What is a membrane? This concept is used in various life spheres and sciences. And in each of them it has a different meaning. But, one way or another, the use of this term is connected with the meaning of the word itself. Translated from Latin, "membrane" is a membrane.
Different interpretations of the concept
In technology and engineering, this concept is used when talking about a thin film or plate fixed along the contour, as in microphones or pressure gauges.
In biology, a membrane is understood as an elastic molecular structure that is present in every cell and performs the function of protection from environmental influences. It ensures the integrity of the cell and participates in metabolic processes with the outside world.
Reverse osmosis membrane
One of the recent inventions is the reverse osmosis module, which is used to purify water. This design is a pipe having a bottom and a lid. And inside this pipe is just the reverse osmosis membrane, the presence of which ensures the production of ultrapure water, freed from various bacteriological contaminants.and biological deposits. The fluid purification mechanism is based on minimizing dead spaces where bacteria can accumulate.
These modules are widely used in medicine, and to be more precise, they supply devices for hemodialysis with ultrapure water.
Membranes for hydraulic accumulators and expansion tanks. Their replacement
Hydraulic accumulators and expansion tanks are devices that are used to compensate for excess pressure (volume) inside heating devices.
What is the membrane in this case? This element is the main component of devices of this type. It affects the performance and reliability of the entire system. The shape of the membrane may vary. It is diaphragm, ball and balloon. If the tank has a large volume, then a metal fitting is inserted into the back of the element, in which there is a hole for bleeding air. Depending on the scope of use of the device, the material for the manufacture of the membrane is selected. For example, in the expansion tanks of the heating system, the main criterion is the level of heat resistance and durability. In the case of cold water supply, the choice of membrane material is guided by the criterion of dynamic elasticity.
Unfortunately, there is no material that can be called universal. Therefore, its correct choice is one of the most important conditions for long-term operation of the device and its efficient operation. Most often, the plates are made of natural rubber,synthetic butyl or ethylene propylene rubber.
The membrane is replaced by disconnecting the accumulator or expansion tank from the system. First, the screws that hold the flange and body together are removed. In some devices there is also a mount in the nipple area. After removing it, the membrane can be easily removed. By performing the reverse action, you need to install a new membrane.
Polymer membranes
The concept of "polymer membrane" is used in several cases. Firstly, it is used, speaking about one of the most modern and advanced roofing materials in terms of practicality. This type of membrane is produced by using an extrusion method, which ensures that there are no voids in the composition of the finished material. The advantages of a polymer product include absolute water resistance, vapor permeability, light weight, strength, low flammability, environmental safety.
The term "polymer membrane" is often used when it comes to the reverse osmosis plates already mentioned above, as well as other types of membranes made from organic polymers. These are micro- and ultrafiltration products, membranes used in nanofiltration. The advantage of polymeric membranes in this context lies in high manufacturability and great possibilities for controlling the properties and structure of the material. This uses small chemical and technological variations in the manufacturing process.
Cell membrane. Cells - unitsof all living things
It has long been known that the basic structural unit of a living organism is a cell. It is a differentiated section of the cytoplasm, which is surrounded by a cell membrane. In the process of evolution, as the limits of functionality expanded, it acquired plasticity and subtlety, because the most important processes in the body occur precisely in the cells.
The cell membrane is the boundary of the cell, which is a natural barrier between its internal contents and the environment. The main characteristic feature of the membrane is semi-permeability, which ensures the penetration of moisture and nutrients into the cell and the removal of decay products from it. The cell membrane is the main structural component of cell organization.
Historical facts related to the discovery and study of the cell membrane
In 1925, Grendel and Gorder successfully set up an experiment to identify the "shadows" of red blood cells. It was they who first discovered the lipid bilayer in the course of experiments. The successors of their work Danielli, Dawson, Robertson, Nicholson in different years worked on the creation of a fluid-mosaic model of the membrane structure. Singsher finally managed to do this in 1972.
Basic functions of the cell membrane
- Separation of the internal contents of the cell from the components of the external environment.
- Contribute to maintaining the constancy of the chemical composition inside the cell.
- Regulate the balance of metabolism.
- Connectivitybetween cells.
- Signal function.
- Protective function.
Plasma Shell
What is the membrane, which is called the plasma sheath? This is the outer cell wall, which in its structure is an ultramicroscopic film 5-7 nanometers thick. It consists of protein compounds, phospholipids, water. The film, being very elastic, absorbs moisture well, and also has the ability to quickly restore its integrity.
