PSU micro exam 3
Five classes of lg
(IgG, IgM, IgA, IgD, IgE)
infectious dose for 50 % of a sample populatiorn
-1D50
Identify other important factors concerning the spread of disease Develop methods for controlling a disease Assemble data and graphs to outline incidence of disease
. Epidemiologists:
Cytopathic effects
. Stopping cell synthesis . Causing cell lysosomes to release enzymes . Creating inclusion bodies in the cell cytoplasm . Fusing cells to create a syncytium Changing host cell function or inducing chromosomal changes Inducing antigenic changes on the cell surface Loss of contact inhibition in the cell, leading to cancer . Producing interferons to protect uninfected cells
Subset of CD4+ cells; carry an additional CD25 molecule Suppress T cells against self; protect intestinal bacteria required for digestion; protect fetus
. T regulatory cells (Treg
immunity in most of a population
.Herd immunity:
is a competition between microbes
.Microbial antagonism (competitive exclusion)
NORMAL RANGES AND PERCENTAGES Basophils
0.5 % to 1 %
NORMAL RANGES AND PERCENTAGES Eosinophils
2 % to 4 %
NORMAL RANGES AND PERCENTAGES Lymphocytes
20 % to 25 %
NORMAL RANGES AND PERCENTAGES Monocytes
3 % to 8 %
Hypothalamus is normally set at
37 C
NORMAL RANGES AND PERCENTAGES Neutrophils
60 % to 70 %
contain an enzyme component (A part) and a binding component (B part)
A-B toxins
exotoxins
AB toxins membrane disrupting toxins superantigens genotoxins
symptoms develop rapidly but the disease lasts only a short time
Acute disease:
Acquired through infection or vaccination
Adaptive immunity:
Primary response: first time the immune system combats a particular foreign substance
Adaptive immunity:
Secondary response: later interactions with the same foreign substance; faster and more effective due to "memory"
Adaptive immunity:
defenses that target a specific pathogen
Adaptive immunity:
immunity or resistance to a specific pathogen; slower to respond, has memory component
Adaptive immunity:
Attachment of a phagocyte to the surface of the microorganism
Adherence
______on the pathogen bind to _______ on the host cells
Adhesins (ligands), receptors
carcinogenic toxin produced by Aspergillus
Aflatoxin
are leukocytes with granules in their cytoplasm that are not visible with a light microscope
Agranulocytes
analyzes a particular disease to determine its probable cause
Analytical epidemiology;
Constant (Fc) region is the stem, which is identical for a particular lg class
Antibodies
Four protein chains form a Y-shape Two identical light chains and two identical heavy chains joined by disulfide links
Antibodies
Globular proteins called immunoglobulins (Ig)
Antibodies
Variable (v) regions are at the ends of the arms bind epitopes
Antibodies
The Classical Pathway
Antibodies bind to antigens, activating C1 C1 splits and activates C2 and C4 C2a and C4b combine and activate C3 C3a functions in inflammation C3b functions in cytolysis and opsonization
the relative amount of antibody in the serum
Antibody titer
Clonal selection differentiates activated B cells into:
Antibody-producing plasma cells Memory cells
Pathogens alter their surface antigens (and antibodies are rendered ineffective)
Antigenic Variation
substances that cause the production of antibodies Usually components of invading microbes or foreign substances
Antigens:
Short peptides produced in response to protein and sugar molecules on microbes Inhibit cell wall synthesis Form pores in the plasma Broad spectrum of activity
Antimicrobial Peptides
blood-derived fluids containing antibodies
Antiserum:
antibodies against specific exotoxins
Antitoxins:
Programmed cell death Prevents the spread of infectious viruses into other cells Cells cut their genome into fragments, causing the membranes to bulge outward via blebbing
Apoptosis
Vectors
Arthropods, especially fleas, ticks, and mosquitoes
Injection vaccination (immunization)
Artificially acquired active immunity
Injection of antibodies
Artificially acquired passive immunity
bacteria in the blood
Bacteremia:
release histamine; work in allergic responses
Basophils:
pathogen reproduces in the vector, transmited via bites or feces
