Topic: Lipids Objectives: Study the structure, properties and functions of lipids in the cell. Chapter I. Chemical composition of the cell. Carbohydrates, lipids a) phospholipids are part of cell membranes

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Lipids are a complex mixture organic compounds, which are found in plants, animals and microorganisms. Their common characteristics are: insolubility in water (hydrophobicity) and good solubility in organic solvents (gasoline, diethyl ether, chloroform, etc.).

Lipids are often divided into two groups: Simple lipids Complex lipids These are lipids whose molecules do not contain nitrogen, phosphorus, or sulfur atoms. Simple lipids include: higher carboxylic acids; waxes; triol and diol lipids; glycolipids. These are lipids, the molecule of which contains nitrogen and/or phosphorus atoms, as well as sulfur.

The main function of lipids is energy. The calorie content of lipids is higher than that of carbohydrates. During the breakdown of 1 g of fat, 38.9 kJ is released. Structural. Lipids take part in the formation of cell membranes. Storage. This is especially important for animals that hibernate during the cold season or make long treks through areas where there are no food sources.

Thermoregulatory. Fats are good thermal insulators due to their poor heat conductivity. They are deposited under the skin, forming thick layers in some animals. For example, whales have a layer subcutaneous fat reaches a thickness of 1 m. Protective-mechanical. Accumulating in the subcutaneous layer, fats protect the body from mechanical stress.

Metabolic water source. One of the products of fat oxidation is water. This metabolic water is very important for desert inhabitants. Thus, the fat that fills a camel’s hump serves primarily not as a source of energy, but as a source of water.

Increased buoyancy. Fat reserves increase the buoyancy of aquatic animals. For example, thanks to subcutaneous fat, the body of walruses weighs approximately the same as the water it displaces.

Lipids (fats) are very important in nutrition because they contain a number of vitamins - A, O, E, K and fatty acids important for the body, which synthesize various hormones. They are also part of the tissue and, in particular, the nervous system.

Some lipids are directly responsible for increasing blood cholesterol levels. Let's consider: 1. Fats that increase cholesterol These are saturated fats found in meat, cheese, lard, butter, dairy and smoked products, palm oil. 2. Fats that contribute little to the formation of cholesterol. They are found in oysters, eggs and skinless poultry. 3. Fats that lower cholesterol. These are vegetable oils: olive, rapeseed, sunflower, corn and others. Fish oil does not play any role in cholesterol metabolism, but it prevents cardiovascular diseases. Therefore, the following types of fish (the fattest ones) are recommended: chum and salmon, tuna, mackerel, herring, sardines.

Grade 10

Lipids

INORGANIC COMPOUNDS

ORGANIC COMPOUNDS

Water 75-85%

Proteins 10-20%

Inorganic substances 1-1.5%

Fats 1-5%

Carbohydrates 0.2-2%

Nucleic acids 1-2%

Low molecular weight organic compounds – 0.1-0.5%

Lipids - a group of organic compounds that do not have a single chemical characteristics. What they have in common is that they are all derivatives of higher fatty acids, insoluble in water, but highly soluble in organic solvents (gasoline, ether, chloroform).

Classification of lipids

COMPLEX LIPIDS

(multicomponent molecules)

SIMPLE LIPIDS

(two-component substances that are esters of higher fatty acids and some alcohol)

Simple lipids

Fats are widely distributed in nature. They are part of the human body, animals, plants, microbes, and some viruses. The fat content in biological objects, tissues and organs can reach 90%.

Fats - These are esters of higher fatty acids and trihydric alcohol - glycerol. In chemistry, this group of organic compounds is usually called triglycerides. Triglycerides are the most common lipids in nature.

Fatty acid

More than 500 fatty acids have been found in triglycerides, the molecules of which have a similar structure. Like amino acids, fatty acids have the same grouping for all acids - a carboxyl group (–COOH) and a radical by which they differ from each other. That's why general formula fatty acids have the form R-COOH. The carboxyl group forms the fatty acid head group. It is polar, therefore hydrophilic. The radical is a hydrocarbon tail that differs in different fatty acids in the number of –CH2 groups. It is non-polar and therefore hydrophobic. Most fatty acids contain an even number of carbon atoms in the tail, from 14 to 22 (most often 16 or 18). In addition, the hydrocarbon tail may contain varying numbers of double bonds. Based on the presence or absence of double bonds in the hydrocarbon tail, the following are distinguished:

saturated fatty acids, which do not contain double bonds in the hydrocarbon tail;

unsaturated fatty acids having double bonds between carbon atoms (-CH=CH-).

