Lipids - what are they? Translated from Greek, the word "lipids" means "small particles of fat." They are groups of natural organic compounds of a broad nature, including fats themselves, as well as fat-like substances. They are part of all living cells without exception and are divided into simple and complex categories. Simple lipids contain alcohol and fatty acids, while complex lipids contain high-molecular components. Both are associated with biological membranes, have an effect on active enzymes, and also participate in the formation of nerve impulses that stimulate muscle contractions.
Fats and hydrophobia
One of them is creating the body’s energy reserve and providing water-repellent properties. skin coupled with thermal insulation protection. Some fat-containing substances that do not have fatty acids are also classified as lipids, for example, terpenes. Lipids are not susceptible to exposure to an aqueous environment, but are easily dissolved in organic liquids such as chloroform, benzene, and acetone.
Lipids, the presentation of which is periodically held at international seminars in connection with new discoveries, are an inexhaustible topic for research and scientific research. The question "Lipids - what are they?" never loses its relevance. However, scientific progress does not stand still. IN Lately Several new fatty acids have been identified that are biosynthetically related to lipids. Classification of organic compounds can be difficult due to similarity in certain characteristics, but significant differences in other parameters. Most often created separate group, after which the overall picture of the harmonious interaction of related substances is restored.
Cell membranes
Lipids - what are they in terms of their functional purpose? First of all, they are essential component living cells and tissues of vertebrates. Most processes in the body occur with the participation of lipids; the formation of cell membranes, interconnection and exchange of signals in the intercellular environment cannot do without fatty acids.
Lipids - what are they if we consider them from the perspective of spontaneously occurring steroid hormones, phosphoinositides and prostaglandins? This is, first of all, the presence in the blood plasma of which, by definition, are individual components of lipid structures. Because of the latter, the body is forced to produce highly complex systems their transportation. Fatty acids of lipids are mainly transported in complex with albumin, and lipoproteins, soluble in water, are transported in the usual manner.
Classification of lipids
Distribution of compounds having biological nature, by category - this is a process associated with some controversial issues. Lipids in connection with biochemical and structural properties can be equally attributed to different categories. The main classes of lipids include simple and complex compounds.
Simple ones include:
- Glycerides are esters of glycerin alcohol and fatty acids of the highest category.
- Waxes are an ester of a higher fatty acid and a 2-hydroxy alcohol.
Complex lipids:
- Phospholipid compounds - with the inclusion of nitrogenous components, glycerophospholipids, ophingolipids.
- Glycolipids - located in the outer biological layers of the body.
- Steroids are highly active substances of the animal spectrum.
- Complex fats - sterols, lipoproteins, sulfolipids, aminolipids, glycerol, hydrocarbons.
Operation
Lipid fats act as material for cell membranes. Participate in the transport of various substances around the periphery of the body. Fat layers based on lipid structures help protect the body from hypothermia. They have the function of energy accumulation “in reserve”.
Fat reserves are concentrated in the cytoplasm of cells in the form of droplets. Vertebrates, including humans, have special cells - adipocytes, which are capable of containing quite a lot of fat. The placement of fat accumulations in adipocytes occurs thanks to lipoid enzymes.
Biological functions
Fat is not only a reliable source of energy, it also has insulating properties, which biology contributes to. In this case, lipids allow you to achieve several useful functions, such as natural cooling of the body or, conversely, its thermal insulation. In northern regions characterized by low temperatures, all animals accumulate fat, which is deposited evenly throughout the body, and thus creates a natural protective layer that serves as heat protection. This is especially important for large marine animals: whales, walruses, seals.
Animals living in hot countries also accumulate body fat, but in them they are not distributed throughout the body, but are concentrated in certain places. For example, in camels, fat accumulates in the humps, in desert animals - in thick, short tails. Nature carefully monitors the correct placement of both fat and water in living organisms.
