Boyle's law describes the relationship between volume and pressure in a gas the initial volume, whereas the final pressure and volume are represented by P2 . Ambient oxygen tension (PO2) fluctuated through the ages in correlation with .. Because of a high redox potential of O2 as the terminal electron acceptor in 3% of that in an equal volume of air, decreasing with water temperature and depth. The electron transfer is the final pathway for all electrons during aerobic What is the difference between air and water as respiratory environments? .. Reducing the thoracic volume raises alveolar pressure and forces air out of the lungs.
This protein allows for a passive diffusion of the Cl- and HCO3- ions to and from the red blood cells and plasma. This keeps the bicarbonate from building up in the red blood cells, which would slow down or stop the reversible conversion of CO2 to HCO Facilitated diffusion occurs in the movement of CO2 across the respiratory surfaces as bicarbonate HCO3- diffuses out of the red blood cells and into the epithelium where it is converted back to CO2.
Excretion of CO2 is limited by the rate of bicarbonate-chloride exchange across the erythrocyte membrane.
Human Physiology/The respiratory system
Thus, more CO2 is formed and can leave the blood across the respiratory surface. Therefore, CO2 that is being transported into and out of the red blood cells minimizes changes in pH in other parts of the body because of proton binding to and proton release from hemoglobin, as it is deoxygenated and oxygenated, respectively Figure 1. The regulation of body pH is important because some organs, tissues, and various types of cells are more affected by changes in pH than others.
For example, the regulation of body pH is needed in animals in order to stabilize volume of hydrogen ions and to regulate enzyme activity. Within cells, pH is regulated in order for cellular functions to proceed. At the tissue level, the body has the ability to redistribute acid between body compartments because some tissues have the ability to tolerate much larger fluctuations in pH than others do. In general, animals have a body pH that is on the alkaline side of neutral, which means that there is less hydrogen than hydroxyl ions in the body.
How does breathing regulate pH? One of the main ways that a mammal regulates pH is through the control of respiration. Hence, when breathing is increased, CO2 levels in the blood decline and pH increases. If pH increases, respiration rate decreases, thereby increasing CO2 levels, which forms more carbonic acid and brings pH back down.
In mammals, a stable body pH is achieved by adjusting the release of CO2 through the lungs and excretion of acid or bicarbonate through the kidneys, so that acid excretion and production are balanced. The collecting duct of the mammalian kidney has acid-excreting and base-excreting cells, which can be altered to increase or decrease acid or base excretion.
In aquatic animals, the external surfaces have the capacity to extrude acid in similar ways to the collecting duct of the mammalian kidney. For example, a protein ATPase exists in the skin of frogs and gills of freshwater fish which excretes protons on the apical surface of the epithelium.
What are alkalosis and acidosis, and what are the consequences? When there is excessive alkalinity in the body and therefore an increase in body pH, this is referred to as alkalosis. Conversely, when there is excessive acidity in the body and therefore a decrease in body pH, this is termed acidosis. In terms of the effects of pH on the respiration of animals, when lung ventilation is decreased causing CO2 excretion to drop below CO2 production, body CO2 levels rise and pH falls. This is referred to as respiratory acidosis.
This is referred to as respiratory alkalosis. It is important to know that body fluids are electroneutral, which means that the sum of the anions equals the sum of the cations. Respiratory acidosis and alkalosis disturb the electroneutrality of the body fluids. However, at the cellular levels, the pH is regulated and electroneutrality is brought back to the body fluids. There are various mechanisms, which regulate cellular pH and thus maintain electroneutrality in the body fluids.
One cellular mechanism involves proteins and phosphates within the cell that act as physical buffers to regulate cellular pH. The most important buffers in the blood are proteins, especially hemoglobin, and bicarbonate because the CO2-to-bicarbonate ratio can be adjusted by excretion of CO2 in order to regulate pH. The CO2 then diffuses out of the red blood cells thus regulating the pH within the cells.
