What excretory organs are characteristic of nematodes. Type Roundworms (Nemathelminthes)

The type roundworms or Nemathelminthes are one of the most numerous in the animal kingdom. There are more than 20,000 species.

Turbellaria are considered their ancestors, but in the course of evolution, roundworms acquired special structural features, which allowed them to form a separate group.

The following classes are distinguished roundworms:

Nematode class;
Class Gastrointestinal;
Kinorinha class;
Hairy Class;
Rotifer class.

Features of the structure of roundworms

Sizes range from 80 microns to 8 meters. Females are usually larger than males. All representatives have bilateral symmetry.

The body shape is often cylindrical or fusiform, lack of segmentation is characteristic. A dense cuticle completely covers the outside of the body. The body cavity of roundworms is surrounded by a skin-muscle sac. It contains liquid that fills the space between internal organs... Serves as a support and carries out a transport function.

Digestive organs

The digestive system of roundworms has a more progressive structure. Roundworms are different from flatworms the presence of the anus. They also have a separate hindgut.

The digestive tract is divided into three parts: anterior, middle, and posterior. Food is absorbed through the mouth opening into the pharynx and esophagus. The digestion of the food lump takes place in the middle section, and after the absorption of nutrients, the remnants are excreted.

The movement of food is now carried out in only one direction, which contributed to better digestion.

Excretory system

The excretory function is performed by the cervical gland, a large unicellular formation, from which a pair of lateral tubules departs. They open outward excretory pores.

Ammonia is able to escape from the body of roundworms through the skin by diffusion.

Reproduction

Most representatives of the type are dioecious organisms. Often, females and males have different appearance(the phenomenon of sexual dimorphism). Development can be direct, without a larval stage, and indirect with a change of hosts.

The reproductive system of roundworms is presented in the form of tubes. In males, it is more often one tube, which is divided into specialized sections. First, the testis is located, where the production of spermatozoa takes place, which through the vas deferens enter the ejaculatory canal. It opens into the distal part of the intestine - the cloaca. With the help of the copulatory organs (cuticular needles), the sperm are removed to the outside.

The female reproductive tract consists of two paired tubes. They are blindly closed in the initial section, here are the ovaries, where there is a constant multiplication of germ cells. Gametes travel through the oviducts and enter the uterus, where internal fertilization takes place.

Roundworm eggs are surrounded by a thin shell, in rare cases it is thick. There are species capable of live birth.

Nervous system

It is represented by the periopharyngeal ring and longitudinal nerves. The ring is located in the pharyngeal region and serves as the main associative organ. The ventral and dorsal nerves extend directly from the main ganglion, and lie in the hypodermis, other nerve fibers are not associated with it.

The sense organs of roundworms are poorly developed. There is chemical reception, organs of touch, free living marine species have light-sensitive cells.

At the distal end of the body of roundworms there are tail glands, the secreted fluid of which is necessary for attachment to the substrate.

Also roundworms in their life cycle intermediate hosts are often used for full development. This is not typical of ringed worms. Ringed worms differ from roundworms by the presence of a closed circulatory system, represented by the abdominal and dorsal vessels.

Comparison of flat and round worms, their similarities and differences

The nutrition of nematodes depends on the lifestyle, some eat algae and bacteria, others feed on the host's body, there are also predatory species.

Significance in nature and human life

Roundworms are an integral part of food webs. Free-living individuals absorb bacteria, protozoa, and themselves become food for fish, crustaceans.

Species living in the ground feed on rotted organic matter, thus participating in soil formation.

Roundworms can infect fungi and plants, significantly reducing yields. Nematodes penetrate the root system and lead to the death of the rhizome, thereby inhibiting plant growth. The most frequently infected are cereals and vegetables (onion, potato, wheat nematodes).

In the animal kingdom. More than 80 thousand species have been described, but in reality, there are many more. Judging by the number of their appearance, adaptability to the environment and good survival, experts have come to the conclusion that this population has more than a million representatives. Nematodes have adapted to living in different sources, such as seas and reservoirs, soil, etc. Their presence in humans and animals causes enormous damage, and the worms themselves are capable of causing various diseases.

