Histology. Epithelial tissue

Free technical library

Lecture notes, cheat sheets
Free library / Directory / Lecture notes, cheat sheets

Histology. Epithelial tissue

Lecture notes, cheat sheets

Directory / Lecture notes, cheat sheets

Comments on the article

Table of contents (expand)

Topic 9. EPITHELIAL TISSUES

Characterization of epithelial tissues

They form the outer and inner layers of the body.

Functions of the epithelium:

1) protective (barrier);

2) secretory;

3) excretory;

4) suction.

Structural and functional features of epithelial tissues:

1) arrangement of cells in layers;

2) location of cells on the basement membrane;

3) the predominance of cells over the intercellular substance;

4) polar differentiation of cells (to the basal and apical poles);

5) absence of blood and lymphatic vessels;

6) high ability of cells to regenerate.

Structural components of epithelial tissue:

1) epithelial cells (epithelial cells);

2) basement membrane.

Epitheliocytes are the main structural elements of epithelial tissues.

The basement membrane (about 1 µm thick) consists of:

1) thin collagen fibrils (from collagen protein of the fourth type);

2) an amorphous substance (matrix) consisting of a carbohydrate-protein-lipid complex.

Basement membrane functions:

1) barrier (separation of the epithelium from the connective tissue);

2) trophic (diffusion of nutrients and metabolic products from the underlying connective tissue and back);

3) organizing (attachment of epitheliocytes with the help of hemidesmosomes).

Classification of epithelial tissues

There are the following types of epithelium:

1) integumentary epithelium;

2) glandular epithelium.

Genetic classification of epithelia (according to N. G. Khlopin):

1) epidermal type (develops from the ectoderm);

2) enterodermal type (develops from the endoderm);

3) whole nephrodermal type (develops from the mesoderm);

4) ependymoglial type (develops from neuroectoderm);

5) angiodermal type (or vascular endothelium developing from the mesenchyme).

Topographic classification of the epithelium:

1) skin type (skin epidermis);

2) gastrointestinal;

3) renal;

4) hepatic;

5) respiratory;

6) vascular (vascular endothelium);

7) epithelium of serous cavities (peritoneum, pleura, pericardium).

The glandular epithelium forms most of the body's glands. Consists of glandular cells (glandulocytes) and basement membrane.

Gland classification

By number of cells:

1) unicellular (goblet gland);

2) multicellular (the vast majority of glands).

According to the location of cells in the epithelial layer:

1) endoepithelial (goblet gland);

2) exoepithelial.

By the method of removing the secret from the gland and by structure:

1) exocrine glands (have an excretory duct);

2) endocrine glands (do not have excretory ducts and secrete (hormones) into the blood or lymph).

According to the method of secretion from the glandular cell:

1) merocrine;

2) apocrine;

3) holocrine.

According to the composition of the allocated secret:

1) protein (serous);

2) mucous membranes;

3) mixed (protein-mucous);

4) sebaceous.

By structure:

1) are simple;

2) complex;

3) branched;

4) unbranched.

Phases of the secretory cycle of glandular cells

There are the following phases of the secretory cycle of glandular cells:

1) absorption of the initial products of secretion;

2) synthesis and accumulation of the secret;

3) secretion (according to the merocrine or apocrine type);

4) restoration of the glandular cell.

Authors: Selezneva T.D., Mishin A.S., Barsukov V.Yu.

<< Back: General principles of tissue organization

>> Forward: Blood and lymph

We recommend interesting articles Section Lecture notes, cheat sheets:

▪ Inheritance law. Lecture notes

▪ Dentistry. Crib

▪ History of psychology. Crib

See other articles Section Lecture notes, cheat sheets.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

The existence of an entropy rule for quantum entanglement has been proven 09.05.2024

