Unicellular eukaryotic organisms without cell walls Most are free-living in the environment; and do not cause disease; Only a small number of species cause disease in humans

-two haploid cells fuse to create a diploid zygote - it happens with some strands of malaria - they form 2 slightly diff haploids that fuse together to make a diploid -all 4 look different so it is easier to diagnose

Lec. 4 Parasites Flashcards by MONICA RUIZ-SOSA

PROTOZOANS, HELMINTHS, ARTHROPODS

Have a eukaryotic cell structure
Do not have cell walls (like fungi, algae,and most bacteria have)
Are heterotrophs – require at least one organic compound made from the environment

•Like all species of living things, have two essential biological functions:
–Survive
–Reproduce

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PROTOZOANS

Unicellular eukaryotic organisms without cell walls
Most are free-living in the environment; and do not cause disease;
Only a small number of species cause disease in humans

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HOW PROTOZOANS SURVIVE

•Mechanisms to enhance feeding/nutrition

–Have chemoreceptors to sense food sources

–Some have means of locomotion to reach food

–Can diffuse nutrients in and waste proudcts out through the cell membrane

–Some have specialized structures to consume food

–Some have specialized structures for eliminating waste products

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LOCOMOTION WITH PSEUDOPODIA

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LOCOMOTION WITH CILIA

Balantidium coli, an intestinal parasite

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LOCOMOTION WITH FLAGELLA

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LOCOMOTION WITH AN UNDULATING MEMBRANE

Undulating membrane is a modifiedflagellum tucked into the cell membrane at different points
Trypanosoma brucei gambiense in human blood (causes African sleeping sickness)

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ADHESIVE DISK (SUCKER) OF GIARDIA LAMBLIA

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SPECIALIZED FEEDING STRUCTURES IN PROTOZOANS

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HOW PROTOZOANS SURVIVE (continued)

•Structures to avoid harm (heat/drying, chemicals, predators)
–Chemoreceptors to sense toxic substances
–Means of locomotion to move away from toxic substances and predators
–Cyst formations to avoid dessication; 2-3 layers of plasma membrane and metabolism in resting state
•Active motile form is called trophozoite
•Nonmotile form is called cyst

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TROPHOZOITE AND CYST OF ENTAMOEBA HISTOLYTICA

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TROPHOZOITE AND CYST OF GIARDIA LAMBLIA

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TYPES OF REPRODUCTION IN PROTOZOANS

•Asexual
–New individuals genetically identical to the parent
–There is an increase in the number of individuals
•Sexual –

–New individuals that are genetically different from both of the two parents
–Genetic material has been exchanged or recombined
–There does not necessarily have to be an increase in the number of new individuals

why would it wanna go through cellular reproduction and not increase the number of organisms? To create genetic variation

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ASEXUAL REPRODUCTION IN PROTOZOANS

-Binary fission in Trichomonas vaginalis

Schizogony – multiple nuclear division without cellular division, then sudden cell Division ( Plasmodium species)
- this happens in some strings of malaria and it makes the person so sick that it makes it easier for mosquitoes to bit them

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SEXUAL REPRODUCTION IN PROTOZOANS

Conjugation in ciliates
Micronuclei undergo meiosisThe two organisms exchange haploidnuclei through a cytoplasmic bridge;Haploid nucleus fuses with the haploid nucleus that remained in the cell.
mirconucleus is the one that is involved in sexual reproduction
- it undergoes meiosis

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Syngamy

-two haploid cells fuse to create a diploid zygote

it happens with some strands of malaria
they form 2 slightly diff haploids that fuse together to make a diploid

-all 4 look different so it is easier to diagnose

PROTOZOANS THAT CAUSE INFECTIOUS DISEASE

Most are simple:
- involve only one developmental stage
- reproduce asexually
- Require only one species as a host organism
A few are complex:
- involve more than one developmental stage
- reproduce asexually and sexually
- require more than one species as a host

LIFE CYCLE OF PLASMODIUM FALCIPARUM

marlia is a good example pf a complex dieases
complex cycle b/c it involves to diff animals (humans and mosquitoes)
look at slide 19 (do not have to memorize the cycle)
for charts on slide 20 we dont memorize all the diseases

HELMINTHS

•Multicellular eukaryotic organisms, most not microscopic

•Life cycles involve different developmental stages
–Fertilized ovum (embryo) stage : all species have
–Larval stage(s) : some species have
–Adult stage : all species have

identifying them at diff. stages are important for diagnosis

OVA OF SOME HELMINTHS THATINFECT HUMANS

ova is probs one of the most important aspects for diagnosis
larva are all in diff shapes, but not as easy to distinguish as ova

