Membranes are what? Biological membrane: functions and structure

Nature has created many organisms and cells, but despite this, the structure and most of the functions of biological membranes are the same, which allows us to consider their structure and study their key properties without attachment to a specific kind of cells.

What is a membrane?

Membranes - a protective element, which is an integral part of the cell of any living organism.

The structural and functional unit of all living organisms on the planet is the cell. Its vital activity is inextricably linked with the environment with which it exchanges energy, information, substance. Thus, the nutritional energy necessary for the functioning of the cell comes from outside and is spent on its various functions.

Structure of the simplest unit of the structure of a living organism: cell membrane , nucleus, organelles, various inclusions. It is surrounded by a membrane, inside which is the core and all the organelles. These are mitochondria, lysosomes, ribosomes, Golgi apparatus, endoplasmic reticulum. Each structural element has its own membrane.

The role in the life of the cell

The biological membrane plays a culminating role in the structure and functioning of the elementary living system. Only a cell surrounded by a protective shell can rightly be called an organism. Such a process as metabolism is also carried out due to the presence of a membrane. If its structural integrity is violated, this leads to a change in the functional state of the organism as a whole.

Cell membrane and its functions

It separates the cytoplasm of the cell from the external environment or from the envelope. The cell membrane ensures proper performance of specific functions, specificity of intercellular contacts and immune manifestations, supports the transmembrane difference in electrical potential. It has receptors capable of perceiving chemical signals - hormones, mediators and other biological active components. These receptors give it another ability - to change the metabolic activity of the cell.

Membrane functions:

1. Active transfer of substances.

2. Passive transfer of substances:

2.1. Diffusion is simple.

2.2. Transfer through the pores.

2.3. Transport, carried out due to the diffusion of the carrier along with the membrane substance or by relaying the substance along the molecular chain of the vector.

3. Transfer of non-electrolytes due to simple and light diffusion.

4. Active ion transport.

The structure of the cell membrane

The membrane components of the cell are lipids and proteins.

Lipids: phospholipids, phosphatidylethanolamine, sphingomyelin, phosphatidylinositol and phosphatidylserine, glycolipids. The share of lipids is 40-90%.

Proteins: peripheral, integral (glycoproteins), spectrin, actin, cytoskeleton.

The main structural element is a double layer of phospholipid molecules.

Roofing membrane: definition and typology

Some statistics. On the territory of the Russian Federation, the membrane as a roofing material has not been used for a long time. The specific weight of membrane roofs from the total number of soft roof slabs is only 1.5%. Bitumen and mastic roofs became more widespread in Russia. And in Western Europe, the proportion of membrane roofs accounted for 87%. The difference is palpable.

As a rule, the membrane in the role of the main material when overlapping the roof is ideal for flat roofs. For those with a large slope, it is less suitable.

The volumes of production and sale of membrane roofs on the domestic market have a positive growth trend. Why? The reasons are more than clear:

• The service life is about 60 years. Imagine, only the warranty period of use, which is set by the manufacturer, reaches 20 years.
• Ease of installation. For comparison: the installation of bituminous roof takes 1.5 times longer than the installation of membrane overlap.
• Easy maintenance and repair work.

The thickness of roofing membranes can be 0.8-2 mm, and the average weight per square meter is 1.3 kg.

Properties of roofing membranes:

• elasticity;
• strength;
• Resistance to ultraviolet rays and other aggressors;
• Frost resistance;
• Fireproofness.

