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16.2: Structure and Function of the Respiratory System

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• Page ID 16817

• Suzanne Wakim & Mandeep Grewal
• Butte College

Seeing Your Breath

Why can you “see your breath” on a cold day? The air you exhale through your nose and mouth is warm, like the inside of your body. Exhaled air also contains a lot of water vapor because it passes over moist surfaces from the lungs 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.

What is 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. Respiration is carried out mainly by the respiratory system. It is important to note that respiration by the respiratory system is not the same process as cellular respiration that occurs inside cells, although the two processes are closely connected. Cellular respiration is the metabolic process in which cells obtain energy, usually by “burning” glucose in the presence of oxygen. When cellular respiration is aerobic, it uses oxygen and releases carbon dioxide as a waste product. Respiration by the respiratory system supplies the oxygen needed by cells for aerobic cellular respiration and removes the carbon dioxide produced by cells during cellular respiration.

Respiration by the respiratory system actually involves two subsidiary processes. One process is ventilation or breathing. This is the physical process of conducting air to and from the lungs. The other process is gas exchange. This is the biochemical process in which oxygen diffuses out of the air and into the blood while carbon dioxide and other waste gases diffuse out of the blood and into the air. All of the organs of the respiratory system are involved in breathing, but only the lungs are involved in gas exchange.

Respiratory Organs

The organs of the respiratory system form a continuous system of passages called the respiratory tract, through which air flows into and out of the body. The respiratory tract has two major divisions: the upper respiratory tract and the lower respiratory tract. The organs in each division are shown in Figure \(\PageIndex{2}\). In addition to these organs, certain muscles of the thorax (the body cavity that fills the chest) are also involved in respiration by enabling breathing. Most important is a large muscle called the diaphragm, which lies below the lungs and separates the thorax from the abdomen. Smaller muscles between the ribs also play a role in breathing. You can learn more about breathing muscles in the concept of Breathing .

Upper Respiratory Tract

All of the organs and other structures of the upper respiratory tract are involved in the conduction or the movement of air into and out of the body. Upper respiratory tract organs provide a route for air to move between the outside atmosphere and the lungs. They also clean, humidity, and warm the incoming air. However, no gas exchange occurs in these organs.

Nasal Cavity

The nasal cavity is a large, air-filled space in the skull above and behind the nose in the middle of the face. It is a continuation of the two nostrils. As inhaled air flows through the nasal cavity, it is warmed and humidified. Hairs in the nose help trap larger foreign particles in the air before they go deeper into the respiratory tract. In addition to its respiratory functions, the nasal cavity also contains chemoreceptors that are needed for the sense of smell and that contribute importantly to the sense of taste.

The pharynx is a tube-like structure that connects the nasal cavity and the back of the mouth to other structures lower in the throat, including the larynx. The pharynx has dual functions: both air and food (or other swallowed substances) pass through it, so it is part of both the respiratory and digestive systems. Air passes from the nasal cavity through the pharynx to the larynx (as well as in the opposite direction). Food passes from the mouth through the pharynx to the esophagus.

The larynx connects the pharynx and trachea and helps to conduct air through the respiratory tract. The larynx is also called the voice box because it contains the vocal cords, which vibrate when air flows over them, thereby producing sound. You can see the vocal cords in the larynx in Figure \(\PageIndex{3}\). Certain muscles in the larynx move the vocal cords apart to allow breathing. Other muscles in the larynx move the vocal cords together to allow the production of vocal sounds. The latter muscles also control the pitch of sounds and help control their volume.

A very important function of the larynx is protecting the trachea from aspirated food. When swallowing occurs, the backward motion of the tongue forces a flap called the epiglottis to close over the entrance to the larynx. You can see the epiglottis in Figure \(\PageIndex{3}\). This prevents swallowed material from entering the larynx and moving deeper into the respiratory tract. If swallowed material does start to enter the larynx, it irritates the larynx and stimulates a strong cough reflex. This generally expels the material out of the larynx and into the throat.

