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Biomedical Parasitology > Nematodes > Flashcards

Nematodes Flashcards

1
Q

Number of nematode species that have been described

A

200,000

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2
Q

The majority of nematodes are _______ and ______

A

small predators and saprophytes (eat decomposing organic matter)

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3
Q 
provide
powerful gene2c models to
study the basis of
development, aging and
many diseases including
cancer
A

Nematodes

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4
Q

Describe the anatomy of nematode

A 
unsegmented:
• bilaterally
symmetric
• triploblas2c:
– ectoderm,
mesoderm and
endoderm.
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5
Q

What does triploblastic mean?

A

has 3 layers:

ecto, meso and endo DERM

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6
Q

thin layer of

lipids and proteins

A

Epicuticle

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7
Q

made from crosslinked
cu2cilin proteins
and collagen fibres

A

cortex

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8
Q

are formed
by collagen fibers which
are put down at angles to
generate a lattice

A

Basal layers

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9
Q

fibrous and

closest to hypodermis

A

Basal layer

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10
Q

Nematodes molt how many times?

A

4x

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11
Q

explain how they molt

A

The old cu2cle separates from the epidermis and the innermost layer
is par2ally hydrolyzed
• A new cu2cula is secreted by the hypodermis star2ng with the
epicu2cle
• The old cu2cle is shed

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12
Q

Nematodes lack _________

A

circular
muscles, they depend
entirely on longitudinal
muscles

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13
Q 
is
generated by the
interplay of muscles,
pressurized pseudocoel
and cuticula
A

Nematode’s motility

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14
Q

The brain consists of

A 
a single ring around the pharynx.
A lateral and a ventral
nerve extend back
through the length of the
worm.
Labial and aphid nerves
extend forward to
enervate sensory organs
(amphids and various
papilla)
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15
Q

What are amphids?

A 
are simple
organs of mechano‐ and
chemorecep2on. The
sensory organelles are
modified cilia
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16
Q

What kind of skeleton do they have?

A

hydrostatic

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17
Q

is tightly attached to the hypodermis and the cuticle

A

musculature

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18
Q

What kind of digestive system do they have?

A

complete but simple.

Mouth is located at the very tip of the animal

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19
Q 
is nonmuscular,
and consists of a single layer
tall columnar cells which carry
microvilli and an underlying
basal lamina
A

The intestine

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20
Q

Most nematodes are what in terms of reproduction?

A

dioecous - two sexes. But, hermaphrodite can occur as well.

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21
Q

Describe the differences between male and female

A

Males are smaller than females. And they have an additional external features at the posterior end of the worm

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22
Q

Both sexes are attracted to _________

A

pheromones

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23
Q

is muscular
an sperm is transferred to
the female against the
pseudcoel pressure

A

The sperm duct

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24
Q

are important
features to tell different
nematodes apart

A

shape and size of spicules

and bursa

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25
Male inserts ______ ________ copulatory spicules
two sclerotized
26
This can close vulva in some species. | Anatomy of a male
cement gland
27
It has no role in sperm motility
actin
28
The sperm motility depends on
Major Sperm Protein (MSP)
29
forms dimers which assemble into subfilaments, two of these form a helical filament
MSP
30
How many ovaries does a female nematode often have?
2
31
oocytes are fertilized by sperm stored in the ______
receptable
32
Eutelic means what?
``` they reach a predefined number of cells which then remains constant (only the germline keeps dividing) ```
33
Some cells lose ____ _____ while other proceed to polypoidy.
nuclear DNA
34
how many larval stages must it have before reaching adulthood?
4 , molting is required each step
35
Many nematodes can develop a specialized resting or ___________
Dauer version of the L3 larval stage
36
it is the infectious stage for the final host
L3 Larval stage
37
Larval stages are mostly aerobic or anaerobic?
aerobic
38
Where do most adults form?
in the intestine because they have little amount of oxygen and have an anaerobic fermentative metabolism.
39
The third most common roundworm of humans
Trichuris trichuria aka the whip worm
40
more frequent in areas with poor sanitation and tropical weather
whip worm
41
Trichuris: adults live here, where they release 20,000 eggs per day.
cecum
42
Embryonation occurs within ____ _____ in soil
3 weeks
43
infection is through
ingestion of eggs
44
Trichuris: Infections with less than 10 worms are asymptomatic or symptomatic?
asymptomatic
45
Clinical symtoms: Trichuris
``` abdominal pain cramps weight loss diarrhea (might be bloody) rectal prolapse ```
46
Diagnosis : Trichuris
by demonstra2on of characteris2c eggs (“champagne corks”) By procotoscopy
47
Treatment : trichuris
mebendazole
48
Prevention: Trichuris
sanitary disposal of feces
49
Trichinosis is caused by
Trichinella spiralis
50
life cycle of trichinella
occurs through larvae encysted in muscle tissue. Larva enters the small intestine and it is freed from its nurse cell. Larvae grow and molt 4 times females give birth to live L1 larvae Larvae enter the blood vessels and carried throughout the body
51
Females die after how many weeks?
4 to 16 weeks
52
Both host cell and | worm are enclosed by __________
Collagen capsule | - collagen RNA
53
symptoms of trichinella. | Remember: this affects MUSCLE
``` Ac2vity of the females can cause inflammatory reac2on in the mucosa, leading to diarrhea and abdominal pain Characteris2c splinter hemorrhages can be found under finger nails • Fever and chills can persist for weeks • Headache is common and dizziness may develop • Muscle swelling, aching and tenderness occurs often ```
54
Father of Pathology
Rudolf Virchow
55
discovered the life cycle of trichinella
Rudolf Virchow
56
How is trichinella diagnose?
muscle samples. | ELISA to detect antibody
57
Large intestinal nematodes
Ascaris lumbricoides
58
Describe the anatomy of ascaris
``` Males are 15‐31 cm and have incurved posterior end, females are 20‐49 cm • The anterior end of both sexes shows three lips ```
59
Infection of ascaris depends on
fecal contamination of: soil food water
60
Differentiate fertilized and unfertilized eggs of ascaris
Fertilized eggs are shorter and rounder than unfertilized
61
a mass of knotted worms | obstructing the intes2ne
volvulus
62
Adult ascaris worms penetrate which organ(s)?
Bile duct and liver
63
are small nematodes.
Ancylostoma duodenale & Necator | americanus ‐‐ human hookworms
64
Describe the anatomy of hookworms
``` Head is slightly bend (hook) and the ‘mouth’ carries characteris2c teeth (Ancylostoma) or plates (Necator, note that these are not real teeth but cu2cular forma2ons of the ‘buccal capsule) • The posterior end of the male worm is elaborated into a copulatory bursa ```
65
``` is found in Europe around the Mediterranean, on the West coast of South America and in parts of China and India ```
ancylostoma
66
is found over much of the western hemisphere, Africa and South East Asia
Necator
67
second most common human helminthic infection
hookworm
68
Adult hookworms live where?
small intestine
69
how many times do hookworms molt?
twice before maturity
70
What happens if hookworms come in contact with a host?
If they come into contact with the host they penetrate the skin, enter blood vessels and leave the circulatory system into the alveoli
71
What is ground itch?
infection by hookworms. | It is the skin penetration and associated with bacterial infection
72
What is the main concern with hook worm disease?
blood loss - anemia - Fe deficiency - manutrition
73
Treatment for hookworms
mebendazole

Biomedical Parasitology (6 decks)

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