Biological transmission:
The Alternative Pathway
C3 present in the blood combines with factors B, D, and P on microbe surface C3 splits into C3a and C3b, functioning the same as in the classical pathway
T helper cells (TH) Cytokine signaling with B cells , interact directly with antigens Bind MHC class Il molecules on B cells and APCs
CD4*
Cytoxic T lymphocytes (CTL) Bind MHC class I molecules
CD8*
Glycocalyx around the cell wall Impair phagocytosis
Capsules
Human reservoirs
Carriers
may have inapparent infections or latent diseases
Carriers
Formed Elements in Blood
Cells and cell fragments suspended in plasma Erythrocytes Leukocytes Platelets
attacks antigens found inside cells Viruses; some fungi and parasites
Cellular immunity
Produces T lymphocytes Recognize antigenic peptides processed by phagocytic cells Mature in the thymus T cell receptors (TCRs) on the T cell surface contact antigens, causing the T cells to secrete cytokines instead of antibodies
Cellular immunity ( cell - mediated immunity )
induce migration of leukocytes
Chemokines:
Chemical signals attract phagocytes to microorganisms
Chemotaxis
The Mechanism of Phagocytosis
Chemotaxis Adherence Ingestion Digestion
symptoms develop slowly
Chronic disease:
transports microbes trapped in mucus away from the lungs
Ciliary escalator
the membrane of nucleated animal cells Identify "self
Class I MHC
on the surface of antigen-presenting cells (APCs), including B cells
Class II MHC
eliminates harmful B cells
Clonal deletion
coagulate fibrinogen
Coagulases:
breaks down collagen
Collagenase:
one organism benefits while the other (host) is unharmed
Commensalism:
one organism benefits, and the other is unaffected
Commensalism:
a disease that is spread from one host to another
Communicable disease:
Normal microbiota protect the host by:
Competing for nutrients Producing substances harmful to invading microbes Affecting pH and available oxygen
Lack of complement proteins susceptibility to infections
Complement and disease
an individual whose resistance to infection is impaired by disease, therapy, or burns
Compromised host:
diseases that are easily and rapidly spread from one host to another
Contagious diseases:
Greek, meaning cell
Cyte:
chemical messengers produced in response to a stimulus
Cytokines
Activated complement proteins create a membrane attack complex (MAC)
Cytolysis
Outcomes of Complement Activation
Cytolysis Opsonization Inflammation
are visible effects of viral infection on a cell
Cytopathic effects (CPE)
Engulf and degrade microbes and display them to T cells Found in the skin, genital tract, lymph nodes, spleen, thymus, and blood
Dendritic cells (DCs)
found in the skin, mucous membranes, and thymus; phagocytic
Dendritic cells:
inner portion made of connective tissue
Dermis:
collection and analysis of data
Descriptive epidemiology:
Protozoa Avoid host defenses by:
Digesting cells and tissue fluids Growing in phagocytes Antigenic variation
Microorganism is digested inside a phagolysosome
Digestion
requires close association between the infected and a susceptible host
Direct contact transmission:
an abnormal state in which the body is not performing normal functions
Disease:
transmission via airborne droplets less than 1 meter
Droplet transmission:
prevents microbes from entering the ear
Earwax
Diseases that are new, increasing in incidence, or showing a potential to increase in the near future Most are zoonotic, of viral origin, and likely to be vector-borne
Emerging Infectious Diseases
disease constantly present in a population
Endemic disease:
phagocytic; toxic against parasites and helminths
Eosinophils:
disease acquired by many people in a given area in a short time
Epidemic disease:
The study of where and when diseases occur and how they are transmitted in populations
Epidemiology
outer portion made of tightly packed epithelial cells containing keratin, a protective protein
Epidermis:
alkaloid toxins that cause hallucinations
Ergot
the cause of a disease
Etiology:
Capsules prevent complement activation
Evading the complement system
Proteins produced and secreted by bacteria
Exotoxins
