Lipids constitute a large and quite heterogeneous in chemical composition group of organic substances that are part of living cells, soluble in low-polar organic solvents (ether, benzene, chloroform, etc.) and insoluble in water. IN general view they are considered as derivatives fatty acids.
A peculiarity of the structure of lipids is the presence in their molecules of both polar (hydrophilic) and non-polar (hydrophobic) structural fragments, which gives lipids an affinity for both water and the non-aqueous phase. Lipids are biphilic substances, which allows them to carry out their functions at the interface.
10.1. Classification
Lipids are divided into simple(two-component), if the products of their hydrolysis are alcohols and carboxylic acids, and complex(multicomponent), when as a result of their hydrolysis, other substances are also formed, for example phosphoric acid and carbohydrates. Simple lipids include waxes, fats and oils, as well as ceramides; complex lipids include phospholipids, sphingolipids and glycolipids (Scheme 10.1).
Scheme 10.1.General classification of lipids
10.2. Structural components of lipids
All groups of lipids have two obligatory structural components - higher carboxylic acids and alcohols.
Higher fatty acids (HFAs). Many higher carboxylic acids were first isolated from fats, which is why they are called fatty. Biologically important fatty acids can be saturated(Table 10.1) and unsaturated(Table 10.2). Their general structural features:
They are monocarbon;
Include an even number of carbon atoms in the chain;
Have a cis configuration of double bonds (if present).
Table 10.1.Essential saturated fatty acid lipids
In natural acids, the number of carbon atoms ranges from 4 to 22, but acids with 16 or 18 carbon atoms are more common. Unsaturated acids contain one or more double bonds in the cis configuration. The double bond closest to the carboxyl group is usually located between the C-9 and C-10 atoms. If there are several double bonds, then they are separated from each other by the methylene group CH 2.
The IUPAC rules for DRCs allow the use of their trivial names (see Tables 10.1 and 10.2).
Currently, our own nomenclature of unsaturated liquid liquids is also used. In it, the terminal carbon atom, regardless of the length of the chain, is designated by the last letter Greek alphabetω (omega). The position of double bonds is counted not, as usual, from the carboxyl group, but from the methyl group. Thus, linolenic acid is designated as 18:3 ω-3 (omega-3).
Linoleic acid itself and unsaturated acids with a different number of carbon atoms, but with the arrangement of double bonds also at the third carbon atom, counting from the methyl group, constitute the omega-3 family of liquid fatty acids. Other types of acids form similar families of linoleic (omega-6) and oleic (omega-9) acids. For normal human life, the correct balance of lipids of three types of acids is of great importance: omega-3 (linseed oil, fish oil), omega-6 (sunflower, corn oils) and omega-9 (olive oil) in the diet.
From saturated acids in lipids human body the most important are palmitic C16 and stearic C18 (see Table 10.1), and of the unsaturated ones - oleic C18:1, linoleic C18:2, linolenic and arachidonic C 20:4 (see Table 10.2).
It should be emphasized the role of polyunsaturated linoleic and linolenic acids as compounds irreplaceable for humans (“vitamin F”). They are not synthesized in the body and should be supplied with food in an amount of about 5 g per day. In nature, these acids are found mainly in vegetable oils. They contribute
Table 10 .2. Essential unsaturated fatty acid lipids
*Included for comparison. ** For cis isomers.
normalization lipid profile blood plasma. Linetol, a mixture ethyl ethers higher fatty unsaturated acids, used as a hypolipidemic herbal medicine. Alcohols. Lipids may include:
Higher monohydric alcohols;
Polyhydric alcohols;
Amino alcohols.
In natural lipids, the most common are saturated and less often unsaturated long-chain alcohols (C 16 or more), mainly with an even number of carbon atoms. As an example of higher alcohols, cetyl CH 3 (CH 2 ) 15 OH and melissil CH 3 (CH 2) 29 OH alcohols that are part of waxes.
Polyhydric alcohols in most natural lipids are represented by the trihydric alcohol glycerol. Other polyhydric alcohols are found, such as the dihydric alcohols ethylene glycol and 1,2 propanediol, as well as myoinositol (see 7.2.2).
The most important amino alcohols that are part of natural lipids are 2-aminoethanol (colamine), choline, and serine and sphingosine, which also belong to the α-amino acids.
Sphingosine is an unsaturated long-chain dihydric amino alcohol. The double bond in sphingosine has trance-configuration, and the asymmetric atoms C-2 and C-3 - D-configuration.
Alcohols in lipids are acylated with higher carboxylic acids at the corresponding hydroxyl groups or amino groups. In glycerol and sphingosine, one of the alcohol hydroxyls can be esterified with a substituted phosphoric acid.
10.3. Simple lipids
10.3.1. Waxes
Waxes are esters of higher fatty acids and higher monohydric alcohols.
Waxes form a protective lubricant on the skin of humans and animals and protect plants from drying out. They are used in the pharmaceutical and perfume industries in the production of creams and ointments. An example is palmitic acid cetyl ester(cetin) - main component spermaceti. Spermaceti is secreted from the fat contained in the cavities of the skull of sperm whales. Another example is Palmitic acid melissil ester- component of beeswax.
10.3.2. Fats and oils
Fats and oils are the most common group of lipids. Most of them belong to triacylglycerols - complete esters of glycerol and IVG, although mono- and diacylglycerols are also found and take part in metabolism.
Fats and oils (triacylglycerols) are esters of glycerol and higher fatty acids.
In the human body, triacylglycerols play the role of a structural component of cells or a reserve substance (“fat depot”). Their energy value is approximately twice that of proteins
or carbohydrates. However, elevated levels of triacylglycerols in the blood are one of the additional risk factors for the development of coronary heart disease.
Solid triacylglycerols are called fats, liquid triacylglycerols are called oils. Simple triacylglycerols contain residues of the same acids, while mixed ones contain residues of different ones.
Triacylglycerols of animal origin usually contain predominantly saturated acid residues. Such triacylglycerols are usually solids. On the contrary, vegetable oils contain mainly residues of unsaturated acids and have a liquid consistency.
Below are examples of neutral triacylglycerols and their systematic and (in parentheses) commonly used trivial names, based on the names of their constituent fatty acids.
10.3.3. Ceramides
Ceramides are N-acylated derivatives of the alcohol sphingosine.
Ceramides are present in small quantities in the tissues of plants and animals. Much more often they are part of complex lipids - sphingomyelins, cerebrosides, gangliosides, etc.
(see 10.4).
10.4. Complex lipids
Some complex lipids difficult to classify unambiguously, since they contain groupings that make it possible to classify them simultaneously into different groups. According to general classification Lipids (see Diagram 10.1) Complex lipids are usually divided into three large groups: phospholipids, sphingolipids and glycolipids.
10.4.1. Phospholipids
The group of phospholipids includes substances that remove phosphoric acid during hydrolysis, for example glycerophospholipids and some sphingolipids (Scheme 10.2). In general, phospholipids are characterized by a fairly high content of unsaturated acids.
Scheme 10.2.Classification of phospholipids
Glycerophospholipids. These compounds are the main lipid components of cell membranes.
According to their chemical structure, glycerophospholipids are derivatives l -glycero-3-phosphate.
l-Glycero-3-phosphate contains an asymmetric carbon atom and, therefore, can exist in the form of two stereoisomers.
