Lesson No. 7.
Topic: External respiration. The structure of the respiratory cycle.
Breath- a set of processes that result in the body consuming oxygen and releasing carbon dioxide.
Respiration in humans and higher animals includes the following processes:
1. Exchange of air between the external environment and the alveoli of the lungs.
2. Exchange of gases between alveolar air and blood flowing through the pulmonary capillaries.
3. Transport of gases by blood.
4. Exchange of gases between blood and tissues in tissue capillaries.
5. Cells consume oxygen and release carbon dioxide.
In unicellular organisms, gas exchange occurs through the entire surface of the body, in insects - through the trachea, which penetrates the entire body, in fish - in the gills. In amphibians, 2/3 of gas exchange occurs through the skin and 1/3 through the lungs. In mammals, gas exchange occurs almost entirely in the lungs and little through the skin and digestive tract.
External breathing.
The lungs of farm animals are located in a hermetically sealed chest cavity, where the pressure is negative (below atmospheric pressure). The inside of the chest cavity is lined with pleura, one of the layers of which (parietal) is adjacent to the chest, and the other (visceral) covers the lungs. Between them there is a gap filled with serous fluid to reduce friction of the lungs during inhalation and exhalation. The lungs are devoid of muscles and passively follow the movement of the chest: when the latter expands, they expand and suck in air (inhalation), when they collapse, they collapse (exhalation). The respiratory muscles of the chest and diaphragm contract due to impulses coming from the respiratory center, which ensures normal breathing. If you open the chest, air enters the pleural cavity (pneumothorax) and the pressure in it becomes equal to atmospheric pressure, as a result of which the lungs collapse (atelectasis).
Negative pressure in the pleural cavity.
In fetal animals, the lungs fill the entire chest cavity. Gas exchange occurs through the placenta. The fetal lungs do not participate in breathing.
After birth, with the first breath, the ribs rise, but cannot return to their original position, as they are fixed in the vertebrae.
The elastic tissue of the lungs tends to collapse; a gap is formed between the lungs and the chest, in which the pressure is below atmospheric. Thus, in the alveoli of the lungs the pressure is equal to atmospheric pressure – 760, in the pleural cavity – 745-754 mm Hg. These 10-30 mm ensure the expansion of the lungs. When you inhale, the volume of the chest cavity increases, the pressure decreases, air enters the lungs. When the chest collapses, the chest cavity decreases, the pressure in it increases and air is forced out - exhalation occurs.
Under frequency breathing refers to the number of respiratory cycles (inhalation-exhalation) in 1 minute. The frequency of respiratory movements in animals depends on the intensity of metabolism, temperature environment, animal productivity, etc.
Large animals breathe less frequently than small ones, young animals more often than adults. Highly productive cows breathe more often than low-producing cows. Physical work, eating food, and excitement increase breathing.
Respiratory rate
In animals in 1 min
| Kind of animal | Frequency |
| Horse Cattle Pig Dog Chicken | 8-12 10-30 8-18 10-30 22-25 |
The external and internal intercostal muscles and the muscles of the diaphragm take part in the act of breathing. Depending on which muscles are more involved in the expansion of the chest, three types of breathing are distinguished: costal or thoracic (when inhaling, the external intercostal muscles mainly contract); abdominal, or diaphragmatic (due to contraction of the diaphragm); costo-abdominal, when the muscles of the chest and diaphragm are involved in breathing. During pregnancy and diseases of the abdominal organs, the type of breathing changes to thoracic, since animals “protect” diseased organs.
When breathing, the chest expands and contracts. A recording of respiratory movements is called a pneumogram, from which the frequency and depth of breathing can be determined.
Protective respiratory reflexes include coughing, sneezing, stopping, increasing or rapid breathing.
Coughing and sneezing occur due to irritation of the receptors of the upper respiratory tract by mechanical particles and mucus. When coughing or sneezing, a sharp exhalation occurs with the glottis closed, as a result of which irritating substances are removed.
The body's defensive reaction is to stop breathing. If an animal is allowed to inhale ammonia, ether, chlorine or other pungent-smelling substances, breathing stops, which prevents the penetration of irritating substances into the lungs.
Painful stimulation initially causes a delay and then an increase in breathing.
Transfer of gases by blood.