Formation of a triglyceride molecule

When a triglyceride molecule is formed, each of the three hydroxyl (-OH) groups of glycerol reacts

condensation with fatty acid (Fig. 268). During the reaction, three ester bonds are formed, so the resulting compound is called an ester. Typically, all three hydroxyl groups of glycerol react, so the reaction product is called a triglyceride.

Rice. 268. Formation of a triglyceride molecule.

Properties of triglycerides

Physical properties depend on the composition of their molecules. If saturated fatty acids predominate in triglycerides, then they are solid (fats), if unsaturated, they are liquid (oils).

The density of fats is lower than that of water, so in water they float and are on the surface.

Waxes- a group of simple lipids, which are esters of higher fatty acids and higher high molecular weight alcohols.

Waxes are found in both the animal and plant kingdoms, where they perform mainly protective functions. In plants, for example, they cover leaves, stems and fruits with a thin layer, protecting them from wetting with water and the penetration of microorganisms. The shelf life of fruit depends on the quality of the wax coating. Honey is stored under the cover of beeswax and the larvae develop. Other types of animal wax (lanolin) protect hair and skin from the effects of water.

Complex lipids

Phospholipids

Phospholipids- esters of polyhydric alcohols with higher fatty acids, containing

Rice. 269. Phospholipid.

containing the phosphoric acid residue (Fig. 269). Sometimes additional groups (nitrogenous bases, amino acids, glycerol, etc.) may be associated with it.

As a rule, a phospholipid molecule contains two higher fatty acid residues and

one phosphoric acid residue.

Phospholipids are found in both animals and plants. There are especially many of them in the nervous tissue of humans and vertebrates; there are many phospholipids in plant seeds, the heart and liver of animals, and bird eggs.

Phospholipids are present in all cells of living things, participating mainly in the formation of cell membranes.

Glycolipids

Glycolipids- These are carbohydrate derivatives of lipids. Their molecules, along with polyhydric alcohol and higher fatty acids, also contain carbohydrates (usually glucose or galactose). They are localized primarily on the outer surface of the plasma membrane, where their carbohydrate components are included among other cell surface carbohydrates.

Lipoids - fat-like substances. These include steroids (cholesterol, widely distributed in animal tissues, estradiol and testosterone - female and male sex hormones, respectively), terpenes (essential oils on which the smell of plants depends), gibberellins (plant growth substances), some pigments (chlorophyll, bilirubin) , some vitamins (A, D, E, K), etc.

Functions of lipids

Energy

The main function of lipids is energy. The calorie content of lipids is higher than that of carbohydrates. During the breakdown of 1 g of fats into CO2 and H2O, 38.9 kJ is released. The only food for newborn mammals is milk, the energy content of which is determined mainly by its fat content.

Structural

Lipids take part in the formation of cell membranes. The membranes contain phospholipids, glycolipids, and lipoproteins.

Storage

Fats are a reserve substance of animals and plants. This is especially important for animals that hibernate during the cold season or make long treks through areas where there are no food sources (camels in the desert). The seeds of many plants contain fat necessary to provide energy to the developing plant.

Thermoregulatory

Fats are good thermal insulators due to their poor thermal conductivity. They are deposited under the skin, forming thick layers in some animals. For example, in whales, the layer of subcutaneous fat reaches a thickness of 1 m. This allows the warm-blooded animal to live in cold water. The adipose tissue of many mammals plays the role of a thermostat.

Protective-mechanical

Accumulating in the subcutaneous layer, fats not only prevent heat loss, but also protect the body from mechanical stress. Fat capsules internal organs, the fatty layer of the abdominal cavity provides fixation of the anatomical position of the internal organs and protects them from shock and injury from external influences.

Catalytic

This function is associated with fat-soluble vitamins (A, D, E, K). Vitamins themselves do not have catalytic activity. But they are cofactors for enzymes; without them, enzymes cannot perform their functions.

Metabolic water source

One of the products of fat oxidation is water. This metabolic water is very important for desert inhabitants. Thus, the fat that fills a camel’s hump serves primarily not as a source of energy, but as a source of water (when 1 kg of fat is oxidized, 1.1 kg of water is released).