Natural glycerophospholipids have the same configuration, being derivatives of l-glycero-3-phosphate, formed during metabolism from dihydroxyacetone phosphate.
Phosphatides. Among glycerophospholipids, the most common are phosphatides - ester derivatives of l-phosphatidic acids.
Phosphatidic acids are derivatives l -glycero-3-phosphate, esterified with fatty acids at alcohol hydroxyl groups.
As a rule, in natural phosphatides, in position 1 of the glycerol chain there is a residue of a saturated acid, in position 2 - an unsaturated acid, and one of the hydroxyls of phosphoric acid is esterified with a polyhydric alcohol or amino alcohol (X is the residue of this alcohol). In the body (pH ~7.4), the remaining free hydroxyl of phosphoric acid and other ionic groups in phosphatides are ionized.
Examples of phosphatides are compounds containing phosphatidic acids esterified for phosphate hydroxyl with corresponding alcohols:
Phosphatidylserines, esterifying agent - serine;
Phosphatidylethanolamines, esterifying agent - 2-aminoethanol (in biochemical literature often, but not quite correctly, called ethanolamine);
Phosphatidylcholines, esterifying agent - choline.
These esterifying agents are related because the ethanolamine and choline moieties can be metabolized from the serine moiety by decarboxylation and subsequent methylation with S-adenosylmethionine (SAM) (see 9.2.1).
A number of phosphatides, instead of an amino-containing esterifying agent, contain residues of polyhydric alcohols - glycerol, myoinositol, etc. The phosphatidylglycerols and phosphatidylinositols given below as examples belong to acidic glycerophospholipids, since their structures do not contain fragments of amino alcohols, which give phosphatidylethanolamines and related compounds a neutral character.
Plasmalogens. Less common than ester glycerophospholipids are lipids with an ether linkage, in particular plasmalogens. They contain an unsaturated residue
* For convenience, the way of writing the configuration formula of the myoinositol residue in phosphatidylinositols has been changed from that given above (see 7.2.2).
alcohol linked by an ether bond to the C-1 atom of glycero-3-phosphate, such as plasmalogens with an ethanolamine fragment - L-phosphatidal ethanolamines. Plasmalogens make up up to 10% of all CNS lipids.
10.4.2. Sphingolipids
Sphingolipids are structural analogues of glycerophospholipids in which sphingosine is used instead of glycerol. Another example of sphingolipids is the ceramides discussed above (see 10.3.3).
An important group of sphingolipids are sphingomyelins, first discovered in nervous tissue. In sphingomyelins, the hydroxyl group of C-1 ceramide is esterified, as a rule, with choline phosphate (less often with colamine phosphate), so they can also be classified as phospholipids.
10.4.3. Glycolipids
As the name suggests, compounds of this group include carbohydrate residues (usually D-galactose, less often D-glucose) and do not contain a phosphoric acid residue. Typical representatives glycolipids - cerebrosides and gangliosides - are sphingosine-containing lipids (therefore they can be considered sphingolipids).
IN cerebrosides the ceramide residue is linked to D-galactose or D-glucose by a β-glycosidic bond. Cerebrosides (galactocerebrosides, glucocerebrosides) are part of the membranes of nerve cells.
Gangliosides- carbohydrate-rich complex lipids - were first isolated from the gray matter of the brain. Structurally, gangliosides are similar to cerebrosides, differing in that instead of a monosaccharide they contain a complex oligosaccharide containing at least one residue V-acetylneuraminic acid (see Appendix 11-2).
10.5. Properties of lipids
and them structural components
A special feature of complex lipids is their biphilicity, caused by non-polar hydrophobic and highly polar ionized hydrophilic groups. In phosphatidylcholines, for example, the hydrocarbon radicals of fatty acids form two non-polar “tails”, and the carboxyl, phosphate and choline groups form the polar part.
At the interface, such compounds act as excellent emulsifiers. As part of cell membranes, lipid components provide high electrical resistance of the membrane, its impermeability to ions and polar molecules, and permeability to non-polar substances. In particular, most anesthetic drugs are highly lipid soluble, which allows them to penetrate the membranes of nerve cells.
Fatty acids are weak electrolytes( p K a~4.8). They're in small degree dissociated into aqueous solutions. At pH< p K a non-ionized form predominates, at pH > p Ka, i.e., under physiological conditions, the ionized form RCOO - predominates. Soluble salts of higher fatty acids are called soaps. Sodium salts of higher fatty acids are solid, potassium salts are liquid. As salts of weak acids and strong bases of soap are partially hydrolyzed in water, their solutions have an alkaline reaction.
Natural unsaturated fatty acids that have cis- double bond configuration, have a large supply of internal energy and, therefore, compared to trance-isomers are thermodynamically less stable. Their cis-trans -isomerization occurs easily when heated, especially in the presence of radical reaction initiators. IN laboratory conditions this transformation can be carried out by the action of nitrogen oxides formed during the decomposition of nitric acid when heated.
Higher fatty acids exhibit general Chemical properties carboxylic acids. In particular, they easily form the corresponding functional derivatives. Fatty acids with double bonds exhibit the properties of unsaturated compounds - they add hydrogen, hydrogen halides and other reagents to the double bond.
10.5.1. Hydrolysis
Using the hydrolysis reaction, the structure of lipids is determined, and valuable products (soaps) are obtained. Hydrolysis is the first stage of utilization and metabolism of dietary fats in the body.
Hydrolysis of triacylglycerols is carried out either by exposure to superheated steam (in industry) or by heating with water in the presence of mineral acids or alkalis (saponification). In the body, lipid hydrolysis occurs under the action of lipase enzymes. Some examples of hydrolysis reactions are given below.
In plasmalogens, as in ordinary vinyl esters, the ether bond is cleaved in an acidic, but not in an alkaline, environment.
10.5.2. Addition reactions
Lipids containing unsaturated acid residues in their structure add hydrogen, halogens, hydrogen halides, and water through double bonds in an acidic environment. Iodine number is a measure of the unsaturation of triacylglycerols. It corresponds to the number of grams of iodine that can add to 100 g of a substance. The composition of natural fats and oils and their iodine numbers vary within fairly wide limits. As an example, we give the interaction of 1-oleoyl-distearoylglycerol with iodine (the iodine number of this triacylglycerol is 30).
Catalytic hydrogenation (hydrogenation) of unsaturated vegetable oils is an important industrial process. In this case, hydrogen saturates the double bonds and liquid oils turn into solid fats.
10.5.3. Oxidation reactions
Oxidative processes involving lipids and their structural components are quite diverse. In particular, the oxidation of unsaturated triacylglycerols by oxygen during storage (auto-oxidation, see 3.2.1), accompanied by hydrolysis, is part of the process known as rancidity of oil.
The primary products of the interaction of lipids with molecular oxygen are hydroperoxides formed as a result of a chain free radical process (see 3.2.1).
Lipid peroxidation - one of the most important oxidative processes in the body. It is the main cause of damage to cell membranes (for example, in radiation sickness).
Structural fragments of unsaturated higher fatty acids in phospholipids serve as targets for attack active forms of oxygen(AFC, see Appendix 03-1).
