Video
Anatomy and physiology of the respiratory systemRespiratory system functions -
Their measurement requires special techniques. The rates at which air is breathed in or out, either through the mouth or nose or into or out of the alveoli are tabulated below, together with how they are calculated. The number of breath cycles per minute is known as the respiratory rate.
An average healthy human breathes times a minute. In mammals , inhalation at rest is primarily due to the contraction of the diaphragm. This is an upwardly domed sheet of muscle that separates the thoracic cavity from the abdominal cavity.
When it contracts, the sheet flattens, i. moves downwards as shown in Fig. The contracting diaphragm pushes the abdominal organs downwards. But because the pelvic floor prevents the lowermost abdominal organs from moving in that direction, the pliable abdominal contents cause the belly to bulge outwards to the front and sides, because the relaxed abdominal muscles do not resist this movement Fig.
This entirely passive bulging and shrinking during exhalation of the abdomen during normal breathing is sometimes referred to as "abdominal breathing", although it is, in fact, "diaphragmatic breathing", which is not visible on the outside of the body. Mammals only use their abdominal muscles during forceful exhalation see Fig.
Never during any form of inhalation. As the diaphragm contracts, the rib cage is simultaneously enlarged by the ribs being pulled upwards by the intercostal muscles as shown in Fig. All the ribs slant downwards from the rear to the front as shown in Fig. Thus the rib cage's transverse diameter can be increased in the same way as the antero-posterior diameter is increased by the so-called pump handle movement shown in Fig.
The enlargement of the thoracic cavity's vertical dimension by the contraction of the diaphragm, and its two horizontal dimensions by the lifting of the front and sides of the ribs, causes the intrathoracic pressure to fall.
The lungs' interiors are open to the outside air and being elastic, therefore expand to fill the increased space, pleura fluid between double-layered pleura covering of lungs helps in reducing friction while lungs expansion and contraction.
The inflow of air into the lungs occurs via the respiratory airways Fig. In a healthy person, these airways begin with the nose. However, chronic mouth breathing leads to, or is a sign of, illness.
The alveolar air pressure is therefore always close to atmospheric air pressure about kPa at sea level at rest, with the pressure gradients because of lungs contraction and expansion cause air to move in and out of the lungs during breathing rarely exceeding 2—3 kPa.
During exhalation, the diaphragm and intercostal muscles relax. This returns the chest and abdomen to a position determined by their anatomical elasticity.
This is the "resting mid-position" of the thorax and abdomen Fig. The volume of air that moves in or out at the nose or mouth during a single breathing cycle is called the tidal volume. In a resting adult human, it is about ml per breath. At the end of exhalation, the airways contain about ml of alveolar air which is the first air that is breathed back into the alveoli during inhalation.
the functional residual capacity of about 2. The oxygen tension or partial pressure remains close to kPa about mm Hg , and that of carbon dioxide very close to 5. This contrasts with composition of the dry outside air at sea level, where the partial pressure of oxygen is 21 kPa or mm Hg and that of carbon dioxide 0.
During heavy breathing hyperpnea , as, for instance, during exercise, inhalation is brought about by a more powerful and greater excursion of the contracting diaphragm than at rest Fig. In addition, the " accessory muscles of inhalation " exaggerate the actions of the intercostal muscles Fig.
These accessory muscles of inhalation are muscles that extend from the cervical vertebrae and base of the skull to the upper ribs and sternum , sometimes through an intermediary attachment to the clavicles.
Seen from outside the body, the lifting of the clavicles during strenuous or labored inhalation is sometimes called clavicular breathing , seen especially during asthma attacks and in people with chronic obstructive pulmonary disease. During heavy breathing, exhalation is caused by relaxation of all the muscles of inhalation.
But now, the abdominal muscles, instead of remaining relaxed as they do at rest , contract forcibly pulling the lower edges of the rib cage downwards front and sides Fig.
This not only drastically decreases the size of the rib cage, but also pushes the abdominal organs upwards against the diaphragm which consequently bulges deeply into the thorax Fig. The end-exhalatory lung volume is now well below the resting mid-position and contains far less air than the resting "functional residual capacity".