Increased buoyancy

Fat reserves increase the buoyancy of aquatic animals.

Classification of lipids

Simple lipids

Complex lipids

Fats (triglycerides)

Wax

Classification of lipids

Simple lipids

Complex lipids

Phospholipids– (glycerol + phosphoric acid + fatty acid)

Fats (triglycerides)– esters of high molecular weight fatty acids. acids and trihydric alcohol glycerol

Glycolipids(lipid + carbohydrate)

Wax– esters of higher fatty acids. acids and alcohols

Lipoproteins(lipid + protein)

FATS (triglycerides)

Fats are widely distributed in nature. They are part of the human body, animals, plants, microbes, and some viruses. The fat content in biological objects, tissues and organs can reach 90%.

GENERAL FORMULA OF FAT:

The density of fats is lower than that of water, so in water they float and are on the surface.

TRIGLYCERIDES

FATS

OILS

are of animal origin

are of plant origin

hard

liquid

contains saturated fatty acids

Contains unsaturated fatty acids

WAXES

This is a group of simple lipids, which are esters of higher fatty acids and higher high molecular weight alcohols.

Bees use wax to build honeycombs.

STRUCTURE OF A PHOSPHOLIPIDE MOLECULE

(hydrophilic, consists of glycerol and a phosphoric acid residue)

head

(hydrophobic, composed of residual fatty acids)

tails

phospholipids

Phospholipids are found in both animals and plants.

Phospholipids are present in all cells of living things, participating mainly in the formation of cell membranes.

GLYCOLIPIDS

Glycolipids are found in the myelin sheath of nerve fibers and on the surface of neurons, and are also components of chloroplast membranes.

Nerve fiber structure

Chloroplast

LIPOPROTEINS

In the form of lipoproteins, lipids are transported with blood and lymph.

For example, cholesterol is transported by blood through vessels as part of so-called lipoproteins - complex complexes consisting of fats and proteins, and having several varieties.

FUNCTIONS OF LIPIDS

Function

Characteristic

Example

FUNCTIONS OF LIPIDS

Function

Characteristic

1. Energy

Example

2 O + CO 2 + 38.9 kJ

FUNCTIONS OF LIPIDS

Function

Characteristic

1. Energy

Example

When 1 g of fat is oxidized, H is formed 2 O + CO 2 + 38.9 kJ

a) before The body receives 40% of its energy from lipid oxidation;

b) Every hour, 25 g of fat enters the general bloodstream, which is used to generate energy.

FUNCTIONS OF LIPIDS

Function

Characteristic

2. Stocking up

Example

a) subcutaneous fatty tissue

STORAGE FUNCTION OF LIPIDS

This is especially important for animals that hibernate during the cold season or make long treks through areas where there are no food sources.

Brown bear

Pink salmon

FUNCTIONS OF LIPIDS

Function

Characteristic

2. Stocking up

Example

Spare source E, because fats – “canned energy”

b) a drop of fat inside the cell

Fatty

drops

Core

The seeds and fruits of plants contain fat necessary to provide energy to the developing plant.

FUNCTIONS OF LIPIDS

Function

Characteristic

Example

a) phospholipids are part of cell membranes

FUNCTIONS OF LIPIDS

Function

Characteristic

3. Structural (plastic)

Example

b) glycolipids are part of the myelin sheaths of nerve cells

FUNCTIONS OF LIPIDS

Function

Characteristic

4. Thermoregulatory

Example

Subcutaneous fat protects animals from hypothermia

a) in whales the subcutaneous layer of fat reaches 1 m, which allows the warm-blooded animal to live in the cold water of the polar ocean

FUNCTIONS OF LIPIDS

Function

Characteristic

5. Protective

Example

a) a layer of fat (omentum) protects delicate organs from shocks and shocks

(eg, perinephric capsule, fat pad near the eyes)

FUNCTIONS OF LIPIDS

Function

Characteristic

5. Protective

Example

Fats protect against mechanical stress

b) wax is used to cover plant leaves with a thin layer, preventing them from getting wet during heavy rains, as well as feathers and wool

FUNCTIONS OF LIPIDS

Function

Characteristic

6. Source of endogenous (metabolic)

Example

chesk) water

Jerboa

Gerbil

FUNCTIONS OF LIPIDS

Function

Characteristic

6. Source of endogenous water

Example

When 100 g of fat is oxidized, 107 ml of water is released

a) thanks to such water, many deserts exist. animals (eg jerboas, gerbils, camels)

A camel may not drink for 10-12 days.

