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Questions and Answers

What is the shape of the body of the flatworms, except for Schistosoma?

Flattened dorsoventrally (correct)

Spherical

Cylindrical

Segmented

Which statement about the digestive system of flatworms is correct?

They possess a specialized stomach.

Their mouth is located at the posterior end.

They obtain food through diffusion. (correct)

They have a well-defined digestive canal.

What type of reproductive system do most flatworms possess?

Asexual reproduction only

Only male reproductive organs

Unisexual with separate sexes

Hermaphroditic with both male and female organs (correct)

What structure is NOT found in the organs of fixation in flatworms?

Excretory pores Signup and view all the answers

Which segment of a tapeworm is characterized by fully developed reproductive organs?

Mature segments Signup and view all the answers

In which type of organism is a unisexual reproductive system commonly found?

Schistosoma Signup and view all the answers

What is the primary method by which flatworms fix themselves in place?

Suckers or grooves Signup and view all the answers

What is a significant feature of the morphologic structure of nematodes compared to flatworms?

Nematodes have a body cavity while flatworms do not Signup and view all the answers

Which parasite transmission method is most commonly associated with contaminated food and water?

Oral route Signup and view all the answers

What type of reproduction is most common in parasitic organisms, except for schistosomes?

Monoecious Signup and view all the answers

Which symptom is not typically associated with parasitic infections?

Skin rash Signup and view all the answers

What is a characteristic feature of adult parasites that have specific adaptations?

Presence of hooklets Signup and view all the answers

Which of the following is an important mode of transmission for parasitic diseases?

Bite of infected insects Signup and view all the answers

Which symptom is typically associated with liver involvement due to parasitic infections?

Hepatomegaly Signup and view all the answers

What might be a consequence of infections caused by certain parasites that affect the respiratory system?

Hemoptysis Signup and view all the answers

What is the usual course of development for parasitic infections?

Egg → Larval stage → Adult Signup and view all the answers

How are parasitic infections commonly transmitted through the oral route?

Through ingestion of contaminated food or water Signup and view all the answers

Which of the following symptoms is least likely to indicate a parasitic infection affecting the gastrointestinal tract?

Jaundice Signup and view all the answers

In which scenario could maternal transmission of a parasitic infection occur?

From mother to fetus in the case of Toxocara Signup and view all the answers

Which parasites are known to be dioecious?

Certain species of schistosomes Signup and view all the answers

Which symptom is associated with infestations affecting the respiratory system?

Coughing of blood Signup and view all the answers

What might be a consequence of parasitic infections related to nutrient absorption?

Vitamin deficiencies Signup and view all the answers

What role do cysts play in the transmission of parasitic diseases?

They are resistant forms allowing survival outside hosts Signup and view all the answers

Which of the following best describes the pattern of symptoms associated with filarial infections?

Hepatosplenomegaly and hematemesis Signup and view all the answers

What distinguishes the reproductive system of Schistosoma from most flatworms?

It has separate sexes. Signup and view all the answers

Which of the following features is NOT characteristic of flatworms?

Presence of a body cavity. Signup and view all the answers

What is the main function of spines on the cuticle of flatworms?

Fixation. Signup and view all the answers

In which segment of a tapeworm are the reproductive organs not fully developed?

Immature segments. Signup and view all the answers

Which of the following statements accurately describes the digestive system of flatworms?

It includes a muscular pharynx. Signup and view all the answers

What type of body shape do tapeworms exhibit?

Elongated and cylindrical. Signup and view all the answers

Which characteristic is typical of the body segments of tapeworms?

Each segment may have both male and female sex organs. Signup and view all the answers

What is the role of the rostellum in tapeworms?

