W7- Phylum Nematoda Flashcards
Phylum Nematoda characteristics
1mm-1m
Bilateral symmetry.
elongated, cylindrical, unsegmented w/ tampering ends
abundant in soil (geohelminth) move by contracting muscles
sexual dimorphism- M shorter than F
3 layer cuticle, hydrostatic skeleton:
1) tough outer cuticle(smooth)
2) middle layer= hypodermic
3) inner later= somatic muscular layer
body cavity= pseudocele (fluid-filled (incomplete coelum) that contains the intestine and reproductive organs.)
Nematodes lack a true coelom
what is Phylum Nematoda
round worms
What are the 3 structural groups?
what is a Coelom?
1) acoelomata (no coelom/ body cavity) e.g flat worms
2) pseudocoelomate (partial coelom) e.g round worms
3) eucoelomata (true coelom) e.g arthropods. most complex
Coelom= fluid-filled cavity lined by mesoderm.
2 types of embryonic development
1) protostomes: blastopore becomes mouth -determined development, stops growth (in simpler invertebrates)
2) deuterosomes: blastopore become anus- indeterminate development, doesn’t stop growing (forms a whole organism- humans)
Phylum Nematoda systems
Digestive: complete= mouth> esophagus> intestine
Excretory: lateral ducts that run longitudinally down either side of body
Nervous: dorsal and ventral nervous cord
Reproduction sexual: males shorter than females, males= hooked posterior and w/ pair of copulatory spicules.
what group does Phylum Nematoda belong to
Ecdysozoa = group of
protostome animals
3 layered cuticle, which is molted as they grow= ecdysis.
what is Ascaris lumbricoides known as?
Giant round worm
Ascaris lumbricoides Transmission
its a geohelminth (soil- transmitted)
eggs are passed in the feces of infected person
Ascaris lumbricoides cause
ascariasis- often in children =abdominal pain)
Ascaris lumbricoides morphology
female: 20-40mm
male: 15-30mm
Ant end= mouth w/ 3 lips
Posterior end male= curved ventrally, forms hook +carries 2 copulatory spiracles (needle like mating structures) posterior end of female = straight and conical.
EGG: light brown, has rough surface due to bile
Ascaris lumbricoides life-cycle
1Female produces eggs which are passed with faeces on fertilised eggs equals ineffective noninfective, fertilised egg develops into infective
Ascaris lumbricoides life-cycle
1) adult worms in SI,
2) unfertilised egg- not infective, within fertilised egg in soil develops a rhabditiform larva
3) human ingest F/w contaminated w/ embryonated egg.
4) rhabditiform larva (L3) hatches in duodenum. Invades intestinal mucosa of SI, uses circulation to reach lungs.
5) Mature in lungs, penetrates alveolar wall, up bronchial tree to reach throat then swallowed to reach SI
Ascaris lumbricoides infective stage
Diagnostic stage
IS: embryon. egg w/ rhabdiform larva
DS: the eggs in the feces.
why do they go to Lungs
they need o2 for respiration
what are Enterobius vermicularis known as?
pin worm
what are Enterobius vermicularis known as?
pin worm
Enterobius vermicularis habitat
SI (cecum, appendix+ prox jejumum)
Enterobius vermicularis Morphology
Female:8-13mm
Male: 2-5mm
white, small. thin pointed pin-like tail. male tail= curved, female tail= elongated,streched
male has copulatory spicule on post end
on anterior, winglike projections for attachment to intestinal mucosa.
EGG: colourless, not bile stained, oval
Enterobius vermicularis Morphology
Female:8-13mm
Male: 2-5mm
white, small. thin pointed pin-like tail. male tail= curved, female tail= elongated,streched
male has copulatory spicule on post end
on anterior, winglike projections for attachment to intestinal mucosa.
has an oesophageal bulb(post) contraction important form attachment to intestinal wall.
EGG: colourless, not bile stained, oval
Enterobius vermicularis transmission
> Ingestion embryon. eggs containing Larva by F/W,, can be airborne and inhaled as they are very small
Auto-infection- ingestion of eggs due to scratching of perianal area infection from anus to mouth
Retro infection eggs laid on perianal skin immediately hatch into inf lava +migrate to anus develop into worms in colon.infection from anus to colon
Enterobius vermicularis life-cycle
1) Gravid female lays embryon. eggs on perianal fold. eggs are ingested by human host.
2) larvae hatch in the SI. Adults in caecum
3) gravid females migrate nocturnally to outside the anus and lay eggs
Enterobius vermicularis host
only humans
What happens after fertilisation of Enterobius vermicularis?
what does it feed on?
Male dies
feeds on intestinal mucosa and blood
what is Trichuris trichiura known as?
whipworm,
trichocephalus trichiurus
Trichuris trichiura Transmission
fecal-oral, eggs deposited in the soil (geohelmith), eggs can be ingested by contaminated hands F/W are infected
Trichuris trichiura cause
causes trichuriasis
Trichuris trichiura habitat
lrg intestine- adults attached to lumen of cecum
Trichuris trichiura infective form
embryonated eggs w/ rhabditiform larva
Trichuris trichiura infective form
embryonated eggs
Trichuris trichiura morphology
male=30-45mm female= 40-50mm male post is coiled, female post is not due to uterus being filled w/ egg so can't coil. narrow anteriorly (threadlike), thick posterior part.