When attacked, in particular, by the hydroxyl radical HO", the most active of the ROS, the lipid molecule LH undergoes homolytic cleavage of the C-H bond in the allylic position, as shown in the example of the model of lipid peroxidation (Scheme 10.3). The resulting allylic radical L" instantly reacts with molecular oxygen present in the oxidation environment to form the lipid peroxyl radical LOO." From this moment, a chain cascade of lipid peroxidation reactions begins, since the constant formation of allylic lipid radicals L" occurs, renewing this process.
Lipid peroxides LOOH are unstable compounds and can spontaneously or with the participation of metal ions of variable valence (see 3.2.1) decompose to form lipidoxyl radicals LO", capable of initiating further oxidation of the lipid substrate. Such an avalanche-like process of lipid peroxidation poses a danger of destruction of membrane structures cells.
The intermediately formed allylic radical has a mesomeric structure and can further undergo transformations in two directions (see diagram 10.3, paths A And b), leading to intermediate hydroperoxides. Hydroperoxides are unstable and even at ordinary temperatures decompose to form aldehydes, which are further oxidized into acids - the final products of the reaction. The result is general case two monocarboxylic and two dicarboxylic acids with shorter carbon chains.
Unsaturated acids and lipids with residues of unsaturated acids under mild conditions are oxidized with an aqueous solution of potassium permanganate, forming glycols, and in more rigid conditions (with the rupture of carbon-carbon bonds) - the corresponding acids.
LIPIDS - this is a heterogeneous group of natural compounds, completely or almost completely insoluble in water, but soluble in organic solvents and in each other, yielding high molecular weight fatty acids upon hydrolysis.
In a living organism, lipids perform various functions.
Biological functions of lipids:
1) Structural
Structural lipids form complex complexes with proteins and carbohydrates, from which the membranes of cells and cellular structures are built, and participate in a variety of processes occurring in the cell.
2) Spare (energy)
Reserve lipids (mainly fats) are the body's energy reserve and participate in metabolic processes. In plants they accumulate mainly in fruits and seeds, in animals and fish - in subcutaneous fatty tissues and tissues surrounding internal organs, as well as liver, brain and nervous tissues. Their content depends on many factors (type, age, nutrition, etc.) and in some cases accounts for 95-97% of all secreted lipids.
Calorie content of carbohydrates and proteins: ~ 4 kcal/gram.
Caloric content of fat: ~ 9 kcal/gram.
The advantage of fat as an energy reserve, unlike carbohydrates, is its hydrophobicity - it is not associated with water. This ensures compactness of fat reserves - they are stored in anhydrous form, occupying a small volume. The average person's supply of pure triacylglycerols is approximately 13 kg. These reserves could be enough for 40 days of fasting under conditions of moderate physical activity. For comparison: total reserves glycogen in the body - approximately 400 g; when fasting, this amount is not enough even for one day.
3) Protective
Subcutaneous adipose tissue protects animals from cooling, and internal organs from mechanical damage.
The formation of fat reserves in the body of humans and some animals is considered an adaptation to irregular nutrition and living in a cold environment. Animals that hibernate for a long time (bears, marmots) and are adapted to living in cold conditions (walruses, seals) have a particularly large reserve of fat. The fetus has virtually no fat and appears only before birth.
A special group in terms of their functions in a living organism are the protective lipids of plants - waxes and their derivatives, covering the surface of leaves, seeds and fruits.
4) An important component of food raw materials
Lipids are an important component of food, largely determining its nutritional value and taste. The role of lipids in various food technology processes is extremely important. Spoilage of grain and its processed products during storage (rancidity) is primarily associated with changes in its lipid complex. Lipids isolated from a number of plants and animals are the main raw materials for obtaining the most important food and technical products (vegetable oil, animal fats, including butter, margarine, glycerin, fatty acids, etc.).
2 Classification of lipids
There is no generally accepted classification of lipids.
It is most appropriate to classify lipids depending on their chemical nature, biological functions, as well as in relation to some reagents, for example, alkalis.
Based on their chemical composition, lipids are usually divided into two groups: simple and complex.
Simple lipids – esters of fatty acids and alcohols. These include fats , waxes And steroids .
Fats – esters of glycerol and higher fatty acids.
Waxes – esters of higher alcohols of the aliphatic series (with a long carbohydrate chain of 16-30 C atoms) and higher fatty acids.
Steroids – esters of polycyclic alcohols and higher fatty acids.
Complex lipids – in addition to fatty acids and alcohols, they contain other components of various chemical natures. These include phospholipids and glycolipids .
Phospholipids are complex lipids in which one of the alcohol groups is not associated with FA, but with phosphoric acid (phosphoric acid can be combined with an additional compound). Depending on which alcohol is included in the phospholipids, they are divided into glycerophospholipids (contain the alcohol glycerol) and sphingophospholipids (contain the alcohol sphingosine).
Glycolipids – these are complex lipids in which one of the alcohol groups is associated not with FA, but with a carbohydrate component. Depending on which carbohydrate component is part of the glycolipids, they are divided into cerebrosides (they contain a monosaccharide, disaccharide or a small neutral homooligosaccharide as a carbohydrate component) and gangliosides (they contain an acidic heterooligosaccharide as a carbohydrate component).
Sometimes into an independent group of lipids ( minor lipids ) secrete fat-soluble pigments, sterols, and fat-soluble vitamins. Some of these compounds can be classified as simple (neutral) lipids, others - complex.
According to another classification, lipids, depending on their relationship to alkalis, are divided into two large groups: saponifiable and unsaponifiable. The group of saponified lipids includes simple and complex lipids, which, when interacting with alkalis, hydrolyze to form salts of high molecular weight acids, called “soaps”. The group of unsaponifiable lipids includes compounds that are not subject to alkaline hydrolysis (sterols, fat-soluble vitamins, ethers, etc.).
According to their functions in a living organism, lipids are divided into structural, storage and protective.
Structural lipids are mainly phospholipids.
Storage lipids are mainly fats.
Protective lipids of plants - waxes and their derivatives, covering the surface of leaves, seeds and fruits, animals - fats.
FATS
The chemical name of fats is acylglycerols. These are esters of glycerol and higher fatty acids. "Acyl" means "fatty acid residue".
Depending on the number of acyl radicals, fats are divided into mono-, di- and triglycerides. If the molecule contains 1 fatty acid radical, then the fat is called MONOACYLGLYCEROL. If the molecule contains 2 fatty acid radicals, then the fat is called DIACYLGLYCEROL. In the human and animal body, TRIACYLGLYCEROLS predominate (contain three fatty acid radicals).
The three hydroxyls of glycerol can be esterified either with only one acid, such as palmitic or oleic, or with two or three different acids:
Natural fats contain mainly mixed triglycerides, including residues of various acids.
Since the alcohol in all natural fats is the same - glycerol, the differences observed between fats are due solely to the composition of fatty acids.
Over four hundred carboxylic acids of various structures have been found in fats. However, most of them are present only in small quantities.
The acids contained in natural fats are monocarboxylic acids, built from unbranched carbon chains containing an even number of carbon atoms. Acids containing an odd number of carbon atoms, having a branched carbon chain, or containing cyclic moieties are present in small quantities. The exceptions are isovaleric acid and a number of cyclic acids found in some very rare fats.
The most common acids in fats contain 12 to 18 carbon atoms and are often called fatty acids. Many fats contain small amounts of low molecular weight acids (C 2 -C 10). Acids with more than 24 carbon atoms are present in waxes.