FUNCTIONS OF LIPIDS

Function

Characteristic

7. Regulatory

Example

Many fats are components of vitamins and hormones

a) fat-soluble vitamins – D, E, K, A

FUNCTIONS OF LIPIDS

Function

Characteristic

8. Solvents of hydrophobic compounds

Example

Provides penetration of fat-soluble substances into the body

a) vitamins E, D, A

Repetition:

Test 1. With complete combustion of 1 g of the substance, 38.9 kJ of energy was released. This substance refers to:

To carbohydrates.
To fats.
Either to carbohydrates or to lipids.
To the squirrels.

Test 2. The basis of cell membranes is formed by:

Fats.
Phospholipids.
Wax.
Lipids.

Test 3. Statement: “Phospholipids are esters of glycerol (glycerol) and fatty acids”:

Wrong.

Repetition:

**Test 4. Lipids perform the following functions in the body:

Structural. 5. Some are enzymes.
Energy. 6. Source of metabolic water
Thermal insulating. 7. Storage.
Some are hormones. 8. These include vitamins A, D, E, K.

**Test 5. A fat molecule consists of residues:

Amino acids.
Nucleotides.
Glycerin.
Fatty acids.

Test 6. Glycoproteins are a complex:

Proteins and carbohydrates.
Nucleotides and proteins.
Glycerol and fatty acids.
Carbohydrates and lipids.

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Carbohydrates, or saccharides, are organic substances that contain carbon, oxygen, and hydrogen. The chemical composition of carbohydrates is characterized by their general formula Cm(H2O)n, where m≥n. The number of hydrogen atoms in carbohydrate molecules is usually twice the number of oxygen atoms (that is, the same as in a water molecule). Hence the name - carbohydrates.

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Properties of monosaccharides: low molecular weight; sweet taste; easily dissolves in water; crystallize; belong to reducing (reducing) sugars.

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Monosaccharide molecules can be in the form of straight chains or cyclic structures.

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Disaccharides (oligosaccharides) The most widespread disaccharides in nature are: maltose, consisting of two glucose residues; lactose – milk sugar (-glucose + galactose); sucrose – beet sugar (-glucose + fructose).

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Disaccharides are formed by the condensation of two monosaccharides (most often hexoses). The bond that occurs between two monosaccharides is called glycosidic. It usually forms between the 1st and 4th carbon atoms of adjacent monosaccharide units (1,4-glycosidic bond).

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Polysaccharides Properties of polysaccharides: high molecular weight (usually hundreds of thousands); do not produce clearly shaped crystals; either insoluble in water or form solutions resembling colloidal ones in properties; sweet taste is not typical;

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Functions of carbohydrates: Energy. One of the main functions of carbohydrates. Carbohydrates are the main sources of energy in the animal body. When 1 g of carbohydrate is broken down, 17.6 kJ is released. С6Н12О6 + О2 = 6СО2 + 6Н2О + 17.6 kJ Reserve. It is expressed in the accumulation of starch in plant cells and glycogen in animal cells. Support and construction. Carbohydrates are part of cell membranes and cell walls (glycocalyx, cellulose, chitin, murein). Combining with lipids and proteins, they form glycolipids and glycoproteins.

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Ribose and deoxyribose are part of the monomers of DNA, RNA and ATP nucleotides. Receptor. Oligosaccharide fragments of glycoproteins and glycolipids of cell walls perform a receptor function. 6. Protective. The mucus secreted by various glands is rich in carbohydrates and their derivatives (for example, glycoproteins). They protect the esophagus, intestines, stomach, bronchi from mechanical damage, and prevent bacteria and viruses from entering the body.

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Lipids Lipids are a group of organic compounds that do not have a single chemical characteristic. What they have in common is that they are all derivatives of higher fatty acids, insoluble in water, but highly soluble in organic solvents (ether, chloroform, gasoline).

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Depending on the structural features of the molecules, they are distinguished: Simple lipids, which are two-component substances that are esters of higher fatty acids and some alcohol. Complex lipids having multicomponent molecules: phospholipids, lipoproteins, glycolipids. Lipoids, which include steroids - polycyclic alcohol cholesterol and its derivatives.