Quantum mechanics continues to amaze us with its mysterious phenomena and unexpected discoveries. Recently, Bartosz Regula from the RIKEN Center for Quantum Computing and Ludovico Lamy from the University of Amsterdam presented a new discovery that concerns quantum entanglement and its relation to entropy. Quantum entanglement plays an important role in modern quantum information science and technology. However, the complexity of its structure makes understanding and managing it challenging. Regulus and Lamy's discovery shows that quantum entanglement follows an entropy rule similar to that for classical systems. This discovery opens new perspectives in the field of quantum information science and technology, deepening our understanding of quantum entanglement and its connection to thermodynamics. The results of the study indicate the possibility of reversibility of entanglement transformations, which could greatly simplify their use in various quantum technologies. Opening a new rule ... >>

Mini air conditioner Sony Reon Pocket 5 09.05.2024

Summer is a time for relaxation and travel, but often the heat can turn this time into an unbearable torment. Meet a new product from Sony - the Reon Pocket 5 mini-air conditioner, which promises to make summer more comfortable for its users. Sony has introduced a unique device - the Reon Pocket 5 mini-conditioner, which provides body cooling on hot days. With it, users can enjoy coolness anytime, anywhere by simply wearing it around their neck. This mini air conditioner is equipped with automatic adjustment of operating modes, as well as temperature and humidity sensors. Thanks to innovative technologies, Reon Pocket 5 adjusts its operation depending on the user's activity and environmental conditions. Users can easily adjust the temperature using a dedicated mobile app connected via Bluetooth. Additionally, specially designed T-shirts and shorts are available for convenience, to which a mini air conditioner can be attached. The device can oh ... >>

Energy from space for Starship 08.05.2024

Producing solar energy in space is becoming more feasible with the advent of new technologies and the development of space programs. The head of the startup Virtus Solis shared his vision of using SpaceX's Starship to create orbital power plants capable of powering the Earth. Startup Virtus Solis has unveiled an ambitious project to create orbital power plants using SpaceX's Starship. This idea could significantly change the field of solar energy production, making it more accessible and cheaper. The core of the startup's plan is to reduce the cost of launching satellites into space using Starship. This technological breakthrough is expected to make solar energy production in space more competitive with traditional energy sources. Virtual Solis plans to build large photovoltaic panels in orbit, using Starship to deliver the necessary equipment. However, one of the key challenges ... >>

Random news from the Archive

Key Optical Transistor Technology 19.07.2013

Scientists and engineers from the Technical University of Vienna were able to control the polarization of a terahertz light beam, which is the basis for creating promising optical microcircuits.

Scientists have managed to change the polarization of a light beam (the direction of light oscillations) using a special material and an electric current. This laboratory technique has the potential to be scaled up and applied to industrial production, paving the way for the mass production of high-speed electronics that are controlled by light rather than electric current. In addition, the control of terahertz radiation can be useful not only for the production of optical computers, but also, for example, for the manufacture of scanners and medical devices.

Light can oscillate in different directions, that is, have different polarizations. This phenomenon has long been known and widely used, for example, in 3D television. Scientists from Austria for the first time managed to control the polarization of light at the micro level. An electric field applied to an ultrathin layer of telluride, mercury, allows you to arbitrarily change the polarization of light. In this case, terahertz light radiation was used, that is, the optical chip can operate at a much higher frequency than current processors with their 3-5 GHz.

One of the advantages of the Austrian invention is the very low power consumption. To change the polarization of terahertz light radiation using an electric field, a voltage of less than 1 V is required.

Thus, scientists and engineers from the Technical University of Vienna have created a technology that could revolutionize the electronics industry. Of course, modern production technologies and the principles of electronics are very firmly rooted, but let's hope that the advantages of optical transistors will eventually outweigh all the costs of reforming production.

Other interesting news:

▪ Current/Power Monitor Chip

▪ Breathing out of control

▪ Portable tomograph for rats

▪ Mobile phones are not associated with brain tumors

▪ US:E smart door lock

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Lecture notes, cheat sheets. Selection of articles

▪ article Combine business with pleasure. Popular expression

▪ article When was the first subway launched? Detailed answer

▪ Article Bricklayer. Job description

▪ article Generator for the locator. Encyclopedia of radio electronics and electrical engineering

▪ article Non-contact shutdown of the starting winding of the electric motor. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews