Reticular tissue. Types of tissues of the human body

All living organisms, with the exception of algae, consist of various tissues. The tissue of an organism is a collection of cells that are similar in structure and are united by a common function. So, what are they?

Vegetable tissues

There are such types of plant tissues:

• educational;
• basic;
• coverslip;
• conductive;
• mechanical.

All of them fulfill their functions. For example, the educational provides the growth of the plant, and from it all other types of tissues are formed. The coverslip serves as a protective function. In addition, gas exchange takes place through it. Conductive provides transport of substances through the plant. Mechanical tissue also plays a protective role. It is present in plants with stiffened stems. The basic tissues of the body are responsible for the formation and accumulation of nutrients.

Tissues of the human body

There are many types of animal tissues, which, in turn, are subdivided into species.

The animal organism is constructed of four types of tissues:

• epithelial;
• muscular;
• nervous;
• connective.

All types of tissues of the human body are divided into species. Let's take a closer look at each of them.

Epithelium: species and functions

The tissues of living organisms of this type perform mainly a protective function.

The epithelium, first of all, can be divided into single-layered and multilayered. In the first there is only one row of cells located close to each other. The second one consists of several layers of cells.

According to the shape of cells, a flat, cubic andcylindrical epithelium. Depending on the specific functions performed by the tissue, ciliary, glandular and sensitive, or sensory epithelium, are also isolated.

Different types of epithelial tissue are found indifferent parts of the body of animals and humans. So, the flat lining the oral cavity and cavity of the esophagus, the cubical - the kidney tubules, the cylindrical - the stomach and intestines. The ciliated epithelium is located inside the respiratory tract, sensory (sensory) - in the nasal cavity, glandular - in the glands.

Muscular tissues: characteristic

Muscular tissues of the human body are divided into three types:

• striated muscles;
• smooth muscles;
• cardiac musculature.

The cells of the muscle tissue are called myocytes, or fibers. The tissue of this species is capable of contracting due to the content of contractile proteins in the cells: actin and myosin.

Striated muscles have thinlong fibers of a cylindrical shape with several nuclei and a large number of mitochondria providing the cell with energy. Of this type of tissue, skeletal muscles are composed. Their main function is to move the body in space. They can also play a protective role. This concerns, for example, the muscles of the abdominal press, which protects internal organs from damage.

Smooth musculature, in contrast tostriated, can not be controlled consciously. Such tissues of the human body lining some internal organs, such as the intestine, uterus. Also, they consist of sphincters - circular muscles, with a narrowing closing hole. Animals have upper and lower esophageal sphincters, a pylorus, several sphincters of the duodenum; sphincters Oddi, Mirizzi, Lutkens and Helly, who are in the organs of the pancreatic system; sphincters of the large intestine, as well as sphincters of the urethra. In addition, animals and humans also have a pupillary sphincter, due to which it narrows and expands. Smooth muscles have spindle-shaped cells containing one nucleus. Reduced muscle of this type is not as fast and active as cross-striped.

Cardiac musculature is similar tostriated, and smooth. Like the smooth one, her person can not control consciously. However, it is able to shrink as quickly and actively as cross-striped. The fibers of the heart tissue intertwine, forming a strong muscle.

Nerve tissue

It is not subdivided into species. Cells of such tissue are called neurons. They consist of a body and several processes: one long axon and several shorter dendrites. In addition to neurons, neuroglia is also present in the neural tissue. It consists of small cells with numerous outgrowths. Neuroglia plays a supporting function, provides the cell with energy, and also forms specific conditions for the formation of a nerve impulse.

Connective tissues: varieties, functions, structure

This type of fabric has numerous types:

• dense fibrous;
• loose fibrous tissue;
• blood;
• lymph;
• bone;
• cartilaginous;
• fat;
• reticular (mesh) tissue.

Despite the fact that they are all related tothey are quite different in structure and functions. The main similarity of all these tissues is the presence of a large amount of intercellular substance. Consider the features of the main types of connective tissue.

Reticular tissue: features

This is one of the most important connective tissues. Reticular tissue forms the organs of hematopoiesis. It contains cells from which blood cells are formed. Reticular tissue forms the red bone marrow - the main hematopoietic organ of humans and animals, as well as the spleen and lymph nodes.

Reticular tissue has a complex structure. It consists of reticular cells (reticulocytes) and reticular fibers. Cells of this tissue have a light cytoplasm and an oval nucleus. On its surface, it has several processes, through which the cells connect to each other and form something like a network. Reticular fibers are also located in the form of a lattice, branch and connect with each other. Thus, the network of reticular fibers together with the reticulocyte network form the stroma of the hematopoietic organs.

Reticulocytes can be isolated from the cellular network anddifferentiate into macrophages or hematopoietic cells. Macrophages are special white blood cells that are part of the phagocyte group. They are able to carry out phagocytosis - capture and absorption of particles, including other cells. The main task of macrophages is to fight with pathogenic bacteria, viruses and protozoa.

Bone and cartilaginous tissue

They perform protective and supporting functions inorganism. Their main feature is that the intercellular substance is solid, consists mainly of inorganic substances. As for the cells, they are in the bone tissue of four types: osteoblasts, osteocytes, osteoclasts and osteogenic. All of them differ in structure and functions. Osteogenic cells are those from which the other three types of bone cells form. Osteoblasts are mainly responsible for the synthesis of organic substances that make up the intercellular substance (collagen, glycosaminoglycans, proteins). Osteocytes are the main cells of the tissue, they have an oval shape and a small amount of organelles. Osteoclasts are large cells with several nuclei.

Cartilage tissue is divided into severalvarieties. This is hyaline, fibrous and elastic cartilage. The main feature of this type of tissue is the presence of a large amount of collagen in the intercellular substance (about 70%). Hyaline cartilage covers the surface of the joints, forms the skeleton of the nose, larynx, trachea, bronchi, is part of the ribs, sternum. Fibrous cartilage can be found in the composition of intervertebral discs, as well as in the places of attachment of tendons to bones. Elastic forms the skeleton of the ear.

Blood

It has a huge amount of liquidintercellular substance, which is called plasma. It is 90% water. The remaining 10% are organic (9%) and inorganic (1%) substances. Organic compounds that make up the blood are globulins, albumins and fibrinogen.

The cells of this tissue are called blood cells. They are divided into red blood cells, platelets and white blood cells. The former perform a transport function: they contain a hemoglobin protein that is capable of carrying oxygen. Platelets provide blood coagulation, and leukocytes are responsible for protecting the body from pathogens.