Also the proton-exchange and the anion-exchange mechanisms in the cell membrane play important roles in adjusting cellular pH. This mechanism adjusts the pH of the cell to a less acidified state. Gas transfer occurs by passive diffusion from the environment across the body surface. Air breathing, in most vertebrate animals, involves the movement of air into and out of the lungs. Insects have developed a very different method of gas transfer between the tissues and the environment and this includes a tracheal system.
Water breathing, on the other hand, for most aquatic animals involves a unidirectional flow of water over the gills. Thus, the structure and design of the mammalian, insect, and fish respiratory systems are radically different. Each gas-transfer system is built according to the needs of the animal and to the medium in which it lives. In air breathing animals, the related respiratory organ that facilitates gas transfer, is the lung. The lungs in air breathing vertebrates are large organs of respiration located in the chest cavity.
In humans, the right lung is made up of three lobes and the left lung is composed of two lobes. They are suspended in the pleural cavity and opens to the outside by the trachea. The respiratory portion of the lung includes the terminal bronchioles under glossary term as bronchusthe respiratory bronchioles, and the alveolar ducts and sacs. In contrast, the associated respiratory organs of the fish include the gills.
The gills consist of a feathery, branched tissue richly supplied with blood vessels. The gills facilitate the exchange of oxygen and carbon dioxide with the surrounding water. Most insects respire by means of a tracheal system. In this system, gas is directly transported to the tissues by air-filled tubules that bypass blood. The pores to the outside, called spiraclesdeliver the gases of respiration.
The drawback of this system is that the gases diffuse slowly in the long narrow tubules; as a result, these tubes need to be limited in size for adequate gas transfer.
The advantage is that O2 and CO2 diffuse much faster, 10, times faster, from the air than in water, blood, or tissues. This feature often uses less energy for ventilation and bypasses the need for a circulatory system. Another advantage of the tracheal system is that oxygen can be delivered directly to tissues that need it, such as flight muscles. What are the components of the mammalian lung?
The mammalian lung is more complex than that of the amphibian, reptile, or other non-mammal species, and consists of a complex network of tubes and sacs. To be more specific, the human respiratory system consists of the nasal cavity, pharynxtrachea, bronchi, and lungs.
Although not considered a part of the respiratory system, the ribs, muscles, and diaphragm are important and help in the expansion and contraction of the lung.
To begin with, the pharynx and larynx lead to the lungs; the larynx is connected to the trachea, which branch into the right and left bronchi. These bronchi further divide and lead to the terminal bronchioles. The terminal bronchioles continue and then lead air to the respiratory bronchioles. The respiratory bronchioles themselves connect to a fan of alveolar ducts and sacs.
The function of the alveolar ducts and sacs is to moisten and cleanse the air taken in, and furthermore, transfer it to the gas-exchanging portion of the lung. These alveolar ducts and sacs are filled with many capillaries, the smallest of the blood vessels, and also consist of connective tissue fibers. Alveolimillions of interconnected sacs, also make up a large part of the lung. The human lung is made up of an average of million alveoli. Through diffusion, gases from the air in the alveoli are exchanged with the gases in the pulmonary capillary blood.
The transport of gases depends on this exchange and relationship between O2 pressure in the alveoli and the surrounding atmospheric pressure. As seen, through a series of branches and smaller ducts, air is delivered to the respiratory portion of the lung the terminal bronchioles, respiratory bronchioles, and the alveolar ducts and sacs ; gas is transferred across the respiratory epithelium in these specific areas.
Gas transfer also occurs across acini and the pores of Kohnwhich allow for collateral side-by-side movement of air. Mammals The lungs of mammals are elastic, multi-chambered bags, which open to the exterior through a single tube, called the trachea.
The lungs are suspended within the pleural cavity. The ribs and the diaphragm form the walls of the pleural cavity, which are referred to as the thoracic cag e. The thoracic cage mostly consists of the lungs, but between the lungs and the thoracic walls there is a low-volume of pleural space sealed and fluid filled.