Roundworm digestive system

Nematodes or, simply put, round worms, unlike their relatives, are endowed with an anus. The intestine passes through the entire body of the helminth, taking the form of a straight tube. Food initially enters the pharynx (the beginning of the intestine), which is represented by the muscular walls.

As a rule, respiration in roundworms occurs through the entire body, since there is no circulatory system of blood supply. Accordingly, there is no need to transfer oxygen to all organs. The energy obtained from food is released due to the breakdown of glycogen - a substance that has an organic nature.

Allocation system

Nematode neurological map

The organs of touch and chemical perception are quite well developed. Nematodes have no sense organs.

Fertilization and reproduction system

Life cycle of a nematode

During their existence, roundworms go through five stages of development: four of them are larval and one is adult. All transitions are associated with a shift environment or by migration from one host to another.

Biohelminths

The main carriers are humans, apes and other mammals. Biohelminths are carried by various blood-sucking insects.

Phyllaria enter the bloodstream only when the carrier is most active. In the case of mosquitoes, this is evening and night time. The horsefly has morning and afternoon. When phylarians are transferred by midges or biting midges, their output does not have a specific period, and depends only on humidity.

The main types of roundworms

Wuchereria banctofti : in humans and monkeys, it concentrates in the blood arteries and lymph nodes. Leads to stagnation of blood and lymph. It is also the cause of the appearance of elephantiasis and allergies. The mosquito is the main vector.
Brugia malayi : the final owners are humans, some species of monkeys, the feline family. Pathogenicity and concentration is similar Wuchereria banctofti... Also transmitted by mosquitoes.
Oncocerca volvulus : carried by midges, and the carrier of the helminth is a person. Concentrates in the body under the skin of the head, chest, arms and legs. Promotes the formation of painful nodules. Concentrating in the area of the organs of vision - can cause blindness.
Loa loa : localized under the skin and mucous membranes in humans and monkeys, forms painful nodules and abscesses. Carried by horseflies.
Mansonella : concentrates in the body of the wearer, which is people, in the subcutaneous fat layer, the mesentery of the intestine and under the serous membranes. Carried by biting midges.

The most common types of roundworms are also worth mentioning.

Ascaris

Roundworm

The most common and most famous, infecting humans and animals, of the representatives of nematodes are considered. The worms infecting vegetation are potato, strawberry and other nematodes.

By their structure, nematodes are considered relatively simple organisms. An adult worm has approximately 1000 somatic cells and hundreds of cells that are associated with the reproductive system. Roundworms can be characterized as a “tube within a tube”, this is based on the location of the gastrointestinal tract, which starts from the head from the mouth to the caudal compartment to the anus. Nematodes have a digestive, nervous, excretory, reproductive system, but they do not have a dedicated circulatory and respiratory system. The sizes of worms range from small 0.3 mm to larger ones up to 8 meters.

Differs in a well-defined skin-muscle sac, consisting of hypodermis, cuticle and musculature. There are 4 hypodermal ridges on the back, peritoneum and sides. The dorsal and abdominal chords are filled with nerve trunks, the lateral chords are needed for excretion and are filled with sensory nerves.

Nervous system

Nervous system nematodes consist of a periopharyngeal ring, which is located at the beginning of the esophagus, six trunks branch off from it forward and backward. To connect both nerve trunks, there are thin half rings on the left and right sides of the body. They also have tactile organs and chemical senses.

Excretory system

In the assumptions described by scientists, it is said about the excretory system of unicellular nematodes that they have intracellular channels (pseudo-cellocytes) on the sides of the body, the cervical gland and waste products (ammonia) come out directly through the membrane.

Digestive system

The digestive system consists of the intestines, which runs through the entire torso in a straight tube. In front of it is the esophagus, which is subdivided into the stoma and the pharynx.

Nematode worms are heterosexual and have external sexual characteristics.

Females have a paired reproductive system. They have a uterus, vagina, oviduct, and ovaries. Roundworms are fertilized internally.

In the male, the tail part is twisted, the reproductive system consists of a tubular testis, which passes into the vas deferens and the ejaculation canal. For fertilization in males, spicules are located in the cloaca.