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Simple lipids. Fats. Fats are widely distributed in nature. They are part of the human body, animals, plants, microbes, and some viruses. The fat content in biological objects, tissues and organs can reach 90%. Fats are esters of higher fatty acids and trihydric alcohol - glycerol. In chemistry, this group of organic compounds is usually called triglycerides. Triglycerides are the most common lipids in nature.

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Waxes are a group of simple lipids, which are esters of higher fatty acids and higher high molecular weight alcohols. Waxes are found in both the animal and plant kingdoms, where they perform mainly protective functions. In plants, for example, they cover leaves, stems and fruits with a thin layer, protecting them from wetting with water and the penetration of microorganisms. The shelf life of fruit depends on the quality of the wax coating. Honey is stored under the cover of beeswax and the larvae develop. Other types of animal wax (lanolin) protect hair and skin from the effects of water.

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Complex lipids. Phospholipids are esters of polyhydric alcohols with higher fatty acids, containing a phosphoric acid residue. Sometimes additional groups (nitrogenous bases, amino acids, glycerol, etc.) may be associated with it. Lipoproteins are derivatives of lipids with various proteins. Some proteins penetrate the membrane - integral proteins, others are immersed in the membrane to varying depths - semi-integral proteins, others are located on the outer or inner surface of the membrane - peripheral proteins.

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Glycolipids are carbohydrate derivatives of lipids. Their molecules, along with polyhydric alcohol and higher fatty acids, also contain carbohydrates (usually glucose or galactose). They are localized primarily on the outer surface of the plasma membrane, where their carbohydrate components are included among other cell surface carbohydrates.

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Lipoids Lipoids are fat-like substances. These include steroids (cholesterol, widespread in animal tissues, its derivatives - estradiol and testosterone - female and male sex hormones, respectively), terpenes (essential oils on which the smell of plants depends), gibberellins (plant growth substances), some pigments (chlorophyll , bilirubin), some vitamins (A, D, E, K), etc.

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Functions of lipids. The main function of lipids is energy. The calorie content of lipids is higher than that of carbohydrates. During the breakdown of 1 g of fats into CO2 and H2O, 38.9 kJ is released. Structural. Lipids take part in the formation of cell membranes. The membranes contain phospholipids, glycolipids, and lipoproteins. Storage. This is especially important for animals that hibernate during the cold season or make long treks through areas where there are no food sources. The seeds of many plants contain fat necessary to provide energy to the developing plant. Thermoregulatory. Fats are good thermal insulators due to their poor thermal conductivity. They are deposited under the skin, forming thick layers in some animals. For example, in whales the layer of subcutaneous fat reaches a thickness of 1 m. Protective-mechanical. Accumulating in the subcutaneous layer, fats protect the body from mechanical stress.

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Catalytic. This function is associated with fat-soluble vitamins (A, D, E, K). Vitamins themselves do not have catalytic activity. But they are coenzymes; without them, enzymes cannot perform their functions. Metabolic water source. One of the products of fat oxidation is water. This metabolic water is very important for desert inhabitants. Thus, the fat that fills a camel’s hump serves primarily not as a source of energy, but as a source of water (when 1 kg of fat is oxidized, 1.1 kg of water is released). Increased buoyancy. Fat reserves increase the buoyancy of aquatic animals.

LECTURE PLAN LIPID CHEMISTRY 1. Definition, role, classification. 2. Characteristics of simple and complex lipids. DIGESTION OF LIPIDS IN THE GASTROINTESTINAL TRACT 1. The role of lipids in nutrition. 2. Bile acids. Emulsification. 3. Enzymes. 5. Absorption of hydrolysis products. 6. Features in children. 7. Resynthesis. DIGESTION AND ABSORPTION DISORDERS Steatorrhea. Steatorrhea.