Structural function of lipids
All processes associated with the life of the body are subject to certain laws. Phospholipids are the basis of the biological layer of cell membranes, and cholesterol regulates the fluidity of these membranes. Thus, most living cells are surrounded by plasma membranes with a lipid bilayer. This concentration is necessary for normal cellular activity. One biomembrane microparticle contains more than a million lipid molecules, which have dual characteristics: they are both hydrophobic and hydrophilic. As a rule, these mutually exclusive properties are of a non-equilibrium nature, and therefore their functional purpose looks quite logical. Lipids in the cell are an effective natural regulator. The hydrophobic layer usually dominates and protects the cell membrane from the penetration of harmful ions.
Glycerophospholipids, phosphatidylethanolamine, phosphatidylcholine, and cholesterol also contribute to cell impermeability. Other membrane lipids are located in tissue structures, these are sphingomyelin and sphingoglycolipid. Each substance performs a specific function.
Lipids in the human diet
Triglycerides are an effective source of energy. Meat and dairy products have acids. And fatty acids, but unsaturated, are found in nuts, sunflower and olive oil, seeds and corn grains. To prevent cholesterol levels from increasing in the body, it is recommended daily norm limit animal fats to 10 percent.
Lipids and carbohydrates
Many animal organisms “store” fats at certain points, subcutaneous tissue, in the folds of the skin, and other places. The oxidation of lipids in such fatty deposits occurs slowly, and therefore the process of their transition to carbon dioxide and water allows you to get a significant amount of energy, almost twice as much as carbohydrates can provide. In addition, the hydrophobic properties of fats eliminate the need to use large amounts of water to promote hydration. The transition of fats into the energy phase occurs “dry”. However, fats act much more slowly in terms of energy release and are more suitable for hibernating animals. Lipids and carbohydrates seem to complement each other during the life of the body.
The main rule for maintaining health is to evenly distribute the proportion of fat when serving a dish. In fact, a person needs fats, but he must control the amount of fat consumed. A person must determine for himself the amount of fat that will be beneficial and not harmful to health. Fat must go into the right direction, to avoid unpleasant consequences associated with weight gain, which leads to heart problems, hypertension, stroke or even death. Therefore, it is worth paying attention to foods that help burn fat. Today we will look at 10 unknown facts about fats.
Average a common person buys 1 g every day excess fat
. In reality, people gain more body fat. More attention should be paid to nutrition and physical activity. Draw conclusions: The higher your fat intake, the sooner health problems will begin.
Fat cells live for ten years after a person's death. However, they die under the influence physical activity. The problem is that brain cells are constantly dying and being renewed, but if their place is taken fat cells, memory problems occur, especially in older people.
8. Source of calories
In fact, fat is an essential source of calories. necessary for the body. It is vital for maintaining all vital processes in the body. It is worth remembering that excess weight leads to health problems. The main rule is choice the right products with enough calories for the body to function.
7. Fat enhances flavor
Most preservatives and flavor enhancers are based on fat. When you mix them with food, it acquires a pleasant and alluring aroma and taste. If you like to cook, try adding meat or animal fat to the dish; the smell and taste will immediately change.
Fat is a kind of absorbent for vitamins. People who regularly take vitamins notice that after eating, the effect of the vitamins is felt weaker. Especially if the vitamins are in soluble form.
5. Women need fat more than men.
First of all, women's greater need for fat is associated with nature. A woman is a mother, in order to conceive a child, the body requires strength to bear the child and grow it in the womb, the body burns calories and fats, and finally, after the birth of the child, the woman breastfeeds, and the basis of milk is lactose and fat. The fat reserves in a woman’s body are explained by the fact that the body saves energy for the expectant mother. This is why many women lose weight after breastfeeding.
There are two types of fat. They are figuratively called good and bad. Good fat classified as unsaturated fats, such fats are essential to the human body. They are found in lean white meat and steamed foods, such as fish. Bad fats are fatty meats, chicken skin or dairy products. Consumption of these foods leads to high cholesterol and heart problems.
Since fat contains high level calories, they are stored in energy reserves. Consuming 1 gram of fat equals 9 calories.
2. Fat storage
The fat needed for health is stored in the muscles, bone marrow and organs nervous system. It is simply necessary for the production of hormones and increased immunity. Subcutaneous fat is an indicator that it is time to lose weight. Fat is found in foods that increase muscle mass.
Women should maintain between 13 and 17% body fat, which are usually stored in the hips, chest, thighs and abdomen. In men, fat is stored in the abdomen. They should maintain a body fat percentage of 3 to 5%, which is significantly less than for women.