When you inhale, air enters the alveoli of the lungs, where gas exchange occurs through the capillaries. The inhaled air is a mixture of gases: oxygen - 20.82%, carbon dioxide - 0.03 and nitrogen - 79.15%. Gas exchange in the lungs occurs as a result of the diffusion of carbon dioxide from the blood into the alveolar air and oxygen from the alveolar air into the blood due to the difference in the partial pressure of gases in the alveolar air and blood.
Partial pressure- this is the part of the total pressure of the gas mixture attributable to the share of a particular gas in the mixture. Thus, the carbon dioxide tension in venous blood is 46 mm Hg. Art., and in the alveolar air - 40, oxygen in the alveoli of the lungs - 100 mm Hg. Art., and venous blood – 90.
The oxygen entering the blood dissolves in the plasma in an amount of 0.3 vol.%, and the rest binds to hemoglobin, resulting in the formation of oxyhemoglobin, which disintegrates in the tissues. The amount of oxygen that can bind 100 ml of blood is called blood oxygen capacity. The released hemoglobin binds with carbon dioxide (forming carbohemoglobin), 2.5 vol.% of carbon dioxide dissolves in the blood plasma. Carbon dioxide is released from the lungs with exhaled air.
Composition of inhaled and exhaled air
Man breathes atmospheric air, which has the following composition: 20.94% oxygen, 0.03% carbon dioxide, 79.03% nitrogen. In the exhaled air 16.3% oxygen, 4% carbon dioxide, 79.7% nitrogen are detected.
Alveolar air its composition differs from that of the atmosphere. In the alveolar air, the oxygen content sharply decreases and the amount of carbon dioxide increases. Percentage content of individual gases in alveolar air: 14.2-14.6% oxygen, 5.2-5.7% carbon dioxide, 79.7-80% nitrogen.
STRUCTURE OF THE LUNGS.
The lungs are paired respiratory organs located in a hermetically sealed chest cavity. Their airways represented by the nasopharynx, larynx, trachea. The trachea in the chest cavity is divided into two bronchi - right and left, each of which, branching repeatedly, forms the so-called bronchial tree. The smallest bronchi - bronchioles at the ends expand into blind vesicles - pulmonary alveoli.
Gas exchange does not occur in the respiratory tract, and the composition of the air does not change. The space enclosed in the respiratory tract is called dead, or harmful. During quiet breathing, the volume of air in the dead space is 140-150 ml.
The structure of the lungs ensures that they perform the respiratory function. The thin wall of the alveoli consists of a single-layer epithelium, easily permeable to gases. The presence of elastic elements and smooth muscle fibers ensures quick and easy stretching of the alveoli, so that they can accommodate large amounts of air. Each alveolus is covered with a dense network of capillaries into which the pulmonary artery branches.
Each lung is covered on the outside with a serous membrane - pleura, consisting of two leaves: parietal and pulmonary (visceral). Between the layers of the pleura there is a narrow gap filled with serous fluid - pleural cavity.
The expansion and collapse of the pulmonary alveoli, as well as the movement of air along the airways, is accompanied by the appearance of respiratory sounds, which can be examined by auscultation (auscultation).
Pressure in the pleural cavity and mediastinum is always normal negative. Due to this, the alveoli are always in a stretched state. Negative intrathoracic pressure plays a significant role in hemodynamics, ensuring venous return of blood to the heart and improving blood circulation in the pulmonary circle, especially during the inhalation phase.
BREATHING CYCLE.
The respiratory cycle consists of inhalation, exhalation and a respiratory pause. Duration inhalation in an adult from 0.9 to 4.7 s, duration exhalation - 1.2-6 s. The breathing pause varies in size and may even be absent.
Breathing movements are performed with a certain rhythm and frequency, which are determined by the number of chest excursions in 1 minute. In an adult, the respiratory rate is 12-18 in 1 min.
Depth of breathing movements determined by the amplitude of chest excursions and using special methods that allow one to study pulmonary volumes.
Inhalation mechanism. Inhalation is ensured by expansion of the chest due to contraction of the respiratory muscles - the external intercostal muscles and the diaphragm. The flow of air into the lungs is largely dependent on the negative pressure in the pleural cavity.
