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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
Q

Male inserts ______ ________ copulatory spicules

A

two sclerotized

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26
Q

This can close vulva in some species.

Anatomy of a male

A

cement gland

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27
Q

It has no role in sperm motility

A

actin

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28
Q

The sperm motility depends on

A

Major Sperm Protein (MSP)

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29
Q

forms dimers which
assemble into subfilaments,
two of these form a helical
filament

A

MSP

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30
Q

How many ovaries does a female nematode often have?

A

2

31
Q

oocytes are fertilized by sperm stored in the ______

A

receptable

32
Q

Eutelic means what?

A 
they reach a
predefined number of cells
which then remains constant
(only the germline keeps
dividing)
33
Q

Some cells lose ____ _____ while other proceed to polypoidy.

A

nuclear DNA

34
Q

how many larval stages must it have before reaching adulthood?

A

4 , molting is required each step

35
Q

Many nematodes can
develop a specialized
resting or ___________

A

Dauer version of the L3 larval stage

36
Q

it is the infectious stage for the final host

A

L3 Larval stage

37
Q

Larval stages are mostly aerobic or anaerobic?

A

aerobic

38
Q

Where do most adults form?

A

in the intestine because they have little amount of oxygen and have an anaerobic fermentative metabolism.

39
Q

The third most common roundworm of humans

A

Trichuris trichuria aka the whip worm

40
Q

more frequent in areas with poor sanitation and tropical weather

A

whip worm

41
Q

Trichuris: adults live here, where they release 20,000 eggs per day.

A

cecum

42
Q

Embryonation occurs within ____ _____ in soil

A

3 weeks

43
Q

infection is through

A

ingestion of eggs

44
Q

Trichuris: Infections with less than 10 worms are asymptomatic or symptomatic?

A

asymptomatic

45
Q

Clinical symtoms: Trichuris

A 
abdominal pain
cramps
weight loss
diarrhea (might be bloody)
rectal prolapse
46
Q

Diagnosis : Trichuris

A

by demonstra2on
of characteris2c eggs
(“champagne corks”)
By procotoscopy

47
Q

Treatment : trichuris

A

mebendazole

48
Q

Prevention: Trichuris

A

sanitary disposal of feces

49
Q

Trichinosis is caused by

A

Trichinella spiralis

50
Q

life cycle of trichinella

A

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
Q

Females die after how many weeks?

A

4 to 16 weeks

52
Q

Both host cell and

worm are enclosed by __________

A

Collagen capsule

- collagen RNA

53
Q

symptoms of trichinella.

Remember: this affects MUSCLE

A 
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
Q

Father of Pathology

A

Rudolf Virchow

55
Q

discovered the life cycle of trichinella

A

Rudolf Virchow

56
Q

How is trichinella diagnose?

A

muscle samples.

ELISA to detect antibody

57
Q

Large intestinal nematodes

A

Ascaris lumbricoides

58
Q

Describe the anatomy of ascaris

A 
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
Q

Infection of ascaris depends on

A

fecal contamination of:
soil
food
water

60
Q

Differentiate fertilized and unfertilized eggs of ascaris

A

Fertilized eggs are
shorter and rounder
than unfertilized

61
Q

a mass of knotted worms

obstructing the intes2ne

A

volvulus

62
Q

Adult ascaris worms penetrate which organ(s)?

A

Bile duct and liver

63
Q

are small nematodes.

A

Ancylostoma duodenale & Necator

americanus ‐‐ human hookworms

64
Q

Describe the anatomy of hookworms

A 
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
Q 
is found in
Europe around the
Mediterranean, on the
West coast of South
America and in parts of
China and India
A

ancylostoma

66
Q

is found over
much of the western
hemisphere, Africa and
South East Asia

A

Necator

67
Q

second most
common human
helminthic infection

A

hookworm

68
Q

Adult hookworms live where?

A

small intestine

69
Q

how many times do hookworms molt?

A

twice before maturity

70
Q

What happens if hookworms come in contact with a host?

A

If they come into contact with the
host they penetrate the skin, enter
blood vessels and leave the
circulatory system into the alveoli

71
Q

What is ground itch?

A

infection by hookworms.

It is the skin penetration and associated with bacterial infection

72
Q

What is the main concern with hook worm disease?

A

blood loss

  • anemia
  • Fe deficiency
  • manutrition
73
Q

Treatment for hookworms

A

mebendazole

Biomedical Parasitology (6 decks)

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