During normal breathing, the thoracic cage expands and contracts by a series of skeletal muscles, the diaphragm, and the external and internal intercostal muscles. The respiratory center within the medulla oblongata controls the contractions of these muscles through the activity of motor neurons. During inhalation, the volume of the thorax increases due to the lowering of the diaphragm. In addition, the ribs are raised and moved outward by the contraction of the external intercostal muscles.
The increase in thoracic volume reduces alveolar pressureand air is drawn into the lungs. During exhalation the diaphragm and external intercostal muscles relax, reducing the thoracic volume. Reducing the thoracic volume raises alveolar pressure and forces air out of the lungs. Birds In the lungs of birds, gas exchange occurs in air capillaries extending from parabronchi, a series of small tube-like structures, which are functionally equivalent to the alveoli in mammals.
The parabronchi extend between large dorsobronchi and ventrobronchi, both of which are connected to an even larger tube, the mesobronchus. The parabronchi and connecting tubes form the lung, which is contained within a thoracic cavity. However, the volume of the thoracic cage and lung changes very little during breathing and therefore, are not directly involved in avian lung ventilation. In birds, the air-sac system connected to the lungs ventilates the avian lungs.
During inspiration, air flows through the mesobronchus into the caudal air sacs.
Air also moves through the dorsobronchus and the parabronchi into the cranial air sacs. Oxygen is then diffused into the air capillaries from the parabronchi and is taken up by the blood. During expiration, air leaving the caudal air sacs passes through the parabronchi and then through the mesobronchus to the trachea. The cranial air sacs, during expiration, move air through the ventrobronchi to the trachea and into the environment.
The bird ventilation mechanism is special because birds are capable of flying at high altitudes while maintaining a sufficient supply of O2 in their bodies. Specifically, the unidirectional flow of air through the parabronchi aids in increasing the efficiency of gas exchange within the avian lungs thus giving birds the capability of flying at high altitudes.
This means of gas exchange is more efficient that thet tidal flow model seen in mammals. Reptiles The ribs of reptiles form a thoracic cage around the lungs. During inhalation, the ribs moving cranially and ventrally, enlarging the thoracic cage. This process reduces the pressure within the cage below atmospheric pressure. The nares and glottis open and air flows into the lungs. Exhalation occurs passively by the relaxation of the muscles that enlarge the thoracic cage, which release energy stored in stretching the elastic component of the lung and body wall.
In tortoises and turtles, the ribs are fused to a rigid shell. The reverse process results in lung deflation, involving the retraction of limbs and head into the shell leading to a decrease in pulmonary volume. Therefore, when a turtle is withdrawn into its shell, its lungs are deflated and the turtle can't breathe. Frogs In frogs, the nares open into a buccal cavitywhich is connected through the glottis to a pair of lungs.
During inhalation, air is drawn into the buccal cavity with the nares open and the glottis closed. Then the nares close and the glottis is opened.
The buccal floor then rises, forcing air from the buccal cavity into the lungs. This lung-filling process may be repeated several times in sequence inhaling air in portions. This same process may also occur during expiration in which the lungs release air in portions. Inhaling and exhaling air in portions may produce a mixture of pulmonary air low in O2 and high in CO2.
This complex method of lung ventilation may be to reduce fluctuations in CO2 levels in the lungs to stabilize and regulate blood PCO2 and control blood pH. Frogs also exchange gasses across their skin, so the lungs are not the only repsiratory surface.
Invertebrates Invertebrates have a variety of gas-transfer mechanisms. In some invertebrates, ventilation does not occur. These invertebrates rely on diffusion of gases between the lung and the environment. Spiders have ventilated lungs called "book lungs". The lungs have respiratory surfaces consisting of thin, blood-filled plates that extend like the leaves of a book into a body cavity guarded by an opening spiracle.
The spiracles open and close to regulate the rate of water loss from these "book lungs". Snails and slugs also have ventilated lungs in which their lung volume changes enabling them to emerge from and withdraw into their rigid shells. Most insects have a gas-transfer mechanism called the tracheal system to know more information on the insect tracheal system, link to the questions: How do insect tracheals work?
