Lab 9 Flashcards
Nematodes I
protective covering of nematodes
external cuticle
alae
lateral thickenings of cuticle
what body systems are well developed in nematodes? (3)
muscular, nervous, digestive
nematode oral cavity is also known as a
buccal cavity
nematode buccal cavity is lined with:
cuticle
what muscular pumping organ is after the buccal cavity
esophagus
nematode gut is lined with:
columnar epithelial cells with microvilli
nematodes digest food in the ______ region
midgut
where is waste expelled from a nematode?
anus
Pseudocoel:
body cavity that is fluid filled that acts like a hydrostatic skeleton
nematodes excrete both ____ and ____ wastes
fluid and solid
nematodes excrete solids out of _____ and fluids out of _____
anus; excretory pore
most nematodes are monecious or dioecious?
dioecious
large part of body of female devoted to:
reproduction
what reproductive organs do females have?
1 or 2 ovaries; uterus; vulva
male reproductive organs are:
single testis; copulatory spicules; gubernaculum
what stage is typically infective?
J3
molting is also known as:
ecdysis
hypobiosis-
a developmental arrest in parasite cycle
when does hypobiosis end and development continue?
usually favorable
environmental conditions—conducive to parasite survival
what does a nematode live on while in hypobiosis?
food reserves
pinworm characteristics tail shape: esophagous has prominent: eggs: life cycle:
pointed
posterior bulb
thin shelled with flattened side
direct
roundworm characteristics
___ prominent lips
lateral external ______ on cephalic end
eggs:
3
papillae
thick shelled with rough coating;very resistant
hookworm characteristics
body shape:
_____ esophagus
eggs:
long and slender
club
thin shelled
threadworm characteristics
size:
size of buccal cavity:
what kind of esophagus:
tiny
small
filariform (J3 and adult female) or rhabditiform (free living stages)
trichurida characteristics body shape: size of buccal cavity: what kind of esophagus: eggs:
anterior more slender than posterior
reduced or absent
stichosome
polar plugs
Enterobius vermicularis
what kind of worm:
distribution:
niche:
pinworm world wide (very common in elementary schools and day care centers) large intestine and rectum
Enterobius vermicularis morphology \_\_\_\_\_ alae \_\_\_\_\_\_ esophagus female tail: male tail:
cephalic
bulbed
very pointy
blunt and curled
Enterobius vermicularis eggs
size:
shape:
50x25 micrometers
ovoid, thin shelled, flattened on 1 side
Enterobius vermicularis life cycle direct or indirect? how does female lay eggs? how long does it take for eggs to embryonate? eggs are so light that....?
- direct
- female migrates out anus at night and lays eggs in perineal regions -expels all the eggs and then dies
- eggs rapidly embryonate and develop to the infective J3 stage (wn 6 hrs)
- they can become airborne
Enterobius vermicularis retroinfection is possible how?
J3 hatches on perineum and crawls right back into rectum and up to colon.
Enterobius vermicularis will rarely but sometimes do what?
J3 larvae crawl into vagina in female instead of anus - an aberrant infection
- most will die quickly
Enterobius vermicularis clinical symptoms:
-most pinworm infections are asymptomatic -some develop intense itching in perineal regions
Enterobius vermicularis diagnosis:
“scotch tape” test
tape applied to perineum first thing in morning (before going to bathroom or bathing) remove immediately and put on slide to see eggs under microscope. No fecal smears!
Ascaris lumbricoides
Aka:
distribution:
highest prevalence distribution:
- human roundworm
- worldwide
- tropical, rural areas where sanitation is low or absent.
Ascaris lumbricoides
niche:
upper small intestine in human host.
-adults live in upper small intestine on predigested food and host cellular debris
Ascaris lumbricoides mechanism for staying in intestine:
-stay in place by continually moving against peristalsis
Ascaris lumbricoides
size:
female tail:
male tail:
huge; can be 30 cm long
straight
curled
Ascaris lumbricoides eggs size: shell: how resistant: what will kill egg?
