UPDATED Unit 3 Study Guide

what is an infection

when a microorganism enters a host and begins to multiply

what is a disease

any deviation from the normal function or structure of the host

what are signs of a disease

objective and are measured

what are symptoms of a disease

subjective and are reported by the patient

what are noninfectious diseases

caused by genetics and the environment

what are infectious diseases

caused by pathogens

what are communicable infectious diseases

transmissible between individuals

what are contagious infectious diseases

easily transmissible between individuals

what are noncommunicable infectious diseases

diseases contracted via contact with environmental reservoirs or animals (zoonoses)

what are diseases contracted by animals called

zoonoses/zoonotic

what are nosocomial diseases

contracted in hospital settings

what are iatrogenic diseases

direct result of a medical procedure

what are acute disease

diseases that are short in duration

what are chronic diseases

diseases that lasts for months or years

what are latent diseases

last for years, lack active replication during extended dormant periods

what are the periods of diseases

incubation, prodromal, illness, decline, and convalescence

what are kochs postulates used for

determine whether a particular microorganism is a pathogen

what are molecular kochs postulates used for

determine what genes contribute to a pathogens ability to cause disease

what is virulence

degree to which a pathogen can cause disease

how can virulence be quantified

calculating either ID50 or LD50 of a pathogen on a given population

what are primary pathogens

capable of causing pathological changes associated with disease in a healthy individual

what are opportunistic pathogens

only cause disease when the individual is compromised by a break in protective barriers or immunosuppression

infections and disease can be caused by what

pathogens in the environment or microbes in an individuals resident microbiota `

what are the classifications of infection depending on the extent to which the pathogen spreads in the body

local, focal, systemic

what is a secondary infection

can sometimes occur after the hosts defenses or normal microbiota are compromised by a primary infection or antibiotic treatment

where do pathogens enter the body through

portals of entry

where do pathogens exit the body through

portals of exit

what are the stages of pathogenesis

exposure, adhesion, invasion, infection, and transmission

what are virulence factors

contribute to a pathogens ability to cause disease

what allows pathogens to invade host tissue and cause tissue damage

exoenzymes and toxins

exoenzymes are classified according to what

the macromolecule they target

exotoxins are classified based on what

mechanism of action

what are some bacterial toxins

endotoxin and exotoxin

what is an endotoxin

lipd A component of the LPS of the gram-negative cell envelope

what are exotoxins

proteins secreted mainly by gram-positive bacteria, but also secreted by gram-negative bacteria

bacterial pathogens evade the host immune response by producing capsules to avoid what

phagocytosis, surviving the intracellular environment of phagocytes, degrading antibodies, or through antigenic variation

how do bacterial pathogens evade the host immune response

by producing capsules

what do viral pathogens use for initiating infections and antigenic variation to avoid immune defenses

adhesins

what do influenza viruses use to avoid being recognized by the immune system

antigenic drift antigenic shift

what is epidemiology

the science underlying public health

what is morbidity

being in a state of illness

what is mortality

refers to death

what are the interest of epidemiologists

morbidity and mortality rates

what is an incidence

number of new cases (morbidity/mortality) usually expressed as a proportion, during a specified time period

what is prevalence

total number of affected in the population, usually expressed as a proportion

what are sporadic diseases

only occur rarely and largely without a geographic focus

what are endemic diseases

occur at a constant (and often low) level within a population

what are epidemic and pandemic diseases

when an outbreak occurs on a significantly larger than expected level, either locally or globally

what do kochs postulates specify

the procedure for confirming a particular pathogen as the etiologic agent of a particular disease

what do the centers for disease control and prevention monitor

notifiable diseases

what are reservoirs of human diseases

human and animal populations, soil, water, and inanimate objects or materials

what is direct contact transmission

physical contact with an infected host

what is indirect contact transmission

contact with a fomite that an infected host has made contact with previously

what is mechanical vector transmission

when a living organism carries an infectious agent on its body

what is biological vector transmission

when a living organisms is an infection host itself and carries an infection to a new host

what is vehicle transmission

when a substance such as soil, water, or air carries an infectious agent to a new host

what are healthcare associated infections (HAI)/nosocomial infections

acquired in clinical setting. Transmission is facilitated by medical interventions and the high concentration of susceptible, immunocompromised individuals in clinical settings

what are emerging diseases

new to human populations or that have been increasing in the past two decades

what are reemerging diseases

make a resurgence in susceptible populations after previously having been controlled in some geographic areas

what is nonspecific innate immunity

provides a first line of defense against infection by nonspecifically blocking entry of microbes and targeting them for destruction or removal from the body.