How are they different from lungs and gills? How do gills work? For most fish species gills work by a unidirectional flow of water over the epithelial surface of the gillwhere the transfer of gases is made O2 in, CO2 out.
The reason for this unidirectional flow of water, and not an inhaling and exhaling of water, is due to the energetics of the system. The energy that would be required to move water into and out of a respiratory organ would be much more than that used to move air because water is more dense and viscous.
The blood flowing just under the epithelial gill tissue usually moves in a countercurrent flow to that of the water moving over it. This allows for the most O2 to be taken in by the blood because the diffusion gradient is kept high by the blood picking up oxygen as it moves along, but always coming in contact with water that has a higher O2 content.
The blood receiving the O2 will continue to pick up O2 as it moves along because fresh water is being washed over the epithelial lining of the gills. An important aspect to remember here is that the water going over the gills needs to be moving unidirectional, either by the fish forcing the water to move in one direction or if the water is moving mostly in one direction. There are two ways fish ventilate their lungs: The pressure in the buccal chamber is kept higher than the pressure in the opercular chamber so the fresh water is constantly being flushed over the gills.
A fish swimming with its mouth open, allowing water to wash over the gills accomplishes ram ventilation. This method of ventilation requires fast water or a fast fish to keep enough oxygen going to the gill surface.
How do insect tracheoles work? The tracheal system terminates at the tracheolesthat often go in between or right into cells to deliver O2 very close to the mitochondria. There is usually fluid between the terminal ends of the tracheols and the body cells, but as the insect becomes more active the fluid is replaced by air so gas exchange is heightened.
The use of tracheal systems is superior to using water or blood as mediums of gas exchange because O2 and CO2 diffuse 10, times more rapidly in air so the necessary gases can be exchanged more quickly.
However, there is a size limit for effective ventilation via a tracheal system, which is one reason that insects cannot grow to gargantuan sizes. The inner wall surface of the tracheal system is made of the same material that composes the exoskeleton, which helps to prevent water loss.
Spiracles, the openings to the outside air, can be opened and closed at will to in regulate air exchange, water loss, and to keep out debris. Ventilation is usually accomplished through convection, the mass movement of gases. Some larger insects can compress and expand their body wall to coincide with the opening and closing of spiracles to pull air in and push air out.
To reduce the amount of energy used in respiration some insects use the discontinuous ventilation cycle DVC which is composed of open, closed, and intermediate flutter phases. During the closed phase spiracles closed the O2 that is in the body is being used more rapidly than the CO2 being produced.
Due to this, when the open phase begins there is a O2 gradientthe low end being within the body, forcing a rush of O2 from the surrounding air into the spiracles and releasing any CO2 that was produced. This process may be helped along by the expansion of respiratory sacs within the body to pull more air in or push more air out.
During the flutter phase there is rapid inhalation and exhalation. This type of ventilation uses the most energy and it is not understood why it is done. What is the role of pulmonary surfactants in respiration?
Pulmonary surfactants are lipoprotein complexes produced in the lungs that are used to reduce the effort in breathing and help prevent the collapse of alveoli. Pulmonary surfactants make expansion of the alveoli easier by lowering the surface tension that holds membranes of different alveoli together and minimizes expansion of individual alveoli.
This makes it easier for alveoli membranes to slide against each other when they are expanded to take in air. Surfactants also reduce the chances of alveolar collapse by stabilizing surface tension when an alveoli sac is expanded.
When alveoli are expanded the surfactant is spread out more, which increases surface tension. Surface tension is a major contributor to wall tension, which determines if a small alveolar sac collapses into a larger alveolar sac.
Human Physiology/The respiratory system - Wikibooks, open books for an open world
Collapse occurs when the pressure inside a small alveolar sac wall tension in relation to the radius of the sac is greater that the pressure in a larger alveolar sac, forcing the air in a small sac high pressure to force its way into the large sac low pressure. The surfactant prevents this by minimizing the surface tension, which minimizes the difference in wall tension and thereby minimizing the pressure difference between alveoli.
