Transfer of nutrients in the body of plants and animals. Transport of substances in living organisms Provides transport of substances throughout the body

Transport of substances:

Transfer of substances through biol. membranes are associated with such important biological phenomena as intracellular ion homeostasis, bioelectric potentials, excitation and conduction of nerve impulses, storage and transformation of energy.

There are several types of transport:

1 . Uniport– is the transport of a substance across a membrane, regardless of the presence and transfer of other compounds.

2. Conveyance– this is the transfer of one substance associated with the transport of another: symport and antiport

a) where unidirectional transfer is called simport – absorption of amino acids through the membrane of the small intestine,

b) oppositely directed - antiport(sodium - potassium pump).

Transport of substances can be - passive and active transport (carrying)

Passive transport is not associated with energy expenditure, it is carried out by diffusion (directed movement) along concentration (from maс towards min), electrical or hydrostatic gradients. Water moves along a water potential gradient. Osmosis is the movement of water through a semi-permeable membrane.

Active transport is carried out against gradients (from min to maс), is associated with energy expenditure (mainly the energy of ATP hydrolysis) and is associated with the work of specialized membrane transport proteins (ATP synthetase).

Passive transfer can be carried out:

A. By simple diffusion through the lipid bilayers of the membrane, as well as through specialized formations - channels. By diffusion through the membrane they penetrate into the cell:

uncharged molecules, highly soluble in lipids, incl. many poisons and medicines,

gases- oxygen and carbon dioxide.

ions- they enter through membrane permeating channels, which are lipoprotein structures. They serve to transport certain ions (for example, cations - Na, K, Ca, Cl, P anions) and can be in an open or closed state. The conductivity of the channel depends on the membrane potential, which plays an important role in the mechanism of generation and conduction of nerve impulses.

b. Facilitated diffusion . In some cases, the transfer of matter coincides with the direction of the gradient, but significantly exceeds the speed of simple diffusion. This process is called facilitated diffusion; it occurs with the participation of carrier proteins. The facilitated diffusion process does not require energy. Sugars, amino acids, and nitrogenous bases are transported in this way. This process occurs, for example, when sugars are absorbed from the intestinal lumen by epithelial cells.

V. Osmosis – movement of the solvent through the membrane

Active transport

The transfer of molecules and ions against an electrochemical gradient (active transport) is associated with significant energy costs. Gradients often reach large values, for example, the concentration gradient of hydrogen ions on the plasma membrane of the cells of the gastric mucosa is 106, the concentration gradient of calcium ions on the membrane of the sarcoplasmic reticulum is 104, while the ion flows against the gradient are significant. As a result, energy expenditure on transport processes reaches, for example, in humans, more than 1/3 of the total metabolic energy.

Active ion transport systems have been found in the plasma membranes of cells of various organs, for example:

sodium and potassium - sodium pump. This system pumps sodium out of the cell and potassium into the cell (antiport) against their electrochemical gradients. Ion transport is carried out by the main component of the sodium pump - Na+, K+-dependent ATPase due to ATP hydrolysis. For each hydrolyzed ATP molecule, three sodium ions and two potassium ions are transported .

There are two types of Ca 2 + -ATPase. One of them ensures the release of calcium ions from the cell into the intercellular environment, the other ensures the accumulation of calcium from the cellular contents into the intracellular depot. Both systems are capable of creating a significant calcium ion gradient.

K+, H+-ATPase is found in the mucous membrane of the stomach and intestines. It is capable of transporting H+ through the membrane of mucosal vesicles during ATP hydrolysis.

An anion-sensitive ATPase was found in microsomes of the frog stomach mucosa, which is capable of antiporting bicarbonate and chloride during ATP hydrolysis.

Proton pump in mitochondria and plastids

secretion of HCI in the stomach,

absorption of ions by plant root cells

Disruption of membrane transport functions, in particular increased membrane permeability, is a well-known universal sign of cell damage. Violation of transport functions (for example, in humans) is caused by more than 20 so-calledtransport diseases, among of which:

renal glycosuria,

cystinuria,

malabsorption of glucose, galactose and vitamin B12,

hereditary spherocytosis (hemolytic anemia, red blood cells have the shape of a ball, while the surface of the membrane decreases, the lipid content decreases, and the permeability of the membrane to sodium increases. Spherocytes are removed from the bloodstream faster than normal red blood cells).

A special group of active transport includes the transfer of substances (large particles) by - Andendo- Andexocytosis.

Endocytosis(from the Greek endo - inside) the entry of substances into the cell, includes phagocytosis and pinocytosis.

Phagocytosis (from the Greek Phagos - devouring) is the process of capturing solid particles, foreign living objects (bacteria, cell fragments) by unicellular organisms or multicellular cells, the latter are called phagocytes, or eater cells. Phagocytosis was discovered by I. I. Mechnikov. Typically, during phagocytosis, the cell forms protrusions, cytoplasm- pseudopodia that flow around captured particles.

