Subject: Type Roundworms (Nemathelminthes). Class Nematoda (Nematoda)

Some of the species of flukes are dangerous to humans due to damage to vital important organs. Flukes are able to live inside a person for years without causing any symptoms.

Kinds

There are the following types of helminths:

• roundworms (nematodes);
• tapeworms (cestodes);
• flukes (trematodes).

• liver fluke (fasciola);
• cat fluke (causative agent of opisthorchiasis);
• schistosoma (causative agent of schistosomiasis).

The digestive organs of flukes form a bag with 2 blindly closed channels. They do not have a circulatory system, so nutrients are distributed due to the presence of a flattened body. In some helminths (liver fluke), the intestines have many branches, due to which food is promoted.

Infection with cat fluke

Trematodes include the causative agent of opisthorchiasis Opisthorchis felineus. The cat fluke has the following distinctive features:

• up to 20 mm long, 2 mm wide;
• has a pointed front;
• has a device for fixation in the organs (2 suction cups);
• is a hermaphrodite;
• does not reproduce in the body of the final host;
• develops with the change of 2 hosts (mollusks, cyprinids);
• distributed almost everywhere;
• lives up to 25 years.

The digestive organs of the helminth are represented by the oral cavity, pharynx, esophagus, and intestines. The source of infection (aka the definitive host) excretes the eggs in the faeces. They fall into the ground, water. Freshwater mollusks swallow eggs, become infected. The larvae penetrate the body of their first intermediate hosts and enter the carp family (carp, roach, ide, bream, minnow).

A person becomes infected while eating fish that has not undergone proper heat treatment. It is also dangerous to eat stroganina, fish kebabs, salted foods (fish meat, caviar). Such a fluke lives in the human liver, biliary tract ducts of the pancreas. Acute stage The disease is manifested by the following symptoms:

• fever;
• chills;
• sweating;
• pain in the joints, muscles, hypochondrium on the right;
• dyspepsia;
• rash;
• weight loss.

In a chronic course, the pain becomes constant. Patients complain of headache, tremor, depression, nausea, impaired stool, lack of appetite.

Schistosomes

Schistosomes live in the genitourinary system, human intestines. These flatworms are transmitted to humans mainly by the percutaneous route, that is, through skin while bathing.

The active movement of schistosome larvae provides a high human susceptibility and the risk of infection. Infection often occurs when swallowing contaminated water, washing, eating food washed with dirty water. The body length reaches 20 mm. The females are larger. Eggs oval shape 0.1 mm.

Intestinal schistosomes cause abdominal pain, diarrhea, bloody stools, and liver enlargement.

IN acute phase illness, the temperature rises, cough and rash appear. Often suffers genitourinary system. Schistosomes cause dysuria (frequent urination, with pain, burning), bleeding from the vagina, pain during sexual intercourse, blood in the urine. In men and women, the reproductive system suffers: prostatitis, epididymitis, vesiculitis, colpitis develops. Such flukes can cause cystitis, pyelonephritis, infertility.

What are dangerous

Thus, flukes are a separate group of helminths that are dangerous to humans. To exclude infection, you need to wash vegetables, berries, fruits. Do not swim in dirty waters, do not walk barefoot on the ground in exotic countries. Drink only boiled water, wash your hands often. You can protect yourself from opisthorchiasis by boiling or frying fish for a long time before eating it.

Characteristics and structural features of roundworms

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 a medical point of view, roundworms are of great interest, since only they contain forms that are pathogenic for 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

Digestive system 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 areas which perform various 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 part 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. The larva hatches from the egg, and begins its journey along 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 of enterobiasis 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 duodenum, there is indigestion, fatigue, headache, depression, impaired memory and attention. With absence timely treatment this disease can lead to death.

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 as often as possible hot water with soap;
• 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.

General characteristics of round and flatworms

general characteristics

Common features for the class roundworms and flatworms are:

• Indirect life cycle. Flatworms and roundworms are born from eggs laid by hermaphrodite adults. They live almost everywhere. To complete the cycle of transformation into an adult, the larva needs to go through several stages. For various kinds flatworms, this requires the presence of a so-called "intermediate" host, that is, an animal (carnivorous or domestic), a mollusk or an insect in whose body the larva turns into a sexually mature unit. Only after the completion of the transformation cycle are flatworms dangerous to humans.
• Structure. Both varieties of worms lack excretory and circulatory system. Settling in the body of the "owner", helminths excrete waste products through the mouth opening.