LARVAL FORM OF WUCHERIA BANCROFTIIS IMPORTANT FORDIAGNOSIS

(elephantiasis) weird ass legs
gets into the body bit and it swells up the lymph nodes
you can see them in the blood smear

BASIC STRUCTURE OF ADULT CESTODE (TAPEWORM)

Long flat ribbon-like form (strobila) consisting of sections (proglittids)

Lives in intestinal tract of humans/animals;

Anchors itself with hooks and suckers on head (scolex)
Protects against host fluids with thick skin

No digestive system – absorbs nutrients directly through skin

All species hermaphroditic – complete set of male and femaleorgans in one worm and in each proglottid

Life span ≈ 25 years
-if a person is infected then they will have it for a long time

CESTODE (TAPEWORM) BASIC STRUCTURE

reproductive organisms
longest tapeworm recorded is 55ft long
they use to sell tapeworm ova to lose weight

Man’s Headache Caused by Tapeworm in Brain Sheds Light on Rare Condition

ConditionDoctors Find Tapeworms Inside Woman’s Brain After She Complained of Headaches
-it realved that a tapeworm can go from the intestient to the bloodstream to the brain

BASIC STRUCTURE OF ADULT TREMATODE (FLUKE)

Flat leaf shaped structure Lives in various organs of humans/animals:bladder, lung, liver Anchor themselves with suckers Have digestive and excretory systems Have rudimentary nervous system Most species hermaphroditic but a few are dioecious(having separate male and female organism), i.e. male and female organs in separate individuals Life span ≈ 30 years

EXAMPLES OF FLUKES

- Paragonimus westermani(Lung fluke) | - Clonorchis sinensis(Chinese liver fluke)

MATING OF SCHISTOSOMA MANSONIIT’S GROOVY!

The genus Schistosoma is dioecious (males and females are separate individuals; female is pink, male blue)) - female crawls into this grove and spends the rest of her life there - male decided what they do and where they go

BASIC STRUCTURE OF ADULT NEMATODE (ROUNDWORM)

Long cylindrical shape Live in various organs of humans: intestinal tract, blood and lymph Some species use hooks and jaws to anchor themselves Their skin protects against host fluids Have well-developed digestive, excretory systems; Have rudimentary nervous system All species are dioecious (separatemale and female individuals); a few species can undergo parthenogensis Life span 1-2 years - they do parthenogensis... if females cant find a male they become haploid organism that looks exactly like diploid but it is haploid... it only occurs in nemotodes of some kinds and the only hemitis that do this - thought to be a desperate way to keep the organism alive - pic is from a little boy who had helllaaa worms inside of him and it would block his intestine

LIFE CYCLE OF HELMINTHS

•May involve different host species –Definitive host : the host species in which the adult occurs and the fertilized ovum is produced –Intermediate hosts : harbor the larval forms

SIMPLE HELMINTH LIFE CYCLE: ENTEROBIUS VERMICULARIS (PINWORM)

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PINWORM DIAGNOSIS

- they can be passed from kids to kids through coughs and shit - also can be passed through fan air - female pinworm will laid eggs on the anal so that they can continued to be passed around. so parent flashlight the anal and look into it to see if they have it - get tape and put it on the slide to see if they have it

PINWORM TREATMENTS

- all over the counter treatment - very commmon - never causes serious disease - and it just get you very itchy

WHY DOES EGYPT HAVE THE HIGHEST PREVALENCE OF SCHISTOSOMIASIS IN THE WORLD?

- they blocking of nile river caused them to have a lot more water in some areas and those the snails loved the water. (snails are an intermidate home for many worms) - thus there was a lot of worms in that area

ROLE OF ARTHROPODS IN PUBLIC HEALTH

* Vectors that carry micro-organisms from a source to a humans/animals * Parasites that live on humans/animals * Sources of substances that cause allergies

ARTHROPOD VECTORS THAT TRANSMITHUMAN DISEASE

- ARACHNIDS (8 legs) - spiders - ticks - INSECTS (6 legs) - louse - fly - mosquitoes - this are vectors that pass disease - important to know how many legs it has so that when you get sick you can tell you Dr. for diagnosis

ECTOPARASITES (LICE) INFECTING A HUMAN

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DUST MITE ALLERGY

- allergy is caused by feces - feeds off of skin and hair so do grooming in the bathroom not your bedroom - v hard to see but can live in your bed

clicker question answer

- flagella | - sexual cuz of diploid

“Developing countries cannot hope to ... be economically competitive with the rest of the world until they get rid of their worms (helminths)...”

- worms makes people so weak | - so getting rid of them will cause them to be more productive