Table of contents:
- Reproduction of the parasite
- Adaptability to parasitism
- Features of the body and fixation of the fluke
- The sense organs of the liver fluke
Video: Features Of The Structure Of The Hepatic Fluke - Development And Reproduction
Last updated 17 February 2020 at 10:37 pm
Reading time: 5 min
The liver fluke is a parasite with a leaf-shaped body. The helminth settles in the organs of animals and people, where it gets with polluted water, an adult, which is also called a cat fluke, grows up to 5 cm in length.The favorite habitat of the liver fluke is the pancreas and the largest gland of the host's body, the worms are fixed to the walls of the bile ducts special suction cups.
- 1 Reproduction of the parasite
- 2 Adaptability to parasitism
- 3 Features of the body and fixation of the fluke
4 The sense organs of the liver fluke
- 4.1 Locomotor apparatus
- 4.2 Reproductive system
4.3 Digestive system
- 4.3.1 Excretory system
- 4.3.2 Hepatic fluke - nervous system
- 4.3.3 Video on the topic: "Hepatic fluke and its development cycle"
- 4.4 Similar articles
Reproduction of the parasite
Helminths often change hosts, which protects individuals from death, and causes fascioliasis in humans, in which metabolic processes are disturbed, and the composition of the blood changes. The sensory organs of the hepatic fluke are simple, since the fluke leads a parasitic lifestyle.
Helminth eggs from the intestines of an animal or a person are sent to the external environment, in the water larvae with cilia crawl out of them, penetrating into the pond snail, where they turn into a sporocyst. In such a sac, several generations of embryos are formed, the last of which live at the bottom of the pond for a long time.
Adaptability to parasitism
Infection with a hepatic worm that feeds on the tissues of the host is rare. The fertility of the fluke promotes survival. Individuals lay a large number of eggs by asexual reproduction; in new embryos, division occurs repeatedly. The liver fluke adjusts to life through the presence of:
- a large number of fastening elements;
- skin that prevents digestion;
- simplified structure of the senses.
In the parasite, the developmental cycle is associated with a frequent change of hosts, the hermaphroditic reproductive system. Larvae with an eye and excretory organs emerge from the eggs of the helminth.
Features of the body and fixation of the fluke
The young generation of feline fluke is adapted to living in the external environment, adults feel comfortable in the bile ducts of animals and people. The integuments of the liver fluke body prevent the parasite from dissolving and digesting the host's gastric juice, release nitrogen, and provide gas exchange.
In the head part of the body of the worm there is an elongated proboscis, 2 suckers - abdominal and oral, which have annular and radial muscles. With their help, the individual is fixed to the walls of the organs, lays eggs, which, together with bile, are sent to the intestine, and from it with feces they go outside.
The sense organs of the liver fluke
The larvae of helminths living in water have miniature eyes with one lens and skin receptors. In adults, there is no visual organ, ciliary epithelium, but sometimes growths form on the sides of the head part of the body. Zoologists attribute these appendages to the sense organs of the hepatic fluke.
One of the important elements of the nervous system is the periopharyngeal ring, from which elongated strong trunks branch, branching into a large number of lateral processes that go along the body of the helminth. In comparison with the nervous system, the sensory organs of the liver fluke are simplified.
The skin and muscle sac of the helminth is covered with tegument, the folded surface of which has a ribbed structure. The bodies of epithelial cells are immersed in the parenchyma, connected to the cytoplasmic layer with the help of cords. The annular and longitudinal muscles of the sac contract, and the fluke moves.
Due to cross fertilization, in which flukes are paired, male eggs are sent to the uterus, where eggs are formed, covered with a dense shell. In the female organ of the feline fluke, a large number of eggs survive, the parasites are very fertile. The fluke is characterized by 2 reproductive systems, the male is represented by paired testes, from which 2 vas deferens departing, heading to the ejaculatory canal.
The female system also consists of one ovary with an oviduct that flows into the ootite. In it, the ducts that produce the yolk cells open, and also the channel departs, through which excess sperm is excreted from the seminal receptacle. If the sensory organs of the hepatic fluke are simple, then the female reproductive system has a complex structure. The uterus, filled with many eggs, fills most of the parenchyma. Spermatozoa enter the vagina, enter the ootitis, then go to the seminal receptacle, where fertilization takes place.
Through the skin, the round worm absorbs useful components from the body of an animal or human. In comparison with the simplified sense organs of the hepatic fluke, the digestive system is more developed. The helminth has a pharynx, 2 suction cups, and intestines, which helps the parasite feast on the tissues and blood of its host.
The digestive system of the hepatic fluke has 2 sections, the middle one is the intestine with blind processes. The anterior canal consists of the pharynx and esophagus. Undigested tissue remnants of a warm-blooded animal or person enter the mouth or anus, from where they exit.
The structure of the digestive system of the liver fluke helps the helminth to digest substances inside the intestines or absorb nutrients through the integuments of the body.
To maintain vital activity, the worms break down the glycogen of the parenchyma, as a result of anaerobic metabolism, complex compounds break down into simple components. Uric acid causes intoxication of the human or animal body. The excretory system of the hepatic fluke consists of small tubules that permeate the entire body. The flow of fluid in them appears due to the flickering of the cilia, which are located in the cavity. The main large excretory canal runs in the middle of the parasite's body.
Hepatic fluke - nervous system
In the front part there is a periopharyngeal ring, from where the longitudinal nerve trunks come, connected by transverse bridges. Their ends branch out and fall into the tegument. In the posterior part of the body, 3 pairs of trunks merge, which exit from the cerebral ganglion. The nervous system of the liver fluke is lattice-like and runs through the entire body.
The space that remains between the internal organs of the helminth is filled with connective tissue, which consists of a large number of cells. The parenchyma accumulates nutrients that are involved in the metabolic processes of the parasite. The roundworm has no blood vessels, no respiratory system, but branched canals pass throughout the body, ending in cells with cilia in the parenchyma. In protonephridia, which perform the functions of excretory organs, there are holes through which the fluke comes into contact with the external environment.
The parasite multiplies at every stage of its development. The larvae of the helminth swim freely in the water, cilia help them to move, the eyes do not allow them to get lost in an unfamiliar environment. An adult is attached to the bile ducts, takes out nutrients from the host's tissues. The sense organs of the liver fluke, which leads a parasitic life, lose their functions.
When it enters the human body, the helminth adapts to the new environment for up to 2 months, and signs of infection do not appear. After the incubation period for the patient:
- temperature rises:
- you feel unwell;
- nausea occurs.
In the chronic stage of fascileosis, the liver enlarges, the biliary tract is damaged. Lack of treatment for the disease ends in cirrhosis or hepatitis.