Exhalation mechanism. Exhalation (expiration) occurs as a result of relaxation of the respiratory muscles, as well as due to the elastic traction of the lungs trying to take their original position. The elastic forces of the lungs are represented by the tissue component and forces surface tension, which strive to reduce the alveolar spherical surface to a minimum. However, the alveoli normally never collapse. The reason for this is the presence of a surfactant stabilizing substance in the walls of the alveoli - surfactant produced by alveolocytes.
PULMONARY VOLUME. PULMONARY VENTILATION.
Tidal volume- the amount of air that a person inhales and exhales during quiet breathing. Its volume is 300 - 700 ml.
Inspiratory reserve volume- the amount of air that can be introduced into the lungs if, following a quiet inhalation, a maximum inhalation is made. The inspiratory reserve volume is equal to 1500-2000 ml.
Expiratory reserve volume- the volume of air that is removed from the lungs if, following a calm inhalation and exhalation, a maximum exhalation is made. It amounts to 1500-2000 ml.
Residual volume- this is the volume of air that remains in the lungs after the deepest possible exhalation. The residual volume is equal to 1000-1500 ml air.
Tidal volume, inspiratory and expiratory reserve volumes
constitute the so-called vital capacity.
Vital capacity of the lungs in men young
amounts to 3.5-4.8 l, for women - 3-3.5 l.
Total lung capacity consists of the vital capacity of the lungs and the residual volume of air.
Pulmonary ventilation- the amount of air exchanged in 1 minute.
Pulmonary ventilation is determined by multiplying the tidal volume by the number of breaths per minute (minute volume of breathing). In an adult in a state of relative physiological rest, pulmonary ventilation is 6-8 l per 1 min.
Lung volumes can be determined using special devices - spirometer and spirograph.
TRANSPORT OF GASES BY BLOOD.
Blood delivers oxygen to tissues and carries away carbon dioxide.
The movement of gases from the environment into the liquid and from the liquid into the environment is carried out due to the difference in their partial pressure. Gas always diffuses from an environment where there is high pressure to an environment with lower pressure.
Partial pressure of oxygen in atmospheric air 21.1 kPa (158 mmHg st.), in the alveolar air - 14.4-14.7 kPa (108-110 mm Hg. st.) and in the venous blood flowing to the lungs - 5.33 kPa (40 mmHg st.). In arterial blood capillaries great circle blood circulation oxygen tension is 13.6-13.9 kPa (102-104 mm Hg), in the interstitial fluid - 5.33 kPa (40 mm Hg), in tissues - 2.67 kPa (20 mm Hg). Thus, at all stages of oxygen movement there is a difference in its partial pressure, which promotes gas diffusion.
The movement of carbon dioxide occurs in the opposite direction. Carbon dioxide tension in tissues is 8.0 kPa or more (60 or more mm Hg), in venous blood - 6.13 kPa (46 mm Hg), in alveolar air - 0.04 kPa (0 .3 mmHg). Hence, the difference in carbon dioxide tension along its route causes gas diffusion from tissues into the environment.
Transport of oxygen by blood. Oxygen in the blood exists in two states: physical dissolution and chemical bond with hemoglobin. Hemoglobin forms a very fragile, easily dissociated compound with oxygen - oxyhemoglobin: 1g of hemoglobin binds 1.34 ml of oxygen. The maximum amount of oxygen that can be bound in 100 ml of blood is blood oxygen capacity(18.76 ml or 19 vol%).
Hemoglobin oxygen saturation ranges from 96 to 98%. The degree of saturation of hemoglobin with oxygen and the dissociation of oxyhemoglobin (formation of reduced hemoglobin) are not directly proportional to oxygen tension. These two processes are not linear, but occur along a curve, which is called oxyhemoglobin binding or dissociation curve.
Rice. 25. Dissociation curves of oxyhemoglobin in aqueous solution(I) and in the blood (II) at a carbon dioxide tension of 5.33 kPa (40 mm Hg) (according to Barcroft).
At zero oxygen tension, there is no oxyhemoglobin in the blood. At low oxygen partial pressures, the rate of oxyhemoglobin formation is low. The maximum amount of hemoglobin (45-80%) binds to oxygen when its tension is 3.47-6.13 kPa (26-46 mm Hg). A further increase in oxygen tension leads to a decrease in the rate of formation of oxyhemoglobin (Fig. 25).