Lower Respiratory Tract

The trachea and other passages of the lower respiratory tract conduct air between the upper respiratory tract and the lungs. These passages form an inverted tree-like shape (Figure \(\PageIndex{4}\)), with repeated branching as they move deeper into the lungs. All told, there are an astonishing 1,500 miles of airways conducting air through the human respiratory tract! It is only in the lungs, however, that gas exchange occurs between the air and the bloodstream.

The trachea, or windpipe, is the widest passageway in the respiratory tract. It is about 2.5 cm (1 in.) wide and 10-15 cm (4-6 in.) long. It is formed by rings of cartilage, which make it relatively strong and resilient. The trachea connects the larynx to the lungs for the passage of air through the respiratory tract. The trachea branches at the bottom to form two bronchial tubes.

Bronchi and Bronchioles

There are two main bronchial tubes, or bronchi (singular, bronchus) , called the right and left bronchi. The bronchi carry air between the trachea and lungs. Each bronchus branches into smaller, secondary bronchi; and secondary bronchi branch into still smaller tertiary bronchi. The smallest bronchi branch into very small tubules called bronchioles. The tiniest bronchioles end in alveolar ducts, which terminate in clusters of minuscule air sacs, called alveoli (singular, alveolus), in the lungs.

The lungs are the largest organs of the respiratory tract. They are suspended within the pleural cavity of the thorax. In Figure \(\PageIndex{5}\), you can see that each of the two lungs is divided into sections. These are called lobes, and they are separated from each other by connective tissues. The right lung is larger and contains three lobes. The left lung is smaller and contains only two lobes. The smaller left lung allows room for the heart, which is just left of the center of the chest.

Lung tissue consists mainly of alveoli (Figure \(\PageIndex{6}\)). These tiny air sacs are the functional units of the lungs where gas exchange takes place. The two lungs may contain as many as 700 million alveoli, providing a huge total surface area for gas exchange to take place. In fact, alveoli in the two lungs provide as much surface area as half a tennis court! Each time you breathe in, the alveoli fill with air, making the lungs expand. Oxygen in the air inside the alveoli is absorbed by the blood in the mesh-like network of tiny capillaries that surrounds each alveolus. The blood in these capillaries also releases carbon dioxide into the air inside the alveoli. Each time you breathe out, air leaves the alveoli and rushes into the outside atmosphere, carrying waste gases with it.

The lungs receive blood from two major sources. They receive deoxygenated blood from the heart. This blood absorbs oxygen in the lungs and carries it back to the heart to be pumped to cells throughout the body. The lungs also receive oxygenated blood from the heart that provides oxygen to the cells of the lungs for cellular respiration.

Protecting the Respiratory System

You may be able to survive for weeks without food and for days without water, but you can survive without oxygen for only a matter of minutes except under exceptional circumstances. Therefore, protecting the respiratory system is vital. That’s why making sure a patient has an open airway is the first step in treating many medical emergencies. Fortunately, the respiratory system is well protected by the ribcage of the skeletal system. However, the extensive surface area of the respiratory system is directly exposed to the outside world and all its potential dangers in inhaled air. Therefore, it should come as no surprise that the respiratory system has a variety of ways to protect itself from harmful substances such as dust and pathogens in the air.

The main way the respiratory system protects itself is called the mucociliary escalator. From the nose through the bronchi, the respiratory tract is covered in the epithelium that contains mucus-secreting goblet cells. The mucus traps particles and pathogens in the incoming air. The epithelium of the respiratory tract is also covered with tiny cell projections called cilia (singular, cilium), as shown in Figure \(\PageIndex{7}\). The cilia constantly move in a sweeping motion upward toward the throat, moving the mucus and trapped particles and pathogens away from the lungs and toward the outside of the body.

What happens to the material that moves up the mucociliary escalator to the throat? It is generally removed from the respiratory tract by clearing the throat or coughing. Coughing is a largely involuntary response of the respiratory system that occurs when nerves lining the airways are irritated. The response causes air to be expelled forcefully from the trachea, helping to remove mucus and any debris it contains (called phlegm) from the upper respiratory tract to the mouth. The phlegm may spit out (expectorated), or it may be swallowed and destroyed by stomach acids.

