Cestodes Flashcards
(78 cards)
1
Q
What is a parasitic helminths?
A
Parasitic worm-like organisms that live in-and feed off -living host.
2
Q
What am I?
Parasitic worm-like organisms that live in-and feed off -living host.
A
parasitic helminths
3
Q
Where do parasitic helminths live?
A
Live inside their host—> endoparasites
4
Q
What am I?
Live inside their host—> endoparasites
A
parasitic helminths
5
Q
What do parasitc helminths do to the host?
A
Disrupt the hosts’ nutrients uptake, causing weakness and disease.
6
Q
T or F: have evolved 1 strategy for entering the host and establishing infection.
A
F: have evolved multiple strategy for entering the host and establishing infection.
7
Q
What is/are the mechanism of survival inside the host for parasitic helminths?
A
They have developed elaborate mechanisms for survival within the host environment like:
- immune evasion
- immunological masking mechanisms
8
Q
Who am I?
I survive in the host by immune evasion and/or immunological masking mechanisms
A
Parastic helminths
9
Q
What are examples of natural products from helminths that are released into the host
A
Peptides that block host clotting and host inflammation
10
Q
What are immune evasion and immunological masking mechanisms examples of?
A
mechanisms of survival inside the host for parasitic helminths
11
Q
What are peptides that block host clotting and host inflammation examples of?
A
Natural products from helminths that are release into the host
12
Q
T or F: most helminths occupy more than one niche in their host during their life cycle.
A
T
13
Q
How many niches do helminths occupy in their host during their life cycle?
A
More than one
14
Q
Do helminths occupy more than one niche in their host during 1 year?
A
No it is during their life cycle
15
Q
At what stage do most helminths live at in the host?
A
Sexually mature adults
16
Q
Where do many helminths live in in the host?
A
Gastrointestinal tract (GI)
17
Q
T or F: Many helinths live as mature adults in the GI or their host.
A
F: live as sexually mature adults
18
Q
T or F: nematodes and cestodes are examples of helminths that live as sexually mature adults in the GI of their host.
A
T
19
Q
What represents one of the most prevalent forms of parasitic disease?
A
GI hleminths
20
Q
T or F: GI helminths represents one of the most prevalent forms of parasitic disease
A
T
21
Q
GI helminths represent?
A
One of the most prevalent forms of parasitic disease
22
Q
How do helminths injure their host?
A
Through mechanical and chemical means
23
Q
T or F: helminths injure their host through only mechanical means
A
F: both though mechanical and chemical means
24
Q
Mechanical and chemical means are what?
A
How helminths injure their host
25
What is an example of a large helminth
Ascaris lumbricoides
26
Large helminths can do what in terms of mechanisms of pathogen?
Can cause physical obstruction of the intestine
27
What are the 3 groups of parasitic helminths?
Cestodesn(tapeworms), trematodes (flukes), and nematodes (roundworms)
28
What are cestodes, trematodes, and nematodes
Parasitic helminths
29
Tapeworms are?
Cestodes
30
Trematodes are?
Flukes
31
Nematodes are?
Roundworms
32
Tapeworms are?
Cestodes
33
Flukes are?
Trematodes
34
Roundworms are?
Nematodes
35
The host is a common site for:
Helminths mating and egg deposition
36
Reproduction of cestodes:
Each proglottid segment of the adult tapeworm is hermaphroditic
37
Who am I?
| Each proglottid segment of the adult tapeworm is hermaphroditic
Cestodes
38
Reproduction of trematodes
They are hermaphrodites, except for the schistosomes
39
Who am I?
| They are hermaphrodities, except for the schistosomes
Trematodes
40
Reproduction of nematodes
Adult parasitic nematodes have separate male and female worms
41
Who am I?
| adult parasitic______have separate male and female worms.