The glycerides of the most common fats contain significant quantities of unsaturated acids containing 1-3 double bonds: oleic, linoleic and linolenic. Arachidonic acid containing four double bonds is present in animal fats; acids with five, six or more double bonds are found in fats of fish and marine animals. Most unsaturated acids of lipids have a cis configuration, their double bonds are isolated or separated by a methylene (-CH 2 -) group.
Of all the unsaturated acids contained in natural fats, oleic acid is the most common. In many fats, oleic acid makes up more than half of the total mass of acids, and only a few fats contain less than 10%. Two other unsaturated acids - linoleic and linolenic acid - are also very widespread, although they are present in much smaller quantities than oleic acid. Linoleic and linolenic acids are found in noticeable quantities in vegetable oils; For animal organisms they are essential acids.
Of the saturated acids, palmitic acid is almost as widespread as oleic acid. It is present in all fats, with some containing 15-50% of the total acid content. Stearic and myristic acids are widely used. Stearic acid is found in large quantities (25% or more) only in the storage fats of some mammals (for example, in sheep fat) and in the fats of some tropical plants, such as cocoa butter.
It is advisable to divide the acids contained in fats into two categories: major and minor acids. The main acids of fat are acids whose content in fat exceeds 10%.
Physical properties of fats
As a rule, fats do not withstand distillation and decompose even if they are distilled under reduced pressure.
The melting point, and therefore the consistency of fats, depends on the structure of the acids that make up them. Solid fats, i.e. fats that melt at a relatively high temperature, consist predominantly of glycerides of saturated acids (stearic, palmitic), and oils that melt at a lower temperature and are thick liquids contain significant amounts of glycerides of unsaturated acids (oleic , linoleic, linolenic).
Since natural fats are complex mixtures of mixed glycerides, they do not melt at a certain temperature, but in a certain temperature range, and they are first softened. To characterize fats, it is usually used solidification temperature, which does not coincide with the melting point - it is slightly lower. Some natural fats are solids; others are liquids (oils). The solidification temperature varies widely: -27 °C for linseed oil, -18 °C for sunflower oil, 19-24 °C for cow lard and 30-38 °C for beef lard.
The solidification temperature of fat is determined by the nature of its constituent acids: the higher the content of saturated acids, the higher it is.
Fats are soluble in ether, polyhalogen derivatives, carbon disulfide, aromatic hydrocarbons (benzene, toluene) and gasoline. Solid fats are poorly soluble in petroleum ether; insoluble in cold alcohol. Fats are insoluble in water, but they can form emulsions that are stabilized in the presence of surfactants (emulsifiers) such as proteins, soaps and some sulfonic acids, mainly in a slightly alkaline environment. Milk is a natural fat emulsion stabilized by proteins.
Chemical properties of fats
Fats undergo all chemical reactions characteristic of esters, but their chemical behavior has a number of features associated with the structure of fatty acids and glycerol.
Among the chemical reactions involving fats, several types of transformations are distinguished.
What are lipids, what is the classification of lipids, what is their structure and function? The answer to this and many other questions is given by biochemistry, which studies these and other substances that are of great importance for metabolism.
What it is
Lipids are organic substances that are insoluble in water. The functions of lipids in the human body are diverse.
Lipids - this word means "small particles of fat"
This is first of all:
- Energy. Lipids serve as a substrate for storing and using energy. When 1 gram of fat is broken down, approximately 2 times more energy is released than when protein or carbohydrates of the same weight are broken down.
- Structural function. The structure of lipids determines the structure of the membranes of the cells of our body. They are arranged in such a way that the hydrophilic part of the molecule is located inside the cell, and the hydrophobic part is on its surface. Thanks to these properties of lipids, each cell, on the one hand, is an autonomous system, fenced off from the outside world, and on the other, each cell can exchange molecules with others and with the environment using special transport systems.
- Protective. The surface layer that we have on our skin and serves as a kind of barrier between us and the outside world is also made up of lipids. In addition, they, as part of adipose tissue, provide thermal insulation and protection from harmful external influences.
- Regulatory. They are part of vitamins, hormones and other substances that regulate many processes in the body.
The general characteristics of lipids are based on their structural features. They have dual properties, since they have a soluble and insoluble part in the molecule.
Entry into the body
Lipids partly enter the human body with food, and partly can be synthesized endogenously. Splitting the main part dietary lipids occurs in the duodenum under the influence of pancreatic juice secreted by the pancreas and bile acids in the composition of bile. Having broken down, they are resynthesized again in the intestinal wall and, already as part of special transport particles ─ lipoproteins, ─ are ready to enter the lymphatic system and the general bloodstream.
A person needs to receive about 50-100 grams of fat from food every day, which depends on the condition of the body and the level of physical activity.
Classification
Classification of lipids depending on their ability to form soaps certain conditions divides them into the following classes of lipids:
- Saponifiable. This is the name for substances that, in an environment with alkaline reaction form salts of carboxylic acids (soaps). This group includes simple lipids and complex lipids. Both simple and complex lipids are important for the body; they have different structure and, accordingly, lipids perform different functions.
- Unsaponifiable. In an alkaline environment they do not form salts of carboxylic acids. Biological chemistry includes fatty acids, derivatives of polyunsaturated fatty acids - eicosanoids, cholesterol, as the most prominent representative of the main class of sterols-lipids, as well as its derivatives - steroids and some other substances, for example, vitamins A, E, etc.
General classification of lipids
Fatty acid
Substances that belong to the group of so-called simple lipids and are of great importance for the body are fatty acids. Depending on the presence of double bonds in the non-polar (water-insoluble) carbon “tail”, fatty acids are divided into saturated (do not have double bonds) and unsaturated (have one or even more carbon-carbon double bonds). Examples of the first: stearic, palmitic. Examples of unsaturated and polyunsaturated fatty acids: oleic, linoleic, etc.
It is unsaturated fatty acids that are especially important for us and must be supplied with food.
Why? Because they:
- They serve as a component for the synthesis of cell membranes and participate in the formation of many biologically active molecules.
- Help maintain normal functioning of the endocrine and reproductive systems.
- Help prevent or slow down the development of atherosclerosis and many of its consequences.
Fatty acids are divided into two large groups: unsaturated and saturated
Inflammatory mediators and more
Another type of simple lipids are: important mediators internal regulation, like eicosanoids. They have a unique (like almost everything in biology) chemical structure and, accordingly, unique chemical properties. The main basis Arachidonic acid, which is one of the most important unsaturated fatty acids, is used for the synthesis of eicosanoids. It is eicosanoids that are responsible for the course of inflammatory processes in the body.
Their role in inflammation can be briefly described as follows:
- They change the permeability of the vascular wall (namely, they increase its permeability).
- Stimulate the release of leukocytes and other cells immune system in fabric.
- By using chemical substances mediate the movement of immune cells, the release of enzymes and the absorption of particles foreign to the body.
But the role of eicosanoids in the human body does not end there; they are also responsible for the blood coagulation system. Depending on the current situation, eicosanoids can dilate blood vessels, relax smooth muscles, reduce aggregation or, if necessary, cause the opposite effects: vasoconstriction, contraction of smooth muscles. muscle cells and thrombus formation.
Eicosanoids are a large group of physiologically and pharmacologically active compounds.