Reproduction

Nematodes reproduce mainly by mating, but hermaphrodites have the possibility of self-fertilization. Males, as a rule, are smaller than females or hermaphrodites, often their tail is curved or fan-shaped, which serves to capture and hold females. Mating occurs when one or more chitinous spicules emerge from the cloaca and enter the opening of the female. Thus, individuals transmit semen, which passes throughout the body of the male during the process.

Since many nematodes are not fully understood, and complete information is lacking, their classification is considered controversial and has been changed several times. In different descriptions, there is a conflicting classification of nematodes. Today it is considered the most modern classification international zoological journal Zootaxa and is presented in the following form:

All the described suborders contain several families, they are subdivided into genera and, accordingly, genera into species.

Habitat

Nematodes are ubiquitous. Round worms easily adapt to any ecosystem, which makes it possible for them to live in salty and fresh water, in the soil (ground), in the tropical zone and in the polar regions.

Infection of people

Ways of getting roundworms into the body

Failure to comply with the rules of personal hygiene, the use of dirty vegetables and fruits, poor-quality food and the use of contaminated water are sources of helminth infection.
Contact with insects can be a source of skin infection.

When infected with human nematodes, the following symptoms occur:

Stool disorder;
Nausea and gag reflex
Lack of appetite;
Dark circles appear under the eyes;
Discomfort (itching) in the anal area.

Infection of animals

Nematodes can affect all organs and tissues of the animal. Contamination is facilitated by:

Climatic conditions (habitats of worms);
The presence of intermediate hosts in the helminth;
Living conditions of the animal;
Lack of preventive measures.

Without following basic hygiene rules, people can become infected with hookworms from cats, dogs and other animals.

Plant infection

The most popular are these types of nematodes:

Plant pests are absolutely safe for humans.

Flatworms - tape cestodes (tapeworms, tapeworms), fluke flukes.
Roundworms - pinworms, roundworms, strongyloids, trichinella, hookworms.
Fungi-mycoses - penicilliums, candida, cryptococci.
The simplest are amoeba, lamblia, Trichomonas.
Bacteriosis - leptospira, staphylococcus, shigella.

Biological and epidemiological characteristics distinguish:

Distribution is distinguished:

Classification of helminths

The body of trematodes is strongly flattened, oval or oblong, no more than 8 cm. They are attached to tissues and organs with suction cups. They feed on blood cells, mucus. Waste products and nutrients that enter the body.

General characteristics of roundworms, what are nematodes and how to deal with them

Nematodes belong to the class of roundworms. The group is the second largest among the representatives of the multicellular diversity of living things on our planet. Let's take a closer look at what nematodes are, what they are. general characteristics round worms.

Details about nematodes

Features of the structure and life cycle

By their structure, all types of nematodes can be attributed to simple organisms.

Eggs laid by nematodes are oval in shape. Through this developmental stage, they are harmless. In eggs, larvae develop with their characteristic first life cycle. Once in the external environment, it matures and turns into a sexually mature individual.

Each type of roundworm has an individual feature of the structure and development cycle, a completely different way of life. This is influenced by the type to which certain individuals of nematodes belong.

Nematodes on plants

On animals

Nematodes in humans

Consider the most common nematodes in humans and helminthic diseases with them.

Ascaris

The causative agent of an unpleasant disease called ascariasis. The disease is very common - both adults and children are sick.

Roundworms can grow from 20 to 40 cm, the body of the worm is cylindrical and tapers towards the end. Refers to such types of geohelminths that live and feed on humans. Eggs that have undergone fertilization come out with feces, and for subsequent development they must get into the soil.

Pinworm

One of the causative agents of enterobiasis is a children's pinworm. Everyone can become infected with it, but most often children are infected with pinworms.

Nematodosis

Nematodes occur in humans after contact with carrier animals, ingestion of agricultural products that have not undergone the necessary processing.
Not observing hygienic rules, you can also become infected with nematodosis.

Hookworm

Infection is obtained from one type of nematode - strongyloids. Ankylostoma is a fairly ancient disease known since the times Ancient egypt... In another way, the ailment is called African cachexia, Egyptian chlorosis, anemia of miners.

Methods and methods of treatment

Having found symptoms that indicate the possible presence of a worm in the body, it is necessary to consult a specialist for confirmation of the diagnosis and the necessary treatment.

