lecture 4 continued

Question 1

what are the structures of the male system?

Answer 1

1. many testes (ranging from 3 to 100’s depending on the tapeworm species)
2. vasa efferentia
3. vas deferens (often highly coiled)
4. cirrus sac with cirrus
5. common genital pore

Question 2

sperm are mostly transferred between mature proglottids ___ ___ to each other

Answer 2

lying next

Question 3

gravid proglottids ___ from parent organisms and ____ or ___ the host

Answer 3

detach
disintegrate
exit

Question 4

eggs that pass from the host are …

Answer 4

embryonated

Question 5

the eggs contain a …., called an ….

Answer 5

hexacanth larva

oncosphere

Question 6

the oncosphere’s inner envelope is surrounded by another membrane structure called the ____

Answer 6

embryophore

Question 7

the outer envelope lies between the ___ and the ___

Answer 7

embryophore

shell/capsule

Question 8

how do cestodes take up nutrients given they lack a gut?

Answer 8

their external surface acts as a metabolically active layer taking up nutrients from the environment and also contains a later through which secretions and excretions must pass

Question 9

the external surface of the cestode =

Answer 9

the tegument

Question 10

what does the tegument have to do?

Answer 10

resist the attack of digestive enzymes and protect against the immune response of the host

Question 11

what covers the entire surface of the tegument?

Answer 11

the glycocalyx - a lyer of carbohydrate containing macromolecules

Question 12

what is the role of the glycocalyx?

Answer 12

1. protecting the parasite from host digestive enzymes
2. enhancing nutrient absorption
3. maintaining the parasite’s surface membrane

Question 13

what is the syntegument?

Answer 13

outer anucleate syncytical cytoplasmic layer containing mitochondria and secretory bodies

Question 14

what is the cytotegument?

Answer 14

nucleated cell bodies lying beneath the tegumental muscles and connected to the syntegument

Question 15

what is the role of the excretory system of all parasitic platyhelminthes?

Answer 15

allows the parasites to conserve water and eliminate salts and survive in the intestine or body cavities of their hosts- makes them act like osmoconformers

Question 16

flame cells are …

Answer 16

ciliated cells located within the basal matrix of platyhelminthes. they are considered the basic units of excretory systems of invertebrates

Question 17

the main excretory canals run the …

Answer 17

length of the strobila from the scolex to the posterior end

Question 18

what are the two pairs of excretory canals?

Answer 18

the ventrolateral and the dorsolateral

Question 19

the excretory ducts are lined with …

Answer 19

microvilli

Question 20

whats the role of the microvilli lining the excretory ducts?

Answer 20

responsible for active transport of excretory waste and ionic regulation of excretory fluid

Question 21

most cestodes are regarded as ____

Answer 21

osmoconformers

Question 22

the main nerve center of a cestode is a ….

Answer 22

rectangular or circular nervous tissue in the scolex varying from a single ganglion to a combination of several ganglia and commissures

Question 23

how is the cestode nervous system arranged?

Answer 23

like a ladder with paired ganglia near the anterior end, nerves running anteriorly toward sensory or holdfast organs and longitudinal nerve trunks extending posteriorly to near the end of the body

Question 24

sensory structures are abundant and are arranged in …. patterns

Answer 24

species-specific

Question 25

taenia saginata is known as the ...

Answer 25

beef tapeworm

Question 26

what is the definitive and intermediate host of the beef tapeworm?

Answer 26

- definitive host : always humans | - intermediate host: always cattle

Question 27

in what organ of the human are adult beef tapeworms located?

Answer 27

the small intestine

Question 28

what is the life cycle of taenia saginata?

