lymphocytes in the wall (beneath the mucosa) of gastrointestinal and respiratory tracts
- Responds to local invasion of MO
-Tonsils
-Breasts
-GALT (Peyer’s patches, appendix…), MALT, SALT, and BALT
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Term
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Definition
- clear. yellowish fluid
- Contains:92% water, dissolved proteins (albumins, globulins including antibodies), fibrinogen & other clotting factors, hormones, nutrients, (glucose, am acids, fatty acids), electrolytes (Na+, Ca2+, Mg2+, HCO3−, Cl−, etc.), dissolved gases (O2 and CO2), waste products
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Term
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Definition
- the same as plasma, except it contains no clotting factors
- used in immune testing and therapy |
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Term
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Definition
- blood cells suspended in plasma, plasma, serum
- Plasma= proteins + clotting factors
- Serum = proteins
- Lymph = plasma + + invaders from tissue
- Buffy coat = wbc
- Buffy coat is in clot but is not functional |
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Term
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Definition
- production of blood cells
– Begins early in embryonic development in the yolk sac
– Taken over by the liver and lymphatic organs
– Assumed permanently by the bone marrow
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Term
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Definition
- Precursor to blood cells
– Pool of undifferentiated cells
– Maintained in the bone marrow
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Term
White blood cells (leukocytes) |
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Definition
- the two major types differentiated by morphology and color (as a reactions to a mixture of hematologic dyes)
Granulocytes: multi-lobed nucleus
---Neutrophils
---Eosinophils
---Basophils
Agranulocytes: unlobed, rounded nucleus
---Lymphocytes
---Monocytes
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Term
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Definition
- prominent cytoplasmic granules that stain with eosin or methylene blue
- granules function in numerous physiological events
Neutrophils (cytoplasm stains purple)
The most numerous (55 – 90% of circulating leukocytes)
Production of toxic chemicals and phagocytosis
Eosinophils (cytoplasm stains red) 4% of circulating WBCs
Granules contain peroxidase, lysozyme, and other digestive enzymes, toxic proteins, inflammatory chemicals
Attack and destroy large eukaryotic pathogens (e.g. worms)
Basophils (cytoplasm stains blue)
Make up less than 0.5% of circulating WBCs
Granules contain histamine (causes allergic reaction)
Share morphological and functional characteristics of mast cells (which are found only in tissues) |
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Term
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Definition
- globular, nonlobed nuclei
- Lack prominent cytoplasmic granules
- Two general types:
- Lymphocytes
- Monocytes |
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Term
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Definition
- do have antigen specificity
–Comprise 20 – 35% of circulating WBCs
–Estimated that 1/10th of all adult body cells are lymphocytes
•Exceeded only by RBCs and fibroblasts
–Three functional types:
•B lymphocytes: bursal equivalent
•T lymphocytes: thymus-derived
•Null cells
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Term
Activation of B-lymphocytes |
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Definition
–Antibody-mediated immunity
•Also called humoral immunity
–Form plasma cells that produce antibodies
•Antibodies: large protein molecules that interlock with antigen and participate in their destruction |
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Term
Activation of T-lymphocytes |
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Definition
– Cell-mediated immunity:
•A wide spectrum of immune functions
•Modulate immune functions and kill foreign cells
•The action of both cell types accounts for recognition and memory typical of immunity
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Term
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Definition
- 7% of circulating WBCs
– Largest of all white blood cells
– Cytoplasm holds TINY granules containing digestive enzymes
– Rapidly leave circulation to mature into Macrophages & Dendritic cells |
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Term
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Definition
–Long-lived and able to multiply
–Among the most versatile and important of cells in tissues
•Functions of macrophages:
–Specific and nonspecific killing & phagocytic functions
•Cellular housekeeping – phagocytose “messes” created by inflammation and infection
–Processing foreign molecules and presenting them to lymphocytes
–Secreting biologically active compounds that assist, mediate, attract, and inhibit immune cells and reactions |
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Term
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Definition
- has long, thin cell processes
- move from the blood to the MPS and lymphatic tissues where they trap pathogens
- ingestion of bacteria and viruses stimulates them to move to the lymph nodes and spleen
- mature into highly effective processors and presenters of foreign proteins
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Term
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Definition
– Simple, biconcave sacks of hemoglobin that transport oxygen and carbon dioxide to and from the tissues
– Most numerous of all circulating cells
– Do not have immune function |
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Term
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Definition
–Sticky cell fragments circulating in blood
–Not whole cells
–Function in blood clotting (hemostasis) and releasing chemicals that act in blood clotting and inflammation |
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Term
