(exam 2) ch 16 Innate immunity: Nonspecific defenses of the host Flashcards
what is susceptibility?
lack of resistance to a disease
what is immunity?
ability to ward off disease
what does the body’s first line of defense consist of?
skin, mucous membranes, and antimicrobial substances
what does the body’s second line of defense consist of?
inflammation, fever, and phagocytes
what does the body’s third line of dense consist of?
humoral and cellular response
which lines of defense by the body is innate immunity?
first and second lines of defense
which lines of defense by the body is adaptive immunity?
third line of defense
what is innate immunity?
defenses against any pathogen (broad scope); rapid and present at birth
what is adaptive immunity?
immunity or resistance to a specific pathogen; slower to respond, has memory component
Toll-like receptors (TLRs) on host defense cells, attach to what structure of pathogens?
attach to pathogen-associated molecular patterns (PAMPs)
what are pathogen-associated molecular patterns (PAMPs) ?
PAMPs are molecular structures common to pathogens
what are some examples of structures on pathogens that host cells recognize as foreign?
host cells recognize the following as foreign because it is stuff the host cells do not have:
1) LPS outer membrane of gram negative bacteria
2) Peptidoglycan cell wall in gram positive bacteria
3) flagellin (protein) in flagella
4) DNA and RNA of viruses
when the TLRs (of host cells) bind to the PAMPs (of the pathogens) what response does this induce from the host cells?
induces the release of cytokines from the host defensive cells (innate system)
what are cytokines?
small cell signaling proteins that regulate the intensity and duration of the hosts immune responses link between innate and adaptive immunity
how does the initial release of cytokines signal the innate immune system and the adaptive immune system?
1) innate - recruits defensive cells to isolate and destroy microbes as part of inflammatory response
2) adaptive- can activate cells involved in adaptive immunity
what two portions make up the skin (first line defense) ?
epidermis and dermis
what is the epidermis?
outer portion of the skin made of tightly packed epithelial cells containing keratin, a protective protein
what is the dermis?
inner portion made of connective tissue
how does the keratin in the epidermis inhibit microbial growth?
Shedding and dryness of skin inhibits microbial growth
what are the mucous membranes (first line of defense)?
Epithelial layer that lines the gastrointestinal, respiratory, and genitourinary tracts
what two structures of mucous membranes are important to stopping entry of microbes?
mucus and cilia
what is mucus? how is this important to stopping microbes?
viscous glycoproteins that trap microbes and prevent tracts from drying out
what is cilia? how is this important to stopping microbes?
little hairs; Ciliary escalator transports microbes trapped in mucus away from the lungs; propels them upwards towards the throat
what is the Lacrimal apparatus?
in the eye; it drains tears and washes eye
what are are some chemical factors of the first line defense?
many secretions of the skin and mucous membranes lower the pH environment to inhibit or destroy microbes (bc most microbes grow at a pH of 7)
what chemical factor of sebum helps inhibit / destroy microbes?
sebum forms a protective film and lowers the pH of the skin to around 3-5
what is in tears, saliva and urine that helps to destroy microbes and how does it target them?
lysosome in these perspirations destroys bacterial cell walls which helps kill microbes
how does the normal microbiota help inhibit microbial growth?
normal microbiota compete with pathogens via microbial antagonism (competitive exclusion)
- compete for space and nutrients
- produce substances harmful to pathogens
- alter conditions to affect pathogen survival
what are probiotics and how do they effect microbial growth?
probiotics live microbial cultures administered to exert a beneficial effect; Often lactic acid bacteria which produce lactic acid and bacteriocins that inhibit pathogen growth
what portions are two components in the blood?
1) plasma (fluid portion)
2) formed elements
what are the formed elements of the blood?
1) Erythrocytes (red blood cells)
2) Leukocytes (white blood cells)
3) Platelets
where are the formed elements of the blood made?
created in red bone marrow stem cells
how are the formed elements of the blood made?
made via hematopoiesis
what is hematopoiesis ?
Creation of blood cellular components
all blood cells arise from what type of cells?
pluripotent stem cells
Leukocytes are important for what type of immunity?
innate immunity
there are two types of leukocytes and these are divided into two types by what?
by appearance under light microscope
what are the two main types of leukocytes?
granulocytes and agranulocytes
what are granulocytes?
visible granules in cytoplasm
what are agranulocytes?
granules in cytoplasm that are not visible via light microscopy
what are three types of granulocytes?
1) neutrophils
2) basophils
3) eosinophils
what are neutrophils?