Answer 28

``` 1. Gravid proglottid ruptures on land during drying and releases eggs onto soil. 2. Grazing cow (intermediate host) must ingest the eggs. 3. Oncosphere hatches from egg in cow small intestine, penetrates intestine, and enters circulation. 4. Oncosphere reaches skeletal muscle and becomes a cysticercus. 5. Human eats raw or poorly cooked beef containing cysticerci. 6. Scolex evaginates, attaches to wall of ileum, and begins strobilization. 7. Adult reaches maturity and maximal length in 3 months ```

Question 29

the released eggs of the Taenia spp are .....

Answer 29

morphologically indistinguishable

Question 30

the taenia eggs are ...

Answer 30

spherical with a thick radially striated brown embryophore

Question 31

inside each taenia egg is an oncosphere that has ....

Answer 31

6 hooklets

Question 32

cysticercus

Answer 32

the larvae of Taenia

Question 33

what does Taenia saginata do in the tissue of the intermediate host?

Answer 33

the small scolex is invaginated into the cysticercus

Question 34

what happens with Taenia saginata in the definitive host?

Answer 34

the scolex evaginates from the cysticercus

Question 35

what is the scolex morphology of Taenia saginata?

Answer 35

scolex contains four suckers and no hooks

Question 36

is taenia saginata hermaphroditic or dioecious?

Answer 36

hermaphroditic

Question 37

taenia: gravid proglottids are identified by ...

Answer 37

the presence of 15 or more side branches on either side of the uterus

Question 38

taenia gravid proglottid is shed in ...

Answer 38

feces

Question 39

taenia solium is known as the ...

Answer 39

pork tapeworm of humans

Question 40

what is the definitive and intermediate host of taenia solium?

Answer 40

definitive: always humans intermediate: pigs

Question 41

why is taenia solium more dangerous than the beef tapeworm?

Answer 41

humans can also serve as accidental intermediate hosts

Question 42

T. solium eggs are ... to T. saginata eggs

Answer 42

identical - the small scolex is also invaginated into the cysticercus (in the tissue of the intermediate host) and evaginated from the scolex in the definitive host

Question 43

what is the adult scolex morphology of T. solium?

Answer 43

scolex has 4 suckers and 2 circles of hooks

Question 44

T. solium; gravid proglottids contain up to ...

Answer 44

14 side branches on either side of the uterus - diagnostic stage in human feces

Question 45

what is the life cycle of Taenia solium?

Answer 45

1. Adult tapeworm is found in the human small intestine. 2. Gravid proglottid is shed in feces. 3. Gravid proglottid ruptures on land, releasing fertilized eggs onto soil. 4. Pig (intermediate host) ingests embryonated eggs. 5. In the pig, the oncosphere hatches from the egg and enters circulation. 6. Oncosphere reaches skeletal muscle and becomes a cysticercus. 7. Human eats raw or poorly cooked pork containing cysticerci (larvae). 8. Cysticerci are released from the muscle in the stomach. 9. Adult tapeworm develops in the small intestine (up to 2 ‐ 7 m in length and produce approx. 1000 proglottids, each with ~ 50,000 eggs) and reside in the small intestine for years

Question 46

T. solium cannot ... if humans are the accidental intermediate host

Answer 46

develop into adult worms

Question 47

what is the effect of humans being the accidental intermediate host?

Answer 47

causes cysticerosis - the resulting disease of being the accidental host

Question 48

cysticerosis ...

Answer 48

an infection of both humans and pigs with the larval stages of Taenia solium. this infection is caused by ingestion of eggs shed in feces of a human tapeworm carrier. pigs and humans become infected by ingesting eggs or gravid proglottids

Question 49

what is autoinfection of Taenia solium?

Answer 49

human infected ingesting eggs produced by that tapeworm, either through fecal contamination or from proglottids carried into the stomach by reverse persistalsis (muscle contractions in the digestive tract)

Question 50

what happens once eggs of T. solium are ingested?

Answer 50

oncospheres hatch in the intestine invade the intestinal wall, and migrate to striated muscles, as well as the brain, liver, and other tissues, where they develop into cysticerci

Question 51

how is cysticercosis diagnosed?

Answer 51

by demonstrating the cysticercus in the tissue involved

Question 52

how is cysticercosis treated?

Answer 52

- treated with anti-parasitic drugs in combination with anti-inflammatory drugs - surgery, usually in the case of infected eyes or brain edemas

Question 53

how is taeniasis treated?

Answer 53

praziquantel

Question 54

what does praziquantel do?

Answer 54

increases the permeability of the worm's membranes towards calcium ions