It helps in fixation. Signup and view all the answers

Study Notes

Parasitology - Lecture 2: Helminthology

Helminths are a group of parasitic worms
Platyhelminths (flatworms) include:
- Cestodes (tapeworms)
  - Live in the intestine
  - Example: Taenia, Echinococcus
- Trematodes (flukes)
  - Live in the liver, intestines
  - Example: Schistosoma, Fasciola
Nematodes (roundworms)
- Live in the intestines, skin, and other tissues.
- Examples: Ascaris, Trichuris, Ancylostoma, Necator, Enterobius, Strongyloides, Wuchereria, Onchocerca, Loa
- Live in either mature or immature forms in humans

Morphological Characteristics of Trematodes (Flukes)

Body: Flattened dorsoventrally (leaf-like), except Schistosoma (rounded female)
Body Cavity: Absent (no body cavity)
Segmentation: Unsegmented
Symmetry: Bilateral symmetry
Organs of Fixation: Oral sucker (anterior end), ventral sucker (ventral surface), spines to aid fixation
Digestive System: Mouth at anterior end, muscular pharynx, two intestinal caeca
Reproduction: Hermaphrodites (except Schistosoma, which is unisexual)

Morphological Characteristics of Cestodes (Tapeworms)

Body: Flattened dorsoventrally
Body Cavity: Absent
Segmentation: Segmented into scolex, neck, and strobila
Fixation: Scolex (head) with suckers or grooves (bothria), rostellum (terminal protuberance) with hooks
Reproduction: Hermaphrodite in each mature segment; cross- and auto-copulation
Strobila: The actively dividing part, which forms the segments (proglottids)

Morphological Characteristics of Nematodes (Roundworms)

Body: Cylindrical, rounded cross section
Body Cavity: Present (pseudocoelom)
Segmentation: Unsegmented
Sexes: Separate sexes (unisexual), females longer than males
Digestive System: Mouth, esophagus (various shapes), intestine that ends in the anus
Other characteristics: May have lips, papillae, buccal cavity, or teeth.

Differences Between Cestodes, Trematodes, and Nematodes

Shape: Tape-like (segmented) for cestodos, leaf-like/unsegmented for trematodes and Cylindrical for nematodes
Head End: Suckers/hooklets present, for cestodes and trematodes, but absent in nematodes.
Alimentary Canal: Absent in cestodes, incomplete/present in trematodes and complete in nematodes.
Body Cavity: Absent for both trematodes and cestodes and present in nematodes
Sexes: Monecious (except Schistosoma) for both trematodes and cestodes, and Diecious in nematodes

Life Cycle of Helminths:

Life cycles vary among different helminth species, often involving multiple hosts and larval stages.
Specifically, the diagrams illustrate the general stages of eggs, larval stage, and adult stage in Trematoda, Cestoda, and Nematoda; showing the involvement of intermediate hosts for some species.

Mode of Transmission of Helminthic Infections

Oral: Ingestion of contaminated food, water or infected fingers
Skin Penetration: Parasites that penetrate the skin
Vector: Transmission by various insects (e.g., mosquitos)
Direct: Person to person transmission
Vertical: Mother-to-child transmission.

Clinical Presentations of Helminthic Infections

Intestinal Flukes: Abdominal colic, diarrhea, vomiting, loss of appetite, weight loss, vitamin deficiencies.
Hepatobiliary Trematodes: Prolonged fever, right hypochondrium pain, jaundice, hepatomegaly.
Lung Trematodes: Chest pain, cough, dyspnea, hemoptysis, respiratory failure.
Blood Flukes (Schistosoma): Hepatosplenomegally, esophageal varices, hematemesis, melena.
Lymphatic Helminths: Elephantiasis.

Diagnosis of Helminthic Infections

Clinical presentation: (Symptoms, physical signs)
Laboratory: Microscopic examination of stool or sputum for eggs, larval stages.
Radiological: X-ray, ultrasound, CT, or MRI.
Serological tests: Detect antibodies in serum.
Skin tests: To detect specific hypersensitivity.

Questions

Which parasite is segmented and has no body cavity?: Cestoda
Which parasite needs a snail as an intermediate host?: Trematoda

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