However, in a normal mammal, the lungs cannot be emptied completely. In an adult human, there is always still at least 1 liter of residual air left in the lungs after maximum exhalation. The automatic rhythmical breathing in and out, can be interrupted by coughing, sneezing forms of very forceful exhalation , by the expression of a wide range of emotions laughing, sighing, crying out in pain, exasperated intakes of breath and by such voluntary acts as speech, singing, whistling and the playing of wind instruments.
All of these actions rely on the muscles described above, and their effects on the movement of air in and out of the lungs.
Although not a form of breathing, the Valsalva maneuver involves the respiratory muscles. It is, in fact, a very forceful exhalatory effort against a tightly closed glottis , so that no air can escape from the lungs.
The abdominal muscles contract very powerfully, causing the pressure inside the abdomen and thorax to rise to extremely high levels. The Valsalva maneuver can be carried out voluntarily but is more generally a reflex elicited when attempting to empty the abdomen during, for instance, difficult defecation, or during childbirth.
Breathing ceases during this maneuver. The primary purpose of the respiratory system is the equalizing of the partial pressures of the respiratory gases in the alveolar air with those in the pulmonary capillary blood Fig.
This process occurs by simple diffusion , [22] across a very thin membrane known as the blood—air barrier , which forms the walls of the pulmonary alveoli Fig. It consists of the alveolar epithelial cells , their basement membranes and the endothelial cells of the alveolar capillaries Fig.
It is folded into about million small air sacs called alveoli [23] each between 75 and µm in diameter branching off from the respiratory bronchioles in the lungs , thus providing an extremely large surface area approximately m 2 for gas exchange to occur. The air contained within the alveoli has a semi-permanent volume of about 2.
This ensures that equilibration of the partial pressures of the gases in the two compartments is very efficient and occurs very quickly. The blood leaving the alveolar capillaries and is eventually distributed throughout the body therefore has a partial pressure of oxygen of kPa mmHg , and a partial pressure of carbon dioxide of 5.
the same as the oxygen and carbon dioxide gas tensions as in the alveoli. This marked difference between the composition of the alveolar air and that of the ambient air can be maintained because the functional residual capacity is contained in dead-end sacs connected to the outside air by fairly narrow and relatively long tubes the airways: nose , pharynx , larynx , trachea , bronchi and their branches down to the bronchioles , through which the air has to be breathed both in and out i.
there is no unidirectional through-flow as there is in the bird lung. This typical mammalian anatomy combined with the fact that the lungs are not emptied and re-inflated with each breath leaving a substantial volume of air, of about 2. Thus the animal is provided with a very special "portable atmosphere", whose composition differs significantly from the present-day ambient air.
The resulting arterial partial pressures of oxygen and carbon dioxide are homeostatically controlled. A rise in the arterial partial pressure of CO 2 and, to a lesser extent, a fall in the arterial partial pressure of O 2 , will reflexly cause deeper and faster breathing until the blood gas tensions in the lungs, and therefore the arterial blood, return to normal.
The converse happens when the carbon dioxide tension falls, or, again to a lesser extent, the oxygen tension rises: the rate and depth of breathing are reduced until blood gas normality is restored. Since the blood arriving in the alveolar capillaries has a partial pressure of O 2 of, on average, 6 kPa 45 mmHg , while the pressure in the alveolar air is kPa mmHg , there will be a net diffusion of oxygen into the capillary blood, changing the composition of the 3 liters of alveolar air slightly.
Similarly, since the blood arriving in the alveolar capillaries has a partial pressure of CO 2 of also about 6 kPa 45 mmHg , whereas that of the alveolar air is 5. This is very tightly controlled by the monitoring of the arterial blood gases which accurately reflect composition of the alveolar air by the aortic and carotid bodies , as well as by the blood gas and pH sensor on the anterior surface of the medulla oblongata in the brain.
There are also oxygen and carbon dioxide sensors in the lungs, but they primarily determine the diameters of the bronchioles and pulmonary capillaries , and are therefore responsible for directing the flow of air and blood to different parts of the lungs.
It is only as a result of accurately maintaining the composition of the 3 liters of alveolar air that with each breath some carbon dioxide is discharged into the atmosphere and some oxygen is taken up from the outside air. If more carbon dioxide than usual has been lost by a short period of hyperventilation , respiration will be slowed down or halted until the alveolar partial pressure of carbon dioxide has returned to 5.
