Patho Chapter 5

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Patho Chapter 5

What has promoted the rapid spread of harmful microbes around the world?

Globalization

What has contributed to infectious disease spread?

Importation and mass distribution

The overuse or incomplete use of antimicrobial drugs has led to:

multiple drug-resistant microbes

How do the eyes defend against bacteria and other microbes?`

Washing and antibiotic activity of tears

How do the lymph nodes defend against bacteria and other microbes?

Phagocytosis by macrophages
Attack by natural killer cells

How does the skin defend against bacteria and other microbes?

physical barrier

How does the respiratory tract defend against bacteria and other microbes?

Entrapment by mucus
Transport to throat by ciliary motion
Phagocytosis by alveolar macrophages

How does blood defend against bacteria and other microbes?

Phagocytosis by macrophages and granulocytes
Digestion by lysozymes
Attack by complement proteins

How does bone marrow defend against bacteria and other microbes?

Phagocytosis by macrophages and granulocytes
Attack by natural killer cells

How does the liver defend against bacteria and other microbes?

Phagocytosis by Kupffer cells (macrophages)

How does the digestive system defend against bacteria and other microbes?

Destruction by gastric acid bile, and enzymes
Competition for nutrients by billions of normal bacteria.

How does the urogenital tract defend against bacteria and other microbes?

Flushing and acidity of urine.

Resident flora are:

microorganisms that live on or within the body in non sterile areas, such as the skin, mucous membranes, bowel, rectum or vagina.

Pathogen is a

disease producing microbe.

What makes a pathogen disease producing?

it must be capable of binding to specific receptors on the human host cell

Three ways the pathogen causes disease in the human host cell:

1. Direct destruction of the host cell by the pathogen
2. Interference with the host cell's metabolic function.
3. exposing the host cell to toxins produced by the pathogen.

Pathogenicity is:

qualities that promote the production of disease.

Eight factors that affect the variability with which the pathogen is able to elicit disease.

1. Virulence
2. Infectivity
3. Toxigenicity
4. Antigenicity
5. Antigenic variability
6. Pathogenic defense mechanisms
7. Coinfection
8. Superinfection

Virulence is:

the potency of the pathogen indicated by the ratio of the number of cases of disease in a population compared with the number of people exposed to the microorganism.

Infectivity is:

proportion of exposures needed to cause infection in an individual based on the pathogen's ability to enter, survive in, and multiply in the host.

Toxigenicity is:

the ability of the pathogen to produce harmful toxins that increase host cell and tissue damage.

Antigenicity is:

the level to which a pathogen is viewed by the host immune system as foreign.

Antigenic variability is:

a process of eluding the human host defenses and is often a result of altering the antigens present within or on the surface of the microorganism.

Pathogenic defense mechanisms are:

the ways in which many pathogens have developed ways in which many pathogens have developed ways to avoid destruction by the host, such as through thick protective capsules, which prevent phagocytosis.

Coinfection is a:

phenomenon of hosting two or more pathogens simultaneously.

Superinfection is:

when an infection arises in addition to on that is already present.

Four types of pathogens:

bacteria, fungi, viruses, and protozoa

Obligate parasites

require the host for metabolism and reproduction

Facultative parasites

may live on the host but can also survive independently

Bacteria are

single celled microorganisms that can reproduce outside of host cells.

Aerobic

require oxygen for growth

Anaerobic

do not require oxygen for growth

What are the shapes of bacteria?

cocci (spheres)
bacilli (rods)
spirochetes (spirals)

Cytosol is:

The cytoplasm of bacteria

The innermost cell membrane, also called the cell envelope, has 3 functions:

1. Formation of a barrier surrounding the bacterial cell
2. Protein and DNA synthesis
3. Cell division

Most bacteria include a ___________cell wall that surrounds an _________membrane.

rigid; inner

Humans do not have a cell _________; therefore, antibiotics are aimed at ___________________________

wall: inhibiting synthesis of the bacterial cell wall during bacterial replication.

Name four structural properties critical to the pathogenicity of bacteria:

1. Independent survival: they can survive outside the host and can infect and reinfect.
2. Stimulation of an inflammatory response: Bacteria can stimulate an inflammatory and immune response that will destroy surrounding host tissues.
3. Bacterial capsule: Encapsulated bacteria are adherent and highly resistant to phagocytosis.
4. Endotoxin: the presence of endotoxin in the gram negative bacterial cell envelope activates the plasma protein systems.

What is an endotoxin?

a complex of phospholipid-polysaccharide molecules that form from the structural component of the gram-negative cell wall.

pyogenic bacteria are:

bacteria that can induce fever.

Endospores

Bacteria that produce spores that survive in a latent state that is resistant to environmental extremes and lack of nutrients.

Exotoxins

toxin produced by bacteria which causes cell dysfunction or lysis.

Viruses

obligate intracellular parasites. They cannont replicate outside of the host cell

How do viruses work?

1. They bind specific receptors on the host cell and then move into the host cell.
2. Once inside the host cell, the virus converts the host cellular metabolism to nucleic acids and proteins that are encoded and controlled by the virus.
3. They either directly kill the cell or modify cellular functions.
4. Cells then proliferate rapidly and randomly.
5. Cell ultimately loses its ability to function.
6. Virus then releases particles outside the cell which enter and infect nearby cells.

Virions

released particles by a virus outside of the cell to infect nearby cells.

Factors that support chronic infection with a virus include:

1. the size of the virus that is inoculated into the body
2. The process of viral replication
3. the viral genotype
4. Host susceptibility

Latency

dormancy of a virus

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