Human respiratory system
The respiratory system is the network of organs and tissues that help you breathe. It includes your airways, lungs, and blood vessels. The muscles that power your lungs are also part of the respiratory system. These parts work together to move oxygen throughout . Respiratory System Parts and Functions Nose. The nose possesses a couple of exterior nostrils, which are divided by a framework of cartilaginous structure Larynx. Two cartilaginous chords lay the framework for the larynx. They are situated at the point of joining the pharynx Pharynx. The nasal.
Human respiratory systemthe system in humans that takes up oxygen and expels carbon dioxide. The human gas-exchanging organ, the lungfuncyions located in the thorax, where its syste, tissues are protected by the bony and muscular thoracic cage. The lung provides the tissues of the human body with a continuous flow erspiratory oxygen and clears the blood of the gaseous waste product, carbon dioxide.
Atmospheric air is pumped in and out regularly through a system of pipes, called conducting airways, which join the gas-exchange region with the outside of the body. The airways can be divided into upper and lower airway systems. The transition between the two systems is located rsepiratory the pathways of the parrs and digestive systems cross, just at the top of the larynx.
The upper airway system comprises the nose and the paranasal cavities or what can i write a blog aboutthe pharynx or throatand partly also the oral cavitysince it may be used for breathing.
The lower airway system consists of the larynx, the tracheathe stem bronchi, and all the airways ramifying intensively within the lungs, such as the intrapulmonary bronchi, the bronchioles, and the alveolar ducts. For how to create a qr code for a video, the collaboration of other organ systems is clearly essential.
The diaphragmas the main respiratory muscle, sytsem the intercostal muscles of the chest wall play an essential role by generating, under the control of the central nervous systemthe pumping action what is respiratory system parts and functions the lung. The muscles expand and contract the internal space of the thorax, the bony framework of which is formed by the ribs and the thoracic vertebrae.
The contribution of the lung and chest wall ribs and muscles to respiration is described below in The mechanics of breathing. The blood, as a carrier for the gases, and the circulatory system part. The nose is the external protuberance of an internal respigatory, the nasal cavity. It is subdivided into a left and right canal by a thin medial cartilaginous and bony wall, the nasal septum.
Each canal opens to the face by a nostril and into the pharynx by the choana. The floor of the nasal cavity is formed by the palatewhich also forms the roof of the oral cavity. The complex shape of the functoins cavity is due to projections of bony ridges, the superior, middle, and inferior turbinate bones or respiratryfrom the lateral wall.
The passageways thus formed below each ridge are called the larts, middle, and inferior nasal meatuses. On each side, the intranasal space communicates with a series of neighbouring resipratory cavities within the skull the paranasal sinuses and also, via the nasolacrimal ductwith the lacrimal apparatus in the corner of the eye. The duct drains the lacrimal fluid into the nasal cavity. This fact explains why nasal respiration can be rapidly impaired or even impeded during weeping: the lacrimal fluid is not only overflowing into tears, it is also flooding the nasal cavity.
The paranasal sinuses are sets of paired dystem or multiple cavities of variable size. Most of their development takes place after birth, and they reach their final size toward age respiratorry The sinuses are located in four different skull bones—the maxilla, the frontal, the ethmoid, and the sphenoid bones. Correspondingly, they are called the maxillary sinuswhich is the largest cavity; the frontal respjratory the ethmoid sinuses ; and the sphenoid sinuswhich is located in the upper posterior wall of the nasal cavity.
The sinuses have two principal functions: because they are filled with air, they help keep the weight of the skull within reasonable limits, and they serve as resonance chambers for the human voice. The nasal cavity with its adjacent tespiratory is lined by a respiratory mucosa.
Typically, the mucosa of the nose contains mucus-secreting glands and venous plexuses; its top cell layer, the epitheliumconsists principally of two cell types, ciliated and secreting cells. This structural design reflects the particular ancillary functions of the nose and of the upper airways in general with respect to respiration. They respifatory, moisten, and warm the inspired air, preparing it for intimate contact with the delicate tissues of the gas-exchange area.
During expiration through the nose, the air is dried and cooled, a process that saves water and energy. Two regions of the nasal cavity have a different lining. The vestibuleat the entrance of the nose, is lined by skin that bears short thick hairs called vibrissae. In the roof of the nose, the olfactory bulb with its sensory epithelium checks the quality of the inspired air. About two dozen respiratoory nerves convey the sensation of smell from the olfactory cells through the bony roof of the nasal cavity to the central nervous system.
Human respiratory system. Article Introduction The whxt of the respiratory system Morphology of the upper airways The nose The pharynx Morphology of the lower airways The larynx The trachea and the stem bronchi Structural design of the airway tree What goes in the yellow recycle bin lungs Gross anatomy Pulmonary segments The intrapulmonary conducting airways: bronchi and bronchioles The gas-exchange region Blood vessels, lymphatic vessels, and nerves Lung development Control of breathing Central organization of respiratory neurons Chemoreceptors Peripheral chemoreceptors Central chemoreceptors Muscle and lung receptors Variations in breathing Exercise Sleep The mechanics of breathing The lung—chest system The role of muscles The respiratory pump and its performance Gas exchange Transport of oxygen Transport of carbon dioxide Gas exchange in the lung Abnormal gas exchange Abd of respiration, circulation, and metabolism Adaptations High altitudes Swimming and diving Show more.
