What is the body shape of the nematode. Nematodes roundworms

Nematodes, other name - roundworms , belong to the type of primary cavity worms. Their diversity is very great. Currently, about a million species of this worm have been discovered.

They were called round because a cross section produces a circle. Their body is shrouded in a dense cuticle, longitudinal muscles are located under it. This can be clearly seen in photo of nematode.

There is no circulatory or respiratory system. Breathing is performed by the entire plane of the body or anaerobically. The digestive system is simple and consists of a mouth and anus, between which there is a straight tube.

There is a "mouth" on the head, which is surrounded by lips. Through it, nutrition occurs: food is sucked in. Several species of free-living nematodes also have developed eyes, which can be with different color pigments. The size of the body of worms ranges on average from 1 mm to 37 cm.

In the photo, the structure of the nematode

Nematodes demonstrate a prime example biological progress. Today they live in all environments. Starting from the salty bottom of the ocean, as a result of evolution, they conquered fresh water bodies, soil, and now they can live and breed in any multicellular organism.

The nature and lifestyle of nematodes

Inhabited in the body of the “owner”, it is able to cause various diseases, but not fatal. Nematode uses his food and body for life, and in order not to cause additional harm, he takes his eggs out of organism"owner". Thus, acquiring an intermediate, and settling over a larger territory.

To survive, all worms nematode class, has additional adaptations that he received as a result of evolution. Its dense shell protects against the action of digestive juices, females are very prolific, special organs for attachment. Some of the nematode species are successfully used to exterminate "harmful" worms.

Types of nematodes

Free-living nematodes number most types of roundworms. All of them are small in size, the giants reach only 3 cm. They can live in any liquid, even in vinegar.

When quite low temperatures even at the North Pole. Many nematodes living in soils provide undoubted benefits and play a major role in the process of soil formation.

These nematodes found and in aquarium. They are excellent food for fry. They are grown on purpose or they reproduce themselves by overfeeding or in accumulations of rotting garbage.

Feeding nematodes

Nematodes pierce tissue with them and inject their digestive juice, and then suck in food. This is called extraintestinal digestion. Nematodes that are in the body of the "owner" exist due to nutrients produced by them. What nematodes simply use for their growth and development.

Reproduction and life span of nematodes

Basically everything nematode types heterosexual. Males are smaller than females, and the rear end is slightly twisted to the side. Reproduction takes place sexually. Some species of females, when ready to mate, emit a strong odor to which the male reacts.

On the photo of the nematode in the fish

The beginning of the life cycle of the nematode begins in the intestine, after fertilization of the female. She descends into the rectum, where she lays her eggs in the anus. After that, she dies. The eggs themselves mature in about 6 hours under favorable conditions.

Through dirty hands they fall into gastrointestinal tract again, re-infection occurs. Turning into larvae, after 2 weeks they become sexually mature individuals.

Depending on the type of nematodes, the following gradations of their life cycle are distinguished:

Eggs, immediately after laying them by the female, can infect if they enter the animal's body.
Eggs in which the embryo must go through an additional stage, after which it is able to infect the "host".
Eggs in which the larva matures and enters the soil, after which it enters the body. On average, the life of any nematode lasts about 2-3 weeks.

Symptoms and treatment for nematodes

This may be damage to the intestinal walls and blockage of the bile ducts, which is manifested by stool disorder, pain in the navel or wandering, nausea and vomiting.

Further, nematodes, entering the bloodstream, migrating throughout the human body, are able to affect absolutely any of its organs. Therefore, the symptoms can be both shortness of breath and conjunctivitis, and muscle pain. The development of a general reaction of the body is also characteristic: allergic rashes, itching, decreased immunity, a feeling of constant weakness and nausea.

Treatment from nematodes carried out with drugs or oxygen therapy. The drugs are usually quite toxic, so they are prescribed by a doctor. With oxygen therapy, oxygen is introduced into the intestine, and the nematodes die without medical treatment.

In dogs, these are: vomiting, specific yellowish mucous diarrhea; increased appetite; tail biting; lethargy and apathy. When these symptoms appear, it is necessary to take the animal to the veterinarian, where he will prescribe drug treatment.

