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Patho ch 7 and 8

Terms in this set (47)

1st line of defense
Physical/chemical barriers
2nd line of defense
Innate responses
non-specific
conferred by leukocytes
results in inflammation
3rd line of defense
Adaptive responses
targeted defenses against specific pathogens
conferred by lymphocytes (T and B cells)
adaptive immunity
Antigens bind to receptors on lymphocytes

Lymphocytes produced in the bone marrow, mature in lymph nodes
B cells are trained in bone marr.
T cells are trained in the thymus

Develop antigen-specific recognition

Central tolerance
humoral defenses (adaptive immunity)
carried out by B cells

Produce antibodies in response to antigen
called immunoglobulins (Ig)
IgD
Ig that activates B cells
IgM
first response Ab
IgG
most abundant antibody, crosses placenta
IgA
found in saliva, tears, milk, intestinal secretions, protects mucosal surfaces
IgE
triggers inflammation and allergic responses
antigen-presenting cells (APCs)
phagocytize pathogen, process fragments

APCs present exogenous antigens to B cells and T cells

Results in differentiation into effector lymphocytes
B cells --> plasma cells that produce antibodies
T cells --> cytotoxic T cells
B cells
plasma cells that produce antibodies
T cells
cytotoxic T cells
cellular defenses (adaptive immunity)
carried out by T cells

Macrophages present antigens to helper T (TH) cells
endogenous antigen presented on abnormal cell
Cytotoxic T (TC) cells activated by TH cell or antigen

Divides rapid to produce memory T cells and more TC cells
communicability
Ability to spread from one individual to others and cause disease: measles and pertussis spread very easily, HIV is of lower _____________
NO. Some microorganisms perform important functions for their human hosts, like producing vitamins, assisting digestion, or preventing harmful pathogens from entering the host.
Are all interactions between humans and microorganisms are detrimental?
human GI bacteria
300 species of bacteria live in large intestine
Bacteria and fungi live on our skin
Mouth & pharynx contain many species of bacteria
Vagina contains acid-producing bacteria
Some are useful - Many have no effect
Pathogens cause disease
All are capable of causing disease if your health and immunity are weakened
Education and lack of scientific research
Cleanliness
Care of food
Transmission routes of disease
Disease symptoms in general
Why is there such a dramatic difference of infectious disease death rates in underdeveloped versus developed countries?
mechanism of action
How the microorganism damages tissue
portal of entry
Infectious agents can gain entry into the human body in a variety of ways
penetration
Disruption of body's surface barrier (skin or mucus membrane) Bites of an animal or insect
direct contact
Exposed to infected tissue/secretions - STDs & Aids
ingestion
Into GI tract - Survives low pH and NZs
inhalation
Into respiratory tract - Many layers of defense (coughing, mucus, cilia, Mast Cells, antibodies, NZs)
colonization
the first stage of infection. Pathogen replicates in host.
toxigenicity
Ability to produce soluble toxins or endotoxins, factors that greatly influence the pathogen's degree of virulence
exotoxins
(cytotoxins, neurotoxins, pneumotoxins, enterotoxins, hemolysins)
Enzymes released during growth of the bacteria, causing specific responses
Immunogenic
Antitoxin production

enzymes released by bacteria
They damage plasma membrane or inactivate enzymes for protein synthesis
endotoxins
Lipopolysaccharides contained in the cell walls of gram-negative organisms released during cell destruction
Pyrogenic effects

parts of the bacterial cell wall
They cause host inflammation, immune reactions and cause fever
virulence
Capacity of a pathogen to cause severe disease; for example, measles virus is of low ________; while rabies virus is highly _______
Variable depending on the pathogen
Directly caused by the pathogen or indirectly caused by its products

Fever
Hallmark symptom of most infectious diseases

Increased pulse and respirations

Lethargy & decreased appetite

Red, swollen painful area

Increased WBCs - neutrophils and phages
clinical manifestations of infection disease?
1) Recovery of a probable pathogen or evidence of its presence from the infected sites.

2) Accurate documentation of clinical signs and symptoms (symptomatology)

3) Techniques for Laboratory Diagnosis of an Infectious Agent
Culture
Serology
DNA & RNA Sequencing
criteria for diagnosis of an infectious disease (3)
culture
growth & identification of pathogen on plate
serology
detection of characteristic antigens/antibody
DNA & RNA sequencing
Genomic sequences or metabolites produced by the pathogen
Bacteria: Surface coats
produce surface coats that inhibit phagocytosis and toxins
have surface receptors to bind host cells
some have toxins, endotoxins

Viruses: Antigenic variation
many can mutate within cells where they are hidden from inflammatory mechanisms or antibodies in circulation.
mutation (antigenic drift)
recombination (antigenic shift)
pathogen defense mechanisms?
antigenic drift
a mechanism for variation in viruses that involves the accumulation of mutations within the genes that code for antibody-binding sites
antigenic shift
the process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains.
Viruses
Chlamydia
Rickettsia
Mycoplasma
Bacteria
Fungi
Protozoa
Helminths
classes of infectious microorganisms
viruses
enter host cells and use the metabolic processes of host cells to proliferate.