The membrane of the roofing is of three types. The main classification feature is the kind of polymer material that makes up the base of the fabric. So, roofing membranes are:

• EPDM. Membranes belonging to the EPDM group are made on the basis of polymerized ethylene-propylene-diene monomer, or, more simply, synthetic rubber. Advantages: high strength, elasticity, water resistance, ecological compatibility, low cost. Disadvantages: adhesive bonding technology by using a special tape, low strength of joints. Scope: it is used as a waterproofing material for tunnel overlaps, water sources, waste storage, artificial and natural reservoirs, etc.
• PVC-membranes. These are shells, in the production of which the main material is polyvinyl chloride. Advantages: resistance to ultraviolet, fire resistance, an extensive range of colors of membrane webs. Disadvantages: low resistance to bitumen materials, oils, solvents; Releases harmful substances into the atmosphere; The color of the fabric fades with time.
• TVE. Are made of thermoplastic olefins. Can be reinforced and unreinforced. The first are equipped with polyester mesh or fiberglass cloth. Advantages: ecological compatibility, durability, high elasticity, temperature resistance (both at high and low temperatures), welded seam joints. Disadvantages: high price category, lack of producers in the domestic market.

Membrane profiled: characteristics, functions and benefits

Profiled membranes are an innovation in the construction market. This membrane is used as a waterproofing material.

The substance used in the manufacture is polyethylene. The latter is of two types: high pressure polyethylene (LDPE) and low pressure polyethylene (HDPE).

The technical characteristics of the membrane from PVD and HDPE

Index	LDPE	HDPE
Breaking strength (MPa)	13	23
Elongation at tension (%)	400	100
Density (kg / m3)	917-930	948-952
Compressive strength (MPa)	12	20-36
Impact toughness (notched) (KJ / sq. M)	-	2-50
The elastic modulus for bending (MPa)	140-250	600-850
Hardness (MPa)	14-25	45-59
Operating temperature (° C)	-60 to +80	-60 to +80
Daily water absorption rate (%)	0.01	0.01

The profiled membrane made of high pressure polyethylene has a special surface - hollow bumps. The height of these formations can vary from 7 to 20 mm. The inner surface of the membrane is even. This makes it possible to smoothly bend the building material.

Changing the shape of individual sections of the membrane is excluded, since the pressure over its entire area is distributed evenly due to the presence of all the same protrusions. Geomembrane can be used as ventilation insulation. In this case, free heat exchange inside the building is ensured.

Advantages of profiled membranes:

• Increased strength;
• Heat resistance;
• The stability of chemical and biological effects;
• Long service life (more than 50 years);
• Simplicity in installation and maintenance;
• Affordable cost.

Profiled membranes are of three types:

• With a single-layered cloth;
• With a two-layer cloth = geotextile + drainage membrane;
• With a three-layer cloth = slippery surface + geotextile + drainage membrane.

Single-layer profiled membrane is used to protect the main waterproofing, installation and dismantling of concrete preparation of walls with high humidity. Two-layer protective is used during the equipment of wall drainage. It consists of three layers applied on the ground, which lends itself to frost heaving, and soil soil, which is deep.

Areas of using drainage membranes

The profiled membrane is used in the following areas:

1. Basic waterproofing of the foundation. Provides reliable protection against the damaging effects of groundwater, root systems of plants, subsidence of soil, mechanical damage.
2. Wall drainage of the foundation. Neutralizes the impact of groundwater, atmospheric precipitation by transferring them to drainage systems.
3. Horizontal drainage of reservoir type - protection against deformation due to structural features.
4. Analog preparation of concrete. Operated in the case of construction work on the erection of buildings in the zone of low groundwater occurrence, in cases where horizontal waterproofing is used to protect against capillary moisture. Also in the function of a profiled membrane is the non-letting of cement milk into the ground.
5. Ventilation of wall surfaces of high humidity level. Can be installed both on the inside and outside of the room. In the first case, air circulation is activated, and in the second case, optimum humidity and temperature are ensured.
6. Used inversion roof.

Superdiffusion membrane

The superdiffusion membrane is a new generation material, the main purpose of which is the protection of roofing elements from wind phenomena, precipitation, and vapor.

The production of protective material is based on the use of non-woven fabrics, high-quality dense fibers. In the domestic market, a three-layer and four-layer membrane are popular. Feedback from specialists and consumers confirm that the more layers underpin the design, the stronger its protective functions, and hence the higher the energy efficiency of the room as a whole.