How are breathing patterns controlled or regulated? Breathing is an automatic and rhythmic behavior regulated by several nerve centers in the brain, more specifically, in the neurons of the pons and medulla oblongata. The central processing of many sensory inputs control breathing movements. The central processor is made up of a pattern generator and a rhythm generator. From these, the depth and amplitude of each breath is controlled and the frequency of breathing is controlled, respectively.
Ventilation helps maintain satisfactory rates of gas transfer and blood pH levels. Breathing movements with eating, talking, or other bodily functions are controlled by sensory inputs as well. The muscles and diaphragm help ventilate the lungs. This action is stimulated by the spinal motor neurons and the phrenic nerve that get information from the neurons that make up the medullary respiratory centers.
The muscles of the respiratory system are finely controlled, and this allows humans to breathe, sing, and whistle. The medullary respiratory center also contains inspiratory and expiratory neurons. The activity of the inspiratory neurons correspond to inspiration. The networks of neurons connect to higher brain centers, the chemoreceptors and mechanoreceptors.
Neuronal action has much to do with breathing and respiratory activity. From the phrenic nerve or from individual neurons in the medulla, scientists have been able to record inspiratory neuronal activity and learn more.
Inspiration is characterized by a changing release of medullary neurons. The activity recorded shows a rapid onset, a gradual rise, and an abrupt termination with a sudden burst of activity related to inhalation.
Following this activity, the inspiratory muscles contract and intrapulmonary pressure decreases. Inspiratory neuronal activity can be said to depend on the cycle of various neurons- inspiratory, early inspiratory, off-switch, post inspiratory, and expiratory neurons. The "off-switch" neurons come about at the sharp cutoff point in the activity of inhalation, and also when neuronal activity has reached a threshold level.
Pulmonary stretch receptors that are stimulated by lung expansion decrease the threshold level. Without these receptors working on the inspiratory neurons, there would be over-expansion of the lung. At the beginning of expiration, the amount of work by the inspiratory muscles begins to decrease, which is caused by the post-inspiratory neurons.
The post-inspiratory neurons are responsible for slowing the rates of expiration. At the end of the post-inspiratory activity, the expiratory neurons are then released. The time between each breath is determined by the interval between the bursts of activity of the inspiratory neurons. The interval between a burst of activity is related to the amount of activity in the burst that came before it, as well as with nerves in the pulmonary stretch receptors.
If the activity of inspiration is great, as is when taking a deep breath, there is a longer interval between inspirations. This allows the ratio of duration on inspiratory and expiratory activity to stay constant no matter how long the breath taken is. The pulmonary stretch receptors can influence this ration, however, depending on their activity. If these receptors are very active, the duration of expiration may be extended, leaving a longer time for exhalation.
This can occur during expiration when the lung empties out slowly and when the pulmonary stretch receptors are still active while the lung stays inflated. Normal blood pH is set at 7. If the pH of our blood drops below 7. Blood pH levels below 6. Another wonder of our amazing bodies is the ability to cope with every pH change — large or small.
There are three factors in this process: So what exactly is pH? The most important buffer we have in our bodies is a mixture of carbon dioxide CO2 and bicarbonate ion HCO3. In a nutshell, blood pH is determined by a balance between bicarbonate and carbon dioxide. With this important system our bodies maintain homeostasis. The CO2 level is increased when hypoventilation or slow breathing occurs, such as if you have emphysema or pneumonia.
Bicarbonate will be lowered by ketoacidosis, a condition caused by excess fat metabolism diabetes mellitus. This condition is less common than acidosis.
CO2 can be lowered by hyperventilation. So, in summary, if you are going into respiratory acidosis the above equation will move to the right. In contrast, if you are going into respiratory alkalosis the equation will move to the left. So the body will try to breathe less to release HCO3. You can think of it like a leak in a pipe: Problems Associated With the Respiratory Tract and Breathing[ edit ] The environment of the lung is very moist, which makes it a hospitable environment for bacteria.