Sneezing is a similar involuntary response that occurs when nerves lining the nasal passage are irritated. It results in forceful expulsion of air from the mouth, which sprays millions of tiny droplets of mucus and other debris out of the mouth and into the air, as shown in Figure \(\PageIndex{8}\). This explains why it is so important to sneeze into a sleeve rather than the air to help prevent the transmission of respiratory pathogens.

How the Respiratory System Works with Other Organ Systems

The amount of oxygen and carbon dioxide in the blood must be maintained within a limited range for the survival of the organism. Cells cannot survive for long without oxygen, and if there is too much carbon dioxide in the blood, the blood becomes dangerously acidic (pH is too low). Conversely, if there is too little carbon dioxide in the blood, the blood becomes too basic (pH is too high). The respiratory system works hand-in-hand with the nervous and cardiovascular systems to maintain homeostasis in blood gases and pH.

It is the level of carbon dioxide rather than the level of oxygen that is most closely monitored to maintain blood gas and pH homeostasis. The level of carbon dioxide in the blood is detected by cells in the brain, which speed up or slow down the rate of breathing through the autonomic nervous system as needed to bring the carbon dioxide level within the normal range. Faster breathing lowers the carbon dioxide level (and raises the oxygen level and pH); slower breathing has the opposite effects. In this way, the levels of carbon dioxide and oxygen, as well as pH, are maintained within normal limits.

The respiratory system also works closely with the cardiovascular system to maintain homeostasis. The respiratory system exchanges gases between the blood and the outside air, but it needs the cardiovascular system to carry them to and from body cells. Oxygen is absorbed by the blood in the lungs and then transported through a vast network of blood vessels to cells throughout the body where it is needed for aerobic cellular respiration. The same system absorbs carbon dioxide from cells and carries it to the respiratory system for removal from the body.

Feature: My Human Body

Choking is the mechanical obstruction of the flow of air from the atmosphere into the lungs. It prevents breathing and may be partial or complete. Partial choking allows some though inadequate airflow into the lung—prolonged or complete choking results in asphyxia, or suffocation, which is potentially fatal.

Obstruction of the airway typically occurs in the pharynx or trachea. Young children are more prone to choking than are older people, in part because they often put small objects in their mouths and do not appreciate the risk of choking that they pose. Young children may choke on small toys or parts of toys or on household objects in addition to food. Foods that can adapt their shape to that of the pharynx, such as bananas and marshmallows, are especially dangerous and may cause choking in adults as well as children.

How can you tell if a loved one is choking? The person cannot speak or cry out or has great difficulty doing so. Breathing, if possible, is labored, producing gasping or wheezing. The person may desperately clutch at his or her throat or mouth. If breathing is not soon restored, the person’s face will start to turn blue from lack of oxygen. This will be followed by unconsciousness if oxygen deprivation continues beyond a few minutes.

If an infant is choking, turning the baby upside down and slapping on the back may dislodge the obstructing object. To help an older person who is choking, first, encourage the person to cough. Give them a few hardback slaps to help force the lodged object out of the airway. If these steps fail, perform the Heimlich maneuver on the person. You can easily find instructional videos online to learn how to do it. If the Heimlich maneuver also fails, call for emergency medical care immediately.

• What is respiration, as carried out by the respiratory system? Name the two subsidiary processes it involves.
• Describe the respiratory tract.
• Identify the organs of the upper respiratory tract, and state their functions.
• List the organs of the lower respiratory tract. Which organs are involved only in conduction?
• Where does gas exchange take place?
• How does the respiratory system protect itself from potentially harmful substances in the air?
• Explain how the rate of breathing is controlled.
• Why does the respiratory system need the cardiovascular system to help it perform its main function of gas exchange?

trachea; nasal cavity; alveoli; bronchioles; larynx; bronchi; pharynx

D. Bronchus

• Describe two ways in which the body prevents food from entering the lungs.
• True or False. The lungs receive some oxygenated blood.
• True or False. Gas exchange occurs in both the upper and lower respiratory tracts.