involves a hypothesis and controlled experiments
Experimental epidemiology:
found in the liver, spleen, and red bone marrow
Ferritin:
.Abnormally high body temperature
Fever
residents in tissues and organs
Fixed macrophages
systemic infection that began as a local infection
Focal infection:
roam tissues and gather at sites of infection
Free (wandering) macrophages
Toxic metabolic products Provoke an allergic response
Fungi
serum fraction containing antibodies
Gamma () globulin:
Predisposing Factors Make the body more susceptible to disease
Gender Inherited traits, such as the sickle cell gene Climate and weather Fatigue . Age Lifestyle Nutrition . Chemotherapy
Emerging Infectious Diseases Contributing factors
Genetic recombination Evolution of new strains Widespread use of antibiotics and pesticides Changes in weather patterns
damage DNA (causing mutations disrupting cell division, and leading to cancer)
Genotoxins
serum proteins
Globulins:
leukocytes with granules in their cytoplasm that are visible with a light microscope
Granulocytes
antigens too small to provoke immune responses; attach to carrier molecules
Haptens:
Acquired while receiving treatment in a health care facility
Healthcare-Associated Infections (HAIs) Also known as nosocomial infections
control stem cells that develop into red and white blood cells
Hematopoietic cytokines:
located in red blood cells
Hemoglobin:
acute-phase proteins
Histamine Kinins Prostaglandins Leukotrienes Cytokines
analyzes relationships between microbial communities on the body and human health
Human Microbiome
Continual sources of infection
Human reservoirs Animal reservoirs Nonliving reservoirs
Produces antibodies that combat foreign molecules known as antigens B cells are lymphocytes that are created and mature red bone marrow Recognize antigens and make antibodies Named for bursa of Fabricius in birds
Humoral immunity
fights invaders outside cells Bacteria and toxins
Humoral immunity
digests polysaccharides that hold cells together
Hyaluronidase:
produced by cells in response to viral infections; cause neighboring cells to produce antiviral proteins (AVPs) that inhibit viral replication
IFN-a and IFN-B:
causes neutrophils and macrophages to kill bacteria
IFN-y:
13 % of serum antibodies
IgA
Monomer serum; dimer in secretions
IgA
Prevent microbial attachment to mucous membranes
IgA
mucous membranes, saliva, tears, and breast milk
IgA
80 % of serum antibodies
IgG
Cross the placenta; trigger complement; enhance phagocytosis; neutralize toxins and viruses; protect
IgG
In the blood, lymph, and intestine
IgG
Monomer
IgG
6 % of serum antibodies
IgM
Cause clumping of cells and viruses
IgM
First response to an infection; short-lived
IgM
Pentamer made of five monomers held with a J chain
IgM
Remain in blood vessels
IgM
ability to ward off disease
Immunity:
number of people who develop a disease during a particular time period
Incidence:
interval between initial infection and first signs and symptoms
Incubation period:
Development of Disease
Incubation period: Prodromal period: Period of illness: Period of decline: Period of convalescence:
spreads to a host by a nonliving object called a fomite
Indirect contact transmission:
invasion or colonization of the body by pathogens
Infection:
Activated complement proteins bind to mast cells, releasing histamine
Inflammation
Destroys injurious agent or limits its effects on the body Repairs and replaces tissue damaged by the injurious agent
Inflammation
defenses against any pathogen; rapid, present at birth
Innate immunity:
Cytokines produced by cells; have antiviral activity
Interferons
interfere with viral infections of host cells
Interferons (IFNs):
cytokines between leukocytes
Interleukins:
presence of toxin without microbial growth
Intoxications:
Surface proteins produced by bacteria that rearrange actin filaments of the cytoskeleton
Invasins
digest fibrin clots
Kinases:
lethal dose for 50 % of a sample population Measures potency of a toxin
LD50
drains tears; washes eye
Lacrimal apparatus:
found in milk, saliva, and mucus
Lactoferrin:
causative agent is inactive for a time but then activates and produces symptoms