Lipids protrude the most important source energy reserves of the body. The fact is obvious even at the nomenclature level: the Greek “lipos” is translated as fat. Accordingly, the category of lipids combines fat-like substances biological origin. The functionality of the compounds is quite diverse, which is due to the heterogeneity of the composition of this category of biological objects.
What functions do lipids perform?
List the main functions of lipids in the body, which are basic. At the introductory stage, it is advisable to highlight the key roles of fat-like substances in the cells of the human body. The basic list is the five functions of lipids:
- reserve energy;
- structure-forming;
- transport;
- insulating;
- signal
The secondary tasks that lipids perform in combination with other compounds include regulatory and enzymatic roles.
Energy reserve of the body
This is not only one of the important, but the priority role of fat-like compounds. In fact, part of the lipids is the source of energy for the entire cellular mass. Indeed, fat for cells is an analogue of fuel in a car tank. Implemented energy function lipids as follows. Fats and similar substances are oxidized in the mitochondria, breaking down to water and carbon dioxide. The process is accompanied by the release of a significant amount of ATP - high-energy metabolites. Their supply allows the cell to participate in energy-dependent reactions.
Building Blocks
At the same time, lipids perform a construction function: with their help, the cell membrane is formed. The following groups of fat-like substances are involved in the process:
- cholesterol is a lipophilic alcohol;
- glycolipids – compounds of lipids with carbohydrates;
- phospholipids – esters of complex alcohols and higher carboxylic acids.
It should be noted that the formed membrane does not contain fats directly. The resulting wall between the cell and external environment turns out to be two-layer. This is achieved due to biphilicity. This characteristic of lipids indicates that one part of the molecule is hydrophobic, that is, insoluble in water, and the second, on the contrary, is hydrophilic. As a result, a cell wall bilayer is formed due to the ordered arrangement of simple lipids. The molecules turn their hydrophobic regions toward each other, while their hydrophilic tails point inward and outward of the cell.
This determines protective functions membrane lipids. First, the membrane gives the cell its shape and even maintains it. Secondly, the double wall is a kind of passport control point that does not allow unwanted visitors to pass through.
Autonomous heating system
Of course, this name is quite arbitrary, but it is quite applicable if we consider what functions lipids perform. The compounds do not so much heat the body as they retain heat inside. A similar role is assigned to fatty deposits that form around various organs and in subcutaneous tissue. This class of lipids is characterized by high heat-insulating properties, which protects vital organs from hypothermia.
Did you order a taxi?
The transport role of lipids is considered a secondary function. Indeed, the transfer of substances (mainly triglycerides and cholesterol) is carried out by separate structures. These are linked complexes of lipids and proteins called lipoproteins. As is known, fat-like substances are insoluble in water, respectively, in blood plasma. In contrast, the functions of proteins include hydrophilicity. As a result, the lipoprotein core is a collection of triglycerides and cholesterol esters, while the shell is a mixture of protein molecules and free cholesterol. In this form, lipids are delivered to the tissues or back to the liver for removal from the body.
Minor Factors
The list of the 5 functions of lipids already listed complements a number of equally important roles:
- enzymatic;
- signal;
- regulatory
Signal function
Some complex lipids, in particular their structure, allow the transmission of nerve impulses between cells. Glycolipids mediate this process. No less important is the ability to recognize intracellular impulses, also realized by fat-like structures. This allows you to select substances needed by the cell from the blood.
Enzymatic function
Lipids, regardless of their location in the membrane or outside it, are not part of enzymes. However, their biosynthesis occurs with the presence of fat-like compounds. Additionally, lipids are involved in protecting the intestinal wall from pancreatic enzymes. The excess of the latter is neutralized by bile, where cholesterol and phospholipids are included in significant quantities.
Lipids - these are fat-like organic compounds, insoluble in water, but highly soluble in non-polar solvents (ether, gasoline, benzene, chloroform, etc.). Lipids belong to the simplest biological molecules.Chemically, most lipids are esters of higher carboxylic acids and a number of alcohols. The most famous among them are fats. Each fat molecule is formed by a molecule of the triatomic alcohol glycerol and the ester bonds of three molecules of higher carboxylic acids attached to it. According to the accepted nomenclature, fats are called triacyl glycerols.