However, it is typical for worms to a large number of differences:

Nutrition. The first thing that distinguishes representatives of both classes is the structural features of the digestive system. In flatworms, for example, digestive tract presented in the form of a very branched tube, but they do not have an anus. In roundworms, the digestive system is in the form of a tube, beginning with the mouth and ending with the anus. Another feature due to which helminths of both classes differ from each other is the ability of flatworms to feed on the entire surface of the body. This mainly concerns flukes, which are attached to the walls of the internal organs of a person or animal and feed on blood.

reproduction features. Most flatworms are hermaphrodites. This means that both male and female germ cells develop in the body of one individual, although this does not happen at the same time. However, later adult the presence of a partner is not necessary to reproduce offspring. But among roundworms there are both males and females.

Nervous system. “Do worms have a brain?” is one of the most common questions on thematic forums. True, the answer to it is somewhat unexpected: worms do have some semblance of a brain. In flatworms, it is represented by the so-called "brain ganglion" (knot of nerve endings), from which longitudinal trunks extend. In roundworms, the number of such trunks is much smaller, and instead of the brain ganglion, a peripharyngeal ring is located in the anterior part of the body.

Additional accessories. The movement of helminths inside the human or animal body is carried out due to the presence of special devices. For this, flatworms have special hooks in the front of the body, the number of which in adults can reach fifty or more units. In roundworms, not all helminths have them. Pinworms, for example, also have hooks, but their number is much smaller than that of flukes. The latter, by the way, also have special suction cups on the head, with the help of which the helminth is attached to the walls of the internal organs.

The presence of an internal cavity. Another essential feature, due to which helminths of both classes differ from each other, is the presence of a body cavity. In flukes, it is represented by parenchyma - a formation located between the outer layer of muscles and the internal organs of helminths. Nematodes belonging to the representatives of round helminths do not have parenchyma. Therefore, they are classified as primary cavitary helminths.

The main differences between helminths are in the structural features of a number of systems, ranging from organs that perform the function of respiration or excretion, and ending with the degree of protection from adverse conditions.

Type Roundworms

OPTION 1

A1. Outside, the body of roundworms covers

1) shell

2) sink

3) calcareous skeleton

4) skin-muscular sac

A2. Unlike flatworms, the digestive system of roundworms contains

3) intestines

4) anus

AZ. Dioecious organisms include

1) bull tapeworm

2) polyp hydra

3) human roundworm

4) liver fluke

B1.

A. The respiratory organs of roundworms are the lungs.

B. reproductive system female roundworms include the ovaries.

1) Only A is true

2) Only B is true

3) Both statements are correct

4) Both judgments are wrong

B2. Choose three true statements. The sense organs of free-living flatworms are

1) primitive eyes

2) taste buds in the language

3) organs of touch on the covers

4) chemical sense organs on the body

5) inner ear

6) olfactory organ in the nasal cavity

BZ. Establish a correspondence between the structural features of the animal and its belonging to a systematic group.

BUILDING FEATURES

A. Dioecious

B. Hermaphrodites

B. Have a body cavity

G. There is no anus in the digestive system

SYSTEMATIC GROUP

1) Flatworms

2) Roundworms

IN 1.

Answer: Houseflies play an important role in the transfer of roundworm eggs. IN human body eggs can come from unwashed hands, vegetables, fruits, or contaminated water.

OPTION 2

A1. The organs of the body of roundworms are located

1) in the intestinal cavity

2) on the surface of the body

3) in the body cavity

4) inside cells

A2. Liquid metabolic products from the body of roundworms are removed through

2) genitals

3) excretory organs

4) nerve nodes

1) human

2) shellfish

4) cattle

B1. Are the following statements true?

A. Transportation of substances in the body of roundworms is carried out by the circulatory system.

B. The male reproductive system of roundworms includes the testes.

1) Only A is true

2) Only B is true

3) Both statements are correct

4) Both judgments are wrong

B2. Choose three true statements. In the body of roundworms, the alimentary canal is formed by

1) mouth

2) stomach

3) intestinal cavity

4) gut

5) gallbladder

6) throat

BZ. Establish a correspondence between the stages of the animal development cycle and the species to which they are inherent.

STAGE OF THE DEVELOPMENT CYCLE

A. Intermediate host

B. The whole cycle of development takes place in the human body

B. Segments filled with eggs enter the external environment

D. Dioecious individuals live in the human intestine

KIND OF ANIMAL

1) Human roundworm

2) Bull tapeworm

Write down the corresponding numbers in the table.

IN 1. Task with a detailed answer (several elements).

A basic level of

For each question, choose one correct answer from the four given.