Studies have been conducted that show that people sufficient quantity those who received the main substrate for the synthesis of eicosanoids ─ arachidonic acid ─ with food (found in fish oil, fish, vegetable oils) suffered less from diseases of cardio-vascular system. Most likely, this is due to the fact that such people have a more advanced eicosanoid metabolism.
Substances of complex structure
Complex lipids are a group of substances that are no less important for the body than simple lipids. The main properties of this group of fats:
- They participate in the formation of cell membranes, along with simple lipids, and also provide intercellular interactions.
- They are part of the myelin sheath of nerve fibers, necessary for the normal transmission of nerve impulses.
- They are one of the important components surfactant ─ a substance that ensures breathing processes, namely preventing the collapse of the alveoli during exhalation.
- Many of them play the role of receptors on the surface of cells.
- The significance of some complex fats secreted from cerebrospinal fluid, nervous tissue, cardiac muscle is not fully understood.
The simplest representatives of lipids in this group include phospholipids, glyco- and sphingolipids.
Cholesterol
Cholesterol is a substance of lipid nature with the most important value in medicine, since disruption of its metabolism negatively affects the condition of the entire organism.
Some of the cholesterol is ingested with food, and some is synthesized in the liver, adrenal glands, gonads and skin.
It is also involved in the formation of cell membranes, the synthesis of hormones and other chemicals. active substances, and also participates in lipid metabolism in the human body. Indicators of cholesterol in the blood are often examined by doctors, as they show the state of lipid metabolism in the human body as a whole.
Lipids have their own special transport forms - lipoproteins. With their help, they can be transported through the bloodstream without causing embolism.
Violations fat metabolism most quickly and clearly manifested by disorders of cholesterol metabolism, the predominance of atherogenic carriers (so-called low- and very low-density lipoproteins) over antiatherogenic ones (lipoproteins with high density).
The main manifestation of the pathology of lipid metabolism is the development of atherosclerosis.
It manifests itself by narrowing the lumen of arterial vessels throughout the body. Depending on the predominance in blood vessels various localizations narrowing of the lumen of the coronary vessels develops (accompanied by angina), cerebral vessels (with impaired memory, hearing, possible headaches, noise in the head), kidney vessels, blood vessels lower limbs, vessels of the digestive organs with corresponding symptoms.
Thus, lipids are at the same time an indispensable substrate for many processes in the body and, at the same time, if lipid metabolism is disturbed, they can cause many diseases and pathological conditions. Therefore, fat metabolism requires monitoring and correction when the need arises.
07.04.2009
Fats make up approximately 44 percent of the diet. Recommendations about proper diet It is advised that this figure should not exceed 30 percent of total calories, and 25 percent would be even better.
Your fat intake should lean towards polyunsaturated and monounsaturated fats with maximum number saturated fat no more than 10 percent or less of that total 25 percent fat.
* To reduce the fat content when preparing an omelet, remove the yolk of every second egg, this will reduce fat and cholesterol levels, and you will not even feel the difference.
*Cottonseed oil is 25 percent saturated fat and is not the best to use.
* Soybean oil changes taste when long-term storage, due to changes in the levels of linolenic acid it contains.
* Sixty-four percent of the calories from caviar come from fat.
*Butter absorbs refrigerator odors, so it should be stored in a closed container.
* Butter can be stored in the refrigerator for only two weeks. If you need to preserve it for a longer period, store it in the freezer.
*Eight ounces of potato chips equals consuming 12 to 20 teaspoons of fat.
*Try using water instead of fat in some recipes. It is true that fats make dressings, etc., the taste becomes smooth, but if you mix water with flour, with corn starch (corn meal) or potato starch, it will save you from extra calories.
* Oils should be stored in dark containers and stored in a dark, cool place to reduce the risk of rancidity.
* When carob is made into candy, fat is added for texture, making the fat level close to that of real chocolate. In fact, the cocoa butter used in chocolate production is 60 percent saturated fat, while the fat in carob candies is, in most cases, 85 percent saturated fat.
*Using non-stick cookware and vegetable oil sprays will reduce fat consumption.
* Never eat mayonnaise-based salad dressing or salad unless you are sure it has been refrigerated until you are ready to eat it. Neglecting this is the culprit in thousands of cases. food poisoning, annually.
* Fish-related oils are more beneficial than meat-related oils. Fish contains a high percentage of omega fatty acids.
* Any margarine containing coconut or palm oil will have a very high level saturated fat content. Labels now call them tropical oils (tropical plant oils).
* New fat substitutes continue to appear in our products. Don't forget that they are still synthetic and not natural product. They should not be seen as a panacea for replacing fat in our diet.
* The best butter is made from AA sweet cream.
*An ounce of sunflower seeds contains 160 calories and is not considered a dietary snack.
* A burrito topped with sour cream and guacamole (a sauce made from mashed avacado, tomatoes, spices and mayonnaise) can contain up to 1,000 calories and 59 percent fat.
* Research has shown that stearic acid, a saturated fat, has little effect on raising cholesterol levels.
*The new reduced-fat peanut butter has the same number of calories per serving as regular peanut butter, approximately 190 calories per serving, and has been added with sweeteners instead of fat.
* When you store some oils in the refrigerator, they may become cloudy (not clear, light cloudy), this is due to the formation of harmless crystals. Manufacturers sometimes refrigerate oils before releasing them for sale and remove these crystals in a process called “winterizing.” Now these oils will remain clear when cooled.
* Pork fat has large crystals, while butter has small crystals. This is highly dependent on the texture of the fat and can be controlled during processing. The size of the crystals can be changed by shaking (shaking) the oil while it cools.
* Studies have shown that people on a diet miss fat more than sweets.
* People on a high-fat diet are more likely to get colon cancer, prostate cancer or breast cancer. Future research may show that this also has an effect harmful effect on the immune system.
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Are organic compounds, insoluble in water. They consist of fatty acid molecules connected in a chain of hydrogen and carbon atoms. If the carbon atoms are connected to each other by a strong bond, then such fatty acids are called “saturated.” Accordingly, if the carbon atoms are loosely bonded, then the fatty acids are unsaturated. The most important fatty acids for the human body are arachidonic, linoleic, and oleic fatty acids.
Division by chemical formula for saturated and unsaturated acids was developed quite a long time ago. Unsaturated ones, in turn, are divided into polyunsaturated and monounsaturated. Today it is known that saturated acids in our food can be found in pates, meat, milk, eggs. And unsaturated ones are found in olive, peanut, and sunflower oil; fish, goose and duck fat.
The term “lipids” refers to the entire spectrum of fat-like substances extracted with fat solvents (chloroform, ether, gasoline).
Lipids include triacylglycerol esters. These are substances in which glycerol binds to three fatty acid residues. Lipids include oils and fats. Oils contain a large number of unsaturated acids, and have a liquid consistency (with the exception of margarines). Fats, on the contrary, have a solid structure and contain large amounts of saturated acids.
Depending on their origin, lipids are divided into two main categories:
- Vegetable fats (olive oil, nut butter, margarine, etc.).
- Animal fats (found in fish, meat, cheese, butter, cream, etc.).
When fats combine with “bad” carbohydrates, metabolism is disrupted, and as a result, most of them are deposited in the body as fatty layers.
As a rule, in our diet there is an excess of fat - fried fatty foods, in particular fast food, are becoming more and more popular and familiar. At the same time, food may well be tasty, even if you refuse sunflower oil and butter when preparing it.