Latent disease:
Membrane-disrupting toxins
Leukocidind Hemolysins Streptolysins
is used to test for endotoxins
Limulus amebocyte lysate (LAL) assay
Endotoxins
Lipid A
portion of lipopolysaccharides (LPS) of gram-negative bacteria Released during bacterial multiplication and when gram-negative bacteria die Stimulate macrophages to release cytokines Cause disseminated intravascular coagulation
Lipid A
pathogens are limited to a small area of the body
Local infection:
The Lymphatic System
Lymph, lymphatic vessels, lymphoid tissue, and red bone marrow
T cells, B cells, and NK cells; play a role in adaptive immunity
Lymphocytes:
changes characteristics a microbe due to incorporation of a prophage
Lysogenic conversion
perspiration, tears, saliva, and urine destroys bacterial cell walls
Lysozyme
resists phagocytosis
M protein
Activated by cytokines or the ingestion of antigenic material Migrate to the lymph tissue, presenting antigen to T cells
Macrophages
The Lectin Pathway
Macrophages ingest pathogens, releasing cytokines that stimulate lectin production in the liver Mannose-binding lectin (MBL) binds to mannose, activating C2 and C4 C2a and C4b activate C3, which functions the same as in the classical and alternative pathways
genes encode molecules on the cell surface
Major histocompatibility complex (MHC)
sticking of phagocytes to blood vessels in response to cytokines at the site of inflammation
Margination
arthropod carries pathogen on its feet
Mechanical transmission:
Vectors Transmit disease by two general methods
Mechanical transmission: Biological transmission:
lyse host cells by disrupting plasma membranes
Membrane-disrupting toxins
HAls result from:
Microorganisms in the hospital environment Weakened status of the host Chain of transmission in a hospital
Emerging Infectious Diseases Contributing factors (cont'd)
Modern transportation Ecological disaster, war, and expanding human settlement Animal control measures Public health failure
mature into macrophages in tissues where they are phagocytic
Monocytes:
number of people affected in relation to the total population in a given time period
Morbidity rate:
number of deaths from a disease in relation to the population in a given time
Mortality rate:
Epithelial layer that lines the gastrointestinal, respiratory, and genitourinary tracts
Mucous membranes
Portals of entry
Mucous membranes Skin Parenteral route
viscous glycoproteins that trap microbes and prevent tracts from drying out
Mucus:
both organisms benefit
Mutualism:
are produced by mushrooms and are neurotoxic
Mycotoxins
Form pores in the target cell, leading to lysis or apoptosis
Natural killer (NK) cells
Granular leukocytes destroy cells that don't express MHC class I self-antigens
Natural killer (NK) cells
Kill virus-infected and tumor cells and attack parasites
Natural killer (NK) cells
Not always stimulated by an antigen
Natural killer (NK) cells
Resulting from infection
Naturally acquired active immunity
Transplacental or via colostrum
Naturally acquired passive immunity
phagocytic; work in early stages of infection
Neutrophils:
Granulocytes
Neutrophils: Basophils: Eosinophils:
a disease that is not spread from one host to another
Noncommunicable disease:
Produce substances harmful to pathogens Alter conditions that affect pathogen survival
Normal microbiota
compete with pathogens via microbial antagonism Produce substances harmful to pathogens Alter conditions that affect pathogen survival
Normal microbiota
permanently colonize the host and do not cause disease under normal conditions
Normal microbiota
diseases in which physicians are required to report occurrence
Notifiable infectious diseases:
Distribution and composition of normal microbiota determined by many factors
Nutrients Physical and chemical factors Host defenses Mechanical factors
allows attachment to host cells
Opa protein
Promotes attachment of a phagocyte to a microbe
Opsonization
microorganism is coated with serum proteins, making ingestion easier
Opsonization:
worldwide epidemic
Pandemic disease:
one organism benefits at the expense of the other
Parasitism:
the functioning part of the tissue that is repaired
