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Flashcards in Lecture 12 Deck (81):
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Pathology

study of disease

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Etiology

cause of the disease (viral or bacterial)

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Pathogenicity

ability to cause disease

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Virulence

ability to cause harm, severity of disease

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High virulence is..

better able to cause disease

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Pathogenesis

how the disease develops

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Pathogen

organism that can cause disease (bug)

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Infection

invasion or colonization of the body by pathogenic organisms

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Disease

abnormal state where the body is not capable of performing normal functions

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Typical human body has approx...

1 x 10^13 human cells

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Transient microbiota

microbes that may be present for days or months and then disappear

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Microbiota is ..

localized in certain regions of the body. generally found in exposed areas (skin, urinary tract, etc)

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Microbial antagonism

members of the microbiota produce substances harmful to invading microbes

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Competitive exclusion

microflora use up available nutrients preventing the growth of pathogens

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Benefits of microbiota

-E.coli in large intestine makes vitamin B and B
-produce enzymes that aid digestion

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Opportunistic pathogens

microbes that are part of the normal microbiota and don't normally cause disease

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Opportunistic pathogens can cause disease if..

-they are transferred to another part of the body
-the human host becomes immunocompromised
-if normal microbiota is disturbed

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Example of opportunistic pathogen

E.coli is normal resident of large intestine tract but transferred to urinary can cause infection

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Symptoms

what patient feels. subjective and variable

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Signs

objective change that a physician can measure

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Syndrome

specific group of signs and symptoms that always accompany a particular disease

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Communicable disease

that spreads from one host to another

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Contagious disease

easily spread

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Non-communicable disease

doesn't spread between hosts

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Incubation period

time between the infection and first sings or symptoms

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Prodromal period

early and mild symptoms such as malaise (feeling of unwell)

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Period of illness

most serve signs and symptoms. active immune response may cause some sings and symptoms

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Period of decline

sings and symptoms subside. can last for hours or days. patient is vulnerable to secondary infections

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Period of convalescence

recovery occurs. pathogen may still be present and spread to others. person can continue to carry the pathogen for months

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A infection can be spread in what sae?

every stage

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Acute

rapidly developing, short duration

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Chronic

slow to develop, continual duration

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Latent

inactive for a period of time, can be reactivated

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Infectious dose (ID50)

amount of bacteria required to cause disease in 50% of the population

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Greater ID it is..

weaker it is

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Lethal dose (LD50)

amount of toxin needed to be given to cause death in 50% of its recipients.

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Local infection

confined to a small area of the body

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Systematic infection

microbes or toxins are spread throughout the body

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Septicemia

systemic infection of the blood

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Bacteremia

bacteria in blood

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Toxemia

toxins in the blood. need a bacteria to cause this toxin

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Viremia

virus particles in the blood

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Sepsis

life threatening systemic inflammatory response, usually due to bacteremia. results in shock and lethal

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Koch's postulates

were developed based on the germ theory of disease, allow the determination of specific microorganisms that cause disease

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4 rules of Koch's postulates

-same pathogen should be present in every case
-pathogen must be isolated and grown in pure culture
-pathogen from the pure culture should cause disease when its inoculated into a healthy lab animal
-same microbe should be isolated again from individual that was inoculated

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Exceptions of Koch's postulates

-some bacteria will not grow in pure culture
-some pathogens cannot be used to infect lab animals
-sometimes several diff microorganisms can cause the same disease
-sometimes one pathogen can cause many diff diseases

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Adherence

surface molecules that allow a pathogen to stick to the surface, often stick to a specific receptors on the host cell surface

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Invasiveness

ability of a pathogen to invade and multiply in healthy tissues

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2 types of molecules that promote invasiveness

-extracellular enzymes
-invasins

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Extracellular enzymes (exoenzymes)

these enzymes erode the surface of host cells and damage tissue. products of degradation are used for food and protect from host defences

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3 types of extracellular enzymes

-fibrinolysin
-collagenase
-coagulase

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Fibrinolysin

degrades fibrin clots

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Collagenase

degrades connective tissue

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Coagulase

promotes blood clots around the bacterial cell

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Invasins

surface proteins that cause the rearrangements of the host cell cytoskeleton, forces host cell to take in bacterium and be protected from host defences

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Germs must first penetrate...

host defences in order to damage tissues and go on to cause disease

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Respiratory tract

most common portal of entry, microbes inhaled into nose of mouth

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Gastrointestinal tract

germs enter in food or water, most are destroyed by the acid of stomach or bile of intestine

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Genitourinary tract

sexually transmitted infection

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Most pathogens required a..

broken mucous membrane (a cut)

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Skin

unbroken skin is impenetrable by most microbes. some can gain access through hair follicles while others require wound (grow on skin like fungi)

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Parenteral route

microbes deposited directly into tissues when skin or membranes are broken

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Parenteral =

injection/inoculation

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Indirect damage to host

inducing an immune response and causing inflammation

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Direct damage to host

production of exoenzymes or toxins

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Toxin

poisonous substance produced by a microorganism

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Toxoid

inactive toxin, can be used as vaccine

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Exotoxins

toxins which are secreted from the bacterial cell, heat sensitive, can be extremely toxic

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Categories of exotoxins

-neurotoxins
-enterotoxins
-cytotoxins

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Neurotoxins

interfere with nerve impulses

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2 types of neurotoxins

-botulinum toxin
-tetanus toxin

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Botulinum toxin

causes flaccid paralysis (botox). produced by clostridium botulinum, muscles permanently relax, heart stops beating and breathing stop

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Tetanus toxin

causes rigid paralysis. produced by clostridium tetani. uncontrollable muscle contractions (spasms) death usually occurs due to spasms of respiratory muscles

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Enterotoxins

interfere with salt absorption in small intestine. to counteract high salt concentration in intestine cells pump out water and causes diarrhea

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Cytotoxins

kill cells, they interfere w/ protein synthesis, killing all types of cell

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Endotoxins

part of the outer membrane of gram negative bacteria (LPS) doesn't cause any problems when embedded in membrane, not as potent as exotoxin

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The endotoxin is released when the bacterium dies resulting in..

worsening of symptoms, causes fever, hemorrhaging and shock

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Example of endotoxin

salmonellosis, due to millions of dead bacteria, antibiotic treatment may do more harm than good

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Cytopathic effects (CPE)

visible effects of viral infection, disruption of cell processes, destruction of intracellular structure. can form inclusion bodies which consist of viral parts

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Giant cell formation

several infected cells fuse to form one giant cell (syncytium)

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CPE infection often results in

host cell death, host cell lysis...