The carbon dioxide that is breathed out with each breath could probably be more correctly be seen as a byproduct of the body's extracellular fluid carbon dioxide and pH homeostats. If these homeostats are compromised, then a respiratory acidosis , or a respiratory alkalosis will occur.
Oxygen has a very low solubility in water, and is therefore carried in the blood loosely combined with hemoglobin. The oxygen is held on the hemoglobin by four ferrous iron -containing heme groups per hemoglobin molecule. The reaction is therefore catalyzed by carbonic anhydrase , an enzyme inside the red blood cells.
The total concentration of carbon dioxide in the form of bicarbonate ions, dissolved CO 2 , and carbamino groups in arterial blood i. Ventilation of the lungs in mammals occurs via the respiratory centers in the medulla oblongata and the pons of the brainstem.
This information determines the average rate of ventilation of the alveoli of the lungs , to keep these pressures constant. The respiratory center does so via motor nerves which activate the diaphragm and other muscles of respiration. The breathing rate increases when the partial pressure of carbon dioxide in the blood increases.
This is detected by central blood gas chemoreceptors on the anterior surface of the medulla oblongata. Exercise increases the breathing rate due to the extra carbon dioxide produced by the enhanced metabolism of the exercising muscles.
Information received from stretch receptors in the lungs' limits tidal volume the depth of inhalation and exhalation. The alveoli are open via the airways to the atmosphere, with the result that alveolar air pressure is exactly the same as the ambient air pressure at sea level, at altitude, or in any artificial atmosphere e.
a diving chamber, or decompression chamber in which the individual is breathing freely. With expansion of the lungs the alveolar air occupies a larger volume, and its pressure falls proportionally , causing air to flow in through the airways, until the pressure in the alveoli is again at the ambient air pressure.
The reverse happens during exhalation. This process of inhalation and exhalation is exactly the same at sea level, as on top of Mt. Everest , or in a diving chamber or decompression chamber.
However, as one rises above sea level the density of the air decreases exponentially see Fig. This is achieved by breathing deeper and faster i. hyperpnea than at sea level see below. There is, however, a complication that increases the volume of air that needs to be inhaled per minute respiratory minute volume to provide the same amount of oxygen to the lungs at altitude as at sea level.
During inhalation, the air is warmed and saturated with water vapor during its passage through the nose passages and pharynx. Saturated water vapor pressure is dependent only on temperature.
At a body core temperature of 37 °C it is 6. In dry air the partial pressure of O 2 at sea level is At the summit of Mt.
Everest at an altitude of 8, m or 29, ft , the total atmospheric pressure is This reduces the partial pressure of oxygen entering the alveoli to 5. The reduction in the partial pressure of oxygen in the inhaled air is therefore substantially greater than the reduction of the total atmospheric pressure at altitude would suggest on Mt Everest: 5.
A further minor complication exists at altitude. If the volume of the lungs were to be instantaneously doubled at the beginning of inhalation, the air pressure inside the lungs would be halved.
This happens regardless of altitude. Thus, halving of the sea level air pressure kPa results in an intrapulmonary air pressure of 50 kPa. Doing the same at m, where the atmospheric pressure is only 50 kPa, the intrapulmonary air pressure falls to 25 kPa.
Therefore, the same change in lung volume at sea level results in a 50 kPa difference in pressure between the ambient air and the intrapulmonary air, whereas it result in a difference of only 25 kPa at m.
The driving pressure forcing air into the lungs during inhalation is therefore halved at this altitude. The rate of inflow of air into the lungs during inhalation at sea level is therefore twice that which occurs at m.
However, in reality, inhalation and exhalation occur far more gently and less abruptly than in the example given.
The differences between the atmospheric and intrapulmonary pressures, driving air in and out of the lungs during the breathing cycle, are in the region of only 2—3 kPa. All of the above influences of low atmospheric pressures on breathing are accommodated primarily by breathing deeper and faster hyperpnea.
The exact degree of hyperpnea is determined by the blood gas homeostat , which regulates the partial pressures of oxygen and carbon dioxide in the arterial blood. This homeostat prioritizes the regulation of the arterial partial pressure of carbon dioxide over that of oxygen at sea level.
