The legislation stipulates that the employer is responsible for safety at work. He is entrusted with the obligation to conduct briefings on labor protection.

These activities are part of the safety training for the organization's team. There are 5 types of them:

  • primary;
  • repeated;
  • unscheduled;

What it is?

Unscheduled briefing is a special part of occupational safety training. It is carried out individually or with a narrow group of employees of the same profession, with a similar work profile. Its program, length of lectures, specific content is determined based on the circumstances that led to the need for this event.

The briefing is recorded in a special journal. It also indicates the reasons for which there was a need for this procedure.

When it is held

Briefing is carried out directly by the work supervisor.

The circumstances due to which this type of training can be carried out are as follows:

  • new regulations have been introduced, existing rules have been changed, current labor protection instructions have been amended;
  • the technological process of production has been radically changed;
  • significant modernization of equipment, replacement of tools, materials was made, which may affect safety during further work;
  • were violated by employees or trainees of the safety rules, which led to injury, explosion, poisoning, accident, fire, as well as the possibility of any of the listed incidents;
  • in an organization with a similar profile of activity, an accident has occurred or a dangerous situation has arisen in connection with a violation of safety rules;
  • in the production process, a forced long break occurred for a period of 30 days for work with increased safety requirements, over six months for other types;
  • the need for briefing was demanded by the state supervision authorities;
  • the corresponding decision was made by the head of the enterprise independently.

For detailed information on this procedure, you can glean from the following video:

Preparation and procedure for its implementation

To conduct this training in the organization, the manager must issue an order in which the following information must be indicated:

  • a list of employees who will be trained in safety techniques;
  • detailed briefing program;
  • persons responsible for organizing the event;
  • the reasons for the procedure.

The unscheduled instruction program is similar to the initial one. During the event, the main focus is on those moments that caused it.

The program usually contains the following items:

  • General acquaintance with the production process at a specific site. At the same time, employees receive information about the composition of technical equipment in the shop, harmful production factors.
  • Identification of possible hazards when using the equipment. The rules for organizing the workplace are determined, which exclude injuries and damage.
  • Determination of safety equipment. Equipment braking devices, light and sound signals, blocking methods are studied.
  • Safe preparation of devices for work. At the same time, the technical serviceability of mechanisms, tools, interlocks is checked. All devices for safe use are confirmed.
  • Necessary overalls, footwear, protective equipment. The workers are being taught the importance of having them and using them correctly. Requirements for safe movement around the workshop are also established.
  • Rules for the use of electrical equipment and similar devices. Failure to comply with these requirements may result in fire, explosion, etc.
  • Collaboration requirements. The greatest risk of injury and accidents is teamwork.
  • Possibility of injury at work, reasons. Methods of preventing such situations are determined. They explain to employees what to do when a danger arises.
  • First aid. Workers need to know how to save a colleague's life if injured.
  • Responsibility for violation of TB. Failure to comply with safety regulations can provoke industrial accidents. A large number of people may suffer, expensive equipment will fail. The guilty person must compensate for the damage caused.

After the training is organized oral exam... Its results are recorded in a special training journal. All employees participating in the event must sign it in their own hand.

Fertilization- the process of fusion of male and female gametes, leading to the formation zygotes. During fertilization, male and female haploid gametes interact, while their nuclei merge (pronuclei), chromosomes unite, and the first diploid cell of a new organism appears - zygote... The beginning of fertilization is the moment of fusion of the membranes of the sperm and the egg, the end of fertilization is the moment of unification of the material of the male and female pronuclei.

Fertilization takes place in the distal part of the fallopian tube and goes through 3 stages:

Stage I - distant interaction, includes 3 mechanisms:

· Chemotaxis - directed movement of spermatozoa towards the ovum (ginigamones 1,2);

Rheotaxis - the movement of sperm in the genital tract against the flow of fluid;

· Capacitation - an increase in the motor activity of spermatozoa, under the influence of factors of the female body (pH, mucus, and others).