The affinity of hemoglobin for oxygen is significantly reduced when the blood reaction shifts to the acidic side, which is observed in the tissues and cells of the body due to the formation of carbon dioxide
The transition of hemoglobin to oxyhemoglobin and from it to reduced one also depends on temperature. At the same partial pressure of oxygen in the environment at a temperature of 37-38 ° C, it goes into the reduced form greatest number oxyhemoglobin,
Transport of carbon dioxide by blood. Carbon dioxide is transported to the lungs in the form bicarbonates and in a state of chemical bonding with hemoglobin ( carbohemoglobin).
RESPIRATORY CENTER.
The rhythmic sequence of inhalation and exhalation, as well as changes in the nature of respiratory movements depending on the state of the body, are regulated respiratory center located in the medulla oblongata.
There are two groups of neurons in the respiratory center: inspiratory And expiratory. When the inspiratory neurons that provide inspiration are excited, the activity of the expiratory nerve cells is inhibited, and vice versa.
At the top of the pons ( pons) located pneumotaxic center, which controls the activity of the lower inhalation and exhalation centers and ensures the correct alternation of cycles of respiratory movements.
The respiratory center, located in the medulla oblongata, sends impulses to motor neurons spinal cord , innervating the respiratory muscles. The diaphragm is innervated by axons of motor neurons located at the level III-IV cervical segments spinal cord. Motor neurons, the processes of which form the intercostal nerves that innervate the intercostal muscles, are located in the anterior horns (III-XII) of the thoracic segments spinal cord.
The meaning of breathing
Breathing is a vital process of constant exchange of gases between the body and its surrounding environment. In the process of breathing, a person absorbs oxygen from the environment and releases carbon dioxide.
Almost all complex reactions of transformation of substances in the body require the participation of oxygen. Without oxygen, metabolism is impossible, and a constant supply of oxygen is necessary to preserve life. In cells and tissues, as a result of metabolism, carbon dioxide is formed, which must be removed from the body. The accumulation of significant amounts of carbon dioxide inside the body is dangerous. Carbon dioxide is carried by the blood to the respiratory organs and exhaled. Oxygen entering the respiratory organs during inhalation diffuses into the blood and is delivered to organs and tissues by the blood.
There are no reserves of oxygen in the human and animal bodies, and therefore its continuous supply into the body is a vital necessity. If a person, in necessary cases, can live without food for more than a month, without water for up to 10 days, then in the absence of oxygen, irreversible changes occur within 5-7 minutes.
Composition of inhaled, exhaled and alveolar air
By alternately inhaling and exhaling, a person ventilates the lungs, maintaining a relatively constant gas composition in the pulmonary vesicles (alveoli). A person breathes atmospheric air with a high content of oxygen (20.9%) and a low content of carbon dioxide (0.03%), and exhales air in which there is 16.3% oxygen and 4% carbon dioxide (Table 8).
The composition of alveolar air differs significantly from the composition of atmospheric, inhaled air. It contains less oxygen (14.2%) and a large number of carbon dioxide (5.2%).
Nitrogen and inert gases that make up the air do not take part in respiration, and their content in inhaled, exhaled and alveolar air is almost the same.
Why does exhaled air contain more oxygen than alveolar air? This is explained by the fact that when you exhale, air that is in the respiratory organs, in the airways, is mixed with the alveolar air.
Partial pressure and tension of gases
In the lungs, oxygen from the alveolar air passes into the blood, and carbon dioxide from the blood enters the lungs. The transition of gases from air to liquid and from liquid to air occurs due to the difference in the partial pressure of these gases in air and liquid. Partial pressure is the part of the total pressure that accounts for the share of a given gas in a gas mixture. The higher the percentage of gas in the mixture, the correspondingly higher its partial pressure. Atmospheric air, as is known, is a mixture of gases. Atmospheric air pressure 760 mm Hg. Art. The partial pressure of oxygen in atmospheric air is 20.94% of 760 mm, i.e. 159 mm; nitrogen - 79.03% of 760 mm, i.e. about 600 mm; There is little carbon dioxide in the atmospheric air - 0.03%, therefore its partial pressure is 0.03% of 760 mm - 0.2 mm Hg. Art.
For gases dissolved in a liquid, the term “voltage” is used, corresponding to the term “partial pressure” used for free gases. Gas tension is expressed in the same units as pressure (mmHg). If the partial pressure of a gas in the environment is higher than the voltage of that gas in the liquid, then the gas dissolves in the liquid.