Functions of lipids: Substrate-energy Substrate-energy Structural (component of biomembranes) Structural (component of biomembranes) Transport (lipoproteins) Transport (lipoproteins) Transmission of nerve impulse Transmission of nerve impulse Electrical insulating (myelin fiber) Electrical insulating (myelin fiber) Thermal insulating (low thermal conductivity) Thermal insulating ( low thermal conductivity) Protective Protective Hormonal Hormonal Vitamin Vitamin

By chemical structure 1. Simple: 1) triacylglycerols (neutral fat) - TG, TAG 1) triacylglycerols (neutral fat) - TG, TAG 2) waxes 2) waxes 2. Complex: 1) phospholipids - PL 1) phospholipids - PL a) glycerophospholipids a ) glycerophospholipids b) sphingophospholipids b) sphingophospholipids 2) glycolipids - GL (cerebrosides, gangliosides, sulfatides) 2) glycolipids - GL (cerebrosides, gangliosides, sulfatides) 3) steroids (sterols and sterides) 3) steroids (sterols and sterides) In relation to water 1. Hydrophobic (form a film on the surface of water) - TG 2. Amphiphilic form: a) bilipid layer - PL, GL (1 head, 2 tails) a) bilipid layer - PL, GL (1 head, 2 tails) b ) micelle - MG, Xs, VZHK (1 head, 1 tail) b) micelle - MG, Xs, VZHK (1 head, 1 tail) According to the biological role 1. reserve (TG) 2. structural - form biological membranes (PL, GL, Xs)

Unsaturated (unsaturated) general formula C n H(2n+1)-2m COOH Monounsaturated: palmitooleic (16:1) C 15 H 29 COOH oleic (18:1) C 17 H 33 COOH Polyunsaturated (vitamin F): linoleic (18 :2) C 17 H 31 COOH linoleic (18:2) C 17 H 31 COOH (ω-6) linolenic (18:3) C 17 H 29 COOH linolenic (18:3) C 17 H 29 COOH (ω-3 ) arachidonic (20:4) C 19 H 31 COOH arachidonic (20:4) C 19 H 31 COOH (ω-6)

The role of polyunsaturated fatty acids (PUFAs) 1. precursors of eicosanoids (prostaglandins, thromboxanes, leukotrienes) - biologically active substances, synthesized from PUFAs with 20 carbon atoms, acting as tissue hormones. 2. are part of phospholipids, glycolipids. 3. help remove cholesterol from the body. 4. They are vitamin F (omega 3, omega 6).

Human fat = glycerol + 2 unsaturated + 1 saturated IVH (dioleopalmitin) Animal fat = glycerol + 1 unsaturated + 2 saturated IVH (oleopalmitostearin glycerol + 1 unsaturated + 2 saturated IVH (oleopalmitostearin) Vegetable fat = glycerin + 3 unsaturated IVH (triolein) Write formulas of the molecule of neutral fat from vegetable, animal and human origin on one's own.

Lysophospholipids Lysophosphatidylcholine (lysolecithin) Contain a free hydroxyl group at the 2nd glycerol atom. They are formed by the action of phospholipase A 2. The membranes in which lysophospholipids are formed become permeable to water, so the cells swell and collapse. (Hemolysis of erythrocytes during the bite of snakes whose venom contains phospholipase A 2)

II. DIGESTION OF LIPIDS IN THE GASTROINTESTINAL TRACT 1. The role of lipids in nutrition 1. The role of lipids in nutrition 2. Bile acids: formation, structure, paired bile acids, role. 2. Bile acids: formation, structure, paired bile acids, role. 3. Emulsification scheme. 3. Emulsification scheme. 4. Digestion enzymes: pancreatic lipase, the chemistry of the action of lipase on triglyceride; phospholipases, cholesterol esterase. 4. Digestion enzymes: pancreatic lipase, the chemistry of the action of lipase on triglyceride; phospholipases, cholesterol esterase. 5. Absorption of lipid hydrolysis products. 5. Absorption of lipid hydrolysis products. 6. Features of lipid digestion in children. 6. Features of lipid digestion in children. 7. Resynthesis of triglycerides and phospholipids in the intestinal wall. 7. Resynthesis of triglycerides and phospholipids in the intestinal wall. III. DISORDERS OF DIGESTION AND ABSORPTION 1. Steatorrhea: causes, types (hepatogenic, pancreatogenic, enterogenic).