Some of the lipids directly affect the increase in cholesterol levels in the blood. Cholesterol can be roughly divided into “good” and “bad”. The goal of a healthy diet is the dominance of “good” cholesterol over “bad” cholesterol. The overall blood level of this substance should be normal. If there is too much cholesterol, then it is deposited on the walls of our blood vessels and disrupts blood circulation, which disrupts the trophism of organs and tissues. And insufficient blood supply, in turn, leads to serious disruption of organ functioning. The main danger is the possibility of a blood clot breaking off from the wall and being carried by the blood flow throughout the body. His blood clot will clog the blood vessels of the heart, causing instant death. Everything happens so instantly that there is simply no chance of helping and saving a person.
Not all fats increase the amount of “bad” cholesterol in the blood; some of them, on the contrary, lower its level.
- Fats that increase cholesterol levels are found in butter, lard, meat, cheese, smoked and dairy products, and palm oil. These are saturated fats.
- Fats that almost do not contribute to the formation of cholesterol are found in eggs, oysters, and poultry meat (without skin).
- Fats that help lower cholesterol are vegetable oils: olive, rapeseed, corn, sunflower.
Saturated
Frequent consumption of saturated fats causes serious harm to health. Sausages, lard, butter and cheese should not form the basis of the diet. By the way, saturated fatty acids are found in both palm and coconut oil. When buying products in a store, pay attention to the composition of the ingredients included in them. Palm oil is a frequent “guest” in our diet, although we don’t always know about it. However, some housewives will use it for baking instead of margarine. Meat contains stearic acid, which is contraindicated for the body in large quantities. The amount of fat in the daily diet should not exceed 50 grams. The optimal nutritional balance should consist of 50% monounsaturated fatty acids, 25% polyunsaturated and 25% saturated.Most of People consume too much saturated fat at the expense of unsaturated fat. Of these, about 70% are “invisible” (sausages, aperitif sets, cheeses, chips, and, of course, meat), and 30% are “visible” (this is everything that can be used for frying dishes and spreading on bread) .
Those fats that the body has not used remain in reserve in the body and, when combined with sugars, become the main cause of excess weight. And only physical activity and a balanced diet can correct this situation. Therefore, it is extremely important to adjust the intake of fatty acids according to their expenditure.
Monounsaturated
This type of fat is found in vegetable oils, and its main component is oleic monounsaturated acid. Monounsaturated fats are neutral in relation to the body and do not affect either the tendency to thrombosis or the level of cholesterol in the blood.Olive oil is great for cooking because it holds up well high temperatures(actually up to 210°C), and at the same time retains a significant part of its valuable properties. It is advisable to buy unrefined, cold-pressed oil, and the darker the color it is, the better. It must be stored in a dark and cool place.
To obtain one liter of oil you need 5 kg of black olives. The cold pressing technique retains most of the vitamins and minerals in the oil. mineral salts: copper, phosphorus, magnesium, calcium, potassium, copper, iron. Interesting fact: lipid balance in olive oil almost the same as in breast milk.
Of all the oils, olive oil is the best absorbed, and it also helps relieve constipation and liver failure. Another useful property is that it can neutralize the intoxication of the body after drinking alcohol. Recent studies have shown that olive oil increases calcium absorption levels. This means that it is indispensable in the diet of children at the age when their bone apparatus is formed and developing.
Oleic acid is found in: olive oil (77%), rapeseed oil (55%), peanut oil (55%), grape seed oil (41%), soybean oil (30%), sunflower oil (25%), in wheat germ oil (25%), in wheat germ oil walnuts (20%).
Polyunsaturated
They consist of two groups, in which active substance is the so-called essential fatty acid. Since the body cannot produce it on its own, this acid must come from food.
Main sources: cereal sprouts (up to 50% fatty acid content), corn, cereals, brown rice, and oils.
Linoleic acid (Omega-6) is found in: sunflower oil (57%), soybean oil (55%), grape seed oil (54%), walnut oil (54%), wheat germ oil (53%) , in pumpkin (45%), sesame (41%), peanut (20%), rapeseed (20%), olive (7%).
Linolenic acid (Omega-3): in flaxseed oil (55%), walnut oil (13%), canola oil (8%), wheat germ oil (6%), soybean oil (6%), sesame oil (1 %), olive (0.8%). Omega-3 is also found in fish.
Linseed oil very rich in omega-6 and omega-3 unsaturated fatty acids, which are necessary for cell building. It softens the skin, helps the body fight allergies, protects brain and nerve structures, and stimulates the production of hormones. It must not be heated and cannot be cooked on it. Flaxseed oil is added exclusively to ready-made cooled dishes: soups, cereals, salads, vegetables.
Fish and fish oil are a valuable source of omega-3 fatty acids. It is these acids that our body needs most. They are very useful for brain activity. However, the current ecology is such that it is advisable to give a child sea fish, not pure fish oil. It is made from cod liver, and the liver tends to accumulate various toxins in high doses. In addition, when eating cod liver, there is a high probability of an overdose of vitamins A and D. For people who eat vegetarian food, flaxseed oil is a good replacement for fish oil.
Food supplements that are valuable sources of polyunsaturated fatty acids:
- Pollen.
- Sprouted wheat.
- Brewer's yeast.
- Aspen and borage oils (they can be found in pharmacies in capsule form).
- Soy lecithins.
In addition to some oils
The table provides data on the critical temperatures of some oils (in degrees Celsius), at which they decompose and release carcinogenic toxic substances that primarily affect the liver.Oils sensitive to light and heat
- Walnut oil.
- Pumpkin.
- Linen.
| Oils | mg per 100g oil |
| From wheat sprouts | 300 |
| From walnuts | 170 |
| Soy | 94 |
| Corn | 28 |
| Olive | 15 |
It is better not to eat coconut oil. It contains too many fatty acids. However, many people, especially those living in areas where coconut oil is produced, consider it a literal panacea for all ills. This is one of the oldest types of oils extracted by people. It is extracted from compressed dried coconut fruits. On the other hand, the good thing about coconut oil is that the saturated fat it contains has a completely different structure than the saturated fat used in fast food. That is why there is still debate about whether this oil is harmful or not.
Butter is, on the one hand, an excellent source of vitamins A and D, and on the other hand, cholesterol. But small children have a small amount butter will be useful because when the body is actively growing, it requires saturated fats for the harmonious and complete development of the brain.
What you should definitely know about butter: it absolutely does not tolerate heating above 120°. This means that you cannot fry food on it. Upon contact with the hot surface of the frying pan, the oil immediately begins to release carcinogenic substances that affect the intestines and stomach.
Margarine is an intermediate product between vegetable oil and butter. It was created as a substitute for butter. The composition of margarines may vary from one manufacturer to another. Some are enriched with wheat germ oil, while others contain only saturated fatty acids or are hydrogenated.
If you carry out a minimum of processing, that is, do not hydrogenate margarine, then some vitamins are retained in it. But it must be remembered that the hardness of margarine depends on the amount of palm and coconut oils added to it. Therefore, those who are prone to cardiovascular diseases are not recommended to use margarine.
Paraffin oil is a petroleum derivative and should be avoided. At food use paraffin oil absorption deteriorates fat-soluble vitamins. Moreover, when oil is excreted from the intestines, it binds to already dissolved vitamins and comes out along with them.