If this switch occurs relatively abruptly, the hyperpnea at high altitude will cause a severe fall in the arterial partial pressure of carbon dioxide, with a consequent rise in the pH of the arterial plasma. This is one contributor to high altitude sickness. On the other hand, if the switch to oxygen homeostasis is incomplete, then hypoxia may complicate the clinical picture with potentially fatal results.
There are oxygen sensors in the smaller bronchi and bronchioles. In response to low partial pressures of oxygen in the inhaled air these sensors reflexively cause the pulmonary arterioles to constrict. At altitude this causes the pulmonary arterial pressure to rise resulting in a much more even distribution of blood flow to the lungs than occurs at sea level.
At sea level, the pulmonary arterial pressure is very low, with the result that the tops of the lungs receive far less blood than the bases , which are relatively over-perfused with blood. It is only in the middle of the lungs that the blood and air flow to the alveoli are ideally matched.
This is a further important contributor to the acclimatatization to high altitudes and low oxygen pressures. When the oxygen content of the blood is chronically low, as at high altitude, the oxygen-sensitive kidney cells secrete erythropoietin EPO into the blood.
In other words, at the same arterial partial pressure of O 2 , a person with a high hematocrit carries more oxygen per liter of blood than a person with a lower hematocrit does.
High altitude dwellers therefore have higher hematocrits than sea-level residents. Irritation of nerve endings within the nasal passages or airways , can induce a cough reflex and sneezing. These responses cause air to be expelled forcefully from the trachea or nose , respectively.
In this manner, irritants caught in the mucus which lines the respiratory tract are expelled or moved to the mouth where they can be swallowed.
This increases the expired airflow rate to dislodge and remove any irritant particle or mucus. Respiratory epithelium can secrete a variety of molecules that aid in the defense of the lungs. These include secretory immunoglobulins IgA , collectins , defensins and other peptides and proteases , reactive oxygen species , and reactive nitrogen species.
These secretions can act directly as antimicrobials to help keep the airway free of infection. A variety of chemokines and cytokines are also secreted that recruit the traditional immune cells and others to the site of infections.
Surfactant immune function is primarily attributed to two proteins: SP-A and SP-D. These proteins can bind to sugars on the surface of pathogens and thereby opsonize them for uptake by phagocytes. It also regulates inflammatory responses and interacts with the adaptive immune response.
Surfactant degradation or inactivation may contribute to enhanced susceptibility to lung inflammation and infection. Most of the respiratory system is lined with mucous membranes that contain mucosa-associated lymphoid tissue , which produces white blood cells such as lymphocytes.
The lungs make a surfactant , a surface-active lipoprotein complex phospholipoprotein formed by type II alveolar cells. It floats on the surface of the thin watery layer which lines the insides of the alveoli, reducing the water's surface tension.
The surface tension of a watery surface the water-air interface tends to make that surface shrink. The more acute the curvature of the water-air interface the greater the tendency for the alveolus to collapse.
Firstly, the surface tension inside the alveoli resists expansion of the alveoli during inhalation i. it makes the lung stiff, or non-compliant. Surfactant reduces the surface tension and therefore makes the lungs more compliant , or less stiff, than if it were not there.
Secondly, the diameters of the alveoli increase and decrease during the breathing cycle. This means that the alveoli have a greater tendency to collapse i.
cause atelectasis at the end of exhalation than at the end of inhalation. Since surfactant floats on the watery surface, its molecules are more tightly packed together when the alveoli shrink during exhalation. The tendency for the alveoli to collapse is therefore almost the same at the end of exhalation as at the end of inhalation.
Thirdly, the surface tension of the curved watery layer lining the alveoli tends to draw water from the lung tissues into the alveoli. Surfactant reduces this danger to negligible levels, and keeps the alveoli dry. Pre-term babies who are unable to manufacture surfactant have lungs that tend to collapse each time they breathe out.
Unless treated, this condition, called respiratory distress syndrome , is fatal. Basic scientific experiments, carried out using cells from chicken lungs, support the potential for using steroids as a means of furthering the development of type II alveolar cells.
The lung vessels contain a fibrinolytic system that dissolves clots that may have arrived in the pulmonary circulation by embolism , often from the deep veins in the legs.
They also release a variety of substances that enter the systemic arterial blood, and they remove other substances from the systemic venous blood that reach them via the pulmonary artery. Some prostaglandins are removed from the circulation, while others are synthesized in the lungs and released into the blood when lung tissue is stretched.
