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PARA424 > lecture 4 continued > Flashcards

lecture 4 continued Flashcards

1
Q

what are the structures of the male system?

A
  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
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2
Q

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

A

lying next

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3
Q

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

A

detach
disintegrate
exit

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4
Q

eggs that pass from the host are …

A

embryonated

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5
Q

the eggs contain a …., called an ….

A

hexacanth larva

oncosphere

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6
Q

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

A

embryophore

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7
Q

the outer envelope lies between the ___ and the ___

A

embryophore

shell/capsule

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8
Q

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

A

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

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9
Q

the external surface of the cestode =

A

the tegument

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10
Q

what does the tegument have to do?

A

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

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11
Q

what covers the entire surface of the tegument?

A

the glycocalyx - a lyer of carbohydrate containing macromolecules

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12
Q

what is the role of the glycocalyx?

A
  1. protecting the parasite from host digestive enzymes
  2. enhancing nutrient absorption
  3. maintaining the parasite’s surface membrane
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13
Q

what is the syntegument?

A

outer anucleate syncytical cytoplasmic layer containing mitochondria and secretory bodies

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14
Q

what is the cytotegument?

A

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

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15
Q

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

A

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

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16
Q

flame cells are …

A

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

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17
Q

the main excretory canals run the …

A

length of the strobila from the scolex to the posterior end

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18
Q

what are the two pairs of excretory canals?

A

the ventrolateral and the dorsolateral

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19
Q

the excretory ducts are lined with …

A

microvilli

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20
Q

whats the role of the microvilli lining the excretory ducts?

A

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

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21
Q

most cestodes are regarded as ____

A

osmoconformers

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22
Q

the main nerve center of a cestode is a ….

A

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

23
Q

how is the cestode nervous system arranged?

A

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

24
Q

sensory structures are abundant and are arranged in …. patterns

A

species-specific

25
Q

taenia saginata is known as the …

A

beef tapeworm

26
Q

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

A
  • definitive host : always humans

- intermediate host: always cattle

27
Q

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

A

the small intestine

28
Q

what is the life cycle of taenia saginata?

A 
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
29
Q

the released eggs of the Taenia spp are …..

A

morphologically indistinguishable

30
Q

the taenia eggs are …

A

spherical with a thick radially striated brown embryophore

31
Q

inside each taenia egg is an oncosphere that has ….

A

6 hooklets

32
Q

cysticercus

A

the larvae of Taenia

33
Q

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

A

the small scolex is invaginated into the cysticercus

34
Q

what happens with Taenia saginata in the definitive host?

A

the scolex evaginates from the cysticercus

35
Q

what is the scolex morphology of Taenia saginata?

A

scolex contains four suckers and no hooks

36
Q

is taenia saginata hermaphroditic or dioecious?

A

hermaphroditic

37
Q

taenia: gravid proglottids are identified by …

A

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

38
Q

taenia gravid proglottid is shed in …

A

feces

39
Q

taenia solium is known as the …

A

pork tapeworm of humans

40
Q

what is the definitive and intermediate host of taenia solium?

A

definitive: always humans
intermediate: pigs

41
Q

why is taenia solium more dangerous than the beef tapeworm?

A

humans can also serve as accidental intermediate hosts

42
Q

T. solium eggs are … to T. saginata eggs

A

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

43
Q

what is the adult scolex morphology of T. solium?

A

scolex has 4 suckers and 2 circles of hooks

44
Q

T. solium; gravid proglottids contain up to …

A

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

45
Q

what is the life cycle of Taenia solium?

A
  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
46
Q

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

A

develop into adult worms

47
Q

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

A

causes cysticerosis - the resulting disease of being the accidental host

48
Q

cysticerosis …

A

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

49
Q

what is autoinfection of Taenia solium?

A

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)

50
Q

what happens once eggs of T. solium are ingested?

A

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

51
Q

how is cysticercosis diagnosed?

A

by demonstrating the cysticercus in the tissue involved

52
Q

how is cysticercosis treated?

A
  • treated with anti-parasitic drugs in combination with anti-inflammatory drugs
  • surgery, usually in the case of infected eyes or brain edemas
53
Q

how is taeniasis treated?

A

praziquantel

54
Q

what does praziquantel do?

A

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

PARA424 (12 decks)

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