The digestive system, like all nemathelminths, consists of three sections: anterior, middle and posterior. The anterior section begins with the mouth, is of ectodermal origin, and is usually divided into the oral cavity, pharynx, and esophagus. Digestion occurs in the middle part of the intestine, formed by a single-layer epithelium of endodermal origin. The hind gut, like the anterior section, is of ectodermal origin and ends with an anus (Fig. 1).

Rice. 2. excretory system
nematodes:
1 - two-celled "cervical" gland,
2 - unicellular "cervical" gland,
3 - phagocytic cells.

The excretory system consists of 1-2 giant cells of the hypodermis, which are called the "cervical" glands. Two longitudinal canals extend from the "cervical" gland, located in the lateral ridges of the hypodermis. In the anterior part of the body there is a transverse canal connecting these longitudinal canals and opening outwards with the excretory pore. In the anterior part of the body, near the excretory canals, there are one or two pairs of large phagocytic cells that capture and accumulate metabolic products in solid form in their cytoplasm (Fig. 2).

The nervous system consists of the peripharyngeal nerve ring and the dorsal and ventral nerve trunks extending from it. The nervous system is made up of a small number nerve cells, which testifies to its primitiveness. The sense organs are poorly developed. Free-living species have organs of touch in the form of tubercles (papillae), organs of chemical sense (amphids).

Nematodes are dioecious animals. The reproductive organs have a tubular structure. The male reproductive system includes one testis, one vas deferens, one ejaculatory canal that opens into the final section of the intestine - the cloaca. Most species have copulatory organs - spicules and rudders.

The female reproductive system includes two ovaries, two oviducts, and two uteruses. The uterus merges with each other, forming an unpaired vagina, which opens with a genital opening on the ventral side of the body. Fertilization is internal, in the uterus.

Females lay eggs or give birth to larvae. Larvae are similar to adults, development without metamorphosis. The larvae molt as they grow, shedding the cuticle, after the last molt they develop into females and males.

Ascaris human (Ascaris lumbricoides) causes ascariasis. Localization of sexually mature roundworms is the human small intestine. Females reach a length of 40 cm, males - 25 cm. In males, the posterior end is pointed and bent to the ventral side. Ascaris feed on intestinal contents.

The female roundworm lays over 200,000 eggs per day. Under favorable conditions (enough high humidity, temperature 20-25°C, obligatory presence of oxygen) after 21-24 days, a mobile larva is formed in the egg. Such an egg is dangerous to humans and is called invasive.

Infection of a person occurs by swallowing invasive eggs, which can be found on unwashed vegetables and fruits, dirty hands. In the small intestine, the larvae are released from the shell, penetrate the intestinal wall into the blood vessels and migrate throughout the body.

Rice. 3. Intestinal blockage
human ball of ascaris

With the blood flow, the larvae first enter the liver, then through the inferior vena cava - into the right atrium, then into the right ventricle and through the pulmonary arteries into the capillaries of the pulmonary alveoli. Starting from this moment, the larvae begin active movement. By drilling into tissues, they penetrate into the cavity of the alveoli, ascend through the bronchioles, bronchi, trachea, and into the pharynx. In the pharynx, together with saliva, they are swallowed again. Once again in the intestines, the larvae turn into sexually mature forms.

Migration of larvae lasts 9-12 days. During this time, the larvae grow and molt several times. The life expectancy of sexually mature roundworms is about 1 year.

Ascaris poisons the human body with poisonous products of its metabolism and, penetrating into various organs and cavities, mechanically damages them. A large number of them can cause blockage of the intestine (Fig. 3). Migrating larvae cause foci of hemorrhage and inflammation in the lungs.

Laboratory diagnosis is based on the detection of eggs in feces.

Pinworm (Enterobius vermicularis) causes enterobiasis. Enterobiasis is the most common helminthiasis, especially common in children. The localization of sexually mature pinworms is the lower sections of the small and the initial sections of the human large intestine. The body length of the female is up to 12 mm, that of the male is up to 5 mm (Fig. 4). Pinworms feed on intestinal contents.

