Microbiology Exam 2 review

Immune system

protects the human host

Immunity

ability to fight off pathogens and prevent disease

Host resistance

host having immunity

Host susceptibility

host lacking immunity

Host defenses

ability of host to remove pathogen to prevent disease

Innate immunity

immunity to any pathogen present at birth, non specific, no immunological memory, rapid immune response

What line of defense is Innate immunity composed of?

1st and 2nd lines of defense

Adaptive immunity

Immunity or resistance to specific pathogens develops later, is specific, and has immunological memory, slow response

What line of defense is Adaptive immunity composed of?

3rd line of host defense

What is the 1st line of composed of?

physical barriers (5), chemical barriers (4), and biological barriers (1)

what is the 3rd line of defense composed of?

humoral immunity and cell mediated immunity

1st line of defence physical barriers

Intact skin, mucous membranes, ciliary escalator, lacrimal apparatus, saliva, urine, and vaginal secretion

Intact skin features

packed epithelial cells, multiple layers, keratin protein, dryness, shedding

Mucous membranes

epithelia layer that lines gastrointestinal, respiratory and genitourinary tracts and secrete mucus

Ciliary Escalator

epithelia cells of lower respiratory tract have cilia, cilia sweep the mucus out of the body

Lacrimal apparatus

protects eyes, flushes tears

Saliva, urine and vaginal secretion

flushing mechanism, washes away pathogens

1st line of defense Chemical Barriers

Chemical factors of skin, lysozymes, gastric juices, blood transferrins

chemical factors

slightly acidic skin and salinity

What type of environment does the salinity of the skin create for invading pathogens?

Hypertonic environment

Lysozymes

enzymes found in body secretion (sweat, tears, and saliva), breaks chemical bonds in peptidoglycan and destroys bacterial cell wall

Gastric juices

produced by stomach contians enzymes and acid

Blood transferrins

proteins that bind to iron, iron is necessary for bacterial growth

1st line of defense Biological Barriers

Normal microbiota

two types of Normal Microbiota

Commensal microbes and beneficial microbes

Opportunist microbes

Not apart of normal microbiota, microbes that act as pathogens under certain circumstances

Commensal microbes with example

microbe benefit not host, ex bacteria on skin

beneficial microbes with example

both microbe and host benefit ex vitamin K producing bacteria e. coli in gastrointestinal tract

Normal microbiota

microbial competition, competes with pathogens leading to decreased populations of pathogenic bacteria

How does normal microbiota defeat the invading pathogenic bacteria?

take up all the nutrients and space, produce substances harmful to invading pathogens

What is the 2nd line of defense composed of?

formed elements, phagocytosis, inflammation, fever, antimicrobial substances (2)

formed elements in blood

cell and cell fragments in plasma, erythrocytes, leukocytes, thrombocytes

How are cells and cell fragments made

created in red bone marrow stem cells via hematopoiesis

What are leukocytes

white blood cells that include a variety different cells

Granulocytes

leukocytes with granules in their cytoplasm that are visible with a light microscope includes BEN

Basophiles

release histamine granules involved in allergic responses

Eosinophils

toxic against parasites and worms

Neutrophils

first responder phagocytic work in early stages of infection

Agranulocytes

leukocytes with granules in their cytoplasm that are not visible with a light microscope includes ML

Monocytes

travels in blood and will mature into macrophages in tissues where they become phagocytic cells

Lymphocytes

T cells, B cells, and NK cells

T cells and B cells are apart of what line of defense?

adaptive immunity 3rd line of defense

Differential white blood cell count

abundance of each type of white blood cell in a sample of 100 white blood cells NLMEB

Phagocytosis of solids

non specific host cell capable of phagocytosis ex. neutrophils, macrophages, and dendritic cells

Mechanisms of phagocytosis

chemotaxis, adherence, ingestion, digestion

chemotaxis

release of chemical signals (cytokines) by pathogen that attract phagocytes

adherence

attachment of phagocyte to surface of the pathogen

ingestion

endocytosis of pathogen to from a phagosome merges with lysosome which forms a phagolysosome inside phagocyte

digestion

pathogen is digested inside a phagolysosome

How do pathogens evade phagocytosis?

capsules, leucocidins, mycolic acid

capsules

pathogen too big to be engulfed

leukocidins

a pore forming toxin capable of killing phagocyte and hide from immune system

myolic acid

a waxy lipid material that inhibits lysosome enzymes, bacteria will multiply and high inside phagocyte