The partial pressure of oxygen in the alveolar air is 100-105 mm Hg. Art., and in the blood flowing to the lungs the oxygen tension is on average 60 mm Hg. Art., therefore, in the lungs, oxygen from the alveolar air passes into the blood.
The movement of gases occurs according to the laws of diffusion, according to which gas spreads from a medium with high partial pressure to a medium with lower pressure.
Gas exchange in the lungs
The transition of oxygen from the alveolar air into the blood in the lungs and the flow of carbon dioxide from the blood into the lungs obey the laws described above.
Thanks to the work of the great Russian physiologist Ivan Mikhailovich Sechenov, it became possible to study the gas composition of the blood and the conditions of gas exchange in the lungs and tissues.
Gas exchange in the lungs occurs between alveolar air and blood by diffusion. The alveoli of the lungs are intertwined with a dense network of capillaries. The walls of the alveoli and capillaries are very thin, which facilitates the penetration of gases from the lungs into the blood and vice versa. Gas exchange depends on the size of the surface through which gases diffuse and the difference in partial pressure (tension) of the diffusing gases. With a deep breath, the alveoli stretch, and their surface reaches 100-105 m2. The surface area of the capillaries in the lungs is also large. There is, and a sufficient, difference between the partial pressure of gases in the alveolar air and the tension of these gases in the venous blood (Table 9).
From Table 9 it follows that the difference between the tension of gases in the venous blood and their partial pressure in the alveolar air is 110 - 40 = 70 mm Hg for oxygen. Art., and for carbon dioxide 47 - 40 = 7 mm Hg. Art.
Experimentally, it was possible to establish that with a difference in oxygen tension of 1 mm Hg. Art. in an adult at rest, 25-60 ml of oxygen can enter the blood in 1 minute. A person at rest needs approximately 25-30 ml of oxygen per minute. Therefore, an oxygen pressure difference of 70 mmHg. st, is sufficient to provide the body with oxygen under different conditions of its activity: when physical work, sports exercises, etc.
The rate of diffusion of carbon dioxide from the blood is 25 times greater than that of oxygen, therefore, with a pressure difference of 7 mm Hg. Art., carbon dioxide has time to be released from the blood.
Transfer of gases by blood
Blood carries oxygen and carbon dioxide. In blood, as in any liquid, gases can be in two states: physically dissolved and chemically bound. Both oxygen and carbon dioxide dissolve in very small quantities in the blood plasma. Most oxygen and carbon dioxide are transported in chemically bound form.
The main carrier of oxygen is hemoglobin in the blood. 1 g of hemoglobin binds 1.34 ml of oxygen. Hemoglobin has the ability to combine with oxygen, forming oxyhemoglobin. The higher the partial pressure of oxygen, the more oxyhemoglobin is formed. In the alveolar air, the partial pressure of oxygen is 100-110 mm Hg. Art. Under such conditions, 97% of blood hemoglobin binds to oxygen. Blood brings oxygen to tissues in the form of oxyhemoglobin. Here the partial pressure of oxygen is low, and oxyhemoglobin - a fragile compound - releases oxygen, which is used by the tissues. The binding of oxygen by hemoglobin is also influenced by carbon dioxide tension. Carbon dioxide reduces the ability of hemoglobin to bind oxygen and promotes the dissociation of oxyhemoglobin. Increasing temperature also reduces the ability of hemoglobin to bind oxygen. It is known that the temperature in the tissues is higher than in the lungs. All these conditions help dissociate oxyhemoglobin, as a result of which the blood releases the oxygen released from the chemical compound into the tissue fluid.
The property of hemoglobin to bind oxygen is vital for the body. Sometimes people die from lack of oxygen in the body, surrounded by the cleanest air. This can happen to a person who finds himself in low pressure conditions (at high altitudes), where the thin atmosphere has a very low partial pressure of oxygen. April 15, 1875 balloon The Zenit, which had three balloonists on board, reached an altitude of 8000 m. When the balloon landed, only one person remained alive. The cause of death was a sharp decrease in the partial pressure of oxygen by high altitude. At high altitudes (7-8 km), arterial blood in its gas composition approaches venous blood; all tissues of the body begin to experience an acute lack of oxygen, which leads to serious consequences. Climbing to altitudes above 5000 m usually requires the use of special oxygen devices.