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Definition
- The Second Line of Defense
• General activities of phagocytes:
–To survey the tissue compartments and discover microbes, particulate matter, and injured or dead cells
–To ingest and eliminate these materials
–To recognize immunogenic information (antigens) in foreign matter |
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Term
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Definition
–React early in the inflammatory response to bacteria, foreign materials, and damaged tissue
–Common sign of bacterial infection is a high neutrophil count |
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Term
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Definition
– Attracted to sites of parasitic infection
– Play a minor phagocytic role in antigen-antibody reactions |
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Term
Monocytes and Macrophages |
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Definition
• Monocytes are transformed into macrophages after emigrating out of the bloodstream into the tissues due to chemical stimuli
–Increase in size
–Enhanced development of lysosomes and other organelles |
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Term
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Definition
– Specialized macrophages that migrate to a certain tissue and remain there during their life span
• Alveolar macrophages
• Kupffer cells in the liver
• Dendritic cells in the skin
• Macrophages in spleen, lymph nodes, bone marrow, kidney, bone, and brain |
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Term
Mechanisms of Phagocytic Recognition, Engulfment, and Killing |
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Definition
Pathogen-associated molecular patterns (PAMPs): Found on the microbe e.g, PGs, LPSs, double-stranded RNA found in viruses
Pattern recognition receptors (PRRs): Found on the surfaces of phagocytes and dendritic cells; gut epithelial crypts; lymphocytes; they recognize and bind PAMPs
Q: How to kill bacteria/ inhibit viral replication?
-With strong oxidizing agents + hydrolytic enzymes + antim. proteins + liberation of lactic acid, lysozyme, NO |
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Term
Chemotaxis and Ingestion:
Toll-like receptors (TLRs) |
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Definition
–A type of PRR
–Recognize PAMPs
–Set in motion a cascade of events inside the cell that amplifies and orchestrates a defense response to the pathogen |
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Term
Phagolysosome Formation and Killing |
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Definition
•Lysosomes migrate to the scene of the phagosome and fuse with it to form the phagolysosome
–Granules containing antimicrobial chemicals are released into the phagolysosome that destroys the ingested material
–Causes death of the bacteria within 30 minutes |
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Term
Destruction and Elimination Systems |
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Definition
• Two systems of destructive chemicals found in phagocytes:
–Oxygen dependent system
• Myeloperoxidase forms halogen ions (OCl-)
–Other oxygen products:
• Superoxide anion
• Singlet oxygen
• Hydroxyl free radical |
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Term
The Inflammatory Response |
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Definition
• Four classic signs and symptoms of the inflammatory response:
– Rubor: redness caused by increased circulation and vasodilation in injured tissues
– Calor: warmth from the increased flow of blood
– Tumor: swelling from increased fluid escaping from tissues
– Dolor: pain caused by the stimulation of nerve endings
Fifth sign of inflammation:
Loss of function
All signs of inflammation serve as a warning that injury has taken place
Set in motion responses that save the body from further injury |
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Term
Chief functions of inflammation |
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Definition
– To mobilize and attract immune components to the site of injury
– To set in motion mechanisms to repair tissue damage and localize and clear away harmful substances
– Destroy microbes and block their further invasion |
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Term
The Inflammatory Response |
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Definition
•EARLIEST CHANGES occur in the vasculature:
–Arterioles, capillaries, venules
•Changes controlled by chemical mediators and cytokines (released by blood cells, tissue cells, and platelets)
–Vasoactive: affect endothelial cells and smooth muscle cells of blood vessels
–Chemotactic factors or chemeokines: affect white blood cells
–Inflammatory mediators: cause fever, stimulate lymphocytes, prevent virus spread, and cause allergic symptoms |
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Term
Edema: Leakage of Vascular Fluid Into Tissues |
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Definition
• Vasoactive substances cause endothelial cells in postcapillary venules to contract and form gaps
–Exudate: blood-borne components that escape into extracellular space
–Edema: local swelling and firmness due to accumulation of exudate into the tissues |
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Term
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Definition
– Tendency of WBCs to migrate in response to a specific chemical stimulus given off at a site of injury or infection |
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Term
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Definition
– Tendency of WBCs to migrate in response to a specific chemical stimulus given off at a site of injury or infection |
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Term
Benefits of Chemotaxis and Edema |
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Definition
• Influx of fluid dilutes toxic substances
• Fibrin clot can trap microbes and prevent further spread
• Neutrophils actively phagocytose and destroy bacteria, dead tissue, and particulate matter.