Rice. four.
A is a female
B is a male.

After fertilization, the males die. Females for laying eggs actively crawl out of the anus to the surface of the skin of the host's perineum. The release of pinworms usually occurs at night and is accompanied by severe itching. Eggs (up to 13,000 pieces) are laid on the skin and stick to it. After laying eggs, the female dies. For further development laid eggs need a special microclimate: high humidity and temperature of 34-36°C. Such conditions exist in the perianal folds of the skin and perineum of a person, the eggs located here become infective after 4-6 hours. Combing itchy places, a sick person puts the eggs of this helminth under his nails, where there are also high temperatures and humidity.

Infection of a person occurs by swallowing invasive pinworm eggs, which can be on household items, toys, hands, etc.

In the intestines, larvae emerge from the eggs, which reach sexual maturity after 2 weeks. The life span of pinworms is approximately 30 days. It can be difficult to cure enterobiasis, since re-infection often occurs.

Laboratory diagnosis is based on the detection of eggs in scrapings from perianal skin folds. After studying, the used materials are burned.

Rice. 5.
A is a female
B is a male.

Vlasoglav (Trichocephalus trichiurus) causes trichuriasis disease. Localization - the caecum, the initial section of the human colon. The body length of the female is up to 5.5 cm, the male is up to 5 cm (Fig. 5). The anterior end of the body is sharply narrowed, looks like a hair (hence the name of the helminth), the posterior end is thickened. The front end of the whipworm is introduced into the mucous membrane of the intestinal wall and feeds on blood. Eggs laid in the intestinal lumen for their further development must necessarily fall into the external environment. The conditions for the maturation of eggs and the method of human infection are the same as with ascariasis. The life span of the whipworm in the host organism is approximately 5 years.

Rice. 6.
A - female, B - cyclops with a guinea worm larva,
B - female, partially extracted from
lower limb, D - extracted guinea worms.

Rishta is a biohelminth, that is, its development occurs with a change of owners. final host- man, monkeys, dogs. Intermediate - freshwater copepods (cyclops). The female rishta with formed larvae brings the head end closer to the surface of the host's skin, where a bubble 2-7 cm in diameter is formed. Upon contact of a person with water, the bladder opens, the female puts forward the anterior end, and through gaps in her integument, the larvae enter the water. For further development, the larva must enter the body of the cyclops. Human infection occurs by accidental ingestion of cyclops with larvae along with water. Once in the human body, the larva perforates the intestinal wall, penetrates into the bloodstream and migrates through the blood vessels to the subcutaneous fatty tissue. lower extremities. It is assumed that during migration, the larvae grow, turn into sexually mature forms, and fertilization occurs, after which the males die.

For diagnosis, special methods are not required, since the helminth is clearly visible through the skin.

Rice. 7. Larva
trichinella,
encapsulated in
muscle fibre.

Sexually mature forms live in the small intestine of the host, larval forms - in some muscle groups. The length of the female is 3-4 mm, the male is 1.5-2 mm. The females are viviparous. The life span of females and males is approximately four weeks. Males die after fertilization, females after the birth of larvae. The larvae are carried by the blood stream throughout the body and stop in the skeletal muscles, the diaphragm, masticatory, intercostal and deltoid muscles are most often affected. After some time, a capsule is formed around the larva due to the surrounding tissue. A year later, the wall of the capsule is calcified. Inside such a capsule, the larva remains viable for 20–25 years (Fig. 7). To become sexually mature, the larvae must enter the intestines of another host. If an animal with encapsulated larvae in its muscles is eaten by another animal, the capsules dissolve in the intestines of that second host and the larvae are released. After 2-3 weeks they become adult females and males. After fertilization, females give birth to a new generation of larvae (one female - up to 2000 larvae).

Human infection occurs when eating trichinella meat of pigs, wild boars, bears. Initial period disease is associated with the migration of born larvae and toxic effect their metabolic products. This period is characterized by high fever, gastrointestinal disorders, swelling of the face. Later, muscle pain and cramps appear. In mild cases, pain disappears after 3-4 weeks. With intense infection, death is possible.