With special training, the body can adapt to the low oxygen content in the atmospheric air. A trained person’s breathing deepens, the number of red blood cells in the blood increases due to their increased formation in the hematopoietic organs and their supply from the blood depot. In addition, heart contractions increase, which leads to an increase in minute blood volume.
Pressure chambers are widely used for training.
Carbon dioxide is carried by the blood in the form of chemical compounds - sodium and potassium bicarbonates. The binding of carbon dioxide and its release into the blood depend on its tension in the tissues and blood.
In addition, blood hemoglobin is involved in the transfer of carbon dioxide. In tissue capillaries, hemoglobin enters chemical compound with carbon dioxide. In the lungs, this compound breaks down to release carbon dioxide. About 25-30% of the carbon dioxide released in the lungs is carried by hemoglobin.
Target: mastering the skills to independently apply knowledge, skills and abilities in a complex manner, to transfer them to new conditions of practical and research activities
Tasks:
Educational: mastering the content of environmental education, the meaning of which is to understand the natural laws of nature and their correlation with the “artificial laws” of the development of society.
Developmental: development of key competencies of schoolchildren using the example of the content of environmental education; development of students' research skills to assess the state of various components of the environment.
Educational: formation of a system of basic values (life, health, people, conservation of biological diversity, cultural heritage etc.), creating conditions for creative self-realization and self-development of schoolchildren.
Regulatory: organize your workplace under the guidance of a teacher; determine a plan for completing tasks in the lesson, evaluate the results of your activities.
Communicative: developed skills and habits of environmentally literate behavior in the environment, with other people, harmonious interaction and sustainable development in the “Nature - Society” system.
Planned results
Cognitive: students’ understanding of the values of the phenomenon of life, the value of each form of existence of life; the value of human existence, his health, socio-cosmic significance; formation of key competencies based on environmental education;
Subject: the formation of a nature-conforming style of human behavior in the environment, based on knowledge of the laws of human interaction with the environment; development of ecological thinking, which presupposes the ability to establish cause-and-effect relationships, system analysis reality, modeling and forecasting of environmental development;
Personal: development of ecological thinking - flexible probabilistic thinking, which presupposes the ability to establish cause-and-effect relationships, systematic analysis of reality, modeling and forecasting of development and the environment; development of research skills in assessment and system analysis of the state of the environment.
Metasubject: connections with such academic disciplines like biology, chemistry, physics, geography - will contribute to more high level mastery of skills in this course and implementation of tasks before specialized training schoolchildren.
Lesson type -- demonstration in which the experiment serves as a visual aid
Form- forms of practice-oriented activities for students
Methods:, partially search, research, students conducting experiments.
Determination of the composition of inhaled and exhaled air
Goal of the work: study of the relative content of carbon dioxide in inhaled and exhaled air.
Information. The determination of carbon dioxide is carried out by the turbidity of lime water in order to compare the content of this air component before and after the student’s breathing. This is how the equation is written chemical reaction, which explains the cloudiness of lime water from exposure to air containing carbon dioxide.
The cloudiness is due to the formation of a suspension of insoluble calcium carbonate (CaC03 ). With further passage of air, a dissolution reaction of calcium carbonate occurs with the formation of the corresponding bicarbonate:
Thus, the turbidity disappears faster (or disappears altogether) in the flask through which the exhaled air passes.
Equipment included: 50 ml conical flasks with stoppers and L-shaped gas outlet tubes - 2 pcs., glass mouthpiece, pieces of rubber tube - 3 pcs., T-shaped glass tee.
Reagents and materials: lime water, swab, disinfectant solution (for preparation of solutions, see paragraph 3.3).
Progress
1.Assemble the device as shown in the figure.
2.Pour 74 volumes of lime water into each flask.
3.Wipe the mouthpiece thoroughly with a swab moistened with a disinfectant solution.
4. Exhale the air, then take the mouthpiece of the device into your mouth and slowly, so that the liquid does not get into your mouth, draw air through the mouthpiece. Through which flask does air enter the device?
5.Inhale and then exhale slowly into the mouthpiece. Through which flask does the exhaled air leave the device?
6.Take several inhalations and exhalations in a row through the mouthpiece. In which vessel did the limewater become cloudy?
