How does a person work? For children, the answer to this question will not be so simple. And to understand this complex mechanism - and even more so. But everything in the human body is subject to certain laws.
Body device
How does the human body work ? Man is a multicellular organism. In terms of taxonomy, this is a representative of the Chordate type. At the stage of embryonic development, he formed a chord, neural tube and gill slits in the throat. Developing, they are transformed into the skeleton, spinal cord and brain, and the lungs become respiratory organs. Like all mammalian animals, humans feed their babies milk, have mammary, sweat and sebaceous glands, hair and horny skin formations.
How does a person work? His body is made up of cells that combine into tissue. The totality of the latter, in turn, forms organs. However, each of them individually is not capable of performing the complex functions of the implementation of vital processes. Therefore, organs are combined into physiological and functional systems.
Features of animal cells
The cells of the human body have a structure typical for animals. They are eukaryotic because they have a nucleus. This constant cellular structure contains genetic information contained in DNA molecules. By type of food, a person is a heterotroph. For this reason, its cells are deprived of green chloroplast plastids, in which the process of photosynthesis takes place. The main organelles are mitochondria, lysosomes, Golgi complex, endoplasmic reticulum, cytoskeleton and centrioles.
How a person works: the main types of body tissues
Groups of cells that have a unity of structure and function are called tissues. In the human body, four types of tissues are distinguished:
1. Epithelial - consists of small, tightly adjacent cells. It forms the integument of the body, internal organs, its special variety is the basis of the glands. It practically does not contain intercellular substance. Epithelial tissues perform the function of protecting and metabolizing with the environment.
2. Connective - is the basis of which human organs are composed. It consists of large cells that are located in a large amount of intercellular substance. Its varieties are bone, cartilage, fat, blood.
3. Muscular - consists of fibers capable of contracting. It performs the function of movement of individual organs and the whole organism in space.
4. Nervous - it is formed by neurons with numerous processes that transmit various types of information, providing the body with the environment.
Human organs and systems: features of the organization
Each organ consists of several types of tissue. For example, the heart is formed by muscle tissue surrounded by a connective tissue membrane. But the largest organ is considered to be the skin. After all, its total area is up to 2 square meters. Why is skin an organ? Because it consists of several tissues: epithelial and connective.
To understand how a person works, you need to get acquainted with the concept of an organ system. Examples of such structures are known to everyone: digestive, circulatory ... Each of them is a collection of organs united by the performance of a single function. Consider these structures of the human body in more detail.
Musculoskeletal system
In the course of anatomy, the very first lesson is devoted to this system. How is the human body? First of all, it is based on the skeleton. It is represented by several departments. This is the skeleton of the head, trunk, belts and free upper and lower extremities. Unlike other animals, upright posture is characteristic of humans. The ability to move is provided by the muscles that attach to the bones with the help of ligaments.
Respiratory and circulatory system
We continue to consider how the human body works. Its existence is impossible without gas exchange. This function is provided by two systems at once. Respiratory is represented by the airways and lungs. When inhaled, oxygen enters them. From the pulmonary vesicles, this gas enters the smallest capillary vessels. With a blood stream, oxygen flows to every cell in the body. In the opposite direction, there is a movement of carbon dioxide, which is also removed through the lungs from the body.
The circulatory system is represented by a four-chamber heart and vessels: arteries, capillaries and veins. The type of this system in humans is closed, because the blood in his body does not mix with the cavity fluid, but circulates only inside the vessels.
Digestive and excretory system
Human life is impossible without metabolism with the environment. The intake, breakdown and assimilation of nutrients is carried out by the digestive system. How is the human body, and specifically this set of organs? It is represented by the oral cavity, pharynx, esophagus, stomach, small and large intestines, which open the anus. This is a digestive system of the through type. But the implementation of its functions would not have been possible without specialized glands, which secrete enzymes that break down complex organic substances into simple ones. These include the salivary glands, pancreas, and liver.
The urinary system is represented by paired bean-shaped kidneys, ureters, a bladder that opens outward by a canal. With its help, the body gets rid of excess water, salts and toxic metabolic products.
Features of the structure of the reproductive system
Consider how a person is arranged in terms of reproductive function. It is a dioecious organism with internal fertilization. Type of development is direct. Both the female and male reproductive systems are represented by glands, ducts, and cells. However, they have significant differences. In men, these are the testes, their ducts and motile small gametes - sperm. These cells are always active and capable of fertilization.
The female reproductive system is represented by paired ovaries, oviducts and immobile, relatively large gametes. For fertilization, they need movement from the gonads to the fallopian tube. This process occurs only during a certain period of the menstrual cycle, which is called ovulation. When gametes merge, a zygote is formed. It divides and gradually forms a multicellular structure, which subsequently turns into a fetus. The intrauterine development of the fetus provides reliable protection for the small organism during pregnancy and viability in the first months of life.
Features of the human nervous system
Only man is a biosocial being. This is largely achieved due to the high level of development of the nervous system. It consists of the spinal cord and brain, as well as the nerve fibers that depart from them. A person is born with a certain set of unconditioned reflexes and animal instincts. However, during his life acquired reactions also form in him. How does the human brain work? More difficult compared to other chord animals. It distinguishes the cerebral cortex and a large number of convolutions, which significantly increase its area. Only human is characterized by meaningful speech and abstract thinking. He lives in society and to some extent obeys social laws.
Function regulation
Naturally, in such a complex system, regulation of functions is necessary. This happens simultaneously in two ways. Using the nervous system, the human body receives information about various changes in environmental conditions and almost instantly reacts to them. This is largely accomplished by sensory systems. A person has five. This is vision, touch, smell, hearing and the ability to perceive odors. Some scientists single out another, which is called the "sixth sense", or intuition. However, no one has yet succeeded in discovering and explaining either the structure or the mechanism of this system. And the endocrine glands, releasing special substances in the blood - hormones, regulate the processes of growth, development and homeostasis. This concept implies maintaining a constant internal environment.
This is how the human body works. This is a complex system that consistently combines cells, tissues, organs and their systems. Each of these structures is distinguished by a high degree of specialization and is coordinated by the nervous and humoral systems of regulation.