Many respiratory illnesses are the result of bacterial or viral infection of the lungs. Because we are constantly being exposed to harmful bacteria and viruses in our environment, our respiratory health can be adversely affected. There are a number of illnesses and diseases that can cause problems with breathing. Some are simple infections, and others are disorders that can be quite serious.
Carbon monoxide binds much tighter, without releasing, causing the hemoglobin to become unavailable to oxygen. The result can be fatal in a very short amount of time. By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs.
Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death. Treatment, usually, is with anticoagulant medication. Upper Respiratory Tract Infections[ edit ] The upper respiratory tract consists of our nasal cavities, pharynx, and larynx.
Upper respiratory infections URI can spread from our nasal cavities to our sinuses, ears, and larynx. Sometimes a viral infection can lead to what is called a secondary bacterial infection. Antibiotics aren't used to treat viral infections, but are successful in treating most bacterial infections, including strep throat. The symptoms of strep throat can be a high fever, severe sore throat, white patches on a dark red throat, and stomach ache. Sinusitis An infection of the cranial sinuses is called sinusitis.
This "sinus infection" develops when nasal congestion blocks off the tiny openings that lead to the sinuses. Successful treatment depends on restoring the proper drainage of the sinuses. Taking a hot shower or sleeping upright can be very helpful. Otherwise, using a spray decongestant or sometimes a prescribed antibiotic will be necessary. Otitis Media Otitis media in an infection of the middle ear.
Even though the middle ear is not part of the respiratory tract, it is discussed here because it is often a complication seen in children who has a nasal infection. The infection can be spread by way of the 'auditory Eustachian tube that leads form the nasopharynx to the middle ear. The main symptom is usually pain.
Sometimes though, vertigo, hearing loss, and dizziness may be present. Antibiotics can be prescribed and tubes are placed in the eardrum to prevent the buildup of pressure in the middle ear and the possibility of hearing loss.
Tonsillitis Tonsillitis occurs when the tonsils become swollen and inflamed. The tonsils located in the posterior wall of the nasopharynx are often referred to as adenoids. If you suffer from tonsillitis frequently and breathing becomes difficult, they can be removed surgically in a procedure called a tonsillectomy. Laryngitis An infection of the larynx is called laryngitis.
It is accompanied by hoarseness and being unable to speak in an audible voice. Usually, laryngitis disappears with treatment of the URI. Persistent hoarseness without a URI is a warning sign of cancer, and should be checked into by your physician. Lower Respiratory Tract Disorders[ edit ] Lower respiratory tract disorders include infections, restrictive pulmonary disorders, obstructive pulmonary disorders, and lung cancer. Lower Respiratory Infections[ edit ] Acute bronchitis An infection that is located in the primary and secondary bronchi is called bronchitis.
Most of the time, it is preceded by a viral URI that led to a secondary bacterial infection. Usually, a nonproductive cough turns into a deep cough that will expectorate mucus and sometimes pus. Pneumonia A bacterial or viral infection in the lungs where the bronchi and the alveoli fill with a thick fluid. Usually it is preceded by influenza. Pneumonia can be located in several lobules of the lung and obviously, the more lobules involved, the more serious the infection.
It can be caused by a bacteria that is usually held in check, but due to stress or reduced immunity has gained the upper hand. Restrictive Pulmonary Disorders[ edit ] Pulmonary Fibrosis Vital capacity is reduced in these types of disorders because the lungs have lost their elasticity.
Inhaling particles such as sand, asbestos, coal dust, or fiberglass can lead to pulmonary fibrosis, a condition where fibrous tissue builds up in the lungs. This makes it so our lungs cannot inflate properly and are always tending toward deflation.
Diagram of the lungs during an asthma attack. Asthma Asthma is a respiratory disease of the bronchi and bronchioles. The symptoms include wheezing, shortness of breath, and sometimes a cough that will expel mucus.
The airways are very sensitive to irritants which can include pollen, dust, animal dander, and tobacco. Even being out in cold air can be an irritant. When exposed to an irritant, the smooth muscle in the bronchioles undergoes spasms.