Functions of fats
Lipids in our body perform energy and plastic functions. Unsaturated fatty acids are essential because not all of them are synthesized in the body. They are precursors of prostaglandins. Prostaglandins are hormones that maintain the liquid state of cellular lipids, and also prevent the development of atherosclerotic plaques and prevent cholesterol and other lipids from sticking to the walls of blood vessels.Phospholipids are the fundamental structures of most cell membranes. They are part of white and gray matter nervous tissue.
Fats by their nature are excellent solvents. Those substances that do not dissolve in water are highly soluble in fats. Most of the fat accumulates in adipose tissue cells, which are fat depots. Depot can account for up to 30% of body weight. The function of adipose tissue is to fix the neurovascular bundles and internal organs. Fat is a thermal insulator that retains heat, particularly in childhood. Lipid metabolism is closely interconnected with protein and carbohydrate metabolism. When excess carbohydrates enter the body, they can turn into fats. In unfavorable conditions for the body, during fasting, fats turn back into carbohydrates.
The energy function is that lipids from all nutrients give the body the greatest amount of energy. It has been proven that the oxidation of 1 gram of fat releases 9.3 kilocalories of heat, which is twice as much as the oxidation of 1 gram of proteins or carbohydrates. The oxidation of 1 g of proteins and carbohydrates releases 4.1 kcal of heat.
Food fats
Triacylglycerols predominate among them. There are vegetable and animal fats, and vegetable fats are more complete because they contain much more unsaturated acids. A small amount of free fatty acids is also ingested with food. Normally, up to 40% of all calories consumed by our body come from lipids.Absorption and digestion of fats
Digestion of fats is a process of enzymatic hydrolysis, which occurs in the small intestine and duodenum under the influence of enzymatic substances found in the juices of the pancreas and intestinal glands.In order for fats to be digested, the body must produce bile. It contains detergents (or bile acids), which emulsify lipids so that enzymes can break them down better. Products that are formed as a result of digestive hydrolysis - fatty acids, bile acids and glycerol - are absorbed from the intestinal cavity into the mucosal cells. In these cells, fat is resynthesized again and forms special particles called “chylomicrons”, which are sent to the lymph and lymphatic vessels, and then enter the blood through the lymph. In this case, only a small part of the fatty acids formed during the hydrolysis process, which have a relatively short carbon chain (in particular, these are the hydrolysis products of dairy fats) are absorbed and enter the blood of the portal vein, and then into the liver.
The role of the liver in lipid metabolism
The liver is responsible for the processes of mobilization, processing and biosynthesis of lipids. Short-chain fatty acids, combined with bile acids, travel from the digestive tract through the portal vein into the bloodstream into the liver. These fatty acids do not participate in the processes of lipid synthesis and are oxidized with the assistance of liver enzyme systems. In adults, they generally do not play an important role in metabolism. The only exception is children; their diet contains the most fat from milk.Other lipids enter through the hepatic artery as lipoproteins or chylomicrons. They are oxidized in the liver, as in other tissues. Most of the lipids, except for a few unsaturated ones, are newly synthesized in the body. Those of them that are not synthesized must necessarily be ingested along with food products. The overall process of fatty acid biosynthesis is called “lipogenesis”, and it is the liver that is most intensively involved in this process.
Enzymatic processes of transformation of phospholipids and cholesterol are carried out in the liver. The synthesis of phospholipids ensures the renewal of the structural units of its cell membranes in the liver.
Blood lipids
Blood lipids are called lipoproteins. They are associated with different protein fractions of the blood. Their own fractions during centrifugation are separated according to their relative density.The first fraction is called "chylomicrons"; they consist of a thin protein shell and fats. The second fraction is lipoproteins with very low density. They contain a large amount of phospholipids. The third fraction is lipoproteins, containing a lot of cholesterol. The fourth fraction is high-density lipoproteins; they contain the most phospholipids. The fifth fraction is lipoproteins with high density and low content.
The function of lipoproteins in the blood is to transport lipids. Chylomicrons are synthesized in the intestinal mucous cells and carry fat that has been resynthesized from the products of fatty hydrolysis. Chylomicron fats are supplied, in particular, to adipose tissue and the liver. Cells of all body tissues can consume chylomicron fatty acids if they have the necessary enzymes.
Very low density lipoproteins transport exclusively fats that are synthesized in the liver. These lipids are consumed, as a rule, by adipose tissue, although they can also be used by other cells. Fatty acids of high-density lipoproteins are products of the enzymatic breakdown of fat contained in adipose tissue. This faction has a kind of mobility. For example, during a fast, up to 70% of the body’s total energy expenditure is covered by fatty acids from this particular fraction. Phospholipids and cholesterol of high- and low-density lipoprotein fractions are a source of exchange with their corresponding components of cell membranes, with which these lipoproteins can interact.
Transformation of lipids in tissues
In tissues, lipids are broken down under the influence of various lipases, and the resulting fatty acids are added to other formations: phospholipids, cholesterol esters, etc.; or they are oxidized to final products. Oxidation processes occur in several ways. One part of fatty acids oxidative processes in the liver, produces acetone. In severe diabetes mellitus, lipoid nephrosis and some other diseases, the amount of acetone bodies in the blood increases sharply.
Regulation of fat metabolism
The regulation of lipid metabolism is carried out through a rather complex neurohumoral pathway, with the mechanisms predominating in it humoral regulation. If the functions of the gonads, pituitary gland, thyroid gland decrease, the processes of fat biosynthesis increase. The saddest thing is that not only the synthesis of lipids increases, but also their deposition in adipose tissue, and this leads to obesity.Insulin is a hormone of the pancreas and is involved in the regulation of lipid metabolism. Since there is a cross-possibility of transformation of carbohydrates into fats, and then fats into carbohydrates, with insulin deficiency, the processes of carbohydrate synthesis are enhanced, which is accompanied by an acceleration of lipid breakdown processes, during which intermediate metabolic products are formed that are used for the biosynthesis of carbohydrates.
Phospholipids are close in structure to triacylglycerols, only their molecules contain phosphorus-containing groups. Steroids are derivatives of cholesterol and have a different structure. Lipids can also include a large group of fat-soluble substances, which includes vitamins A, D, K, E. Lipids are needed not only to create the lining of our body - they are necessary for hormones, for brain development, for blood vessels and nerves, for the heart. It is known that lipids make up 60% of the brain.
Disturbance of normal blood lipid concentrations
If there are abnormally elevated levels of lipids in the blood, then this pathological condition called hyperlipemia. With hypothyroidism, nephrosis, diabetes and disorders, doctors are faced with a secondary form of hyperlipemia. These diseases cause high levels of cholesterol and triglycerides. Primary hyperlipemia is a fairly rare hereditary pathology that contributes to the development of arteriosclerosis and coronary disease.
During hypoglycemia, fasting, after injections of growth hormone, adrenaline, the amount of free fatty acids in the body sharply increases and mobilization of previously deposited fat begins. This form of the disease is called mobilization hyperlipemia.
With hypercholesterolemia in the blood serum there is a high level of cholesterol and moderate levels of fatty acids. When interviewing close relatives, their medical history will necessarily reveal cases of early atherosclerosis. Hypercholesterolemia even in early age may contribute to the development of myocardial infarction. As a rule, there are no external symptoms. When a disease is detected, treatment is carried out with diet therapy. Its essence is to replace saturated acids with unsaturated acids. Correct diet correction significantly reduces the likelihood of developing pathologies of the vascular system.