The lungs activate one hormone. The physiologically inactive decapeptide angiotensin I is converted to the aldosterone -releasing octapeptide, angiotensin II , in the pulmonary circulation.
The reaction occurs in other tissues as well, but it is particularly prominent in the lungs. Angiotensin II also has a direct effect on arteriolar walls , causing arteriolar vasoconstriction , and consequently a rise in arterial blood pressure. The converting enzyme also inactivates bradykinin.
Four other peptidases have been identified on the surface of the pulmonary endothelial cells. The movement of gas through the larynx , pharynx and mouth allows humans to speak , or phonate. Vocalization, or singing, in birds occurs via the syrinx , an organ located at the base of the trachea.
The vibration of air flowing across the larynx vocal cords , in humans, and the syrinx, in birds, results in sound. Because of this, gas movement is vital for communication purposes.
Panting in dogs, cats, birds and some other animals provides a means of reducing body temperature, by evaporating saliva in the mouth instead of evaporating sweat on the skin. Disorders of the respiratory system can be classified into several general groups:.
Disorders of the respiratory system are usually treated by a pulmonologist and respiratory therapist. Where there is an inability to breathe or insufficiency in breathing, a medical ventilator may be used.
Cetaceans have lungs, meaning they breathe air. An individual can last without a breath from a few minutes to over two hours depending on the species.
Cetacea are deliberate breathers who must be awake to inhale and exhale. When stale air, warmed from the lungs, is exhaled, it condenses as it meets colder external air. As with a terrestrial mammal breathing out on a cold day, a small cloud of 'steam' appears.
This is called the 'spout' and varies across species in shape, angle and height. Species can be identified at a distance using this characteristic.
Horses are obligate nasal breathers which means that they are different from many other mammals because they do not have the option of breathing through their mouths and must take in air through their noses.
A flap of tissue called the soft palate blocks off the pharynx from the mouth oral cavity of the horse, except when swallowing. This helps to prevent the horse from inhaling food, but does not allow use of the mouth to breathe when in respiratory distress, a horse can only breathe through its nostrils.
The elephant is the only mammal known to have no pleural space. Instead, the parietal and visceral pleura are both composed of dense connective tissue and joined to each other via loose connective tissue. In the elephant the lungs are attached to the diaphragm and breathing relies mainly on the diaphragm rather than the expansion of the ribcage.
The respiratory system of birds differs significantly from that found in mammals. Firstly, they have rigid lungs which do not expand and contract during the breathing cycle.
Instead an extensive system of air sacs Fig. Inhalation and exhalation are brought about by alternately increasing and decreasing the volume of the entire thoraco-abdominal cavity or coelom using both their abdominal and costal muscles.
This pushes the sternal ribs, to which they are attached at almost right angles, downwards and forwards, taking the sternum with its prominent keel in the same direction Fig. This increases both the vertical and transverse diameters of thoracic portion of the trunk.
The forward and downward movement of, particularly, the posterior end of the sternum pulls the abdominal wall downwards, increasing the volume of that region of the trunk as well.
During exhalation the external oblique muscle which is attached to the sternum and vertebral ribs anteriorly , and to the pelvis pubis and ilium in Fig.
Air is therefore expelled from the respiratory system in the act of exhalation. During inhalation air enters the trachea via the nostrils and mouth, and continues to just beyond the syrinx at which point the trachea branches into two primary bronchi , going to the two lungs Fig.
The primary bronchi enter the lungs to become the intrapulmonary bronchi, which give off a set of parallel branches called ventrobronchi and, a little further on, an equivalent set of dorsobronchi Fig.
Each pair of dorso-ventrobronchi is connected by a large number of parallel microscopic air capillaries or parabronchi where gas exchange occurs Fig.
This is due to the bronchial architecture which directs the inhaled air away from the openings of the ventrobronchi, into the continuation of the intrapulmonary bronchus towards the dorsobronchi and posterior air sacs.
So, during inhalation, both the posterior and anterior air sacs expand, [46] the posterior air sacs filling with fresh inhaled air, while the anterior air sacs fill with "spent" oxygen-poor air that has just passed through the lungs.