(type of granulocytes) phagocytic; work in early stages of infection; can leave the blood and enter infected tissue; type of polymorphonuclear cells (PMNs)
what are basophils?
(type of granulocytes) release histamine; mediate inflammation and allergic responses; type of polymorphonuclear cells (PMNs)
what are eosinophils?
(type of granulocytes) phagocytic; toxic against parasites and helminths; can leave the blood; type of polymorphonuclear cells (PMNs)
what are three types of agranulocytes?
1) monocytes
2) dendritic cells
3) lymphocytes
what are monocytes?
(type of agranulocytes) leave blood, enter body tissues, and mature into macrophages (become phagocytic)
what are dendritic cells?
(type of agranulocytes) found in the skin, mucous membranes, and thymus; phagocytic, initiate adaptive responses
what are lymphocytes?
(type of agranulocytes) T cells, B cells, and NK cells; play a role in adaptive immunity
what are differential while blood cell counts?
a measure of leukocytes in the blood; % per 100 cells counted
what can high white blood cell counts indicate?
may indicate bacterial infections, autoimmune diseases or side effects of medications
what is the term for high white blood cell counts?
leukocytosis
what can low white blood cell counts indicate?
may indicate viral infections, pneumonia, autoimmune diseases or cancer
what is the term for low white blood cell counts?
leukopenia
what is lymph?
fluid
what are lymphatic vessels?
vessels, similar to the circulatory system
what are lymphatic tissues?
scattered throughout mucous membranes that line GI, respiratory, urinary, and reproductive organs
what are four specific organs and aggregations of lymphoid tissues?
1) spleen
2) thymus
3) tonsils
4) Peyer’s patches
what is phagocytosis?
the ingestion of microbes or other substances by a cell; performed by phagocytes
what are the four steps to the mechanism of phagocytosis?
1) chemotaxis
2) adherence
3) ingestion
4) digestion
what is chemotaxis?
first step in phagocytosis; chemical signals attract phagocytes to microorganisms
what is adherence?
second step in phagocytosis; attachment of a phagocyte to the surface of the microorganism (TLRs and PAMPs) and is enchanted by opsonization
what is opsonization?
process that marks microbial antigens with serum proteins (marks them for destruction) (can be done by antibodies)
what is ingestion?
third step in phagocytosis; pseudopods (plasma membrane extensions) engulf microbe; pseudopods meet, fuse, and form a phagosome (internal pH shifts to 4); phagosome pinches off membrane and enters cytoplasm
what is digestion?
four step in phagocytosis; phagosome contacts and fuses with lysosome (contains digestive enzymes and bactericidal substances) forming a phagolysosome which then digests the microorganism. Phagolysosome (now called “residual body” releases indigestible material outside the cell
what is a phagosome?
a vacuole in the cytoplasm of a cell, containing a phagocytosed particle enclosed within a part of the cell membrane
what is a phagolysosome?
cytoplasmic body formed by the fusion of a phagosome with a lysosome; its formation is essential for the intracellular destruction of microorganisms and pathogens
how do you remember the signs and symptoms of inflammation?
“PRISH”
what is inflammation?
local defense response triggered by injury to body tissue
what are the signs and symptoms of inflammation?
1) Pain - release of chemicals
2) Redness - increased blood flow
3) Immobility - loss of function in severe cases
4) Swelling - fluid accumulation
5) Heat - increased blood flow
what are three functions of inflammation?
1) Destroys injurious agent; removes it and by-products
2) Limits its effects on the body; isolating / walling off it and by-products
3) Repairs and replaces damaged tissue; by the injurious agent and buy products
what are two types of inflammation?
acute or chronic inflammation
what is acute inflammation?
Primarily caused by neutrophils; rapid development of signs and symptoms, last days to weeks; mild and self-limiting (appendicitis, cold, flu, sore throat, minor cuts/scratches)
what is chronic inflammation?
Primarily caused by monocytes and macrophages; slow development of signs and symptoms; last months to years; more severe and progressive (mononucleosis, peptic ulcers, tuberculosis, rheumatoid arthritis)
macrophage TLRs recognize PAMPs and release cytokines (TNF-alpha) — the liver responds to TNF-alpha in the blood and activates what? what does this do?
activates acute-phase proteins; serum concentration changes (+/-) by >25% in response to cytokines; indication of inflammation
what are the three STEPS in the inflammation process in the body?
1) Vasodilation and increased permeability of blood vessels
2) Phagocyte migration and phagocytosis
3) Tissue repair
what happens during Vasodilation and increased permeability of blood vessels ?