EGG: brown, bile-stained, lemon shaped. have pole covered by thick wall. they have bipolar protuberance, and is covered by thick 4 layered wall.
Trichuris trichiura morphology
male=30-45mm female= 40-50mm male post is coiled, female post is not due to uterus being filled w/ egg so can't coil. narrow anteriorly (threadlike), thick posterior part.
EGG: brown, bile-stained, lemon shaped. have pole covered by thick wall. they have bipolar protuberance, and is covered by thick 4 layered wall.
how does Trichuris trichiura attach to host
attach to host intestinal mucosa through slender ant end and feed on tissue secretion+ blood
how does Trichuris trichiura attach to host?
attach to host intestinal mucosa through slender ant end and feed on tissue secretion+ blood
what are Trichinella spiralis known as?
trichina worm
Trichinella spiralis cause
trichinellosis
Trichinella spiralis Host
Optimum host: Pig.
Alternate host: Man.
it uses its host as a def and then an inter as well (biohelminth)
Trichinella spiralis transmission
ingestion of undercooked meat containing encysted larvae
Trichinella spiralis morphology
Females= 2.2 mm
males= 1.2 mm
small white worm
Ant. body= thin+pointed, adapted for borrowing into mucosal epithelium.
Post end of male= pair clusters used to hold female while mating
Female worm= viviparous and discharges larva instead of eggs
they paralyse muscle cells- produces new cells- cancer
Trichinella spiralis infective form
encysted larva in muscle of pigs
Trichinella spiralis life cycle
1) ingestion of undercooked meat containing encysted larvae
2) digestive enzymes result in cyst releasing larvae in SI
3) they invade bowel mucosa where they develop into adult worms.
4) females release larvae that migrate to striated muscles where they encyst
Trichinella spiralis habitat
buried deeply in mucosa of SI in big, bear, rat, human
how to get slide of Enterobius vermicularis eggs
use scotch tape around anus skin to get eggs to stick to tape
place on slide
Strongyloides stercoralis cause
strongyloidiasis
Strongyloides stercoralis transmission
Penetration of skin by filariform lather when peas person walks barefoot.
Soil-transmitted helminth
Strongyloides stercoralis morphology
smallest
Female=2.2mm, ovoviviporous uterus has thin walled transparent ovoid eggs. ant 1/3=esophagus, post 2/3= intestines
males= 1.2 mm, shorter+broader, has spicules (copulation)
thin and transparent.
filariform larva has notched tail
Strongyloides stercoralis host
humans can be cats, dogs
Strongyloides stercoralis habitat
SI (duodenum, jejunum)
Strongyloides stercoralis infective stage
filariform larva
Strongyloides stercoralis life cycle
1) Rhabditiform larvae passed in stool of infected host either infective filariform larvae (direct development) or free-living adult worms that mate and produce embryon eggs from which rhabditiform larvae hatch and eventually become infective filariform (L3) larvae
2) Filariform larvae penetrate human skin and migrate to SI where they become adults.
3) Parasitic adult remain in SI.
4) eggs deposited in intestinal mucosa. rabitiform larva hatch + migrate to intestinal lumen.
Autoinfection: Rhabditiform larvae in lrg intestine become filariform + penetrate intestinal mucosa and migrate to other organs
types of autoinfection Strongyloides stercoralis
external: rhaditiform larva mature into filariform during passage to gut- larva causes reinfection by penetrating perianal area
internal: rhaditiform larva mature into filariform in bowel. larva penetrate the deeper layers of intestine
what is Ancylostoma duodenale known as
Hookworm
Ancylostoma duodenale cause
intestinal hookworm
attach to capillary beds in
the SI, they suck blood
resulting in anemia
Ancylostoma duodenale host
humans
Ancylostoma duodenale morphology
- male= 8-11 mm copulatory bursa at post =three lobes for reproduction
- females= 10-13 mm
Ant= dorsally curved (hook)
EGG: not bile stained, colourless
Ancylostoma duodenale habitat
duodenum+ SI of human
Ancylostoma duodenale infective form
3rd stage filariform larva
Ancylostoma duodenale life cycle
geohelminth
1) eggs past with faeces rhabditiform larvae hatches in soil it develops into filariform larva– two molts
2) filariform larva penetrate skin carried through the blood vessels to the heart+ lungs. (for o2- aerobic resp)
3) then reach pharynx+ are swallowed. settle in SI + develop into adult worms (2 molts)
4) Adult worms reside in SI and copopulate
Ancylostoma duodenale digestive system and mouth
Has bucca capsule.
6 sharp Chitnis teeth (4 ventral, 2 dorsal) at base there are glands secreting enzymes anticoagulant and hemolytic activity (prevent clotting and allows break down of RBCs)
attaches to intestinal mucosa using teeth. it cuts and feeds on blood
What’s Oviparous, Ovoviviparous and Viviparous?
> Oviparous- young develop and hatch from eggs laid outside of mothers body e.g birds
Ovoviviparous- young develop +hatch from eggs within uterus, mother gives birth to live young e.g sharks
Viviparous- young develops directly inside mother+ she gives birth to live young e.g mammals