During exhalation the pressure in the posterior air sacs which were filled with fresh air during inhalation increases due to the contraction of the oblique muscle described above.
The aerodynamics of the interconnecting openings from the posterior air sacs to the dorsobronchi and intrapulmonary bronchi ensures that the air leaves these sacs in the direction of the lungs via the dorsobronchi , rather than returning down the intrapulmonary bronchi Fig.
The air passages connecting the ventrobronchi and anterior air sacs to the intrapulmonary bronchi direct the "spent", oxygen poor air from these two organs to the trachea from where it escapes to the exterior.
The blood flow through the bird lung is at right angles to the flow of air through the parabronchi, forming a cross-current flow exchange system Fig. The blood capillaries leaving the exchanger near the entrance of airflow take up more O 2 than do the capillaries leaving near the exit end of the parabronchi.
When the contents of all capillaries mix, the final partial pressure of oxygen of the mixed pulmonary venous blood is higher than that of the exhaled air, [46] [49] but is nevertheless less than half that of the inhaled air, [46] thus achieving roughly the same systemic arterial blood partial pressure of oxygen as mammals do with their bellows-type lungs.
The trachea is an area of dead space : the oxygen-poor air it contains at the end of exhalation is the first air to re-enter the posterior air sacs and lungs. In comparison to the mammalian respiratory tract , the dead space volume in a bird is, on average, 4.
In some birds e. the whooper swan , Cygnus cygnus , the white spoonbill , Platalea leucorodia , the whooping crane , Grus americana , and the helmeted curassow , Pauxi pauxi the trachea, which some cranes can be 1.
The anatomical structure of the lungs is less complex in reptiles than in mammals , with reptiles lacking the very extensive airway tree structure found in mammalian lungs.
Gas exchange in reptiles still occurs in alveoli however. Thus, breathing occurs via a change in the volume of the body cavity which is controlled by contraction of intercostal muscles in all reptiles except turtles.
In turtles, contraction of specific pairs of flank muscles governs inhalation and exhalation. Both the lungs and the skin serve as respiratory organs in amphibians. The ventilation of the lungs in amphibians relies on positive pressure ventilation. Muscles lower the floor of the oral cavity, enlarging it and drawing in air through the nostrils into the oral cavity.
With the nostrils and mouth closed, the floor of the oral cavity is then pushed up, which forces air down the trachea into the lungs. The skin of these animals is highly vascularized and moist, with moisture maintained via secretion of mucus from specialised cells, and is involved in cutaneous respiration.
While the lungs are of primary organs for gas exchange between the blood and the environmental air when out of the water , the skin's unique properties aid rapid gas exchange when amphibians are submerged in oxygen-rich water. tadpoles of frogs , while others retain them into adulthood e.
some salamanders. Oxygen is poorly soluble in water. the rate at which a substances diffuses from a region of high concentration to one of low concentration, under standard conditions of the respiratory gases is typically 10, faster in air than in water.
Fish have developed gills deal with these problems. Gills are specialized organs containing filaments , which further divide into lamellae. The lamellae contain a dense thin walled capillary network that exposes a large gas exchange surface area to the very large volumes of water passing over them.
Gills use a countercurrent exchange system that increases the efficiency of oxygen-uptake from the water. Water is drawn in through the mouth by closing the operculum gill cover , and enlarging the mouth cavity Fig.
Simultaneously the gill chambers enlarge, producing a lower pressure there than in the mouth causing water to flow over the gills. Back-flow into the gill chamber during the inhalatory phase is prevented by a membrane along the ventroposterior border of the operculum diagram on the left in Fig.
Thus the mouth cavity and gill chambers act alternately as suction pump and pressure pump to maintain a steady flow of water over the gills in one direction. Oxygen is, therefore, able to continually diffuse down its gradient into the blood, and the carbon dioxide down its gradient into the water.
In certain active pelagic sharks, water passes through the mouth and over the gills while they are moving, in a process known as "ram ventilation". But a small number of species have lost the ability to pump water through their gills and must swim without rest. These species are obligate ram ventilators and would presumably asphyxiate if unable to move.
Obligate ram ventilation is also true of some pelagic bony fish species. There are a few fish that can obtain oxygen for brief periods of time from air swallowed from above the surface of the water.