Stage II - contact interaction, in 1.5-2 hours the spermatozoa approach the egg, surround it and lead to rotational movements, at a speed of 4 revolutions per minute. At the same time, spermatozoa are released from the acrosome of spermatozoa, which loosen the membranes of the egg. In the place where the shell of the egg becomes thinner, fertilization occurs as much as possible, the ovolemma protrudes and the head of the sperm enters the cytoplasm of the egg, bringing the centrioles with it, but leaving the tail outside.

Stage III - penetration, the most active spermatozoon sticks with its head into the egg, immediately after that, a fertilization membrane is formed in the cytoplasm of the egg, which prevents polyspermy. Then the fusion of the male and female pronuclei occurs, this process is called syncarion. This process (syngamia) is actually fertilization, it appears diploid zygote(a new organism, so far unicellular).

Conditions necessary for fertilization:

· The concentration of spermatozoa in the ejaculate, not less than 60 million in 1 ml;

· Patency of the female genital tract;

· Normal body temperature of a woman;

· Slightly alkaline environment in the female genital tract.

Fragmentation is a sequentially proceeding mitosis, without the growth of the formed cells, to the original size. During cleavage, a relatively rapid increase in the number of cells occurs. (blastomeres). The fragmentation continues until the ratio of the volume of the nucleus to the volume of the cytoplasm, which is characteristic of the given species, is restored. The number of blastomeres increases from 2 to about 12-16 by the third day after fertilization, when concept reaches the stage morula and goes into the uterine cavity from the fallopian tubes.

Distinguish crushing:

· Complete, incomplete;

· Uniform, uneven;

· Synchronous, asynchronous.

In humans, fragmentation is complete, asynchronous, and uneven. As a result of the first division, 2 blastomeres are formed, dark and light, light ones divide quickly and envelop the zygote from the outside - trophoblast, and the dark ones are inside and divide slowly - embryoblast. The fragmentation of the zygote in humans stops at the 107 blastomere stage.

Fertilization in plants, animals and humans is the fusion of male and female germ cells - gametes, as a result of which the first cell of a new organism is formed - a zygote. Fertilization is associated with sexual reproduction and the transmission of hereditary information from parents to offspring.

Fertilization is characteristic of most plants. It is usually preceded by the formation of gametangia (genitals), in which gametes develop. If a plant undergoes a sexual process in the development cycle, then meiosis also occurs, that is, a change in nuclear phases is detected (see Alternation of generations).

The types of sexual process in lower plants are diverse. Let's name only the main ones. The fusion of gametes with flagella, the shape and size of which are the same, is called isogamy, and gametes are called isogametes. Thus, many unicellular algae are isogamous, for example, some chlamydomonas; being unicellular, they themselves become gametangia, forming gametes. In the multicellular alga ulotrix, some cells that do not differ from others become gametangia. In some isogamous brown algae, the gametangia are different from the rest of the plant cells.

In many isogamous algae, not every pair of gametes can form a zygote, since the gametes are physiologically different. Outwardly identical gametes cannot be called either male or female; physiological differences are denoted in isogamy by the signs + and -. Only gametes of different signs formed by physiologically different (+ and -) algae individuals can merge.

The fusion of gametes with flagella that differ physiologically and in size is called heterogamy, and gametes are female (larger) and male (smaller). Heterogamous, for example, some chlamydomonas. The fusion of a large non-flagellated female gamete (ovum) with a small, male one, which usually has a flagellum or flagella (sperm), is called oogamy. The female gametangia of most oogamous lower plants are called oogonia, and the male gametangia are called antheridia. Oogamny, for example, many green and brown algae, as well as red algae.

In iso-, hetero-, and many oogamous lower plants, gametes emerge from the gametangia into the water, where fertilization takes place. In some (for example, the green alga volvox), the egg remains in the oogony, where the spermatozoa released into the water penetrate and where the gametes merge.