But the formation of pseudopodia is not necessary.

Phagocytosis plays an important role in the nutrition of unicellular and lower multicellular animals, which are characterized by intracellular digestion, and is also characteristic of cells that play an important role in the phenomena of immunity and metamorphosis. This form of absorption is characteristic of connective tissue cells - phagocytes, which perform a protective function; they actively phagocytize placental cells, cells lining the body cavity, and the pigment epithelium of the eyes.

The process of phagocytosis can be divided into four successive phases. In the first (facultative) phase, the phagocyte approaches the object of absorption. Here, the positive reaction of the phagocyte to chemical stimulation, chemotaxis, is essential. In the second phase, adsorption of the absorbed particle on the surface of the phagocyte is observed. In the third phase, the plasma membrane in the form of a sac envelops the particle, the edges of the sac close and separate from the rest of the membrane, and the resulting vacuole ends up inside the cell. In the fourth phase, ingested objects are destroyed and digested inside the phagocyte. Of course, these stages are not delimited, but imperceptibly transform into one another.

Cells can also absorb liquids and large molecular compounds in a similar way. This phenomenon is called pinocytosis (Greek rupo - drink and sutoz - cell). Pinocytosis is accompanied by vigorous movement of the cytoplasm in the surface layer, leading to the formation of an invagination of the cell membrane, extending from the surface in the form of a tubule into the cell. At the end of the tubule, vacuoles are formed, which break off and move into the cytoplasm. Pinocytosis is most active in cells with intensive metabolism, in particular in cells of the lymphatic system and malignant tumors.

By pinocytosis, high-molecular compounds penetrate into cells: nutrients from the bloodstream, hormones, enzymes and other substances, including drugs. Electron microscopic studies have shown that by pinocytosis fat is absorbed by intestinal epithelial cells, renal tubular cells and growing oocytes are phagocytosed.

Foreign bodies that enter the cell by phagocytosis or pinocytosis are exposed to lysing enzymes inside the digestive vacuoles or directly in the cytoplasm. The intracellular reservoirs of these enzymes are lysosomes.

Functions of endocytosis

Are being carried out nutrition(egg cells absorb yolk proteins in this way: phagosomes are the digestive vacuoles of protozoa)

Protective and immune reactions (leukocytes absorb foreign particles and immunoglobulins)

Transport(renal tubules absorb proteins from primary urine).

Selective endocytosis certain substances (yolk proteins, immunoglobulins, etc.) occurs when these substances come into contact with substrate-specific receptor sites on the plasma membrane.

Materials that enter the cell by endocytosis are broken down (“digested”), accumulated (for example, yolk proteins), or again removed from the opposite side of the cell by exocytosis (“cytopempsis”).

Exocytosis(from the Greek exo - outside, outside) - a process opposite to endocytosis: for example, from the endoplasmic reticulum, Golgi apparatus, various endocytic vesicles, lysosomes merge with the plasma membrane, releasing their contents to the outside.

89. Let’s find out why transport of substances is needed for multicellular organisms.
Thanks to the transport of substances, all minerals and various proteins, carbohydrates, fats reach their “destination” and begin to rapidly synthesize with other molecules.

90. Let's draw a plant and label its organs.

91. Let’s write what substances move:
a) through wood vessels: minerals
b) along the sieve tubes of the bast: organic substances.

92. Let’s define the concept of blood and its functions in the body.
Connective tissue. Thanks to the proteins contained in the blood, it performs many functions, including transport and protective.

93. Let's write the differences between a closed and open circulatory system.
In a closed c.s. the blood moves in a circle, and in an open circle, the blood vessels open into the body cavity.

94. Let’s label the sections of the circulatory system shown in the pictures. Let's determine their type.

95. Let's supplement the sentences.

96. Let us define the concepts.
An artery is a vessel through which oxygenated blood moves to the organs.
A vein is a vessel through which blood saturated with carbon dioxide moves from the organs.
A capillary is the smallest vessel that penetrates the entire body of an animal.

97. Let’s label the parts of the heart indicated by numbers in the pictures. Let's write down the animals to which the hearts shown belong.

Laboratory work.
"Movement of water and minerals along the stem."

Answers to school textbooks

During the transport of substances, they are delivered from the places of entry into the body from the environment or the places of their formation in the body to the organs that need these substances for life. Thus, in mammals, oxygen entering the lungs, thanks to the transport system, is transferred to all cells of the animal body, and carbon dioxide, on the contrary, is transported to the lungs and released into the external environment.

2. How does the transfer of substances occur in unicellular organisms?

In unicellular organisms, various substances are transported by the movement of the cytoplasm. For example, in an amoeba this occurs during its movement, during which the cytoplasm flows from one part of the body to another. The substances contained in it are mixed and distributed throughout the cell. In the slipper ciliate - a protozoan with a constant body shape - the movement of the digestive vesicle and the distribution of nutrients throughout the cell is achieved by continuous circular movement of the cytoplasm.