Parenchyma
Deposited directly into tissues when barriers are penetrated
Parenteral route
the development of disease
Pathogenesis:
the ability to cause disease
Pathogenicity:
the study of disease
Pathology:
body returns to its prediseased state
Period of convalescence:
signs and symptoms subside
Period of decline:
disease is most severe
Period of illness:
microfold cells (M cells) located over
Peyer's patches
Greek, meaning eat
Phago:
Protozoa
Presence of protozoa and their waste products causes symptoms
number of people who develop a disease at a specified time, regardless of when it first appeared
Prevalence:
acute infection that causes the initial illness
Primary infection:
live microbial cultures administered to exert a beneficial effect
Probiotics:
short period after incubation; early, mild symptoms
Prodromal period:
Control of Healthcare-Associated Infections
Reduce number of pathogens Infection control committees
Regulatory proteins readily break down complement proteins, minimizing host cell destruction
Regulation of complement
Portals of Exit
Respiratory Gastrointestinal tract Genitourinary tract Skin Blood
forms a protective film and lowers the pH (3-5) of skin
Sebum
occurs after the second exposure to an antigen
Secondary (memory or anamnestic) response
opportunistic infection after a primary ( predisposing ) infection
Secondary infection:
toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection
Sepsis:
also known as blood poisoning; growth of bacteria in the blood
Septicemia:
the study of reactions between antibodies and antigens
Serology:
proteins secreted by pathogens that bind iron more tightly than host cells
Siderophores
changes in a body that can be measured or observed as a result of disease
Signs:
First Line of Defense:
Skin and Mucous Membranes
Nonliving reservoirs
Soil and water
Exceptions to Koch's postulates
Some pathogens can cause several disease conditions Some pathogens cause disease only in humans Some microbes have never been cultured
Algae
Some produce a neurotoxin called saxitoxin
disease that occurs only occasionally
Sporadic disease:
the supporting connective tissue that is repaired
Stroma
intermediate between acute and chronic
Subacute disease:
no noticeable signs or symptoms (inapparent infection)
Subclinical disease:
cause an intense immune response due to release of cytokines from host cells (T cells) Cause symptoms of fever, nausea, vomiting, diarrhea, shock, and death
Superantigens
lack of resistance to a disease
Susceptibility:
is the relationship between normal microbiota and the host
Symbiosis
changes in body function that are felt by a patient as a result of disease
Symptoms:
a specific group of signs and symptoms that accompany a disease
Syndrome:
an infection throughout the body
Systemic (generalized) infection:
Attach to antigens via T-cell receptors (TCRs)
T cells
Migrate from the thymus to lymphoid tissues
T cells
Mature in the thymus
T cells combat
Antigen that requires a TH cell to produce antibodies
T-dependent antigen
Stimulate the B cell without the help of T cells Provoke a weak immune response, usually producing lgM No memory cells generatecd
T-independent antigens
produce IFN-Y, which activates macrophages, enhances complement, and stimulates antibody production that promotes phagocytosis
TH1 cells produce
cells produce IL-17 and contribute to inflammation
TH17
Tg cells produce cytokines and differentiate into
TH1cells TH2 cells TH17 cells Memory cells
activate B cells to produce lgE; activate eosinophils
TH2 cells
Serum proteins produced by the liver that assist the immune system in destroying microbes
The Complement System
Lymph, lymphatic vessels, lymphoid tissue, and red bone marrow
The Lymphatic System
Koch's Postulates 3.
The pathogen from the pure culture must cause the disease when it's inoculated into a healthy, susceptible laboratory animal.
Koch's Postulates 2.
The pathogen must be isolated from the diseased host and grown in pure culture.
Koch's Postulates 4.
The pathogen must be isolated from thee inoculated animal and must be shown to be the original organism.
Koch's Postulates 1.
