Microbiology lecture chapter 12-Helminths
Are Helminths eukaryotic or prokaryotic?
Are Helminths heterotrophs?
yes- other eaters
Are helminths unicellular or multi-cellular?
many different types of cells
Helminthic disease is typically?
Helminths belong to 2 phyla:
Nematoda (round worms)
True or false most helminths are environmental and don't cause human disease.
Helminths have bilateral symmetry which means?
if cut in half there is a mirror image on the other side
Helminths modes of nutrition are:
absorptive- flatworms-lack a digestive system and they absorb nutrients from the hosts food, bodily fluids and tissues. Absorb through the cuticle. No cell wall but has a cuticle.
ingestive-round worms/if ingestive means that it will have complete digestive tract nutrition goes in one way excrement out the other.
Phyla Platyhelminthes (flatworms)are:
broad flat stem
both male and female structures present-monoecious
they don't need to find partner to reproduce
The two groups of flatworms is:
Trematodes (flukes)oral and ventral sucker
Cestodes (tapeworms)sucker and a hook
most are intestinal parasites
Phyla Nematode are:
Ingestive mode of nutrition
Two ventrally located suckers-hook on to intestinal wall
absorb food through their cuticle
Most medicine you take to get rid of these are to release the suckers
Two types of hosts are:
definitive and intermediate
The definitive host __________.
harbors the adult stage
The intermediate houses the _____ or _______ stage.
larval or asexual
Why is the lifecycle of the helminths considered complex?
They need the perfect host. The host must have both the definitive and intermediate stage in order to complete the life cycle.
Is a human always the definitive host?
The life cycle of the trematode is:
adult---->egg----> miracidium ----> redia----> rediae -----> cercaria ----> metacercaria
in this cycle the human is the definitive host
Tapeworm (cestode)characteristics are:
The region that latches on is the head (scolex) region and attach to intestinal tract
Usually have suckers or hooks not both
he and she components
the region that produces segments (proglottids) is the neck- the neck is what produces more and more segments - the closer the segments are to the neck the more immature they are the further away from the neck the more mature
The segments have male and female components and if they break off each has the ability to create a new tape worm
Egg ---> larvae----> hydatid cysts containing brood capsules---> (broodcapsules with scolecses)
this one human not the definitive host its a dog
The tapeworm is dangerous because?
it can transport itself to different part of the body - can get into circulatory system
Hydatids of E. Granulosa may travel to other parts of the body such as
It will engorge with fluid and exert pressure on organs, rupture of cysts releases infective units, proteinaceous material may cause cyst may cause anaphylactic shock ----> fatal
Nematodes- roundworms are:
over 25,000 nematodes identified
most free living
some are agricultural pests that eat roots of plants
few are human parasites (50 species)
-larvae or eggs are infective
exoskeleton (cuticle)- clear helps them burrow
complete digestive tract
dioecious- male and female separate and have to come together to reproduce
cutting plates (teeth)
Roundworm life cycle: pin worm
common in children
spread through bedding, clothing and contaminated hands.
Other roundworm characteristics are: Hookworm
head region shaped like hook
enter host through feet or legs
-travel via blood or lymphatic system to lungs or heart
-coughed up or swallowed
-larvae latch onto intestinal walls
-sharp teeth aestheticize
-clogs the lymphatic system (swelling)
Summary of Helminth characteristics