–Pus: whitish mass of cells, liquefied cellular debris, and bacteria |
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Term
Late Reactions of Inflammation |
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Definition
• Long-lived inflammatory reactions:
– Attract monocytes, lymphocytes, and macrophages
– Macrophages clear pus, cellular debris, dead neutrophils, and damaged tissue
– B lymphocytes react with foreign molecules and produce antibodies
– T lymphocytes kill intruders directly
– Tissue is completely repaired or replaced by a scar |
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Term
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Definition
–An abnormally elevated body temperature
–Universal sign of infection
• Ranges of fever:
–Low grade: 37.7- 38.3°C (100-101°F)
–Moderate: 38.8-39.4°C (102-103°F)
–High: 40.0-41.1°C (104-106°F) |
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Term
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Definition
- agents that cause fever
–Exogenous: originating outside the body, products of inf. agents (eg, bacterial endotoxin), blood products, vaccines, injectable solutions
–Endogenous: originating inside the body; factors released by monocytes, neutrophils, and macrophages during the process of phagocytosis (eg Interleukin-1 (IL-1) and tumor necrosis factor (TNF)
•Benefits: Impedes the nutrition of bacteria; stimulates immune reactions and naturally protective physiological processes. |
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Term
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Definition
– Small protein produced naturally by certain WBCs and tissue cells
– Used in therapy against certain viral infections and cancer
– Involved in defenses against other microbes and in immune regulation and intercommunication
Is not virus specific
– Synthesis in response to one cell type will also protect against other cell types
– Produced industrially as a treatment for virus infections |
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Term
Antimicrobial Proteins: Complement |
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Definition
• Complement:
–Consists of over 30 blood proteins
–Work together to destroy bacteria and viruses
• Cascade reaction:
–Sequential physiological process
–First substance in a chemical series activates the next substance, which activates the next, and so on until the desired end product is reached |
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Term
Antimicrobial Proteins: Iron-Binding Proteins |
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Definition
• Iron is required by humans and bacteria for enzymes and metabolism to function properly
–Rate-limiting factor in the growth of bacteria that have invaded a host
–Iron-binding proteins keep it bound tightly so that it is not available for microbial use |
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Term
Host produced Iron-Binding Proteins |
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Definition
• Hemoglobin: Located within red blood cells
• Transferrin: Found in blood and tissue fluids
• Lactoferrin: Found in milk, blood, tears, and saliva
• Ferritin: Found in every cell type
Bacteria produced iron scavengers:
Siderophores: Bind iron more tightly than human proteins |
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Term
Antimicrobial Proteins: Antimicrobial Peptides |
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Definition
• Short proteins capable of inserting themselves into bacterial membranes
– Between 12 – 50 amino acids
– Bacteriosins, defensin, magainins, protegrins
– Part of the innate immune system
– Have an effect on other actions of nonspecific and specific immunity |
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