Carbon atoms in molecules of higher carboxylic acids can be connected to each other by both simple and double bonds. Of the saturated (saturated) higher carboxylic acids, palmitic, stearic, and arachidic acids are most often found in fats; from unsaturated (unsaturated) - oleic and linoleic.
The degree of unsaturation and chain length of higher carboxylic acids (i.e., the number of carbon atoms) determine physical properties one kind of fat or another.
Fats with short and unsaturated acid chains have a low melting point. At room temperature These are liquids (oils) or ointment-like substances (fats). Conversely, fats with long and saturated chains of higher carboxylic acids become solid at room temperature. This is why, when hydrogenation occurs (the saturation of acid chains with hydrogen atoms at double bonds), liquid peanut butter, for example, becomes creamy and sunflower oil turns into hard margarine. Compared to the inhabitants of southern latitudes, in the body of animals living in cold climates (for example, in fish arctic seas), usually contains more unsaturated triacylglycerols. For this reason, their body remains flexible even when low temperatures.
In phospholipids, one of the extreme chains of higher carboxylic acids of triacylglycerol is replaced by a group containing phosphate. Phospholipids have polar heads and nonpolar tails. The groups forming the polar head group are hydrophilic, while the non-polar tail groups are hydrophobic. The dual nature of these lipids determines their key role in the organization of biological membranes.
Another group of lipids consists of steroids (sterols). These substances are based on cholesterol alcohol. Sterols are poorly soluble in water and do not contain higher carboxylic acids. These include bile acids, cholesterol, sex hormones, vitamin D, etc.
Lipids also include terpenes (plant growth substances - gibberellins; carotenoids - photosynthetic pigments; essential oils plants, as well as wax).
Lipids can form complexes with other biological molecules - proteins and sugars.
The functions of lipids are as follows:
Structural. Phospholipids together with proteins form biological membranes. The membranes also contain sterols.
Energy. When fats are oxidized, they are released a large number of energy that goes into the formation of ATP. A significant portion of the body’s energy reserves are stored in the form of lipids, which are consumed when there is a lack of nutrients. Hibernating animals and plants accumulate fats and oils and use them to maintain vital processes. High content Lipids in plant seeds ensure the development of the embryo and seedling before they transition to independent nutrition. The seeds of many plants (coconut palm, castor oil, sunflower, soybean, rapeseed, etc.) serve as raw materials for producing vegetable oil industrially.
Protective and thermal insulating. Accumulating in the subcutaneous tissue and around some organs (kidneys, intestines), the fat layer protects the animal’s body and its individual organs from mechanical damage. In addition, due to low thermal conductivity, the layer of subcutaneous fat helps retain heat, which allows, for example, many animals to live in cold climates. In whales, in addition, it plays another role - it promotes buoyancy.
Lubricating and water repellent. Wax covers the skin, wool, feathers, makes them more elastic and protects them from moisture. The leaves and fruits of many plants have a waxy coating.
Regulatory. Many hormones are derivatives of cholesterol, such as sex hormones (testosterone in men and progesterone in women) and corticosteroids (aldosterone). Cholesterol derivatives, vitamin D play a key role in the metabolism of calcium and phosphorus. Bile acids participate in the processes of digestion (emulsification of fats) and absorption of higher carboxylic acids.
Lipids are also a source of metabolic water. The oxidation of 100 g of fat produces approximately 105 g of water. This water is very important for some desert inhabitants, in particular for camels, which can do without water for 10-12 days: the fat stored in the hump is used precisely for these purposes. Bears, marmots and other hibernating animals obtain the water they need for life as a result of fat oxidation.
In the myelin sheaths of the axons of nerve cells, lipids are insulators during the conduction of nerve impulses.
Wax is used by bees to build honeycombs.
Fat has always been regarded as a component of food that is harmful to the body, and some nutritionists are of the opinion that it is better to limit the intake of fat. But are fats really that bad for us?