Doctors prescribe medication and calculate the dose based on the patient's weight. Usually, when taking anthelmintic drugs, you need to know the exact dose.

The widespread use of ruminator preparations for nematodes - magnesium sulfate, Glauber's salt, or containing plants (cassia holly, rhubarb).

The medicine for worms is often replaced with recipes common in traditional medicine. There are a number of plants that have been found to have anthelmintic properties. They are found in condiments and spices.
Recipes using Bogorodskaya grass, wormwood, tansy flowers are effective.

Garlic and onions are also often used to control nematode roundworms. Ginger has anthelmintic properties - its root is fresh, tincture and processed product.

Preventive measures

Nematodes and other helminthic diseases are always more difficult to treat than to prevent. Prevention of infection with roundworms is possible if the following rules are observed.

It is necessary to maintain cleanliness in the premises, in personal plots.
If there are pets, then you need to clean up the excrement in a timely manner.
It is necessary to dust regularly. You can use ultraviolet paws for disinfection of premises.
Outside, sand is mixed in sandboxes to provide access to the rays of the sun.
To carry out prophylaxis of pets, farm animals. It is best to do this once every 90 days for walking animals. For pets, prevention is carried out every six months.
You need to swim only in proven reservoirs.
Meat and fish products can be used for food only after they have undergone complete heat treatment.
Wash vegetables and fruits thoroughly. Root crops are first cleaned of adhering soil, then rinsed and peeled.
It is not recommended to use dirty dishes. For hiking, it is better to purchase disposable appliances.
Cesspools and waste water should be located away from houses and drinking sources in accordance with sanitary standards.
Hands should be washed regularly. Antibacterial soaps do not kill eggs and larvae of worms or even remove them. Children need to cut their nails short.
Each person should have their own linen, as well as bedding. If the work is carried out on a rotational basis, then it is necessary to thermally treat the linen by ironing.

Knowledge about nematodes and how to deal with them will help prevent disease or complications.

The human essence is so interesting that it strives to try everything right away, without even washing your hands, and then they are surprised at the multi-colored bouquet of diseases. This article will be devoted to nematodes.

What are nematodes?
Morphological signs of nematodes
Classification of roundworms that live in humans
Ways of human infection with nematodes
Clinical picture of helminthiasis
Diagnosing the disease
Drug therapy
Traditional therapy
Preventive actions
Varieties of roundworms in plants

What are nematodes?

Simple organisms, consisting of thousands of somatic cells and hundreds of cells responsible for the reproductive ability of an individual. Experts have defined nematode roundworms as "a tube in a tube." So they characterized them because of the digestive tract running along the entire length of the body.

Until now, science has not fully studied all types of roundworms, therefore, the systematization and classification has been modified many times as new knowledge about them is obtained.

Any suborder of helminth includes several families, then they are subdivided into genera and those already into species. Roundworms are ubiquitous.

Ways of human infection with nematodes

The defeat of human organs with round worms is a very dangerous disease that can even lead to mental abnormalities. Timely diagnosed and immediately started treatment will not make it possible to aggravate the situation and reduce to zero the protective function of the body.

Diagnosing the disease

Drug therapy

Helminthiasis is not a sentence. In the XXI century, pharmacology is very well developed, so it will not be difficult to overcome the disease. Any therapy, as well as drugs, is prescribed only by the attending physician after drawing up a complete history of the patient. Medications are taken based on body weight and require careful preliminary calculation, since in most cases they are toxic.

Thyme and thyme contain thymol, which gives off a specific aroma.
Ginger can be eaten fresh, as a spice supplement, or made into a tincture.
Garlic, onions are best insisted on vodka, then taken orally in the morning on an empty stomach. For children, it is recommended to make an infusion with water.
The inflorescences of tansy have a choleretic effect, so people with gallstone disease should be treated with caution.

Preventive actions

Now we know what nematodes are. It remains to take measures so as not to get infected. Almost every second family has a pet in the house, which, unfortunately, is also a carrier of worms.