Device for determining the composition of inhaled and exhaled air:
Processing of results and conclusions
1. Record the results of the experiments in your notebook.
2. Draw a conclusion from the experiment and write an equation for the chemical reaction that explains the turbidity of lime water
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Physiology of respiration.
The body exists on the energy that comes with nutrients. In the body these nutrients oxidize, and the energy necessary for life is released. Oxygen is constantly needed for the body, and carbon dioxide must also be released from the body constantly. Therefore, breathing is a vital process of life. A person can live without food for 60 days, without water for 2-3 days, and without air for 3 minutes. There are several stages of breathing:
1. Transport of air from the external environment to the lungs, and from the lungs to external environment- called ventilation.
2. Exchange of gases between the alveoli and the blood of the pulmonary circulation.
3. Transport of gases by blood
4. Exchange of gases in tissues.
5. Cellular or tissue respiration.
The respiratory system consists of the airways and lungs.
1. The respiratory or airways include the nasal cavity, nasopharynx, larynx, trachea, and armor.
3. Respiratory muscles
4. Respiratory centers
5. Respiratory nerves that leave the respiratory centers and innervate the respiratory muscles.
The morphofunctional unit of the lungs is the Acinus. The volume of air in the lungs is 150 ml3. This airway air does not participate in gas exchange and is therefore called dead space. But here's what happens:
1. Air purification, dust particles are retained due to lint.
2. Warming due to a dense network of capillaries
3. Moisturizing due to mucus
4. Neutralization due to lysozyme. The volume of the airways can be determined on a corpse by filling the airways with plaster, then this cast is immersed in water, and the volume of dead space is determined by the volume of displaced water.
External breathing. On average, a person makes 16-20 respiratory movements per minute, in newborns from 30 to 70. The lungs are covered with a film called pleura.
Pressure in the pleural cavity. The pleural cavity contains fluid, which is similar in composition to lymph, but there are no proteins there, because proteins attract water. And therefore there is very little water in the pleural cavity. In the pleural fissure, the pressure is always negative, this is negative. pressure is provided by the elastic traction of the lungs. With a quiet exhalation, the pressure is 3 mm Hg, with a quiet inhalation - 6 mm Hg; with a deep breath -20mm Hg. The pressure force acts on the lungs and the elastic resistance of the lungs is associated with the superficial active substance Surfantant. It lines the surface of the alveoli with a thin layer. The function of the surfactant is to prevent overextension and collapse of the lungs. The force of surface tension provides elastic traction of the lungs; it is determined by 3 factors:
1. Presence of elastic fibers
2. Bronchial muscle tone
3. Presence of surfactant.
Surfactant is formed by type II pneumocytes and its synthesis is controlled by the vagus nerve. Transection of the vagus inhibits surfactant production. This can cause the lungs to stick together and can be fatal. If the integrity of the pleural cavity is disrupted, air can enter the pleural cavity - this is called pneumothorax. It can be one-sided or two-sided. Bilateral pneumothorax is not compatible with life, and if blood gets there, it is called hemothorax.
The mechanism of inhalation and exhalation. Inhalation and exhalation is the respiratory cycle. Inhalation is inspiration, exhalation is expiration. During the respiratory cycle, air moves, which is accompanied by an alternating increase and decrease in the volume of the chest. In the act of breathing, the lungs take a passive role, while the respiratory muscles are active. The passive role of the lungs was proven by the scientist Donders.
Inhalation mechanism. It can be calm and deep. Calm breath– the main respiratory muscles take part in it:
1. Aperture. During a quiet inhalation, the diaphragm flattens, i.e. becomes flat
2. Intercostal muscles. They raise the ribs.
3. External intercartilaginous muscles. They also participate in raising the ribs. The pressure in the pleural cavity becomes -6mm Hg. The amount of air that enters the lungs is on average 500 ml.
Calm exhalation - the main respiratory muscles: diaphragm, external intercostal and external intercartilaginous muscles relax. A calm exhalation occurs, the pressure in the pleural fissure becomes -3 mm Hg.
Deep breath. The mechanism of deep inspiration involves:
1. Main muscles: diaphragm. During a deep inhalation, the diaphragm moves down 1-1.5 cm. The external intercostal and intercartilaginous muscles contract, giving the ribs a horizontal position.