A1. Outside, the body of roundworms covers

1. shell
2. sink
3. calcareous skeleton
4. skin-muscle sac

A2. Unlike flatworms, the digestive system of roundworms contains

1. pharynx
2. intestines
3. anus

AZ. Dioecious organisms include

1. bull tapeworm
2. polyp hydra
3. human roundworm
4. liver fluke

- - - Answers - - -

A1-4; A2-4; A3-3.

Increased difficulty level

B1. Are the following statements true?

A. The respiratory organs of roundworms are the lungs.
B. The reproductive system of female roundworms includes the ovaries.

1. Only A is true
2. Only B is true
3. Both statements are correct
4. Both statements are wrong

B2. Choose three true statements. The sense organs of free-living flatworms are

1. primitive eyes
2. taste buds on the tongue
3. organs of touch on the integument
4. chemical sense organs on the body
5. inner ear
6. olfactory organ in the nasal cavity

BZ. Establish a correspondence between the structural features of the animal and its belonging to a systematic group.

Structural feature

A. Dioecious
B. Hermaphrodites
B. Have a body cavity
G. There is no anus in the digestive system

Systematic group

1. flatworms
2. roundworms

Write down the corresponding numbers in the table.

- - - Answers - - -

B1-2; B2-134; B3-2121.

Type Roundworms

Answer plan:

• general characteristics roundworms
• The structure of the body of Ascaris human
• Reproduction and development of Ascaris human
• Classification of Roundworms, variety of species
• The value of roundworms in nature and human life

General characteristics of roundworms

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

Digestive system. At the level of Roundworms, a grand event occurs in the evolution of the digestive system, which made all subsequent types of animals happy. It is in Roundworms that the hindgut and anus first appear. Now their digestive system consists of three sections: the anterior, middle and posterior intestines. The anterior section is usually divided into the mouth, muscular pharynx, and esophagus. Digestion takes place in the middle part of the intestine. With the appearance of the anus, food begins to move in one direction, which allows different departments to specialize and more effectively perform their function of digestion.

excretory organs- in some protonephridia, in the anterior part of the body on the ventral side there is an excretory opening. Some representatives have modified skin glands, they are called "neck glands". Some excretory organs are absent.

Nervous system and sense organs. Nervous system of ladder type (orthogon). It consists of a near-pharyngeal nerve ring surrounding the pharynx, and 6 nerve trunks extending forward and backward, of which the dorsal and abdominal are most strongly developed. The trunks 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 ensures the genetic diversity of offspring. There is sexual dimorphism (females look different from males). Development is indirect, that is, with a larval stage, without a change of host.
Sexual organs in the form of tubes. Male - testes, open with a vas deferens into the final section of the intestine - the cloaca. The male has copulatory organs - cuticular needles, with the help of which he injects spermatozoa into the female genital tract. Fertilization is internal. In the female, the paired ovaries continue into the oviducts, which pass into two uteruses, 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 Nematode class: Ascaris, pinworms.

The structure of the body of Ascaris human

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

Questions for reinforcement.

Literature:

1. Bilich G.L., Kryzhanovsky V.A. Biology. Full course. In 3 volumes - M .: LLC Publishing House "Onyx 21st Century", 2002
2. Pimenov A.V., Pimenova I.N. Zoology of invertebrates. Theory. Tasks. Answers.: Saratov, JSC publishing house "Lyceum", 2005.
3. Chebyshev N.V., Kuznetsov S.V., Zaichikova S.G. Biology: a guide for applicants to universities. T.2. - M .: New Wave Publishing LLC, 1998.
4. www.collegemicrob.narod.ru
5. www.deta-elis.prom.ua

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-1.jpg" alt="> Subject: Type Roundworms (Nemathelminthes) Objectives: To study"> Тема: Тип Круглые черви (Nemathelminthes) Задачи: Изучить характеристику типа, особенности строения и биологию представителей Пименов А. В. 2004!}

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-3.jpg" alt="> General characteristics of the Cavity type"> Общая характеристика типа Полость тела. Внутри !} skin-muscular sac the primary body cavity develops, the schisocoel, which corresponds to the primary cavity of the embryo - the blastocoel. The interstitial fluid replaces the parenchyma. The internal organs are found in this primary body cavity. The digestive system consists of three sections: the anterior, middle and posterior intestines. The anterior and hindgut are ectodermal in origin, while the middle is endodermal. An anus appears and food begins to move in one direction.