Roundworms, or nematodes (Greek "nema" - thread), have an elongated body in the form of a string or thread, round in cross section. This group of worms, like flatworms, belongs to protostomes.

Since roundworms originated from, they retained some commonality with them in structure. For example, both have no respiratory and circulatory organs, and their eyes are so poorly developed that they can only distinguish light from darkness. At the same time, the muscular and nervous systems of nematodes have undergone a number of simplifications in terms of their level of development. They do not have transverse muscles and true ganglionic nodes, so the movements of roundworms do not differ in variety. Nematodes are easily recognizable by the snake-like, “dangling” vibrations from side to side, which occur as a result of the alternating contraction of longitudinally running muscle cords. If these muscles act simultaneously, then the nematodes are able to slightly shorten or lengthen.

Coagulation is also possible for them if one muscle contracts. In addition to the shape of the body, nematodes have a number of features of the internal structure, which make it possible to reveal the features of further complication of the organization of roundworms in comparison with flatworms, in particular with planarians. In the process of evolution, nematodes developed a real body cavity, in which there is a cavity fluid that washes the internal organs of digestion and reproduction located in it. However, this cavity does not have its own walls (epithelium) and is formed from the cavity of the blastula (blastocoel), which indicates that it belongs to the primary cavity.

The body of the nematodes is not segmented, spindle-shaped - tapering towards the anterior and posterior ends, in cross section - round. The mouth is located apically at the anterior end of the body. An anus is located at the posterior end of the body in front of the tail section.

The body is covered with a multi-layered elastic transparent cuticle, which is secreted by the integumentary epithelium - the hypodermis. Usually the hypodermis is syncytial (the boundaries between cells disappear), but it can also have cellular structure. Along the circumference of the body of the worm, the hypodermis forms four ridges protruding into the body cavity. According to their position, these are dorsal, ventral, and two lateral ridges. The ridges of the hypodermis divide the layer of longitudinal muscles into four longitudinal strands, respectively, two - dorsal, two - ventral. The contractions of the dorsal and ventral muscle bands are antagonistic, so the body bends in the dorsoventral plane and the worm moves on its side. Muscle cells are very large, consisting of a cytoplasmic part, directed into the body cavity, and a contractile part, in which muscle fibrils are located. The contractile parts of the cells are adjacent to the hypodermis. The cuticle, hypodermis, and longitudinal musculature form a skin-muscular sac.

Between the musculocutaneous sac and internal organs there is a large cavity. It is the primary body cavity. The primary body cavity does not have its own epithelial lining; it is formed as a result of the collapse of the parenchyma (schisocoel). The body cavity is filled with fluid under pressure. Functions of the primary body cavity: supporting (liquid internal skeleton), distribution (transport of nutrients from the intestines to tissues and organs, as well as gas exchange), excretory (transport of metabolic products to the excretory organs).

Nematodes are characterized by the complete absence of ciliary formations in the body - even their spermatozoa lack flagella. The reduction of the ciliated epithelium occurred due to the strong cuticleization of the integument of these animals.

The excretory system is formed by unicellular cutaneous (cervical) glands, which are modified protonephridia (cells without a flickering "flame"). In the body cavity, there is usually one such cell, the duct of which opens with an excretory pore on the surface of the worm's body. In large nematodes (for example, ascarids), the cervical gland is associated with long excretory canals that lie in the lateral ridges of the hypodermis. In nematodes, the excretory function is also performed by special phagocytic cells located in the body cavity and not connected with external environment. These cells throughout the life of the worm accumulate insoluble metabolic products and foreign particles. This method of excretion is called "accumulation kidney".

Nematodes have separate sexes, sexual dimorphism is clearly expressed (difference in appearance between females and males). The genital organs are paired, have a tubular structure. In females, the ovaries pass into the oviducts, the oviducts into the uterus, which, merging, are connected to the unpaired vagina. The vagina opens with the female genital opening, approximately in the middle of the ventral side of the body. In males, the paired testes pass into the vas deferens, which merge and form a muscular ejaculatory canal. The ejaculatory canal opens with the male genital opening into the cloaca located at the posterior end of the body. Fertilization is internal.