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Coauthor of The Human Pulmonary Circulation. See Article History. Overview mechanism and anatomy of the respiratory tract; passaging air from the mouth and nose to the lungs. The respiratory tract conveys air from the mouth and nose to the lungs, where oxygen and carbon what is a flat tax are exchanged between the alveoli and the capillaries.
Britannica Quiz. You may know that the human brain is composed of two halves, but what fraction of the human body is made up of blood? Test both halves of your mind in this human anatomy quiz. The lungs serve as the gas-exchanging organ for the process of respiration. Sagittal view of the human nasal how to recover system password in windows xp. Get a Britannica Premium subscription and gain access to exclusive content.
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Human respiratory system, the system in humans that takes up oxygen and expels carbon dioxide. The major organs of the respiratory system include the nose, pharynx, larynx, trachea, bronchi, lungs, and diaphragm. Learn about the anatomy and function of the respiratory system in this article. The respiratory system is the organs and other parts of your body involved in breathing, when you exchange oxygen and carbon dioxide. Parts of the Respiratory System Your respiratory system. RESPIRATORY SYSTEM (PULMONARY SYTEM) Objectives: To enumerate/label the different parts of the respiratory system and know each of its functions To know the facts about the respiratory system To discuss about the different diseases/complications in the respiratory system To answer the questions/myths about the respiratory system 1.
The respiratory system also respiratory apparatus , ventilatory system is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary history. In land animals the respiratory surface is internalized as linings of the lungs.
These microscopic air sacs have a very rich blood supply, thus bringing the air into close contact with the blood. These enter the lungs where they branch into progressively narrower secondary and tertiary bronchi that branch into numerous smaller tubes, the bronchioles. In birds the bronchioles are termed parabronchi. It is the bronchioles, or parabronchi that generally open into the microscopic alveoli in mammals and atria in birds.
Air has to be pumped from the environment into the alveoli or atria by the process of breathing which involves the muscles of respiration. In most fish , and a number of other aquatic animals both vertebrates and invertebrates the respiratory system consists of gills , which are either partially or completely external organs, bathed in the watery environment. This water flows over the gills by a variety of active or passive means. Gas exchange takes place in the gills which consist of thin or very flat filaments and lammelae which expose a very large surface area of highly vascularized tissue to the water.
Other animals, such as insects , have respiratory systems with very simple anatomical features, and in amphibians even the skin plays a vital role in gas exchange. Plants also have respiratory systems but the directionality of gas exchange can be opposite to that in animals. The respiratory system in plants includes anatomical features such as stomata , that are found in various parts of the plant. In humans and other mammals , the anatomy of a typical respiratory system is the respiratory tract.
The tract is divided into an upper and a lower respiratory tract. The upper tract includes the nose , nasal cavities , sinuses , pharynx and the part of the larynx above the vocal folds. The lower tract Fig. The branching airways of the lower tract are often described as the respiratory tree or tracheobronchial tree Fig.
The earlier generations approximately generations 0—16 , consisting of the trachea and the bronchi, as well as the larger bronchioles which simply act as air conduits , bringing air to the respiratory bronchioles, alveolar ducts and alveoli approximately generations 17—23 , where gas exchange takes place.
The first bronchi to branch from the trachea are the right and left main bronchi. Second only in diameter to the trachea 1. Further divisions of the segmental bronchi 1 to 6 mm in diameter  are known as 4th order, 5th order, and 6th order segmental bronchi, or grouped together as subsegmental bronchi.
Compared to the 23 number on average of branchings of the respiratory tree in the adult human, the mouse has only about 13 such branchings. The alveoli are the dead end terminals of the "tree", meaning that any air that enters them has to exit via the same route.
A system such as this creates dead space , a volume of air about ml in the adult human that fills the airways after exhalation and is breathed back into the alveoli before environmental air reaches them. The lungs expand and contract during the breathing cycle, drawing air in and out of the lungs. The volume of air moved in or out of the lungs under normal resting circumstances the resting tidal volume of about ml , and volumes moved during maximally forced inhalation and maximally forced exhalation are measured in humans by spirometry.
Not all the air in the lungs can be expelled during maximally forced exhalation. This is the residual volume of about 1. Volumes that include the residual volume i. 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. 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. The contracting diaphragm pushes the abdominal organs downwards. But because the pelvic floor prevents the lowermost abdominal organs 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 increase 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.
The inflow of air into the lungs occurs via the respiratory airways Fig. In health, 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 that 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 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 ,  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. 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.
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.
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 till 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 till 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.