With dyslipidemia, the balance of various types of lipids in the blood is disturbed. In particular, the main lipids contained in the blood are cholesterol and triglycerides in different proportions. It is the imbalance that leads to the development of diseases.
High levels of low-density lipids in the blood, as well as low level high-density cholesterol are serious risk factors for cardiovascular complications in patients diagnosed with type 2 diabetes mellitus. Abnormal lipoprotein levels in this case may be a consequence of improper glycemic control.
Dyslipidemia is considered the main cause of the development of atherosclerotic changes.
Factors influencing the development of dyslipidemia
Most significant reasons The formation of dyslipidemia is a genetic disorder of lipid metabolism. They consist of mutations in the genes responsible for the synthesis of apolipoproteins - the components of lipoproteins.The second important factor is healthy/unhealthy lifestyle. Under unfavorable circumstances, lack of physical activity, and drinking alcohol, lipid metabolism is disrupted. Obesity is directly related to increased triglyceride levels and impaired cholesterol concentrations.
Another factor in the development of dyslipidemia is psychoemotional stress, which, through neuroendocrine stimulation, contributes to disorders lipid metabolism. Neuroendocrine stimulation refers to increased activity of the autonomic nervous system.
The clinical classification of types of dyslipidemia involves dividing them into so-called primary and secondary. Among the primary ones, we can distinguish polygenic (acquired during life, but due to hereditary disposition), and monogenic (genetically determined family diseases).
Reason secondary form diseases may be: alcohol abuse, insufficient kidney function, diabetes, cirrhosis, hyperthyroidism, medications that give side effects (antiretroviral drugs, progestins, estrogens, glucocorticosteroids).
Diagnostic methods used to diagnose dyslipidemia include determining lipoprotein levels (high and low density), total cholesterol, and triglycerides. During the daily cycle, even completely healthy people experience fluctuations in cholesterol levels of about 10%; and fluctuations in triglyceride levels - up to 25%. To determine these indicators, blood donated on an empty stomach is centrifuged.
It is recommended to determine the lipid profile once every five years. At the same time, it is desirable to identify other potential risk factors for the development of cardiovascular pathologies (smoking, diabetes mellitus, a history of ischemia in close relatives).
Atherosclerosis
The main factor in the appearance of ischemia is the formation of many small atherosclerotic plaques, gradually increasing in the lumens of the coronary arteries and narrowing the lumen of these vessels. In the early stages of the disease, plaques do not impair blood flow, and the process does not manifest itself clinically. The gradual growth of the plaque and the simultaneous narrowing of the vessel duct can provoke the manifestation of signs of ischemia.
First, they will begin to appear during intense physical stress, when the myocardium requires more oxygen and this need cannot be met by an increase in coronary blood flow.
Clinical manifestation ischemic condition myocardial is a sharply occurring attack of angina. It is accompanied by such phenomena as pain and a feeling of constriction behind the sternum. The attack passes as soon as the stress of an emotional or physical nature stops.
Doctors consider lipid metabolism disorders to be the main (but not the only main) cause of ischemia, but besides this, significant factors are smoking, obesity, disorders carbohydrate metabolism And genetic predisposition. Cholesterol levels directly affect the occurrence of complications of heart disease.
Treatment for this disease consists of normalizing cholesterol levels. To achieve this, diet correction alone is not enough. It is also necessary to combat other risk factors for development: lose weight, increase physical activity, quit smoking. Nutrition correction involves not only reducing the total calorie content of food, but also replacing animal fats with vegetable fats in the diet: reducing
consumption of animal fats and a simultaneous increase in consumption of vegetable fats and fiber. We must remember that a significant part of the cholesterol in our body does not come with food, but is formed in the liver. Therefore, diet is not a panacea.
Used to lower cholesterol levels medications- nicotinic acid, estrogen, dextrothyroxine. Of these drugs, nicotinic acid is the most effective against ischemia, but its use is limited due to the accompanying side effects. The same applies to other medications.
In the 80s of the last century, know-how began to be used in lipid-lowering therapy - drugs from the group of statins. Currently on pharmaceutical market There are 6 drugs available that belong to this group. Pravastatin and lovastatin are drugs based on fungal waste products. Rosuvastatin, atorvastatin, fluvastatin are synthetic drugs, and simvastatin is semi-synthetic.
These drugs help reduce low-density lipoprotein levels, reduce total cholesterol, and to a lesser extent, triglycerides. Several studies have also shown a reduction in overall mortality among ischemic patients.
Cardiosclerosis
This disease is a complication of atherosclerosis and consists of replacement of the myocardium with connective tissue. Connective tissue is not elastic, unlike the myocardium; accordingly, the elasticity of the entire organ on which the inelastic “patch” appears suffers, and the heart valves become deformed.Cardiosclerosis (or myocardiosclerosis) is a logical consequence of an untreated disease: myocarditis, atherosclerosis, rheumatism. Acute development This disease occurs with myocardial infarction and coronary artery disease. When atherosclerotic plaques appear throughout the coronary arteries in the heart, the blood supply to the myocardium suffers, and it lacks oxygen carried through the bloodstream.
The acute form of ischemic disease is myocardial infarction. So the wrong way of life, unbalanced diet and smoking can become an implicit cause of a heart attack, and acute psycho-emotional stress, against the background of which a heart attack appears, is a visible, but far from the main reason.
Besides acute form, they also distinguish chronic. It is manifested by regularly occurring attacks of angina (that is, chest pain). You can relieve pain during an attack with nitroglycerin.
The body is designed in such a way that it tries to decompensate for any violation. Connective tissue scars prevent the heart from elastically stretching and contracting. Gradually, the heart adapts to the scars and simply increases in size, which leads to disruption of blood circulation through the vessels, disruption of muscle contractility, and expansion of the cardiac cavities. All this together causes insufficiency of heart function.
Cardiosclerosis is complicated by a violation heart rate(extrasystole, arrhythmia), protrusion of a fragment of the heart wall (aneurysm). The danger of an aneurysm is that the slightest tension can cause it to rupture, which leads to instant death.
Diagnosis of the disease is carried out using an electrocardiogram and ultrasound of the heart.
Treatment consists of the following: identifying and treating exactly the disease that was main reason development of cardiosclerosis; compliance bed rest in the event that the disease has led to myocardial infarction (at rest, scarring and healing occurs without formation dangerous aneurysm); normalization of rhythm; stimulation of metabolic processes in the heart muscle, limitation of any stress; maintaining a properly balanced diet, in particular, reducing the amount of lipids in the diet.
The diet has a good anti-allergic and anti-inflammatory effect, and is also considered an excellent preventive measure for the prevention of heart disease.
The basic rule of nutrition is moderation in the amount of food. It is also useful to lose extra pounds, which put a strain on the heart. The selection of food products should be carried out from the point of view of their value as energy and plastic materials for the heart. It is imperative to exclude spicy, sweet, fatty, and salty foods from food. Use alcoholic drinks patients with vascular disorders contraindicated. Food must be enriched minerals and vitamins. Fish, boiled meat, vegetables, fruits, dairy products should be the basis of the diet.
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