The development of nematodes proceeds with metamorphosis: 4 larval and 1 adult stages are necessarily present in the life cycle. The transition from stage to stage is made in the process of molting - dropping the old cuticle.

Gastrotrichous are very small, worm-like animals. They live in freshwater and marine waters. Cilia are located on the ventral side of the body, with the help of which animals move. At the posterior end of the body are adhesive glands. There is no continuous skin-muscular sac. The intestine is through, digestion is intracellular. Excretory organs - two protonephridia. The nervous system is formed by the brain ganglion and two longitudinal nerve trunks. Hermaphrodites or parthenogenetic females.

Kinoryncha class

Cynorhynchus are small, worm-shaped organisms that live in the sand at the bottom of the seas. The body is covered with chitinous plates arranged in transverse rows, so the animals have a characteristic segmented appearance. The body consists of a head, with a corolla of hooks or spines, a neck, and 11 segments. The skin-muscular sac is absent. The muscles are striated. The excretory system is formed by one pair of protonephridia. The front part of the body can turn out in the form of a proboscis. Intestine through. The nervous system is represented by the peripharyngeal nerve ring and the ventral nerve trunk. Sex glands are paired, animals have separate sexes, development proceeds with metamorphosis. Growth and development is accompanied by molting.

Hairy class (Gordiacea)

Hairy have a very thin long body, resembling a hair. The adults are dark in color, while the larvae are whitish. The body of the hairy is covered with a cuticle, which is secreted by the hypodermis, the muscles are only longitudinal. The space inside the skin-muscle sac is filled with parenchyma, in which there are free cavities, which are the primary cavity of the body. The intestines are completely or partially reduced, nutrition occurs through the entire surface of the body, visually. There is no excretory system. The nervous system is formed by the peripharyngeal nerve ring and the ventral nerve trunk.

The head section can be retracted into the trunk. The torso is dressed in a dense shell, it houses the internal organs. The leg is jointed, muscular, ends with two movable fingers. At the level of the fingers, special cement glands open, secreting a sticky secret, with the help of which rotifers can temporarily or permanently attach themselves to the substrate. The skin-muscular sac is absent, the striated muscles are represented by separate strands. The body cavity is primary.

The mouth leads into a muscular pharynx. In the pharynx there is a chewing apparatus (mastax), characteristic only for rotifers, formed by four chitinous plates of various shapes. With the help of mastax, animals grind food. The pharynx passes into the esophagus. The pharynx and esophagus make up the foregut. The midgut begins with a voluminous stomach, which leads to a narrow hindgut. The hindgut opens with an anus into the cloaca. The excretory system is protonephridial, there are fiery cells.

The nervous system consists of a large supraesophageal ganglion and nerves extending from it. The sense organs are represented by the organs of touch and sight.

Rotifers have separate sexes, sexual dimorphism is pronounced. The gonadal ducts open into the cloaca. Animals lay large eggs, there are viviparous species. Males are dwarf, do not feed, are unknown in some groups. Life cycle represents the alternation of the sexual generation (males and females) and the parthenogenetic generation (only females). Rotifers serve as food for fish fry and aquatic invertebrates.

frog nematode

Onion stem nematode

potato nematode

The potato nematode belongs to the genus of root-knot nematodes. The male has a cylindrical worm-shaped body, and the female is spherical. Unlike mobile males, females are immobile. They form a cyst filled with eggs (200-800 pieces), wintering in the soil. In the spring, larvae emerge from the eggs; after the third molt they become sexually mature. Larvae and adults damage not only potatoes, but also tomatoes and cucumbers. Affected plants develop root tumors surrounding the nematode body. Stems lag behind in growth, leaves turn yellow and wither, tubers and fruits become smaller or do not form at all. Gall nematodes infect greenhouse, garden, melon, fruit and berry and technical crops.

The fight against nematodes - pests of agricultural crops is difficult and complex, it requires various agrotechnical measures, sorting tubers and bulbs in storage, maintaining a certain regime in them, selecting seed, etc.

