As a person is arranged: the external and internal structure of the human body

How does the person work? For children, the answer to this question will not be so simple. And really to understand this complex mechanism - and even more so. But everything in the human body is subject to certain regularities.

Body Device

How is the human body arranged ? Man is a multicellular organism. From the point of view of taxonomy, it is a representative of the Chordov type. At the stage of embryonic development, he has formed a chord, a neural tube and gill slits in the pharynx. Developing, they are transformed into a skeleton, a dorsal and a brain, and respiratory organs become lungs. Like all mammalian animals, a man feeds his cubs with milk, has milky, sweat and sebaceous glands, hair and horny skin formations.

How does a person work? His body consists of cells that combine into tissues. The totality of the latter, in turn, forms the organs. However, each of them individually is not able to perform complex functions of the implementation of vital processes. Therefore, the organs are combined into physiological and functional systems.

Features of animal cells

The cells of the human body have a typical structure for animals. They are eukaryotic, since they have a nucleus. This constant cellular structure contains genetic information contained in DNA molecules. By type of nutrition a person is a heterotroph. For this reason, its cells are devoid of green plastids of chloroplasts, 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

Cell groups that have a unity of structure and functions are called tissues. In the human body, four types of tissues are distinguished:

1. Epithelial - consists of small, closely adjacent cells. It forms the covers of the body, the internal organs, its special variety is the basis of the glands. It practically does not contain intercellular substance. Epithelial tissues perform the function of protection and metabolism with the environment.

2. Connecting - is the basis of which human organs are composed. It consists of large cells that are located in a large number of intercellular substance. Her varieties are bone, cartilaginous, fatty, blood.

3. Muscular - consists of fibers that are capable of contraction. Performs the function of the movement of individual organs and the whole organism in space.

4. Nervous - it is formed by neurons with numerous processes that transmit various kinds of information, providing the body with the surrounding world.

Human organs and systems: features of the organization

Each organ consists of several types of tissue. For example, the heart is formed by a muscle tissue surrounded by a connective tissue membrane. But the largest body is considered to be skin. After all, its total area is up to 2 square meters. Why is the skin an organ? Because it consists of several tissues: epithelial and connective.

To understand how a person is arranged, it is necessary to get acquainted with the concept of a system of organs. Examples of such structures are known to everyone: digestive, circulatory ... Each of them is a set of organs united by the implementation of a single function. Consider these structures of the human body in more detail.

Musculoskeletal system

This system is the first lesson in the course of anatomy. How is the human body? First of all, it is based on a skeleton. It is represented by several departments. This is the skeleton of the head, trunk, belts and free upper and lower extremities. In contrast to other animals, for a person inherent in the upright. 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 is arranged. Its existence is impossible without gas exchange. This function is provided by two systems at once. Respiratory is represented by airways and lungs. When they breathe in, they get oxygen of the air. From the pulmonary vesicles, this gas enters the smallest capillary vessels. With the flow of blood oxygen comes to every cell of the body. In the opposite direction, carbon dioxide moves, which is also removed from the body through the lungs.

The system of circulatory organs is represented by a four-chambered heart and vessels: arteries, capillaries and veins. The type of this system in a person 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, cleavage and absorption 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 intestine, which are opened by the anal opening. This is a digestive system of a through type. But the implementation of its functions would be impossible without specialized glands, which secrete enzymes that break down complex organic substances to simple ones. These include salivary glands, pancreas and liver.

The urinary system is represented by paired bean-like kidneys, ureters, a bladder opening outward through the canal. With its help, the body gets rid of excess water, salts and toxic products of metabolism.

Features of the structure of the reproductive system

Consider how a person is arranged in terms of reproductive function. He is a dioecious organism with internal fertilization. The type of development is direct. Both female and male sexual system is represented by glands, ducts and cells. However, they have significant differences. In men, these are testes, their ducts and mobile small gametes are spermatozoa. 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 to move from the genital glands to the uterine tube. This process occurs only in a certain period of the menstrual cycle, which is called ovulation. When the gametes merge, a zygote is formed. It divides and gradually forms a multicellular structure, which later becomes a fruit. Intrauterine development of the embryo provides reliable protection of a small organism during pregnancy and vitality in the first months of life.

Features of the human nervous system

Only man is a biosocial being. This is largely due to the high level of development of the nervous system. It consists of the spinal cord and the brain, as well as the nerve fibers that leave them. Man is born with a certain set of unconditioned reflexes and animal instincts. However, during the course of his life, the acquired reactions are also formed. How is the human brain? More difficult, compared to other chordates. It distinguishes the cerebral cortex and a large number of convolutions, which significantly increase its area. Only for a person is typical speech and abstract thinking. He lives in society and to a certain extent obeys social laws.

Regulation of functions

Naturally, in such a complex system, regulation of functions is necessary. This happens simultaneously in two ways. With the help of the nervous system, the human body receives information about various changes in environmental conditions and almost instantly reacts to them. In many ways this is done by sensory systems. A person has five. This vision, touch, smell, hearing and the ability to perceive smells. Some scholars distinguish one more, which is called the "sixth sense", or intuition. However, neither the structure nor the mechanism of this system was discovered and explained to anyone yet. A gland of internal secretion, releasing into the blood of special substances - hormones, regulate the processes of growth, development and homeostasis. This concept implies maintaining the constancy of the internal environment.

That's how the human body works. It is a complex system that consistently integrates cells, tissues, organs and their systems. Each of these structures is characterized by a high degree of specialization and is coordinated with the help of nervous and humoral regulation systems.