Breathing Mechanism

NOTE 2 : BREATHING MECHANISM Human breathing all the time. This is because all cells in our body need oxygen. Cells will have their metabolic processes hampered and die if they don't get oxygen, even brain cells will be damaged if they don't get oxygen for even three to four minutes. Do the following practical activities before we study the mechanism of breathing in humans. Air flow from free air to the lungs and vice versa is determined by changes in air pressure in the lung cavity, chest cavity and abdominal cavity. Pressure changes are caused by changes in the volume of each room.Changes in the volume of each room are regulated by the respiratory muscles, namely the intercostal muscles, diaphragm muscles and abdominal wall muscles.Based on the muscles that play an active role in the breathing process, human breathing can be divided into chest breathing and abdominal breathing. a. Chest breathing The muscles that play an active role in chest breathing are the intercostal muscles. These muscles can be divided into two, namely the outer intercostal muscles (external intercostals) which play the role of lifting the ribs, and the inner intercostal muscles (internal intercostals) which play the role of lowering the ribs to their original position.When the muscles between the outer ribs contract, the ribs are lifted until the volume of the chest cavity increases. This causes the air pressure in the chest cavity to be less than the air pressure in the lung cavity, thereby encouraging the lungs to expand and changing the pressure to be less than the free air pressure. Next, there will be a flow of air from outside into the lung cavity through the nasal cavity, windpipe, bronchi and alveoli.This process is called inspiration.When the muscles between the ribs contract, the ribs will be pulled to their original position, pressing against the walls of the lungs. As a result, the lung cavity shrinks and causes the air pressure inside to increase.This causes the air in the lung cavity to be pushed out. This process is called expiration. b. Abdominal Breathing In abdominal breathing, the muscles that play an active role are the diaphragm muscles and the muscles of the abdominal wall. When the diaphragm muscle contracts, the position of the diaphragm will be flat. This causes the volume of the chest cavity to increase, so that the air pressure inside decreases. A decrease in air pressure will be followed by expansion of the lungs. This causes air to flow into the lungs (inspiration).If the diaphragm muscles relax and the abdominal wall muscles contract, the contents of the abdominal cavity will be pushed towards the diaphragm, so that the position of the diaphragm will be concave towards the chest cavity. This causes the volume of the chest cavity to decrease and the pressure to increase, causing the contents of the lung cavity to be pushed out and expiration to occur. Respiratory Frequency Respiratory movements are regulated by the respiratory center in the brain, while respiratory nerve activity is stimulated by stimuli from carbon dioxide (CO2). In general, humans are able to breathe between 15-18 times every minute.Respiratory frequency is influenced by the following factors. a. Age Babies and toddlers have a higher respiratory rate than adults. This is because the volume of the lungs is relatively small and the body's cells are growing so they need a lot of oxygen. Older people also have a higher respiratory frequency because the contractions of the chest muscles and diaphragm are not as good as when they were young, so they breathe less air. b. Gender Women's respiratory frequency is generally higher than men's. This is because women generally have a smaller lung volume than men so they breathe more frequently. c. Body Temperature The higher the body temperature, the faster the respiratory frequency. This is closely related to increasing the body's metabolic processes. d. Body Position Body position greatly influences respiratory frequency. When the body is standing, the leg muscles will contract so that energy is needed to keep the body standing upright. This requires a lot of O2 and a lot of CO2 is produced. In a standing body position, the respiratory frequency increases.In a sitting or lying position, the weight of the body is supported by most parts of the body so that the load is distributed. This results in the amount of energy needed to support the body not being too large so that the respiratory frequency is also low. e. Body Activities People who do a lot of activities need itmore energy compared to people who don'tdoing activities (relaxing/sleeping). Therefore, the bodyrequires more oxygen for biological oxidation andproduces more waste. The body needs to increase its respiratory frequency to provide oxygenwhich is more. Respiratory Air Volume Respiratory air volume can be measured using a respirometer. Broadly speaking, respiratory air volume can be divided into six as follows. a. Tidal volume, namely the normal volume of breathing air (inspiration), which is approximately 500 cc (cm3) or 500 mL. b. Inspiratory reserve volume or complementary air, namely the volume of air that can still be maximally inhaled after normal breathing (inspiration), which is approximately 1,500 cc (cm3) or 1,500 mL . c. Expiratory reserve volume or supplementary air, namely the volume of air that can still be expelled maximally after a normal exhalation, which is approximately 1,500 cc (cm3) or 1,500 mL. d. Residual volume, namely the volume of air remaining in the lungs after maximum exhalation (expiration), which is approximately 1,000 cc (cm3) or 1,000 mL . d. Vital capacity, namely the maximum possible volume of air that can be expelled after inhaling as fully as possible, is approximately 3,500 cc (cm3) or 3,500 mL. So, vital capacity is the sum of tidal volume + inspiratory reserve volume + expiratory reserve volume. e. Total lung volume, namely the volume of air that the lungs can hold as much as possible, is approximately 4,500 cc (cm3) or 4,500 mL. So, total lung volume is the sum of residual volume + vital capacity.