In order to avoid the invasion of family members, long debilitating treatment, pets should be dewormed every quarter and a few more points should be followed:

Regular wet cleaning of the premises, cleaning of the local area, playgrounds, parks, squares from animal excrement, rotting products, garbage, where favorable conditions are created for the life of helminths. The hot summer sun helps to disinfect open surfaces, so it is enough to stir the sand in the children's sandbox every day in dry weather.
Avoid swimming in untested bodies of water, do not walk in hot weather without shoes.
Do not eat meat, fish that have not undergone heat treatment.
Wash fruits and vegetables using a brush. If possible, peel the fruit.
Do not draw water from roadside springs.

Competent prevention of infection should be aimed at destroying worms thanks to the banal rules of personal hygiene, high-quality disinfection of food.

Varieties of roundworms in plants

In addition to people, animals, plants suffer from nematode diseases. Harmful individuals settle in the ground, soil, plant tissue. They hit cultures not only in the wild nature, but also on farmland. Their size is microscopic - less than 2 mm. As agronomists and gardeners note, the characteristics of plant nematodes depend on the type of worm that infects various parts of the plant, but they are absolutely safe for humans.

Nematodes can infest not only garden lands, but also soil bought in a store, intended for planting indoor plants. Ultraviolet light emitted will help to overcome the disease sunlight... Do not forget about the treatment with chemical and biological remedies that garden shops offer in abundance.

Type Roundworms

Response plan:

General characteristics of Roundworms
The structure of the body of Ascaris human
Reproduction and development of Ascaris human
Roundworm classification, variety of species
The value of roundworms in nature and human life

General characteristics of Roundworms

Veils. Outside, the skin-muscular sac is covered with a protective sheath - cuticle. During the growth of worms, it is periodically discarded and then resumed. Under the cuticle is the hypodermis, which is the result of the fusion of skin cells. 4 ribbons of longitudinal muscles are located under the hypodermis. During contraction, the dorsal and abdominal bands act oppositely, and the body of the worm can bend in the dorsal-abdominal direction. The cuticle, hypodermis and muscles form a skin-muscular sac.

Digestive system. At the level of Roundworms in the evolution of the digestive system, a grandiose event takes place that made all subsequent types of animals happy. It is in Roundworms that the hindgut and anus first appear. Their digestive system now consists of three sections: the anterior, middle, and posterior intestines. The anterior region is usually divided into the mouth, muscular pharynx, and esophagus. Digestion takes place in the middle of the intestine. With the appearance of the anus, food begins to move in one direction, which makes it possible for various departments to specialize and more efficiently perform their digestive function.

Excretory organs- in some protonephridia, there is an excretory opening in the front of the body on the ventral side. Some representatives have modified skin glands, they are called "cervical glands". Some have no excretory organs.

Nervous system and senses... The nervous system is a ladder type (orthogon). It consists of a periopharyngeal nerve ring that surrounds the pharynx, and 6 nerve trunks extending forward and backward, of which the dorsal and abdominal are most strongly developed. The barrels are connected by jumpers (commissures). There are organs of touch, organs of chemical sense (smell). Free-living people have primitive eyes.

Reproduction. Most Roundworms are dioecious organisms, which provides genetic diversity in offspring. Sexual dimorphism occurs (females are outwardly different from males). Development is indirect, that is, with a larval stage, without a change of host.
The genitals are in the form of tubes. Male ones - testes, open by the vas deferens into the final section of the intestine - the cloaca. The male has copulatory organs - cuticular needles, with the help of which he introduces spermatozoa into the female genital tract. Fertilization is internal. In the female, the paired ovaries continue into the oviducts, which pass into two uterus, which open with a genital opening on the ventral side of the body.

Representatives: The type is divided into several classes, the most numerous among them is the class of Nematodes: Ascaris, pinworms.

The structure of the body of Ascaris human

New concepts and terms: cuticle, helminth, invasion, copulatory organs, sexual dimorphism, hydroskeleton, anus, detritophage.

Questions for consolidation.

Literature:

Bilich G.L., Kryzhanovsky V.A. Biology. Complete course... In 3 volumes - M .: LLC Publishing House "Onyx 21st Century", 2002
Pimenov A.V., Pimenova I.N. Zoology of invertebrates. Theory. Tasks. Answers .: Saratov, Lyceum Publishing House, 2005.
Chebyshev N.V., Kuznetsov S.V., Zaichikova S.G. Biology: a guide for university applicants. T.2. - M .: OOO "New Wave Publishing House", 1998.
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