what are physical defenses of innate immunity

physical barriers, mechanical actions that remove microbes and debris, and the microbiome

what do physical defenses of innate immunity do

compete with and inhibits the growth of pathogens.

what are physical barriers throughout the body that prevent microbes from reaching potential sites of infection

The skin, mucous membranes, and endothelia

what prevents microbes from passing through tissues

tight cell junctions

Microbes trapped in dead skin cells or mucus are removed from the body by mechanical actions such as

shedding of skin cells, mucociliary sweeping, coughing, peristalsis, and flushing of bodily fluids (urination, tears)

how do resident microbiota provide physical defenses

by occupying available cellular binding sites and competing with pathogens for available nutrients

what do numerous chemical mediators that are produced endogenously and exogenously exhibit

nonspecific antimicrobial functions

what are some chemical mediators found in body fluids

sebum, saliva, mucus, gastric and intestinal fluids, urine, tears, cerumen, and vaginal secretions

what does plasma contain

various proteins that serve as chemical mediators such as acute-phase proteins, complement proteins, and cytokines.

what happens in the complement system

involves numerous precursor proteins that circulate in plasma. These proteins become activated in a cascading sequence in the presence of microbes, resulting in the opsonization of pathogens, chemoattraction of leukocytes, induction of inflammation, and cytolysis through the formation of a membrane attack complex (MAC

what are cytokines

proteins that facilitate various nonspecific responses by innate immune cells, including production of other chemical mediators, cell proliferation, cell death, and differentiation.

what do cytokines do

play a key role in the inflammatory response, triggering production of inflammation-eliciting mediators such as acute-phase proteins, histamine, leukotrienes, prostaglandins, and bradykinin

what are the formed elements of the blood

red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)

which formed element is primarily involved in immune response

leukocytes

where do all formed elements originate in

bone marrow as stem cells (HSCs)

how do formed elements differentiate

hematopoiesis

what are granulocytes

leukocytes characterized by a lobed nucleus and granules in the cytoplasm

what do granulocytes include

neutrophils (PMNs), eosinophils, and basophils

what are the leukocytes that are found in the largest numbers in the bloodstream and primarily fight bacterial infections

Neutrophils

what do eosinophils target

parasitic infections

what are eosinophils and basophils involved in

allergic reactions, release histamine and other proinflammatory compounds from their granules upon stimulation

what are mast cells

function similarly to basophils but can be found in tissues outside the bloodstream.

what are natural killer cells

lymphocytes that recognize and kill abnormal or infected cells by releasing proteins that trigger apoptosis

what are monocytes

large, mononuclear leukocytes that circulate in the bloodstream. They may leave the bloodstream and take up residence in body tissues, where they differentiate and become tissue-specific macrophages and dendritic cells

what are phagocytes

cells that recognize pathogens and destroy them through phagocytosis

Recognition often takes place by the use of phagocyte receptors that bind molecules commonly found on pathogens, known as

pathogen-associated molecular patterns (PAMPs).

what are the receptors that bind PAMPs called

pattern recognition receptors (PRRs)

what are toll-like receptors (TLRs)

one type of PRR found on phagocytes

Extravasation of white blood cells from the bloodstream into infected tissue occurs through the process of

transendothelial migration

how do phagocytes degrade pathogens

phagocytosis

what does the process of phagocytosis involve

engulfing the pathogen, killing and digesting it within a phagolysosome, and then excreting undigested matter.

what is inflammation

results from the collective response of chemical mediators and cellular defenses to an injury or infection

what is acute inflammation

short lived and localized to the site of injury or infection

what is chronic inflammation

occurs when the inflammatory response is unsuccessful, and may result in the formation of granulomas (with tuberculosis) and scarring (with hepatitis C viral infections and liver cirrhosis)

what are the cardinal signs of inflammation

erythema, edema, heat, pain, and altered function

inflammation signs result from

innate responses that draw increased blood flow to the injured or infected tissue

what is a fever

a system-wide sign of inflammation that raises the body temperature and stimulates the immune response

what is adaptive immunity

acquired defense against foreign pathogens that is characterized by specificity and memory

the first exposure to an antigen stimulates what

a primary response

the subsequent exposure stimulates a faster and stronger…

secondary response