All higher plants are oogamous. Their typical gametangia - antheridia (male) and archegonia (female) - are multicellular. In archegonia, one ovum is formed, in the antheridium, many spermatozoa. In moss and ferns, the spermatozoa released from the antheridia swim in the water to the opened archegonia and merge with the eggs inside the archegonia. In fern-like and seed plants, fertilization occurs on (or in) the outgrowths (gametophytes), which develop independently in the former, and on sporophytes in the latter (see Alternation of generations). The outgrowths of homosporous fern-like bisexual, and heterosporous and all seed - dioecious (see Disputes). A strong reduction in the male overgrowth of seed plants led to the fact that antheridia in it (i.e., in the pollen grain) do not form in either the head or the angiosperms. In the female germ (primary endosperm) of almost all gymnosperms, archegonia are still developing, and in the female germ - the embryo sac - there are no angiosperms anymore.

In seed plants, fertilization is preceded by pollination - the transfer of pollen grains from microsporangia, where they began to develop from microspores, into the pollen chamber of the ovule (in gymnosperms) or on the stigma of the pistil (in angiosperms). Only a few gymnosperms (cycads, ginkgoes) develop multi-flagellate spermatozoa in male outgrowths, while in the rest, for example, in conifers, and in all angiosperms, male gametes - sperm - do not have flagella.

Spermatozoa reach archegonia, moving in the liquid produced by the plant itself. In seed plants with sperm, the latter go to the eggs through the pollen tubes formed by the male outgrowths. In angiosperms, after pollination, the pollen grain forms a pollen tube, which, elongating, grows between the cells of the stigma and the column, enters the cavity of the ovary and, after passing through the pollen duct, the ovule grows into the embryo sac. Here sperm emerge from the opened pollen tube (see fig.). One sperm fuses with the egg, forming a diploid zygote, giving rise to the embryo. The second one fuses with the central cell of the embryo sac, which in most angiosperms has two haploid nuclei or one diploid (if the nuclei are fused). After the fusion of the central cell with sperm, its nucleus becomes triploid. This peculiar process, characteristic only of angiosperms, was first described by the Russian scientist S.G. Navashin (1898) and called double fertilization. A multicellular storage tissue, a secondary endosperm, develops from a triploid cell, the nutrients of which are used by the embryo in the early stages of its development.

Fertilization, independent of the presence of free water, is one of the most important adaptations of seed plants to existence on land.

Fertilization in multicellular animals consists in the fusion of two gametes of different sexes - a sperm and an egg. The sperm cell introduces the hereditary material contained in its nucleus into the egg cell. The place where the sperm enters the egg can determine the location of the parts of the future organism. For example, in amphibians, that part of the egg cell into which the sperm has entered will turn into the anterior end of the body during development.

Until the moment when one of the spermatozoa touches the surface of the egg, the latter affects their behavior, releasing certain substances. They make the sperm move faster or, conversely, stick together and immobilize them (this is necessary if there are too many sperm). Particularly active interactions begin as soon as the sperm touches the surface of the egg. Within a few seconds, the front of the sperm cell turns into a tube, the tip of which sticks to the surface of the egg. Through this tube, the contents of the sperm, including its nucleus with hereditary material, are pressed into the egg cell.

In the egg, violent changes immediately begin, which outwardly manifest themselves in the fact that a shell is formed on its surface, which prevents the penetration of other spermatozoa. In addition, rapid rearrangements of the structures of the cytoplasm responsible for protein synthesis occur in the egg: the synthesis processes are immediately and many times faster. Only after this is the hereditary material of the sperm that has entered the egg is combined with the hereditary material of the nucleus of the egg. Maternal and paternal chromosomes (carriers of hereditary material) are distributed equally across all cells of the embryo, which is formed from the zygote - a fertilized egg.

Fertilization is the process of fusion of a sperm with an egg, resulting in a diploid zygote; each pair of chromosomes in it is represented by one paternal and another maternal. The essence of fertilization lies in the restoration of the diploid set of chromosomes and in the unification of the hereditary material of both parents, as a result of which the offspring, combining the beneficial characteristics of the father and mother, are more viable.

Violation of fertilization, its consequences.

Fertilization is one of the links in the biological existence of a species. This is preceded by a long and complex preparation of two individuals, during which they are exposed to various environmental influences, which negatively affect the fertilization process.

The egg and sperm have a limited lifespan and an even shorter duration of fertility. So, in mammals, and in humans in particular, the ovum released from the ovary retains the ability to fertilize for 24 hours. Violation of this time period will inevitably lead to the loss of the ability to fertilize.