- 45-75x35-50 micrometers
- thick shelled and rough surface
- -very resistant
- -can survive for years in warm, moist soil
- -can survive sub-arctic conditions
- -resistant to most chemicals
- -ubiquitous in regions where infections are common
- heat will kill eggs
Ascaris lumbricoides
life cycle:
infective stage:
direct
J3 stage
Ascaris lumbricoides infection
- embryonated egg containing ___ stage which immediately molts to the __ stage in the intestine before it hatches.
- eggs shed in feces are not ________(eggs require ______ to embryonate)
- J1 molts to J2 within the egg (will remain as J2 until egg is ingested)
- J2 molts to J3 when egg is ingested and J3 hatches out in small intestine
- J2
- J3
- embryonated
- oxygen
Ascaris lumbricoides
-round worms have a migratory phase that goes from ___ to ____ to ____ and back to ____:
-___ penetrates gut wall to capillary to ____
-In ____, ___ migrates through tissue, feeds on _______ and grows
-J3 migrates to _____ via bloodstream
-in _____, ____ molts to ______, which breaks out of ______ and migrates up bronchi
to pharyngeal area and is swallowed
(lung migration stage may cause signs of ______)
-J4 molts to adult stage in _____ intestine
-adults mate
-female produces about _______ eggs per day
Ascaris lumbricoides
-round worms have a migratory phase that goes from gut to liver to lung and back to gut:
-J3 penetrates gut wall to capillary to liver
-In liver, J3 migrates through tissue, feeds on liver parenchyma and grows
-J3 migrates to lungs via bloodstream
-in Lungs J3 molts to J4, which breaks out of alveolus and migrates up bronchi
to pharyngeal area and is swallowed
(lung migration stage may cause signs of pneumonitis)
-J4 molts to adult stage in small intestine
-adults mate
-female produces about 200,000 eggs per day
Ascaris lumbricoides eggs require certain conditions to hatch:
37 degrees C, pH 7, low oxygen, high CO2
Ascaris lumbricoides host reaction
_______ Phase – causes most host response
-______ substances very antigenic
-_______ and ________ occur
-Intensity of host reaction related to:
-heavy infections = enlarged ____, and _________ in lung
- Migratory
- molting
- eosinophilia and increased levels of IgE
- the number of worms migrating at any one time
- liver; pneumonitis
Ascaris lumbricoides intestinal phase
symptoms:
obstruction, and there are cases on record where what happened?
- few
- worms migrated to stomach and were vomited up
Ascaris lumbricoides intestinal phase
heavy infection can cause what:
- obstruction
- perforate intestine and cause peritonitis
- obstruct biliary tree causing a peritonitis
- malabsorption
- stunting
- cholecystitis
Ascaris lumbricoides Dx:
eggs in feces
Ascaris lumbricoides
although rare, juveniles can enter placenta and migrate to fetus, causing:
neonatal ascariasis
Toxocara canis
host:
dogs and other canids
Toxocara canis life cycle is dependent on age and immune status of host
- young puppy or adult never before infected:
- adult, reinfected dog:
- Adult reinfected female that becomes pregnant
- puppies can also get J3’s via a _________ route
- life cycle in dog like A. lumbricoides in man with migratory phase from gut to liver to lung and back to gut
- parasite does not complete the lung migration. J3’s wander through body and eventually go into developmental arrest
- the dormant J3’s become active and migrate to placenta and to the fetus. In the fetus, the J3’s complete the lung migration back to gut. Puppies can be born with T canis infections.
- transmammary
Toxocara cati
host:
life cycle is similar to T. canis except:
- cats
- there is no transplacental transmission
- human infection with Toxocara cati or Toxocara canid can lead to:
- what areas of human body are most seriously affected?
- Visceral Larval Migrans, Ocular Larval Migrans
- CNS, liver, lungs, and eyes most seriously affected
what is human host response to T. cati and canid?
inflammatory and formation of eosinophilic granulomas