RA 3 -parasitology

Question 1

What are ectoparasites?

Answer 1

Parasites that live on the surface of a host

Question 2

What are endoparasites?

Answer 2

Parasites that live within a host

Question 3

What are obligate parasites?

Answer 3

Parasites that must spend at least part of their life cycle in association with a host

Question 4

What are facultative parasites?

Answer 4

Parasites that are capable of leading both a free and a parasitic existence

Question 5

What are vectors?

Answer 5

Insects that transmits infectious agents from one host to the next

Question 6

What are protozoa?

Answer 6

Unicellular euaryotic microbes

Question 7

What are helminths?

Answer 7

Worms

Question 8

What are nematodes?

Answer 8

Roundworms

Question 9

What are cestodes?

Answer 9

Tapeworms

Question 10

What are Trematodes?

Answer 10

Flukes

Question 11

True or false: parasitic infections, although extremely important, make up only a small percentage of total morbidity and mortality worldwide

Answer 11

False- In fact, parasitic infections currently account for greater morbidity and mortality than any other class of infectious agents.

Question 12

Mortality of parasitic infections in the US occur in what type of individuals?

Answer 12

Immunosuppressed

Question 13

What is the definitive host?

Answer 13

A host in which the parasite reaches sexual maturity

Question 14

What is an intermediate host?

Answer 14

a host that harbors larval or asexual stages of the parasite

Question 15

What is a reservoir?

Answer 15

animal (definitive host) that serves to maintain the parasite’s life cycle in the environment.

Question 16

In general, the more complicated an organism’s life cycle, the less likely chance of survival it has. How do organisms with complicated life cycles off set this?

Answer 16

Produce copious amount of eggs

Question 17

What is he metabolically active, motile, “feeding stage” of a parasitic protist?

Answer 17

Trophozoite

Question 18

What are the four main classes of protozoa and their mode of locomotion?

Answer 18

1. Ameba- pseudopodia
2. Flagellates -flagella
3. Sporozoa- gliding
4. Ciliates-cilia

Question 19

What is the only ciliate that is known to infect humans?

Answer 19

Balantidium coli

Question 20

Ameba, flagellates, and ciliates generally reproduce how?

Answer 20

Asexual binary fission

Question 21

Sporozoans (and some amoebas) can also reproduce asexually by a process known as what?

Answer 21

Schizogony- (Multiple intracellular nuclear divisions (mitosis) that precede cytoplasmic division)

Question 22

What is sporogony?

Answer 22

a sexual form of reproduction that entails multiple nuclear divisions (meiosis) followed by cytokinesis after zygote formation

Question 23

What are cysts in relation to parasites?

Answer 23

Like spores in bacteria, but for parasites

Question 24

How do cysts tavel from one host to the next?

Answer 24

Use a vector

Question 25

What is the thick membrane that covers helminths?

Answer 25

Cuticle

Question 26

What are the two classes of helminths?

Answer 26

Roundworms and flatworms

Question 27

What type of helminth are nematodes?

Answer 27

Roundworms

Question 28

What type of helminth are cestodes and trematodes?

Answer 28

Flatworms

Question 29

What do cestodes have that trematodes do not?

Answer 29

alimentary canals

Question 30

Which class of flatworms have sexes: cestodes or trematodes?

Answer 30

Trematodes

Question 31

What are the two ways that parasites generate pathology?

Answer 31

Mechanical damage
Byproducts
Immune response

Question 32

What is the immunologic pathology behind Schitosome eggs?

Answer 32

These are in the liver and cause disruptive granulomas

Question 33

What are the three examples of deleterious immune responses to parasites?

Answer 33

Granuloma formation
Antigen mimicry
Immune complex formation

Question 34

What are the five major immunological responses to parasites (similar to all pathogens)?

Answer 34

1. Neutralize with antibody
2. antibody + complement
3. Opsonization
4. Activation of macrophages
5. CD8+ cytotoxic T cells

Question 35

Elevation of what type of WBC is the hallmark of parasite infections?

Answer 35

Eosin

Question 36

What is the primary antibody used to attack parasites?

Answer 36

IgE

Question 37

Why are helminth infections particularly hard for the imune system to deal with? (2)

Answer 37

1. Too large for phagocytosis

2. Cuticle prevents antibody action

Question 38

How does size protect parasites from the immune system?

Answer 38

Too big for phagocytosis

Question 39

How does anatomical location protect parasites from the immune system?

Answer 39

Intestines are hard for the immune system to get to

Question 40

How does intracellular sequestration protect parasites from the immune system?

Answer 40

Hide from antibodies

Question 41

How does cyst formation protect parasites from the immune system?

Answer 41

Form barrier to immune system

Question 42

How does phago-lysosomal destruction protect parasites from the immune system?

Answer 42

Allows for them to live within macrophages

Question 43

How does antigen masking protect parasites from the immune system?

Answer 43

some helminths will coat themselves with host cellular or serum proteins or lipids as a way of masking their own antigens from the immune system

Question 44

How does immunosuppression by the parasites protect parasites from the immune system?

Answer 44

Production of immunosuppressive cytokines by parasite inhibit the immun system

Question 45

How is differential toxicity achieved?

Answer 45

1. preferential uptake of drug by the parasite
2. metabolic alteration of the drug by the parasite
3. differences in the susceptibility of functionally equivalent sites in the parasite and the host.