Most asthma patients have at least some degree of bronchial inflammation that reduces the diameter of the airways and contributes to the seriousness of the attack.
Emphysema Emphysema is a type of chronic obstructive pulmonary disease. Typically characterized by a loss of elasticity and surfactant in the alveoli, a loss of surface area decreases the gas exchange in the lungs. These patients have difficulty with too little expiratory pressure, not retaining inspired air long enough for sufficient gas exchange to happen.
Chronic Bronchitis Another type of chronic obstructive pulmonary disease, Chronic Bronchitis is caused by overproduction of mucus in the airways, causing an inadequate expiration of inspired air. Retention of air in the lungs reduces gas exchange at the alveoli, and can lead to a hypoxic drive.
These patients are known as "blue bloaters", vulnerable to cyanosis and often have increased thoracic diameters.
Respiratory Distress Syndrome[ edit ] Pathophysiology At birth the pressure needed to expand the lungs requires high inspiratory pressure. In the case of deficiency of surfactant the lungs will collapse between breaths, this makes the infant work hard and each breath is as hard as the first breath.
If this goes on further the pulmonary capillary membranes become more permeable, letting in fibrin rich fluids between the alveolar spaces and in turn forms a hyaline membrane.
The hyaline membrane is a barrier to gas exchange, this hyaline membrane then causes hypoxemia and carbon dioxide retention that in turn will further impair surfactant production.
Etiology Type two alveolar cells produce surfactant and do not develop until the 25th to the 28th week of gestation, in this, respiratory distress syndrome is one of the most common respiratory disease in premature infants. Furthermore, surfactant deficiency and pulmonary immaturity together leads to alveolar collapse.
Predisposing factors that contribute to poorly functioning type II alveolar cells in a premature baby are if the child is a preterm male, white infants, infants of mothers with diabetes, precipitous deliveries, cesarean section performed before the 38th week of gestation. Surfactant synthesis is influenced by hormones, this ranges form insulin and cortisol. Insulin inhibits surfactant production, explaining why infants of mothers with diabetes type 1 are at risk of development of respiratory distress syndrome.
Cortisol can speed up maturation of type II cells and therefore production of surfactant. Finally, in the baby delivered by cesarean section are at greater risk of developing respiratory distress syndrome because the reduction of cortisol produced because the lack of stress that happens during vaginal delivery, hence cortisol increases in high stress and helps in the maturation of type II cells of the alveoli that cause surfactant.
Treatment Today to prevent respiratory distress syndrome are animal sources and synthetic surfactants, and administrated through the airways by an endotracheal tube and the surfactant is suspended in a saline solution. Treatment is initiated post birth and in infants who are at high risk for respiratory distress syndrome. Sleep apnea or sleep apnoea is a sleep disorder characterized by pauses in breathing during sleep.
These episodes, called apneas literally, "without breath"each last long enough so one or more breaths are missed, and occur repeatedly throughout sleep. The standard definition of any apneic event includes a minimum 10 second interval between breaths, with either a neurological arousal 3-second or greater shift in EEG frequency, measured at C3, C4, O1, or O2or a blood oxygen desaturation of percent or greater, or both arousal and desaturation.
Sleep apnea is diagnosed with an overnight sleep test called polysomnogram. This machine forces the wearer to breathe a constant number of breaths per minute. CPAPor continuous positive airway pressure, in which a controlled air compressor generates an airstream at a constant pressure. This pressure is prescribed by the patient's physician, based on an overnight test or titration.
When metabolizing macronutrients carbon dioxide and water are produced. The respiratory quotient RQ is a ratio of produced carbon dioxide to amount consumed. Carbohydrates metabolism produces the most amount of carbon dioxide so they have the highest RQ. Fats produce the least amount of carbon dioxide along with proteins. Protein has a slightly higher RQ ratio. It is recommended that this kind of patient not exceed a 1. Lowering carbohydrates and supplementing fat or protein in the diet might not result in maintaining the desired outcome because, excess amounts fat or protein may also result in a respiratory quotient RQ higher than 1.