Bellwork: 10/18/2012
Today – Complete Notes over Helminthes,
Complete lab from Tuesday.
Friday – Weekly chemistry, begin review,
begin review quiz
Monday – Complete review, complete review
quiz
Tuesday – Unit #3 Exam
Microbial Contaminant Lab: Station 6
**Groups of 3 or fewer
1. Atrazine is an endocrine disruptor. What does that mean?
What type of product is atrazine found in? What threat does
this pose to human & non-human life?
2. What is bioaccumulation? What types of chemicals tend to
bioaccumulate? Describe an environmental situation where
this occurred.
3. What is thermal pollution? How/why does this occur? Is this
damaging to an environment? If so, how? In what way have
we prevented environmental damage while maintaining
factory/power plant output?
4. Write out the nitrogen cycle. Label the aerobic & anaerobic
reactions. Label the reaction that is responsible for fixing
nitrogen. What does it mean to “fix” nitrogen? If this reaction
ceased to occur, what would the consequence be for higherlevel organisms?
HELMINTHES
Water Born Flat worms and Round
worms
HELMINTHOLOGY
Phylum Platyhelminthes = Flat worms
Class Trematoda = Flukes
Class Cestoda = Tape worms
Phylum Ashelminthes = Round worms
Class Nematoda
Genus Ascaris
Genus Trichinella
Genus Necator, Ancylostoma
Genus Enterobius
Genus Dranunculus
Genus Wucereria
HELMINTHOLOGY
Phylum Platyhelminthes = Flat worms
Class Trematoda = Flukes
Some flukes are single sex, some are
hermaphroditic possessing both ovaries
and testes.
Hermaphroditic Flukes
FIGURE 13-45 Schistosoma mansoni egg in a fecal specimen (X1000, D’Antoni’s iodine stain).
Schistosoma mansoni eggs are large (114 to 175 µm long by 45 to 70 µm wide) and contain a larva called
a miracidium. They are thin-shelled, lack an operculum, and have a distinctive lateral spine (arrow).
FIGURE 13-46 Schistosoma mansoni egg in a fecal specimen (X1000). The lateral spine
may be oriented in such a way as to be difficult to see. In this specimen, the spine (arrow)
is above the egg and the egg may be misidentified as S. haematobium.
FLAT WORMS
Phylum Platyhelminthes = Flat worms
Class Cestoda = Tape worms
Scolex contained in egg
holdfast structure with hooks
and suckers
Proglottids major body of tapeworm
contains both ovaries and
testes = hermaphroditic
Eggs can penetrate intestine of host and
form hydatid cysts in tissues
FIGURE 13-57 Taenia solium scolex (X64).
The Taenia solium scolex has two rings of hooks and four suckers.
ROUND WORMS
Phylum Ashelminthes = Round worms
Class Nematoda
Genus Ascaris – most common
Genus Trichinella Biblical worm
Genus Necator, Ancylostoma hookworms
Genus Enterobius – pinworm 2nd most common
Genus Dranunculus - Guinae
Genus Wuchereria - Elephantiasis Mosquito
borne
Hookworms
► Ancylostoma
duodenali:
Human phase of this worm begins with a filaform
larvae penetrating the skin, enters circulation,
carried to the lungs, coughed up and swallowed,
develops to adulthood in small intestine. Adult
worms lay between 10,000 and 20,000 eggs per
day. Daily blood loss 0.2ml/adult/day. Microcytic
hypochromic anemia develops.
a
b
FIGURE 13-64 Heads of adult hookworms.
(a) Ancylostoma duodenale head (X64) showing the pairs of chitinous teeth (arrow).
(b) Necator americanus head (X160) showing the cutting plates (arrow).
Biblical worm
► Trichinella
spiralis etiological agent of
trichinosis. Infectious larva is present in the
striated muscle of carnivorous and
omnivorous mammals. Swine most
common organism to transmit to humans.
Encysted larvae live for many years. Polar
bears and walruses are accounting for new
human infestations in our Alaskan artic
regions.
FIGURE 13-68 Trichinella spiralis larva in skeletal muscle (W.M., X260).
The spiral juvenile and its nurse cell are visible in this preparation.
FIGURE 13-69 Trichinella spiralis larvae in skeletal muscle (sec., X260). Each larva has entered
a different skeletal muscle cell and converted it into a nurse cell that sustains it with nourishment.
Ascaris Lumbricoides
► Large
worms 25cm – 45cm in length. Most
common helminth with over a billion infested a
year. Prevalent in areas where sanitation is poor
and human waste is used as fertilizer.
► Ingested egg releases a larva that penetrates the
duodenal wall and carried to the liver and the
heart, enters the pulmonary system, enters the
alveoli where they molt and mature. They are
coughed up, swallowed and returned to the small
intestine. Adults can be passed out into the feces.