Characteristics
Protein coat surrounding nucleic acid core
Have no metabolic enzymes of their own
Insert their genome into a host cell's DNA
Use that cell's metabolic machinery to make new _______
The virion:
becomes attached to the cell's plasma membrane by absorption
releases enzymes that weaken the membrane and allow it to penetrate the cell
uncoats itself
replicates
matures and escapes from the cell by budding from the plasma membrane
The infection then can spread to other host cells.
stages of viral infection of a host cell
measles-typical viral infection
Virus enters through the oropharynx, from where it infects the regional lymph nodes.
After 5 to 7 days, virus enters the blood (viremia) and spreads to the body surfaces (respiratory, gastrointestinal, and urinary tracts, and the skin).
Virus replicates in these tissues, leading to upper respiratory tract symptoms, with the appearance of red spots with bluish-white specks (Koplik spots) in the oral mucosa and later to an extensive rash involving most parts of the skin.
At or near the onset of overt symptoms, the infected individual is shedding virus and is highly infectious to others.
Antibodies against the virus resolve infection.
Abs are produced within 10 to 11 days but are immediately absorbed by viral particles in the blood so that free antibody is not measurable until about 2 weeks after the initial infection.
the common cold
portal of entry: nasal mucosa
THE most common RI
Many different viruses cause a cold
Rhinoviruses: portal is nasal mucosa and conjunctiva.
Occur in early fall and late spring in persons between ages 5 and 40
S/S: Rhinitis - Inflammation of nasal mucosa
Rhinorrhea: dryness or stuffy nose and throat, tearing and runny nose
Sinusitis: Inflammation of paranasal sinuses.
Infection or allergy obstructs sinus drainage
Acute: 1 day - 3 wks: facial pain, headache, purulent nasal discharge, decreased sense of smell, fever
Chronic: > 3 mos: nasal obstruction, fullness in the ears, postnasal drip, hoarseness, chronic cough, loss of taste and smell, unpleasant breath, headache

Pharyngitis: Mucosa of UR tract becomes red, swollen/ sore throat
Laryngitis: coughing and hoarseness
Headache/general malaise, maybe chills, fever, exhaustion
Spread person/person by fingers - so wash hands.
Tx: symptom relief: rest & antipyretics, antihistamines, decongestants, vitamin C
influenza
Orthomyxoviridae family of viruses: A, B, & C
Infection of ET cells (kills mucus & columnar)
More contagious than bacterial RI
Xmission by inhalation of droplet nuclei
1-4 day incubation before symptoms
Profound malaise and abrupt onset of symptoms.
If it moves into lower RT it leads to viral pneumonia.
Tx: goal is to limit infection to UR tract
Rest (limit respir mvmts and spread of infection)
Keep warm (inhibit viral replication)
Drink fluids - fever increases metabolism = water

Orthomyxoviridae family of viruses: A,B & C
infects 1/3 of the world population
In the United States, approximately 36,000 persons die each year of influenza-related illness
Xmission by inhalation of droplet nuclei (three or more particles) or direct contact
Viral infection of ET cells (kills mucus & columnar)
More contagious than bacterial RI
1-4 day incubation before symptoms
S/S
Upper respiratory infection like a cold with profound malaise - abrupt onset of symptoms - can be within 1-2 minutes
If it moves into lower RT it leads to viral pneumonia.
Respiratory viral infection followed by a bacterial infection
Tx: goal is to limit infection to UR tract
Rest (limit respir mvmts and spread of infection)
Keep warm (inhibit viral replication)
Drink fluids - fever increases metabolism = water
Blocking:
viral RNA or DNA synthesis
viral binding to cells
production of the protein coats (capsids) of new viruses
how do antiviral agents kill viruses?
bacteria
Cells without membrane-bound organelles (prokaryotes)
Can live independently
Use infected organism for food and shelter
bacteremia or septicemia
Presence of bacteria in the blood as a result of a failure of the body's defense mechanisms
Usually caused by gram-negative bacteria
Toxins released in the blood cause the release of vasoactive peptides and cytokines that produce widespread vasodilation
septic shock
Most common vasodilatory shock
Infection with systemic inflammation & organ dysfunction (hypotension) despite fluid replacement
TX: Antibiotics, fluids, vasoconstrictors, O2, increase CO, coronary perfusion

bacterial or fungal - vasodilation - peripheral pooling = ↓ BP

Mechanisms: Endothelial cells release inflammatory mediators (NO)
increase metabolic rate of tissues, so need more oxygen - go anerobic - inflammation
Increases coagulation factors
S/S: unlike other shocks: vasodilation, edema, 3rd spacing, fever, ↑ WBCs, flushed skin, personality changes
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