Question 1. What is the body shape of a nematode?
The shape of the body of nematodes is spindle-shaped, since their body usually tapers towards both ends. The cross section of the body is round.

Question 2. What are the structural features of the nematode.
In the structure of the nematode, the following features can be noted:
- the body is non-segmented, covered with a dense cuticle;
- the skin-muscular sac contains a weakly expressed annular and well-developed longitudinal muscles in the form of four ribbons (bending and unbending the body in the dorsal-abdominal direction, nematodes can crawl forward, lying on their side);
- there is a cavity between the layer of muscles and internal organs; this primary body cavity performs the functions of the internal environment of the body and the hydroskeleton, provides intestinal movement independent of the body walls and participates in metabolism and their transport;
- the mouth opening is located at the front end of the body;
- excretory system represented by unicellular skin glands, - emitting soluble metabolic products;
- no circulatory and respiratory systems;
- nervous system formed by the peripharyngeal nerve ring with several nerve trunks;
- the reproductive system is represented by the ovaries and testes; as a rule, nematodes are dioecious;
- The sense organs are poorly developed.

Question 3. What is a cuticle? What is its meaning?
The cuticle is a dense multilayer non-cellular formation on the surface of the body. It is a kind of external skeleton, which creates a support for the muscles. The protective role of the cuticle is also important: it protects the body from mechanical damage and toxic substances.

Question 4. What is the role of the body cavity?
The body cavity plays an important role in metabolic processes. Through it, the digested substances and food are transported from the intestines to the muscles and the reproductive system; the removal of metabolic products to the excretory organs is also partially carried out. Thus, the fluid that fills the body cavity takes on the function of the internal environment of the body, like blood.

Question 5. How is the nervous system of nematodes arranged?
The nervous system of nematodes is formed by a near-pharyngeal nerve ring surrounding the anterior part of the esophagus. Several short branches extend forward from the ring; six trunks are sent back, and two of them, passing along the median dorsal and abdominal lines, are more powerful than the others. Both main nerve trunks are interconnected by numerous jumpers, which look like thin half-rings encircling the body.

Question 6. What departments make up the digestive system of roundworms?
The digestive system begins with a mouth opening located at the front end of the body. The intestines form a straight tube that runs through the entire body. Its anterior section is subdivided into the oral cavity and pharynx. The pharynx is followed by a poorly differentiated intestine ending in the anus.

Question 7. Describe the development of roundworm.
Getting into the faeces environment, eggs with access to oxygen in humid conditions and with enough high temperature(about 25 ° C) develop, and a larva forms under their shell. The latter in egg shells enters the human digestive system. In the small intestine, it is released from the membranes, penetrates into the intestinal wall and enters the bloodstream. With the blood flow it is transferred to the liver, heart and through the pulmonary arteries to the lungs. In the lungs, the larva enters the bronchi, causing inflammation, accompanied by a cough. With sputum, the larvae enter the oral cavity, and then swallowed again with saliva. Adult sexually mature roundworms develop in the intestine.

Question 8. How can you get infected with ascaris?
Common house flies play an important role in spreading roundworm eggs and infecting people with them. Eggs can enter the human body from unwashed hands, from contaminated water, from unwashed vegetables and fruits.

Question 9. What hygiene measures should be observed to prevent ascariasis?
Hygienic measures to prevent ascariasis: compliance with the rules of personal hygiene; disposal of faeces used as fertilizers; sanitary improvement of dwellings (water supply, sewerage); cleaning drinking water; systematic medical examinations.

The solution contains answers to the questions of the educational edition and is made in an easy-to-read PDF format.

Type roundworms, or nematodes, are thought to have evolved from turbellarians. Evolving, this class acquired a peculiar structure, which is strikingly different from the structure flatworms. This fact forces us to consider nematodes as a separate specimen of the animal world. Since the relationship of nematodes with the groups standing above has not been proven, they are considered a side branch of the animal family tree. This type has more than 10,000 species of organisms.