The plasma membrane is characterized by a universal structure. Its boundary position causes participation in the process of selective permeability during the removal of decay products from the cell. Interacting with neighboring elements and reliably protecting the contents from damage, the outer membrane is one of the most important components of the cell structure.
The thinnest layer that sometimes covers the cell membrane of living organisms is called the glycocalyx. It is made up of proteins and polysaccharides. And in plant cells, the membrane is protected from above by a special wall, which also performs a supporting function and maintains its shape. It is primarily made up of fiber, an insoluble polysaccharide.
Thus, we can conclude that the main functions of the outer cell membrane are repair, protection and interaction with neighboring cells.
Building features
What is a membrane? This is a mobile shell, the width of which is 6-10 nanometers. Its structure is based onlipid bilayer and proteins. Carbohydrates are also present in the membrane, but they account for only 10% of the mass of the membranes. But they are necessarily found in glycolipids or glycoproteins.
If we talk about the ratio of proteins and lipids, then it can vary greatly. It all depends on the type of fabric. For example, myelin contains about 20% protein, while mitochondria contain about 80%. The composition of the membrane directly affects its density. The higher the protein content, the higher the density of the shell.
Diversity of lipid functions
Each lipid is a phospholipid in nature, resulting from the interaction of glycerol and sphingosine. Membrane proteins are densely packed around the lipid scaffold, but their layer is not continuous. Some of them are immersed in the lipid layer, while others, as it were, penetrate it. This is the reason for the presence of areas permeable to water.
It is obvious that the composition of lipids in different membranes is not random, but a clear explanation for this phenomenon has not yet been found. Any given shell can contain up to one hundred different types of lipid molecules. Consider the factors that may affect the determination of the lipid composition of the membrane molecule.
- Firstly, a mixture of lipids must necessarily have the ability to form a stable bilayer in which proteins can function.
- Secondly, lipids should help stabilize severely deformed membranes, establish contact between membranes or bind certainproteins.
- Third, lipids are bioregulators.
- Fourthly, some lipids are active participants in biosynthesis reactions.
Cell membrane proteins
Proteins perform several functions. Some play the role of enzymes, while others transport various kinds of substances from the environment into the cell and back.
The structure and functions of the membrane are arranged in such a way that integral proteins penetrate through it, providing a close connection. But peripheral proteins are not closely associated with the membrane. Their function is to maintain the structure of the shell, receive and transform signals from the external environment, and serve as catalysts for various reactions.
The composition of the membrane is represented primarily by a bimolecular layer. Its continuity ensures the barrier and mechanical properties of the cell. In the process of vital activity, a violation of the structure of the bilayer can occur, which leads to the formation of structural defects through hydrophilic pores. Following this, all functions of the cell membrane may be disrupted.
Shell properties
Features of the cell membrane due to its fluidity, due to which it does not have a rigid structure. The lipids that make up its composition can move freely. You can observe the asymmetry of the cell membrane. This is the reason for the difference in the composition of the protein and lipid layers.
The polarity of the cell membrane has been proven, that is, its outer side has a positive charge, and the inner side has a negative one. Alsoit should be noted that the shell has selective insight. It lets in, in addition to water, only certain groups of molecules and ions of dissolved substances.
Features of the structure of the cell membrane in plant and animal organisms
The outer membrane and the endoplasmic reticulum of the cell are closely connected. Often the surface of the shell is also covered with various protrusions, folds, microvilli. The plasma membrane of an animal cell is covered on the outside with a glycoprotein layer that performs receptor and signal functions. In plant cells, outside this shell is another one, thick and clearly visible under a microscope. The fiber it is made of is involved in the formation of support for plant tissues such as wood.
Animal cells also have external structures located outside the membrane. They perform an exclusively protective function. An example is chitin, which is found in the integumentary tissue of insects.
In addition to the cellular, there is an intracellular, or inner membrane. It divides the cell into specialized closed compartments called organelles. They must maintain a certain environment at all times.
Based on the above, we can conclude that the cell membrane, the characteristics of which prove its importance in the functioning of the whole organism, has a complex composition and structure, depending on many internal and external factors. Damage to this film may result in deathcells.
Thus, the structure and function of the membrane depends on the field of science or industry in which this concept is applied. In any case, this element is a shell or partition that is flexible and fastened at the edges.