The spermatozoa of a man in the genital tract of a woman remain mobile for more than 4 days, but they lose their fertilizing ability after 1 - 2 days. With an increase in the duration over time, unprotected cells are negatively influenced by various factors.

The latter can cause disturbances in the ascending state of the gamete gene pool, which will inevitably lead to unprogrammed deviations in the development of the zygote with corresponding consequences for the species as a whole.

The speed of movement of spermatozoa, under normal conditions, is 1.5-3 mm / min. Different deviations from such a translational movement cause the loss of the ability to fertilize. This is also caused by a change in the pH of the vaginal environment, inflammation, etc. The ejaculate of a man contains an average of 350 million spermatozoa capable of fertilization. If the sperm count is less than 150 million (or less than 60 million in 1 ml), then the probability of fertilization is sharply reduced. So, an excessive concentration of spermatozoa in the ejaculate is of exceptional importance in the mechanism of fertilization.

Violation of fertilization occurs with pathological changes in the morphology of sperm. The biological usefulness of gametes is significantly influenced by the duration of their stay in the genital tract of a woman. So, overripe sperm and egg cells in the female genital tract for various reasons causes an increase in the frequency of chromosomal aberrations in aborted fetuses.

Irregular types of sexual reproduction.

Classification of irregular types of sexual reproduction.
The irregular types of sexual reproduction include parthenogenetic, gynogenetic and androgenetic reproduction of animals and plants (Fig. 27).
Parthenogenesis is the development of an embryo from an unfertilized egg. The phenomenon of natural parthenogenesis is characteristic of lower crustaceans, rotifers, hymenoptera (bees, wasps), etc. It is also known in birds (turkeys). Parthenogenesis can be artificially stimulated by inducing the activation of infertile eggs by exposure to various agents.
Distinguish between somatic or diploid parthenogenesis and generative or haploid parthenogenesis. During somatic parthenogenesis, the egg does not undergo reduction division, or if it does, two haploid nuclei, merging together, restore the diploid set of chromosomes (autokaryogamy); thus, a diploid set of chromosomes is preserved in the cells of the tissues of the embryo.
In generative parthenogenesis, the embryo develops from a haploid egg. For example, in the honey bee (Apis mellifera), drones develop from unfertilized haploid eggs by parthenogenesis.

Parthenogenesis in plants is often called apomixis. Since apomixis is widespread in the plant kingdom and is of great importance in the study of inheritance, let us consider its features.
The most common type of apomictic reproduction is the type of partenogenetic formation of the embryo from the ovum. In this case, diploid apomixis (without meiosis) is more common.
Hereditary information both during the formation of the endosperm and during the formation of the embryo is obtained only from
Different types of sexual reproduction:
1 - normal fertilization; 2 - parthenogenesis; 3 - gynogenesis; 4 - androgesis.
mother. In some apomicts, the formation of full-fledged seeds requires pseudogamy - the activation of the embryo sac by the pollen tube. In this case, one sperm from the tube, reaching the embryonic sac, is destroyed, while the other merges with the central nucleus and participates only in the formation of endosperm tissue (species from the genera Potentilla, Rubus, etc.). Inheritance here is somewhat different from the previous case. The embryo inherits traits only through the maternal line, and the endosperm - both maternal and paternal.
Gynogenesis. Gynogenetic reproduction is very similar to parthenogenesis. Unlike parthenogenesis, spermatozoa are involved in gynogenesis as stimulators of egg development (pseudogamy), but fertilization (karyogamy) does not occur in this case; the development of the embryo is carried out exclusively at the expense of the female nucleus (Fig. 27, 3). Gynogenesis has been found in roundworms, the viviparous fish Molliensia formosa, in the goldfish (Platypoecilus) and in some plants - buttercup (Ranunculus auricomus), bluegrass (genus Poa pratensis), etc.
Gynogenetic development can be induced artificially if sperm or pollen are irradiated with X-rays, treated with chemicals, or exposed to high temperatures before fertilization. In this case, the nucleus of the male gamete is destroyed and the ability to karyogamy is lost, but the ability to activate the egg remains.