Thus lungfish possess one or two lungs, and the labyrinth fish have developed a special "labyrinth organ", which characterizes this suborder of fish. The labyrinth organ is a much-folded supra branchial accessory breathing organ.
It is formed by a vascularized expansion of the epibranchial bone of the first gill arch, and is used for respiration in air. The labyrinth organ helps the oxygen in the inhaled air to be absorbed into the bloodstream. As a result, labyrinth fish can survive for a short period of time out of water, as they can inhale the air around them, provided they stay moist.
Labyrinth fish are not born with functional labyrinth organs. The development of the organ is gradual and most juvenile labyrinth fish breathe entirely with their gills and develop the labyrinth organs when they grow older. Some species of crab use a respiratory organ called a branchiostegal lung.
Some of the smallest spiders and mites can breathe simply by exchanging gas through the surface of the body. Larger spiders, scorpions and other arthropods use a primitive book lung.
Most insects breath passively through their spiracles special openings in the exoskeleton and the air reaches every part of the body by means of a series of smaller and smaller tubes called 'trachaea' when their diameters are relatively large, and ' tracheoles ' when their diameters are very small.
The tracheoles make contact with individual cells throughout the body. Diffusion of gases is effective over small distances but not over larger ones, this is one of the reasons insects are all relatively small.
Insects which do not have spiracles and trachaea, such as some Collembola, breathe directly through their skins, also by diffusion of gases. The number of spiracles an insect has is variable between species, however, they always come in pairs, one on each side of the body, and usually one pair per segment.
Some of the Diplura have eleven, with four pairs on the thorax, but in most of the ancient forms of insects, such as Dragonflies and Grasshoppers there are two thoracic and eight abdominal spiracles. However, in most of the remaining insects, there are fewer. It is at the level of the tracheoles that oxygen is delivered to the cells for respiration.
Insects were once believed to exchange gases with the environment continuously by the simple diffusion of gases into the tracheal system. More recently, however, large variation in insect ventilatory patterns has been documented and insect respiration appears to be highly variable.
Some small insects do not demonstrate continuous respiratory movements and may lack muscular control of the spiracles. Others, however, utilize muscular contraction of the abdomen along with coordinated spiracle contraction and relaxation to generate cyclical gas exchange patterns and to reduce water loss into the atmosphere.
The most extreme form of these patterns is termed discontinuous gas exchange cycles. Molluscs generally possess gills that allow gas exchange between the aqueous environment and their circulatory systems. These animals also possess a heart that pumps blood containing hemocyanin as its oxygen-capturing molecule.
The respiratory system of gastropods can include either gills or a lung. Plants use carbon dioxide gas in the process of photosynthesis , and exhale oxygen gas as waste. The chemical equation of photosynthesis is 6 CO 2 carbon dioxide and 6 H 2 O water , which in the presence of sunlight makes C 6 H 12 O 6 glucose and 6 O 2 oxygen.
Photosynthesis uses electrons on the carbon atoms as the repository for the energy obtained from sunlight. It reclaims the energy to power chemical reactions in cells.
In so doing the carbon atoms and their electrons are combined with oxygen forming CO 2 which is easily removed from both the cells and the organism. If there were no surfactant, the bag would collapse in on itself and the internal sides would stick together.
Surfactant prevents this from happening to the alveoli. Pulmonary surfactant carries out its role by reducing the amount of surface tension. By doing this, it reduces the effort necessary to inflate the alveoli. Respiration is the best-known role of the lungs, but they carry out other important functions, including:.
Respiratory diseases can affect any part of the respiratory system, from the upper respiratory tract to the bronchi and down into the alveoli. Some examples of conditions that affect the lungs include the below. COPD usually results from the damage that tobacco smoking causes to the lungs.
Asthma involves an obstructive narrowing and swelling of the airways and the production of excess mucus. This triggers shortness of breath and wheezing. Triggers can include :. This means that the airway is restricted, so the amount of air a person can take in is reduced, and breathing in becomes harder.
It can occur due to :. Infections can occur at any point in the respiratory tract. Some examples include:. Complications can develop from these types of infections, including lung abscesses and the spread of infection to the pleural cavity.
Lung cancer is when cells in the lungs divide uncontrollably. Evidence suggests lung cancer is the third most common cancer and the main cause of cancer-related death in the U. Smoking is the most common cause of lung cancer, but other risk factors can include a family history of the disease and exposure to radiation or certain chemicals.