Nematodes
42
Cestodes: morphological aspects
```
Shape: segmented plane
Body cavity: no
Body covering: tegument
Digestive tube: no
Sex: hermaphroditic
Attachment organs: Sucker or bothridia a rostellum with hooks
```
43
Trematodes: morphological aspects
Shape: Unsegmented, plane
Body cavity: no
Body covering: tegument
Digestive tube: ends in cecum
Sex: hermaphroditic, except for schistosomes, which are dioecious
Attachment organs: Oral sucker and ventral sucker (acetabulum)
44
Nematodes: morphological aspects
```
Shape: unsegmented, cylindrical
Body cavity: yes
Body covering: cuticle
Sex: dioecious
Attachment organs: lips, teeth, filariform extremities
```
45
What are platyhelminths?
- flatworms because most are dorsoventrally flattened
- bilaterally symmetrical and have a definite anterior end
- range in size from nearly microscopic to over 60 meters in length
46
Phylum platyhelminths examples:
Class cestoda: tapeworms
| Class trematoda: flukes
47
What is/are the subclass for cestoda and what does it contain?
Cestodaria: contains only a few species of unusual worms.
Eucestoda: contains all the animls we usually think of as tape worms
48
How many subclasses and order does cestoda have?
2 subsclasses and 2 orders
49
What are/is the order(s)of Cestoda?
Order chclphyllidea amd Order Pseudophyllidea
50
What are the cestodes in the subclass eucestoda?
```
Taenia saginata
Taenia solium
Echinoccus granulosus
Echinoccus multiocularis
Hymenolepis nana
Hymenolepis diminuta
Dipylidium caninus
Diphyllobothrium latum
```
51
Adult Taenia saginata infecting humans
Site of infection?
Distribution?
Site of infection: small intestine
| Distribution: Everywhere
52
Adult Taenia solium infecting humans
Site of infection?
Distribution?
Site of infection: small intestine, brain, eyes
| Distribution: everywhere
53
Adult Echinococcus granulosus infecting humans
Site of infection?
Distribution?
Site of infection: small intestine, liver, lung, brain
| Distribution: everywhere, also arctic
54
Adult Echinococcus multilocularis infecting humans
Site of infection?
Distribution?
Site of infection: small intestines, liver, lung, brain
| Distribution: everywhere, also artic
55
Adult Hymenolepis diminuta infecting humans
Site of infection?
Distribution?
Site of infection: small intestine
| Distribution: everywhere
56
Adult Hymenolepis nana infecting humans
Site of infection?
Distribution?
Site of infection: small intestine
| Distribution: Everywhere
57
Adult Dipylidium caninus infecting humans
Site of infection?
Distribution?
Site of infection: small intestine
| Distribution: Everywhere
58
Adult Diphyllobothrium latum infecting humans
Site of infection?
Distribution?
Site of infection: small intestine
| Distribution: Argentina, Europe, Japan, Siberia, Great Lakes area USA, Canada
59
What do cestodes lack?
Mouth and digestive tract
60
Cestodes are______ _____ and are entirely______
1) obligate
2) parasites
3) endoparasitic
61
T or F: Cestodes are not hermaphrodites
F: They are hermaphrodies, each proglottid haveing its own complete set if male and female reporductive organs
62
What so adult cestodes inhabit?
They inhabit gut tracts of various vertebrate hosts
63
Cestodes life cycle requires soemthing specific, what is it?
The life cycle requires at least two host
| EXCEPTION: Hymenolepis nana
64
What is the basic life cycle of tapeworm?
The adults tapeworms live in the definitive host (predator), while the prey plays host to the intermediate host.
Eggs laid by the adult pass out in the feces of the definitive host and are eaten by the intermediate host.
These develop into the intermediate stage, which generates the adult when eaten by the definitive host.
A tapeworm may pass through several intermediate hosts before it finds the right definitive host.
65
What are examples of intermediate hosts for cestodes?
Mammal, arthropod, fish, bird
66
What is a scolex?
Anterrior point of attachment structure.
A key feture in identifying the different tapeworms.
NOT A MOUTH.
67
What is the structure for attachment fro scolex in Cyclophyllidea and Pseudophyllidea?
Order Cyclophyllidea: scolex contains 4 suckers and sometimes hooks
Order Pseudophyllidea: scolex contains slit-like suckers or grooves called bothria
68
How/what is the neck like in cestodes?