Inflammation

due to infection

signs and symptoms of inflammation

pain due to release of cytokines that damage nerve endings, redness (erythema), immobility, swelling (edema), heat

Process of inflammation

tissue gets damages releasing cytokines that promote chemotaxis of phagocytes, phagocytes squeeze through blood vessels and move to site of injured tissue, phagocytosis of invading pathogens begins, tissue gets repaired

Consequences of fever

Increases metabolic rate, enhances immune response, induces antimicrobial substances

antimicrobial substances

complement system and interferons

complement system

proteins found in blood that enhances the immune system in destroying pathogens

complement activation

complement proteins act in a cascade manner

outcomes of complete activation

opsonization, inflammation, cytolysis

opsonization

antibodies coat surface of pathogen, promotes attraction of phagocyte to pathogen (happens in 2nd line of defense and 3rd line of defense)

inflammation

complement proteins bind mast cell, mast cell releases histamine that increases permeability, phagocyte arrives to site of injury

cytolysis

complement proteins create a membrane attack complex that creates a hole in pathogen cell wall, fluid enters the pathogen and pathogen bursts

Microbial evasion of the complement system

capsule production complement proteins cannot bind easily, inhibition of mac formation enzymes from bacteria prevent MAC assembly, inactivation of complement proteins bacteria produce protease

interferons

small proteins produces by some animal host cells upon animal viral infection

Antiviral action

part of IFNs cause uninfected neighboring animal cells to heighten their anti viral defenses

Mechanisms of action of interferons

animal virus enters host cell and multiplies, animal host cell produces INFs, INFs binds to cell membrane of unaffected neighboring animal cell and makes anti viral proteins (AVPs), newly released viruses that infect neighboring animal cell has AVPs waiting to destroy virus

immunology

study of host defense against foreign substances

Antigen (Ag)

substance that stimulates a certain immune response in the form of antibody production

Examples of Antigens

pathogens, foreign substances, vaccines

Antibody (Ab)

Protective proteins made by the host response to certain antigens

Examples of Antibodies

Immunoglobulins (Ig)

What type of cells does adaptive immunity involve?

Certain lymphocytes like B cells and T cells

Types of adaptive immunity

Humoral Immunity and cell mediates immunity

Humoral immunity

fights invader and threats extracellularly like extracellular Ag’s

Example of Humoral immunity

extracellular pathogens and toxins

Cell mediated immunity

Attacks antigens that have entered the cell like intracellular Ag’s

Example of cell mediated immunity

animal virus present inside the host cell

what type of cells does humoral response involve?

B cells which indirectly make antibodies that help destroy foreign molecules known as antigens

what type of cells does cell mediated immune response produce?

produce T cells that recognize parts of antigens that get processed by phagocytoses and will destroy the antigen

What is the parent cell of B and T cells?

Stem cells

Where do B cells mature?

in bone marrow

Where do T cells mature?

in thymus

How do Antigens (Ag’s) interact with Antibodies (Ab’s)

Antigens have external components called antigenic determinants that Antibodies will bind to

Humoral immunity

immunoglobulins which equal Ab’s recognize and interact with antigenic determinants forming a Ag-Ab complex (immune complex), Ab will not destroy antigen but mark it to be destroyed

Clonal selection

process of B cell activation, surface Ig on B cell recognized specific Ag B cell is not selected

Clonal expansion

selected B cell proliferation into clone of activated B cells that will differentiate into plasma cells that produce antibodies

Antibodies structure

four protein chains form a Y shape, 2 identical light chains and two identical heavy chains joined together

Antibody regions

Variable regions which are at the end of the arms that bind to the antigenic determinants and constant region that is the stem includes 5 classes

5 classes of Antibodies

IgG, IgM, IgA, IgD, IgE

IgG

Monomer, most abundant in blood serum, long lived long term protection, in blood, lymph and intestine, crosses placenta (transplacental passage), enhanced phagocytosis by coating surface if antigen (opsonization), and neutralizes toxins and viruses

IgM

Pentamer, Largest Ab, 6% of serum antibodies, remain in blood vessels, cause agglutination (clumping) of pathogens, primary response to injection, short lived

Agglutination

Ab clumps several Ags in one place to attract phagocyte

neutralization

on mucosal membrane blocks attachment of toxins and viruses to mucosa

What would elevated IgM and lov IgG suggest?

recent/new infection

IgA

mostly a dimer but can be a monomer when present in mucosal lining, 13% of serum antibodies , most abundant Ig in the BODY,common on mucous membrane surface and secretion, prevents attachment of pathogens to mucous membranes