Depending on the type of roof, the features of its construction, climatic conditions, manufacturers recommend giving preference to one type of diffusion membranes. So, they exist for pitched roofs of complex and simple structures, for pitched roofs with a minimum slope, for roofs with rebated coating, etc.

The superdiffusion membrane is laid directly on the heat-insulating layer, flooring from the boards. There is no need for a ventilation gap. The material is fixed with special staples or steel nails. The edges of the diffusion sheets are connected by a mounting tape. Installation work can be carried out even under extreme conditions: in a frosty morning, with strong gusts of wind, etc.

In addition, the coating in question can be used as temporary roof overlapping.

PVC membranes: essence and function

PFX membranes are a roofing material made from polyvinyl chloride and having elastic properties. Such modern roofing material completely replaced the bituminous rolled analogues, which have a significant drawback - the need for systematic maintenance and repair. To date, the characteristic features of PVC membranes allow them to be used when repairing old flat roofs. They are also used in the installation of new roofs.

Roofing from such material is convenient in operation, and its installation is possible on any type of surfaces, at any time of the year and under any weather conditions. PVC membrane has the following properties:

• strength;
• Stability when exposed to UV rays, various kinds of precipitation, point and surface loads.

Due to its unique properties, PVC membranes will serve you faithfully for many years. The term of use of such a roof is equal to the lifetime of the building itself, while the roll roofing materials need regular maintenance, and in some cases even in the dismantling and installation of a new floor.

Between the membrane PVC liners are connected by welding with a hot sigh, the temperature of which is between 400-600 degrees Celsius. Such a connection is absolutely sealed.

Advantages of PVC membranes

Their advantages are obvious:

• Flexibility of the roofing system, which corresponds to the construction project;
• Sturdy, sealed connection joint between membranes;
• Ideal tolerance of climate change, weather conditions, temperature, humidity;
• Increased vapor permeability, which promotes the evaporation of moisture accumulated in the under-roof space;
• A variety of color options;
• Fireproof properties;
• The ability to preserve the original properties and appearance for a long period;
• PVC membrane is absolutely ecological material, which is confirmed by the corresponding certificates;
• The installation process is mechanized, so it does not take much time;
• The operating rules allow the installation of various architectural additions directly from the top of the membrane PVC roof;
• Single-layer stacking will save your money;
• Simplicity in maintenance and repair.

Membrane tissue

The textile industry is known for a long time. From such material, footwear and clothes are made: adult and children's. Membrane is the basis of membrane tissue, presented in the form of a thin polymer film and possesses such characteristics as waterproofness and vapor permeability. To produce this material, this film is covered with outer and inner protective layers. The structure of them determines the membrane itself. This is done in order to preserve all the useful properties even in case of damage. In other words, membrane clothing does not get wet when exposed to precipitation in the form of snow or rain, but at the same time it perfectly passes the steam from the body to the external environment. This capacity allows the skin to breathe.

Considering all the above, it can be concluded that such a fabric is used to make perfect winter clothes. The membrane that forms the basis of the tissue can be:

• With pores;
• Without pores;
• Combined.

In the composition of membranes that have many micropores, Teflon is listed. The dimensions of such pores do not reach the dimensions even of a drop of water, but more than an aqueous molecule, which indicates water resistance and the ability to excrete sweat.

Membranes that do not have pores are usually made of polyurethane. Their inner layer concentrates in itself all the fatty discharges of the human body and pushes them out.

The structure of the membrane combined implies the presence of two layers: porous and smooth. This fabric has high quality characteristics and will last for many years.

Thanks to these advantages, clothes and shoes made from membrane fabrics and designed for wear during the winter season are durable but lightweight and excellently protect against frost, moisture and dust. They are simply irreplaceable for a lot of active types of winter recreation, mountaineering.