Undifferentiated/unsegmented region between the scolex and the strobila.
The narrowest part of the tapeworm
Contains srem cells that are responsible for giving rise to new proglottids.
69
How/what is the strobila like in cestodes?
Linear series of segments or proglottids
Proglottids are contiously formes posterior to the neck region in a process called strobilization
As new proglottids are formed, the older proglottids move posteriorly and become sexually mature
70
What is an immature proglottid?
Newly formed
71
What is a mature proglottid?
Possess borh male and female sex organs
72
What is a gravid proglottid?
Develop after matin; contain hundreds to thousands of embryonated eggs
Male and female organs degenerate as the uterus fills with eggs.
Posterior gravid proglottids often detach from the strobila:
- disintergrate during passage through the digestive tract releasing eggs in the feces
- or are released intact in the feces
73
What happens for the male reproductive system in cestodes? What are the structures?
Male system develops first within proglottid
Structures begin to form in the immature proglottids and are fully developped in mature proglottids
```
Structures are:
- many testes (ranging from 3 to 100's,
depending on the tapeworm species)
- vasa efferentia
- vas deferens (often highly coiled)
- cirrus sac with cirrus
- common genital pore
```
The male organs disappear in gravid proglottidsmany testes (ranging from 3 to 100's,
depending on the tapeworm species)
• vasa efferentia
• vas deferens (often highly coiled)
• cirrus sac with cirrus
• common genital pore
The male organs disappear in gravid proglottids
74
What happens for the female reproductive system in cestodes? What are the structures?
Female system structures form and are functional
in mature proglottids.
```
Structures are:
• ovaries (always 2)
• vitellaria (yolk gland) ‐ scattered or
compact
• Mehlis' gland
• uterus (contains eggs in branches)
• vagina (carries sperm to ootype)
• common genital pore
```
Most of the female organs disappear in gravid
proglottids, except for the egg‐filled uterus.
75
What happens in the reproduction for cestodes? What happens with the reproductive organs and reporduction in the gravid proglottid?
Self‐mating within a segment is unusual.
Sperm are mostly transferred between mature proglottids lying next to each other.
Gravid proglottids develop after mating and contain
hundreds to thousands of embryonated eggs.
Gravid proglottids detach from parent organisms and
disintegrate or exit the host
76
What/how are cestode eggs? Where do they pass from?
Eggs that are passed from the host are embryonated.
The eggs contain a hexacanth larva, called an oncosphere.
The oncosphere is encased in an inner envelope,
which is surrounded by another membrane structure
called the embryophore.
The outer envelope lies between the embryophore
and the shell (or capsule).
Eggs remain viable in the external environment for
weeks to months.
77
How is the digestive tract in cestodes? What do they do to digest food? How is the nutrients processed?
Cestodes lack a digestive tract.
The lack of a gut in cestodes means that the external surface of the parasite must function not only for protection, locomotion, and as a sensory surface, but
also as a metabolically active layer taking up nutrients from the environment and a layer through which secretions and excretions must pass.
The external surface of the cestode = the tegument.
The tegument has to resist the attack of digestive enzymes and protect against the immune responses of the host.
Cestodes do not produce digestive enzymes of any sort, instead they rely entirely on the digestive enzymes of their hosts to breakdown nutrients into low molecular weight compounds, which they can then absorb.
Cestode transport systems have been characterized for amino acids, sugars, fatty acids, purines and pyrimidines and vitamins.
78
What is rhe cestode tegument? What does it have?
Covering the entire surface of the tegument is a layer of carbohydrate containing macromolecules ‐ the glycocalyx ‐ that serve several important purposes:
* protecting the parasite from host digestive enzymes
* enhancing nutrient absorption
* maintaining the parasite’s surface membrane
The microvilli on the tapeworm surface increase the surface area of the parasite approx. 20 times.
Syntegument ‐ outer anucleate syncytial cytoplasmic layer containing mitochondria and secretory bodies.
Cytotegument ‐ nucleated cell bodies lying beneath the tegumental muscles and connected to the syntegument.