Both of these occur immediately following tissue damage; vasodilation = dilation of blood vessels; increased permeability = defensive substances can leave blood vessels and enter injured area
what does vasodilation cause?
causes redness (erythema) and heat
what does increased permeability cause?
causes fluid accumulation (edema)
what causes vasodilation and increased permeability?
vasoactive mediators which are chemicals released by damaged cells that elicit a response
what is the result of Vasodilation and increased permeability of blood vessels ?
an abscess forms = cavity created by breakdown of tissue containing pus (mixture of dead cells and body fluids)
what is margination?
as blood flow decreases, phagocytes (neutrophils and monocytes) stick to the inner surface of blood vessel (caused by cytokines)
what is diapedesis?
(after margination occurs) phagocytes squeeze between endothelial cells of blood vessels
when can tissue be repaired?
when stroma or parenchyma produce new cells
what is parenchyma and how is the tissue repair?
functioning part of the tissue that is repaired; near perfect repair
what is the stroma and how is the tissue repair?
supporting connective tissue that is repaired; scar tissue
how does scar tissue arise?
(with chronic inflammation) cytokines released by macrophages cause stroll cells to synthesize connective tissue (fibrosis)
what is fibrosis?
accumulation of connective tissue resulting in scar tissue
what is fever?
abnormally high body temperature; overall systemic response to infection
what typically causes fever?
typically caused by bacterial or viral infection; released cytokines cause the hypothalamus to reset to higher temperature; higher temperature is maintained until cytokines are eliminated
is fever a good defense against disease?
to a certain point; it increases production and effects of certain antimicrobial molecules but complications can be worse; these include dehydration, rapid heart rate, electrolyte imbalances (death above 44-46 decreases celsius)
what is the complement system?
> 30 proteins produced by the liver that circulate and blood serum and body tissues; aids and enhancing immune system ability to destroy microbes
how are complement proteins labeled?
Designated with uppercase C and numbered in order of discovery
(inactive until split into fragments)
Activated fragments indicated with lowercase a and b (i.e C3a)
what do we know about complement activation?
proteins act in a cascade, one reaction triggers another?
what are the three activation pathways resulting in activation of C3?
1) classical
2) alternative
3) lectin
what is the classical pathway resulting in activation of C3?
initiated when antibodies bind antigens; results in C3a and C3b (activated)
what is the alternative pathway resulting in activation of C3?
activated by contact between complement proteins and microbe; results in C3a and C3b (activated)
what is the lectin pathway resulting in activation of C3?
initiated when lectins bind carbohydrates on microbe surface; results in C3a and C3b (activated)
what are three outcomes of the complement activation?
1) cytolysis
2) opsonization
3) inflammation
what is cytolysis, one of the outcomes of complement activation?
activated complement proteins create a membrane attack complex (MAC); this creates hole in plasma membrane and fluid inflow bursts the cell-lysis
cytolysis is more effective against what type of bacteria and why?
more effective against Gram negative bacteria due to their thinner peptidoglycan wall
what is opsonization, one of the outcomes of complement activation?
activated complement proteins promotes attachment of phagocytes to microbe
what is inflammation, one of the outcomes of complement activation?
activated complement proteins bind to mast cells, releasing histamine which increases inflammation
how is the complement system regulated?
regulatory proteins readily break down complement proteins, minimizing host cell destruction
what can happen if a person has a lack of complement proteins?
they can be more susceptible to infections
what is one structure that allows microbes are able to evade the complement system?
CAPSULES prevent complement activation
what are interferons (IFNs)?
class of cytokines with antibacterial and antiviral activity; great variation between types
what are three primary types of human IFNs?
1) IFN-a (alpha)
2) IFN-b (beta)
3) IFN-y (gamma)
what are IFN-a and IFN-b?
produced by cells in response to viral infections; cause neighboring cells to produce antiviral proteins (AVPs) that inhibit viral replication (prevents spreads of viral infection to non-infected cells-stopping infection)
what are IFN-y?
causes neutrophils and macrophages to kill bacteria
what are iron-binding proteins?
iron is essential for survival of humans and pathogens; concentration of free iron in the body is low due to competition between human cells and pathogens for iron
what is transferrin?
(human iron binding proteins) found in blood and tissue fluids
what is lactoferrin?
(human iron binding proteins) found in milk, saliva, and mucus
what is ferritin?
(human iron binding proteins) found in the liver, spleen, and red bone marrow
what is hemoglobin?
(human iron binding proteins) located in red blood cells
bacteria produce _____________ which pull iron form host to compete with iron-binding proteins of the host
siderophores
what are antimicrobial peptides?
short peptides produced in response to protein and sugar molecules on microbes