2. Accessory muscles: chest and back muscles: the pectoralis major and minor pull the sternum forward, and the back muscles such as the scalene, rhomboids, trapezius, and levator scapulae pull the ribs back. The volume of the chest cavity increases in the anteroposterior and lateral directions. In this case, up to 4-5 liters of air can enter the lungs. And in the pleural fissure, the pressure becomes more negative to -20 mm Hg.
3. Deep exhalation. The main muscles involved are the diaphragm. During deep exhalation, the diaphragm bends inward by 1-1.5 cm because... the muscles of the abdominal wall contract and press on internal organs, and they put pressure on the diaphragm, so the diaphragm bends inward. The external intercostal and intercartilaginous muscles contract and lower the ribs and give them a more vertical position. Additional muscles: the major and minor muscles contract and pull the sternum inward. The contracting muscles of the back also take part in reducing the volume of the chest cavity and a deep exhalation occurs. Breathing is achieved through the work of muscles. There is a distinction between the abdominal type of breathing - it is mainly in men, due to changes in the diaphragm, and the thoracic type of breathing, it is mainly in women due to the contraction of the respiratory muscles. Normal breathing is called eipnea, increased breathing is called tachypnea, decreased breathing is called bradypnea, and shortness of breath is dyspnea. Respiration rate per 1 minute – 16 respiratory movements. An important indicator is the volume of pulmonary ventilation.
Tidal volumes:
1. Vital capacity (vital capacity of the lungs) – the number air that can be exhaled as much as possible after taking the deepest breath. For men it is 4-5l, for women it is 3-4l. Vital vital capacity depends on gender, age, and height, then it will be called proper vital capacity. Vital capacity consists of 3 volumes:
1) tidal volume(TO)- the amount of air that can be exhaled calmly after a calm inhalation. It is equal to 300-800ml (average 500).
2) inspiratory reserve volume– this is the amount of air that can be additionally inhaled after a calm breath. It is equal to 2-2500 ml.
3) expiratory reserve volume- this is the amount of air that can be exhaled additionally after a calm exhalation, it is equal to 1500 ml.
VC=BLO + inspiratory reserve volume + expiratory reserve volume
4) residual volume- this is the amount of air that remains in the lungs after a deep exhalation, it is equal to 1000-1200 ml.
5) total lung capacity. Determined by the formula Vital capacity + residual volume.
6) minute volume of respiration (MOV). Determined by the formula:
Respiratory frequency(16) *TO(600)=9600. MOD increases with physical activity due to the depth and frequency of breathing. In children due to frequency. MVR reflects pulmonary ventilation, but alveolar ventilation also exists. This alveolar ventilation is the difference between pulmonary ventilation and dead space ventilation. In order for the exchange of gases in the alveoli to be sufficient for the body, it is necessary that the alveolar ventilation corresponds to the blood flow in the pulmonary circulation. Then the exchange of gases will be normal and the coefficient is called the ventilation perfusion coefficient, it is equal to 0.8. There are alveoli with insufficient blood circulation, then gas exchange will be impaired.
Composition of inhaled, exhaled and alveolar air.
As can be seen from the table, the difference is between exhaled air and alveolar air in terms of CO2. Alveolar air is the internal gaseous environment of the body, and the composition of the arterial blood and the condition of the whole organism depend on the composition of the alveolar air. Gas exchange in the lungs occurs as a result of the difference in partial pressure in gases and in the blood. Partial pressure is the force with which a gas tends to pass through a semi-permeable membrane from an area of high value to an area of low value. Gas is in a gas mixture. The gas mixture is O2, CO2, Nitrogen and other gases. The force of gas movement depends on its voltage, i.e. number of gases in the gas mixture. If the gas voltage is proportional to the pressure, this indicates that the gas dissolved in the liquid is in equilibrium with the gas above the liquid. And if the gas tension in the gas mixture is higher, then this gas, in terms of partial pressure, will tend to move from the gas mixture into the liquid, i.e. into the blood, and the gas will dissolve in the blood. It is known that gases in the blood are in 2 states, chemically bound and free. Diffusion involves gases that are in a state of simple physical dissolution. The main force for the transition of O2 and CO2 is the difference in partial pressure in the alveoli of the air and in the blood. Reasons for diffusion:
1. Tissue permeability
2. Blood flow speed. If the voltage increases, then movement occurs, i.e. diffusion.
Partial pressure