In fact, fats perform several very important functions for our body, and first of all, fat is an important supplier of energy for us. We can highlight the fact that 1g of fat supplies more calories than proteins and carbohydrates in double quantity. The body does not burn all fats at once, but puts some of them in storage as a reserve to be used in the future as needed. We bring you information about fats that will help you look at fats in a new way.
Why is fat necessary for our body?
Fats supply essential fatty acids for the functioning of our body, which are involved in metabolism and are energy suppliers. In addition, fats are part of cell membranes, for example, nerve cells have shells that are 60% fat. Thus, we can distinguish several important functions fat:
Fats are suppliers of energy material - approximately 30% of energy comes from fats,
By forming subcutaneous fatty tissue, they protect organs and tissues from mechanical damage and also prevent heat loss,
They are carriers for vitamins A, D, E, K, as well as minerals, since without fats their absorption in the body is impossible,
They are part of cell membranes (mainly cholesterol). Without them, the cell loses its function and collapses,
Fats produce female sex hormones, which is especially important in postmenopause, when ovarian function has practically disappeared. They also play an important role during the reproductive period, since they support hormonal background at the proper level. If the level of adipose tissue in the body is below 10-15%, then hormonal imbalance up to the cessation of the menstrual cycle,
Omega-6 unsaturated acid(aka arachidonic acid) is involved in the activation of blood coagulation and anticoagulation systems.
Almost 35% daily diet must consist of fats. Wherein significant role plays a role in fat.
Which fats are healthy and which are not?
Depending on the chemical structure Fats are divided into saturated and unsaturated fatty acids. Saturated fatty acids contain large amounts of hydrogen ions and are found in foods of animal origin. These are precisely the fats that are deposited on the stomach, thighs, and buttocks. This is a kind of energy reserve of the body. Saturated fats hinder growth muscle mass because they reduce the effect of insulin. But at the same time, they are the basis for the production of testosterone. When they are excluded from food, the level of this hormone, important for men, also decreases. The same can be achieved by consuming them excessively. Therefore, they are also important for the body, but in moderation.
Unsaturated fatty acids (Omega-3 and Omega-6) contain few hydrogen ions and are found primarily in animal products, such as olive oil or vegetable oil, fish oil. These fats are not stored in the body, but are completely burned. They are a beneficial nutritional component for the body and a raw material for the production of hormones.
There are also so-called trans fats, or artificial fats. They are filled with hydrogen ions and are found in candies and cookies, as well as in foods fast food(fast food). They are used primarily for food storage and increase the risk of developing oncological diseases and diseases of the cardiovascular system.
Omega-3 and Omega-6 are unsaturated fatty acids.
Of all types of fats, these fatty acids are the most valuable for our body. They are found in sunflower and corn oils, and rapeseed oil contains them in an ideal ratio.
Omega-3 fatty acids that are beneficial for the body are also found in flaxseed, nut and soybean oils. Salmon, mackerel and herring also contain them sufficient quantity.
Omega-3 and Omega-6 fatty acids:
Reduce the risk of developing atherosclerosis, thus preventing the development of cardiovascular diseases
Reduces cholesterol levels,
Strengthens the walls of blood vessels,
Reduce blood viscosity, thus preventing the development of blood clots,
Improve blood supply to organs and tissues, restoration of nerve cells.
Ideally, you need to mix saturated and unsaturated fats, for example, season meat dishes and salads with canola oil.
Which is better, margarine or butter?
Unlike butter, margarine contains more unsaturated fatty acids. But according to new teachings, this does not mean that the oil is more harmful. In terms of calories, both products are almost equal. But margarine contains harmful trans fats, which contribute to the growth of several diseases.
If you are a fan of margarine, then it is better to choose high-quality types with low content solid fats.
Do fats lead to obesity?
Although fat contains more calories, there is no proven link between fat intake and increased weight.
Excess calories lead to obesity: those who consume more calories than they burn gain weight. Food containing sufficient amounts of fat satiates us for a long period and allows us to eat less.
Those who, on the contrary, try to save on fats, often eat more carbohydrates. Cereal products such as White bread And pasta increase blood sugar levels, and with it insulin, which leads to the growth of adipose tissue. In addition, saturation of the body occurs quickly, but does not last long, resulting in more frequent food consumption.
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