In the general characteristics of roundworms, attention is focused on external structure. From the point of view of medicine, roundworms are of great interest, since only they contain forms that are pathogenic to the human body.

Such a peculiar structure allows them to crawl freely, bend the body in different directions. A characteristic of the type of roundworms shows that they lack blood and respiratory system. These organisms breathe through their bodies.

Digestive system

The digestive system of roundworms resembles a tube, that is, it is through. Starting from oral cavity, gradually passes into the esophagus, then into the anterior, middle and hindgut. The hindgut ends with an anus on the other side of the body.

Many representatives of roundworms have a terminal mouth opening, in some cases it is displaced to the ventral or dorsal side.

Selection system

breeding system

The nematode has a reproductive system with a tubular structure. These organisms are heterogeneous. Males have only one tube, different sections of which perform different functions. The narrowest section is the testis, which, in turn, is divided into two sections - reproduction and growth. Next is the seed tube, and the channel for the eruption of the seed.

Females have a 2-tubular reproductive system. One tube, ending in a dead end, plays the role of an ovary, it is filled with germ cells capable of reproduction. This organ flows into a larger department, which plays the role of the oviduct. The largest section of the female reproductive system is the uterus. Two uterus, connecting with each other, form a vagina, access to which is open on the front of the body.

Females and males differ significantly in outward signs. Males tend to be smaller and the back of the body in many is twisted towards the side of the belly. In most species of nematodes, reproduction is viviparous - females carry an egg in the uterus until the larva hatches from it.

Nervous system

The nervous system of roundworms is a nerve ring, nerve trunks branch off from it. Of these, the ventral and dorsal trunks are the most developed.

Life cycle

Nematodes in humans in the body cause diseases called hookworms, many of which pose a serious threat to health. There are classes of roundworms that are most common among humans.

Roundworm

An egg produced by an ascaris enters a person with unwashed vegetables or berries, on which they fell, respectively, from the ground. A larva hatches from the egg, and begins its journey through the human body. It has the ability to pass through the walls of the intestine, penetrates into the vessels, with the blood flow enters the liver, atrium and lungs. In order to develop safely, roundworms need oxygen, so the larvae migrate to the pulmonary alveoli, and from there to the bronchi and trachea.

The waste products of ascaris are very toxic, so patients may experience a strong headache, constant fatigue, outbursts of irritability. In addition, ascariasis often provokes intestinal obstruction.

Very common helminths, small nematodes white color. The size of males is no more than 3 mm, females reach a length of 12 mm. Infection with pinworms can occur due to non-compliance with the rules of hygiene, so the victims are most often babies visiting Kindergarten. The patient is tormented by severe itching, he combs the skin to the blood, pinworm eggs remain on the hands and under the nails, after which they are transferred to household items and food.

The structure of roundworms of this species is such that they cling tightly to the walls of the intestine and feed not only on its contents, but also on blood. Toxins released by pinworms can cause headaches, insomnia, fatigue and dizziness, and allergies.

Through the blood vessels, the crooked head enters the heart, from there to the lungs, upper Airways and throat. Together with saliva, they penetrate the esophagus, then the stomach, the destination is the duodenum. This type of nematode can enter the body in two ways - either with contaminated food and water, or through the skin. Soon after entering the body, the patient begins to suffer from pain in the duodenum, there is indigestion, fatigue, headache, depression, impaired memory and attention. In the absence of timely treatment, this disease can be fatal.

How to deal with the penetration of nematodes into the body? Prevention measures are quite simple, but, nevertheless, require strict adherence:

do not neglect the rules of personal hygiene, wash your hands with hot water and soap as often as possible;
carefully process all vegetables, fruits and berries before eating (to protect yourself, you need to put them in boiling water for 3 seconds, or for 10 seconds in hot water then rinse thoroughly with cold water).
it is not recommended to use human and pig feces that have not gone through the composting process as garden fertilizer;
cut nails for adults and children as often as possible, change bed linen and underwear daily.

Nematodes are an integral part of nature, and it is impossible to eliminate them, but with the help of simple measures, you can protect yourself from their invasion into the body.