ROLE OF LIPIDS IN NUTRITION 1. Food lipids are 99% represented by triglycerides. 2. Lipids come from such food products as vegetable oil - 98%, milk - 3%, butter%, etc. 3. Daily requirement for lipids = 80 g/day (50 g animal +30 g vegetable). 4. Fats provide % of the daily energy requirement. 5. An irreplaceable component of nutrition - polyunsaturated fatty acids (essential), the so-called. Vitamin F is a complex of linoleic, linolenic and arachidonic acids. Daily requirement of vitamin F = 3-16 g. 6. Food lipids serve as solvents for fat-soluble vitamins A, D, E, K. 7. High consumption of saturated fats increases the risk of developing atherosclerosis. Therefore, with age, animal fats are replaced with vegetable fats. 8. Increases the taste of food and provides satiety.

DIGESTION OF LIPIDS IN THE GASTROINTESTINAL TRACT They are not digested in the oral cavity. They are not digested in the mouth. In the stomach only in children (gastric lipase acts only on emulsified milk fats, optimum pH 5.5-7.5). In the stomach only in children (gastric lipase acts only on emulsified milk fats, optimum pH 5.5-7.5). In the small intestine: 1) emulsification, In the small intestine: 1) emulsification, 2) enzymatic hydrolysis. 2) enzymatic hydrolysis. Emulsification factors 1. bile acids 2. CO2 3. fiber 4. peristalsis 5. polysaccharides 6. salts of fatty acids (so-called soaps)

Emulsification mechanism - reducing the surface tension of a fat droplet Emulsification mechanism - reducing the surface tension of a fat droplet The purpose of emulsification is to increase the area of contact of fat molecules with enzyme molecules The purpose of emulsification is to increase the area of contact of fat molecules with enzyme molecules Emulsification scheme:

BILE ACIDS are derivatives of cholanic acid. They are formed in the liver from cholesterol. They are formed in the liver from cholesterol. They are secreted with bile. They are secreted with bile. They circulate up to 10 times. They circulate up to 10 times. ROLE OF BALL ACIDS 1) EMULSIFIATE FATS 2) ACTIVATE LIPASE 3) FORM CHOLEIC COMPLEXES FOR SUCTION ( IVH, MG, Xc, vitamins A, D, E, K)

Pancreatic lipase Optimum pH 7-8 Optimum pH 7-8 Activated by bile acids Activated by bile acids Acts only on emulsified fats (at the fat/water interface) Acts only on emulsified fats (at the fat/water interface)

ABSORPTION OF HYDROLYSIS PRODUCTS OF FOOD LIPIDS 1. CONTAINING CHOLEIN COMPLEXES (MICELLES): - IVFA (with the number of carbon atoms more than 10) - IVFA (with the number of carbon atoms more than 10) - monoacylglycerides - monoacylglycerides - cholesterol - cholesterol - fat-soluble vitamins A, D, E, K - fat-soluble vitamins A, D, E, K 2. By diffusion: glycerol, IVZh (with the number of carbon atoms less than 10). 3. Pinocytosis.

IMPAIRED DIGESTION AND ABSORPTION Always accompanied by steatorrhea - the detection of undigested neutral fat in the feces. Types of steatorrhea: 1. Hepatogenic (for liver diseases) – emulsification is impaired in obstructive jaundice, hepatitis, cirrhosis, congenital biliary atresia. There are a lot of TGs in the feces, a high concentration of IVH salts (soaps), especially calcium. Feces are acholic (low bile pigments). 2. Pancreatogenic (for diseases of the pancreas) – hydrolysis is impaired in chronic pancreatitis, congenital hypoplasia, cystic fibrosis. Feces have a high concentration of TG, little IVF, with normal pH and bile acid content.

3. Enterogenous – the absorption of fat hydrolysis products is impaired in diseases of the small intestine, extensive resection of the small intestine, amyloidosis, and a-beta-lipoproteinemia. In feces, the content of IVH increases sharply, the pH shifts to the acidic side, bile pigments are normal.

Triacylglycerols (triglycerides, neutral fats) are esters of trihydric alcohol glycerol and VZhK. Role of TG: energy (storage), heat-insulating, shock-absorbing (mechanical protection). Glycerol General formula of fat VFA (3 molecules) Ester bond - 3 H 2 O esterification

Lysophospholipids Lysophosphatidylcholine (lysolecithin) Contain a free hydroxyl group at the 2nd glycerol atom. Formed by the action of phospholipase B (A 2). The membranes in which lysophospholipids are formed become permeable to water, so the cells swell and collapse. (Hemolysis of erythrocytes during the bite of snakes whose venom contains phospholipase B)