Chapter 13 Part 2

Question 1

What is the difference between an opportunistic and primary (true) pathogen?

Answer 1

True pathogens are capable of causing disease in healthy persons with normal immune function

Opportunistic pathogens cause disease when the host’s immune system is comprised

Question 2

What factors weaken host defenses and increases susceptibility to infections?

Answer 2

Age
Genetic defects in immunity, and acquired defects in immunity (AIDS)
Surgery and organ transplants
Underlying disease: cancer, liver malfunction, diabetes
Chemotherapy/immunosuppressive drugs
Physical and mental stress
Other infections

Question 3

What is microbial virulence and how is it determine?

Answer 3

Microbial virulence is the degree of pathogenicity an organism exhibits

Determined by:
The ability to establish in the host
The ability to cause damage to the host

Question 4

What are virulence factors?

Answer 4

Any characteristic or structure of a microbes that contributes to infection and disease

Question 5

What three things does establishment involve?

Answer 5

1) entering the host
2) attaching firmly to host tissues
3) surviving host defenses

Question 6

How is establishment different in primary vs opportunistic pathogens?

Answer 6

Primary pathogens have the greatest ability to establish

Opportunistic pathogens are often those that cause disease but do not establish well in a healthy individual

Question 7

What are portals of entry?

Answer 7

Routes of entry into the human body

Question 8

What is the most common portal of entry?

Answer 8

Respiratory tract

Question 9

What does the term infectious dose indicate about a microbe?

Answer 9

It is the minimum number of microbes needed to cause an infection

Question 10

If a microbe has a high infectious dose, would it be more or less virulent than a microbe with a low infectious dose?

Answer 10

More virulent

Question 11

What is the process of attaching to a host and the mechanisms used by microbes?

Answer 11

Adhesion is the process by which microbes gain more stable foothold on host tissues. Adhesion is dependent upon binging between specific molecules of host and pathogens

Bacteria:fimbriae, pili, capsules, slime layers
Fungi and Protozoa: various surface proteins
Viruses: spikes
Helminths: suckers, hooks, and barbs

Question 12

What are phagocytes?

Answer 12

White Blood cells that engulf and destroy pathogens by means of enzyme and antimicrobial chemicals, and are often the first cells encountered by invading microbes.

Question 13

What are antiphagocytic factors?

Answer 13

A type of virulence factor used by certain pathogens against pathogens

Question 14

How do microbes avoid attachment by phagocytes?

Answer 14

Kill or inhibit the phagocyte with toxic substances

Secretion of slime layers or capsules

Question 15

What are leukocidins?

Answer 15

Substances that are toxic to WBCs, including phagocytes, and are a primary mechanism of killing or inhibiting phagocytes

Question 16

What are three ways microbes cause damage in the host?

Answer 16

Secretion of enzymes and toxins
Inducing excessive inflammation
Altering the host’s DNA in a manner that disrupts cell function

Question 17

What are the four types of pathogenic enzymes?

Answer 17

Mucinase= digests protective mucous coating found on mucous membranes

Keratinase= digests keratin, a principle component of skin and hair

Collangenase= digests collagen, principle component of connective tissue

Hyaluronidase= digests hyaluronic acid, a cellular glue that cements many animal cells together.

Question 18

How do microbes cause indirect damage to the host?

Answer 18

They can cause the immune response to cause as much damage than the pathogen itself. For example, inflammation is intended to activate key immune factors and facilitate the removal of pathogens, as well as their harmful enzymes and toxins. However, this process can actually cause harm and discomfort to the host.

Question 19

What are the epigenetic changes caused by pathogens?

Answer 19

Damage to the cell

Loss of cell functions

Question 20

What are the four patterns of infection?

Answer 20

Localized infection= microbe enters the body and remains confined to a specific tissue

Systemic infection= microbe spreads to several sites and tissue fluids, usually in the bloodstream

Focal infection= microbes breaks loose from a local infection and is carried into other nearby tissues

Toxemia= infection remains localized at portal of entry, but toxins produced by pathogen are carried to the target organ

Question 21

What does it mean for microbes to enter into dormant state called latency?

Answer 21

It is when the initial symptoms and the infectious agents retreat.

Question 22

What are asymptomatic infections?

Answer 22

Infections that manifest any signs or symptoms of disease

Question 23

What is the reservoir of a pathogen?

Answer 23

The primary habitat in the natural world where pathogens originate

Question 24

What is a vector and what are the most common types?

Answer 24

A vector is used to describe a living animal that transmits an infectious agent from one host to another, the most common types are mosquitoes, ticks, flies, and fleas.

Question 25

What is the difference between a biological vector and a mechanical vector?

Answer 25

Biological vectors actively participate in the life cycle of the pathogen they transmit and are usually necessary for the pathogen to complete its life cycle

Mechanical vectors= not a necessary component of the pathogens life cycle, but may transmit the pathogen without being infected.

Question 26

What are zoonotic pathogens?

Answer 26

Pathogens that are harbored or vectors by animals and are transmissible to humans