Describe the function and morphological structure of roundworms, as well as their life history

Ascaris is a common digestive parasite in humans and other mammals, belonging to the Ascarididae family. They have a complex life cycle, including an adult stage that parasitizes inside the host body and a larval stage in the external environment.

Function**: The main function of roundworms is to absorb nutrients from the host, including sugars, fats, and proteins in food, as well as certain elements in the blood. Their presence can have a certain impact on the nutrient absorption and health of the host, and severe infections may lead to anemia, malnutrition, intestinal inflammation and even death.

Morphological structure**:

The body of roundworms is usually long cylindrical, and adult roundworms are usually between 15-35 cm in length. Their head has a retractable mouth suction cup that attaches to the host's intestines. There are longitudinal stripes on the surface of the body, which are formed when their muscle fibers contract.

Life History**:

The life cycle of roundworms consists of two main stages: the adult stage, which parasitizes the host, and the larval stage, which is in the external environment.

1.Adult stage: After the eggs of roundworms are swallowed by the host, larvae hatch in the intestines. The larvae pass through the intestinal wall into the bloodstream and then travel with the bloodstream to the lungs. In the lungs, the larvae continue to develop and eventually travel through the respiratory tract to the intestines, where they become adults.

2.Larval stage: In the external environment, the eggs and larvae of roundworms can survive in water and soil. If these larvae are swallowed by other animals or humans, they begin a new life cycle.

Infection with roundworms is usually due to ingestion of food or water contaminated with roundworm eggs. Ascaris infestation is common in developing countries and in some areas with poor sanitation. In these areas, public health measures are important to control the spread and infection of roundworms.

Roundworms are nematoids.

The body is composed of three germ layers, distributed in the northern and southern provinces, medium-sized individuals, the body is slender and rounded, the surface of the skin is transparent and many fine horizontal lines, and the oral cavity is irregular.

Morphology: Slightly pointed at one end, slightly blunt at the other.

Structure: egg shell, outer egg shell membrane, air cell, inner egg shell membrane, yolk frenulum, egg white, vitelline membrane, placenta, yolk,

The body is cylindrical, tapering towards both ends, the whole is milky white, and the lateral line is distinct. The female is 20-35 cm long, the male is 15-30 cm, the diameter is 5 mm, the male is short and thin, and the tail end is hooked.

It is parasitic in the small intestine of the human body and causes ascariasis, which is a large human parasitic nematode. Mature females and males mate in the small intestine to lay eggs.

The fertilized egg is excreted in the patient's feces and develops under suitable conditions, and it can infect a person with ascariasis, which is called an infected egg.

It is the morphological structure and life history characteristics of Tree Silver Ascaris and explains it.

Roundworms are adapted to parasitic life.

Ascaris body slender and long, sharp mouthparts are easy to wander around in the body, ascariasis is very dangerous and terrible, roundworms are anaerobic and have no respiratory organs and digestive organs, roundworms lay 100,000 eggs a day and have strong reproductive ability, and love to run around day and night.

The life of roundworms does not need to be judged by the middle ridge, and it is a direct poor sale development type ().

a.That's right. b.Mistake.

Correct Answer: a