The same pathogen must be present in every case of the disease
eliminates immature T cells
Thymic selection
Cannot be completed until all harmful substances are removed or neutralized
Tissue Repair
presence of toxin in the host's blood
Toxemia:
toxins in the blood
Toxemia:
ability of a microorganism to produce a toxin
Toxigenicity:
poisonous substances produced by microorganisms
Toxins
inactivated exotoxins used in vaccines
Toxoids:
found in blood and tissue fluids
Transferrin:
Iron-Binding Proteins
Transferrin: Lactoferrin: Ferritin: Hemoglobin: siderophores
may be present for days, weeks, or months
Transient microbiota
involved in the inflammation of autoimmune diseases
Tumor necrosis factor (TNF):
cleans the urethra via flow
Urine
Helminths
Use host tissue for growth Produce large masses, cause cellular damage Produce waste products Produce waste products that cause symptoms
move microorganisms out of the vaginal tract
Vaginal secretions
the number of antigen-binding sites on an antibody
Valence
viruses in the blood
Viremia:
the degree of pathogenicity
Virulence:
Transmission by an inanimate reservoir
Waterborne Foodborne Airborne
resists digestion
Waxy lipid (mycolic acid)
Animal reservoirs
Zoonoses
are diseases transmitted from animals to humans
Zoonoses
Inflammation activates ______ by the liver that cause vasodilation and increased permeability of blood vessels
acute-phase proteins
Almost all pathogens attach to host tissues in a process called
adherence (adhesion)
antigen-antibody complex Strength of the bond is the
affinity
An antigen-antibody complex forms when
antibodies bind to antigens
Protects the host by tagging foreign molecules or cells for destruction
antigen-antibody complex
High WBC counts may indicate
bacterial infections, autoimmune diseases, or side effects of medications
Microbes form
biofilms
Act in a cascade in a process called
complement activation
Overproduction of cytokines leads to a
cytokine storm
TLRs bound to PAMPs induce the release of
cytokines from the host cell that regulate the intensity and duration of immune responses
IgA proteases:
destroy IgA antibodies
Phagocytes squeeze between endothelial cells of blood vessels via
diapedesis
Antibodies interact with
epitopes, or antigenic determinants, on the antigen
Hemolysins-kill
erythrocytes by forming protein channels
Low pH (1.2-3.0) destroys most bacteria and toxins
gastric juice
Streptolysins
hemolysins produced by streptococci
Proteases modify
host cell membranes
T cells combat
intracellular pathogens
White blood cell (WBC) counts measure
leukocytes in the blood
0.02 % of serum antibodies
lgD
In blood, in lymph, and on B cells
lgD
Monomer
lgD
No well-defined function; assists in the immune response on B cells
lgD
Structure similar to lgG
lgD
0.002 % of serum antibodies
lgE
Cause the release of histamines when bound to antigen; lysis of parasitic worms
lgE
Monomer
lgE
On mast cells, on basophils, and in blood
lgE
Lymph carries microbes to lymph nodes where
lymphocytes and macrophages destroy the pathogen
The Lymphatic System .Contains
lymphocytes and phagocytic cells
Shedding and dryness of skin inhibits
microbial growth
Pathogens entering the gastrointestinal tract pass through
microfold cells (M cells)
.Some normal microbiota are
opportunistic pathogens
Toll-like receptors (TLRs) on host cells attach to
pathogen-associated molecular patterns (PAMPs)
Leukocidins-kill
phagocytic leukocytes
Capsules prevent
phagocytosis
Cytokines cause the hypothalamus to release
prostaglandins that reset the hypothalamus to a higher temperature
Trichothecene toxins inhibit
protein synthesis
Formed Elements in Blood Created in
red bone marrow stem cells via hematopoiesis
Inflammation Four signs and symptoms:
redness, swelling (edema), pain, heat
.Body constricts the blood vessels, and
shivering occurs (which raises temperature)
Bacteria produce compete with iron-binding proteins
siderophores
Koch's postulates are used to prove
the cause an infectious disease
Plasmids may carry genes for
toxins, production of antibiotics, and enzymes
Low pH (3-5) inhibit microbes
vaginal secretions
As body temperature falls (crisis),
vasodilation and sweating occurs
Low WBC counts may indicate
viral infections, pneumonia, autoimmune diseases, or cancers
The Complement System .Proteins are designated
with uppercase C and numbered in order of discovery Activated fragments are indicated with lowercase a and b