3. What is the role of the circulatory system?

The circulatory system, consisting of vessels, provides blood access to all organs and tissues of the body and carries out one of the most important functions - the transport of substances and gases.

4. What is blood?

5. What does blood consist of?

Blood is one of the types of connective tissue that circulates through the circulatory system. Blood carries nutrients and oxygen throughout the body, and removes carbon dioxide and other waste products. Blood consists of a colorless liquid - plasma and blood cells. There are red and white blood cells, as well as platelets. Red blood cells give blood a red color, since they contain a special substance - the pigment hemoglobin (from the Greek “theme” - blood and the Latin “globulus” - ball). Combining with oxygen, hemoglobin carries it throughout the body. Thus, the blood performs the respiratory function. White blood cells perform a protective function: they destroy pathogens that enter the body. Blood platelets are involved in the process of blood clotting. So, when wounded, thanks to blood platelets, the blood at the wound site coagulates and the bleeding stops.

6. What are stomata, where are they located?

7. How do water and minerals move in a plant?

Water and minerals dissolved in it move in the plant from the roots to the above-ground parts through the vessels of the wood.

8, Which part of the stem does organic matter move through?

Organic substances move from the leaves to other parts of the plant through the sieve tubes of the phloem.

9. What is the role of root hairs? What is root pressure?

10. What is the significance of water evaporation from leaves?

Water enters the plant through root hairs. Covered with mucus, in close contact with the soil, they absorb water with minerals dissolved in it. Then the water rises under pressure through the vessels of the root to other, above-ground organs of the plant. Root pressure is the force that causes one-way movement of water from roots to shoots.

Water evaporates from the surface of leaf cells in the form of steam and enters the atmosphere through the stomata. This process ensures a continuous upward flow of water through the plant. Having given up water, the cells of the leaf pulp, like a pump, begin to intensively absorb it from the vessels surrounding them, where water enters through the stem from the root.

71. Let's find out why transport of substances is needed for multicellular organisms.
Thanks to the transport of substances, all minerals and various proteins, carbohydrates, fats reach their “destination” and begin to rapidly synthesize with other molecules.

72. Let's draw a plant and label its organs.

73. Let's write what substances move:
a) through wood vessels: minerals
b) along the sieve tubes of the bast: organic substances.

74.
Connective tissue. Thanks to the proteins contained in the blood, it performs many functions, including transport and protective.

75. Let's define the concept of blood and its functions in the body.
In a closed c.s. the blood moves in a circle, and in an open circle, the blood vessels open into the body cavity.

76. Let's label the sections of the circulatory system shown in the pictures. Let's determine their type.

77. Let's supplement the sentences.

78. Let's give definitions.
An artery is a vessel through which oxygenated blood moves to the organs.
A vein is a vessel through which blood saturated with carbon dioxide moves from the organs.
A capillary is the smallest vessel that penetrates the entire body of an animal.

79. Let's label the parts of the heart indicated by numbers in the pictures. Let's write down the animals to which the hearts shown belong.

Laboratory work.
"Movement of water and minerals along the stem."

Transport of substances for multicellular organisms is a condition for their life. Many cells interact with each other, but each performs its own function. In order for them to act in concert, it is necessary to move substances that can enter from the outside or be removed from the body.

Transport of incoming substances

Everything that the body needs for life comes from the environment. This is what it does:

• Oxygen;
• Water;
• Nutrients from food - proteins, fats, carbohydrates, vitamins;
• Microelements.

Each component performs its function in a specific organ and a transport system is needed to transport it.

Oxygen is carried by blood. After gas exchange, air from the lungs enters the bloodstream into red blood cells. They contain special transport protein - hemoglobin. It is responsible for delivering oxygen to all tissues that need it. Without this, cells and the body will die from hypoxia.

Water does not need a special carrier, since it can move itself along a concentration gradient. It goes to where the concentration of salts or proteins is greater. Water washes freely to pass and leave the cells if necessary. It is a universal medium in which all processes take place, thus, without water transport there would be no life or any other transport.

Transport of nutrients in multicellular animals is carried out by a special digestive system. Once in the intestines, proteins, fats and carbohydrates are broken down and absorbed into the blood. Along it they are transported to other cells. Carbohydrates provide energy for life. If they are not transported to all tissues, the body will not be able to exist.

Trace elements and minerals support the internal environment of cells and the body as a whole. They enter with food and are transported as products of its breakdown. Most emollients pass through cells freely or through special openings.

Output transport

In the process of life, the body produces many unnecessary substances:

• Carbon dioxide;
• Urea;
• Ammonia;
• Ketones and other elements.

To prevent them from poisoning the body, they need to be removed. The blood acts as a transporter, which carries them to the excretory organs.

Thus, in a multicellular organism, substances necessary for respiration, nutrition, disinfection of toxic substances and other vital processes are transported.