The pleural cavity is the gap between the inner and outer pleural membranes that encase the outside of the lungs. Pleural effusion describes a build-up of fluid in the pleural cavity. It always results from other conditions, such as cancer, congestive heart failure , or liver cirrhosis.
A collapsed lung, also known as pneumothorax , occurs when air gets into the space between the chest wall and the lung, called the pleural space. This can compress the lungs, and when severe, it causes them to collapse like a balloon.
Pulmonary vascular diseases affect the vessels that carry blood through the lungs. Examples can include:. Some ways of keeping the lungs healthy include :. Immunotherapy is an emerging treatment option for cancer. It changes the way the immune system interacts with cancer cells and may help treat lung….
A look at interstitial lung disease, a group of diseases that make it difficult to get enough oxygen. Included is detail on types and complications.
Chronic obstructive pulmonary disease COPD refers to two lung diseases that cause difficulty breathing. Smoking is the most common cause.
Learn more…. Bronchitis is an infection of the tubes that lead to the lungs. It can be acute or chronic. Symptoms include a cough and wheezing. Smoking is a major…. The limbic system is a group of structures in the brain that help with memory, learning, and emotional regulation.
Learn more here. My podcast changed me Can 'biological race' explain disparities in health? Why Parkinson's research is zooming in on the gut Tools General Health Drugs A-Z Health Hubs Health Tools Find a Doctor BMI Calculators and Charts Blood Pressure Chart: Ranges and Guide Breast Cancer: Self-Examination Guide Sleep Calculator Quizzes RA Myths vs Facts Type 2 Diabetes: Managing Blood Sugar Ankylosing Spondylitis Pain: Fact or Fiction Connect About Medical News Today Who We Are Our Editorial Process Content Integrity Conscious Language Newsletters Sign Up Follow Us.
Medical News Today. Health Conditions Health Products Discover Tools Connect. What is the function and structure of the lungs, and how to do a lung function test. Medically reviewed by Adithya Cattamanchi, M. Function Structure Anatomy Lung function tests The alveoli Surfactant Other functions Respiratory disease Tips for good lung health The most important lung function is to take oxygen from the environment and transfer it to the bloodstream.
Fast facts on the lungs The left and right lungs are different sizes. The lungs play a part in many functions, including regulating the acidity of the body. Smoking tobacco is the biggest cause of lung-related complaints. Preventive and lifestyle measures can help keep the lungs healthy.
Was this helpful? Lung function tests. The alveoli. Surfactant in the lungs. Other functions of the lungs. Respiratory disease. Tips for good lung health. How we reviewed this article: Sources. Medical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations.
We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles.
You can learn more about how we ensure our content is accurate and current by reading our editorial policy.
Respiratory system functions lungs and respiratory Respirxtory Respiratory system functions us to breathe. They bring oxygen into Respiratory system functions bodies called inspiration, or inhalation Respiratpry send Lean Body Strength dioxide out called expiration, or exhalation. Fnuctions nose, Rewpiratory, and lungs are just a few parts of the body that make up the respiratory system. They work together to bring oxygen into the body and take carbon dioxide a waste product out. When you breathe in through your nose or mouth, you pull air into your throat and down the windpipe. To pull air into the body and push it out againthe body uses a strong muscle just below the lungs called the diaphragm. From the windpipe, air moves into the lungs through tubes called bronchi. Respiratory system functions air you exhale through your nose and Resoiratory is Respiratory system functions, like the inside of funcions body. Exhaled air Respirattory contains a lot of water vapor because it passes over moist surfaces Energy metabolism and gut health the functkons to the nose or mouth. The water vapor in your breath cools suddenly when it reaches the much colder outside air. This causes the water vapor to condense into a fog of tiny droplets of liquid water. You release water vapor and other gases from your body through the process of respiration. Respiration is the life-sustaining process in which gases are exchanged between the body and the outside atmosphere. Specifically, oxygen moves from the outside air into the body; and water vapor, carbon dioxide, and other waste gases move from inside the body into the outside air.
Ich meine, dass Sie sich irren.
Ich entschuldige mich, aber es nicht ganz, was mir notwendig ist. Es gibt andere Varianten?