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-4.jpg" alt=">General characteristic of the type The excretory system is represented by hypodermal (skin)"> Общая характеристика типа Выделительная система представлена гиподермальными (кожными) одноклеточными железами и "шейными железами". Нервная система состоит из окологлоточного нервного кольца, окружающего глотку, и отходящих вперед и назад 6 нервных стволов, из которых спинной и брюшной развиты наиболее сильно. Размножение. Преимущественно раздельнополые организмы, развитие прямое.!}

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-5.jpg" alt="> General type characteristic The appearance of roundworms was accompanied by the following aromorphoses:"> Общая характеристика типа Появление круглых червей сопровождалось следующими ароморфозами: 1. Образовалась первичная полость, схизоцель, которая сформировалась путем замещения паренхимы жидкостью. Жидкость находится под большим давлением и является гидроскелетом, выполняя опорную функцию; участвует в обмене веществ внутри организма, транспортируя !} various substances; 2. The hindgut and the anus appeared, which made it possible to make the process of digestion phased; 3. Further concentration has occurred nerve cells, 6 nerve trunks are formed and the peripharyngeal nerve ring is formed; 4. There was a separation of the sexes, which ensured combinative variability and genetic diversity of descendants.

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-6.jpg" alt="> Structure and activity of nematodes Body shape and skin-muscular sac. Body whole, unsegmented,"> Строение и жизнедеятельность нематод Форма тела и кожно-мускульный мешок. Тело цельное, несегментированное, веретеновидное или нитевидное, круглое в поперечном сечении, снаружи покрыто кутикулой. Кутикула обычно достигает большой толщины и прочности, во время роста червей она периодически сбрасывается, затем возобновляется. Под кутикулой находится гиподерма, которая представляет собой продукт слияния клеток.!}

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-7.jpg" alt="> Structure and activity of nematodes Under the hypodermis there are longitudinal muscles separated by ridges"> Строение и жизнедеятельность нематод Под гиподермой расположены продольные мышцы, разделенные валиками гиподермы на 4 ленты. При сокращении спинные и брюшные ленты действуют как антагонисты. Внутри кожно-мускульного мешка имеется первичная полость (схизоцель), она не имеет собственной мезодермальной выстилки, и в ней находятся !} internal organs body. The cavity is filled with fluid, which is under pressure and plays the role of "hydroskeleton".

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-9.jpg" alt=">The structure and activity of nematodes The excretory system is peculiar. There is a cervical">!}

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-10.jpg" alt=">The structure and activity of nematodes The excretory system is peculiar. There is a cervical"> Строение и жизнедеятельность нематод Выделительная система своеобразна. Имеется шейная железа, представленная одной или двумя секреторными клеткой, расположенной снизу передней части тела. От них отходят один или два канала, проходящие в боковых валиках гиподермы. Сзади они слепо замкнуты, спереди соединяются в выводной проток, открывающийся выделительной порой. На стенках выделительных каналов в передней части тела находятся четыре крупные фагоцитарные клетки. Они захватывают и накапливают в цитоплазме остаточные продукты обмена.!}

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-11.jpg" alt=">The structure and activity of nematodes The nervous system consists of"> Строение и жизнедеятельность нематод Нервная система состоит из окологлоточного нервного кольца, окружающего глотку и пищевод и отходящих вперед и назад 6 нервных стволов, из которых спинной и брюшной наиболее развиты. Нервная система образована небольшим числом нервных клеток, что свидетельствует о ее примитивности (у аскариды, например, !} nervous system consists of 162 cells). The sense organs are poorly developed. There are organs of touch, organs of chemical sense.

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-12.jpg" alt=">The structure and activity of nematodes Reproductive organs have a tubular structure. Male"> Строение и жизнедеятельность нематод Органы размножения имеют трубчатое строение. Мужские половые органы имеют форму непарной трубки, тонкая часть которой является семенником, средняя часть - семяпроводом, наиболее толстый отдел - семяизвергательным каналом, открывающимся в конечный отдел кишечника - клоаку. У самки парные яичники продолжаются в яйцеводы, которые, расширяясь, переходят в две матки, открывающиеся в непарное влагалище, заканчивающееся половым отверстием на брюшной стороне тела. Оплодотворение яиц происходит в матке.!}

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-20.jpg" alt="> Repetition What is indicated"> Повторение Что обозначено на рисунке цифрами 1 - 10? Важнейшие термины и понятия: 1. Первичная полость тела, схизоцель, псевдоцель. 2. Шейная железа. 3. Фагоцитарные клетки. 4. Клоака. 5. Инвазионные яйца. 6. Гиподерма.!}

Src="http://present5.com/presentation/3/175622154_135143061.pdf-img/175622154_135143061.pdf-21.jpg" alt=">Repetition What is indicated in the figure by numbers 1"> Повторение Что обозначено на рисунке цифрами 1 - 16?!}