B. food particles

D. All of the above

• What is the relationship between respiration and cellular respiration?

Explore More

Attributions.

• Snowboarders breath on a cold day by Alain Wong via Unsplash License
• Conducting Passages by Lord Akryl , Jmarchn, public domain via Wikimedia Commons
• Larynx by Alan Hoofring , National Cancer Institute, public domain via Wikimedia Commons
• Lung Diagram by Patrick J. Lynch ; CC BY 2.5 via Wikimedia Commons
• Lung Structure by National Heart Lung and Blood Institute, public domain via Wikimedia Commons
• Alveoli by helix84 licensed CC BY 2.5 , via Wikimedia Commons
• Ciliated Epithelium by Blausen.com staff (2014). " Medical gallery of Blausen Medical 2014 ". WikiJournal of Medicine 1 (2). DOI : 10.15347/wjm/2014.010 . ISSN 2002-4436 . licensed CC BY 3.0 via Wikimedia Commons
• Sneeze by James Gathany, CDC , public domain via Wikimedia Commons
• Abdominal Thrusts by Amanda M. Woodhead, public domain via Wikimedia Commons
• Text adapted from Human Biology by CK-12 licensed CC BY-NC 3.0

22.1 Organs and Structures of the Respiratory System

Learning objectives.

By the end of this section, you will be able to:

• List the structures that make up the respiratory system
• Describe how the respiratory system processes oxygen and CO 2
• Compare and contrast the functions of upper respiratory tract with the lower respiratory tract

The major organs of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help to maintain acid-base balance. Portions of the respiratory system are also used for non-vital functions, such as sensing odors, speech production, and for straining, such as during childbirth or coughing ( Figure 22.2 ).

Functionally, the respiratory system can be divided into a conducting zone and a respiratory zone. The conducting zone of the respiratory system includes the organs and structures not directly involved in gas exchange. The gas exchange occurs in the respiratory zone .

Conducting Zone

The major functions of the conducting zone are to provide a route for incoming and outgoing air, remove debris and pathogens from the incoming air, and warm and humidify the incoming air. Several structures within the conducting zone perform other functions as well. The epithelium of the nasal passages, for example, is essential to sensing odors, and the bronchial epithelium that lines the lungs can metabolize some airborne carcinogens.

The Nose and its Adjacent Structures

The major entrance and exit for the respiratory system is through the nose. When discussing the nose, it is helpful to divide it into two major sections: the external nose, and the nasal cavity or internal nose.

The external nose consists of the surface and skeletal structures that result in the outward appearance of the nose and contribute to its numerous functions ( Figure 22.3 ). The root is the region of the nose located between the eyebrows. The bridge is the part of the nose that connects the root to the rest of the nose. The dorsum nasi is the length of the nose. The apex is the tip of the nose. On either side of the apex, the nostrils are formed by the alae (singular = ala). An ala is a cartilaginous structure that forms the lateral side of each naris (plural = nares), or nostril opening. The philtrum is the concave surface that connects the apex of the nose to the upper lip.

Underneath the thin skin of the nose are its skeletal features (see Figure 22.3 , lower illustration). While the root and bridge of the nose consist of bone, the protruding portion of the nose is composed of cartilage. As a result, when looking at a skull, the nose is missing. The nasal bone is one of a pair of bones that lies under the root and bridge of the nose. The nasal bone articulates superiorly with the frontal bone and laterally with the maxillary bones. Septal cartilage is flexible hyaline cartilage connected to the nasal bone, forming the dorsum nasi. The alar cartilage consists of the apex of the nose; it surrounds the naris.

The nares open into the nasal cavity, which is separated into left and right sections by the nasal septum ( Figure 22.4 ). The nasal septum is formed anteriorly by a portion of the septal cartilage (the flexible portion you can touch with your fingers) and posteriorly by the perpendicular plate of the ethmoid bone (a cranial bone located just posterior to the nasal bones) and the thin vomer bones (whose name refers to its plough shape). Each lateral wall of the nasal cavity has three bony projections, called the superior, middle, and inferior nasal conchae. The inferior conchae are separate bones, whereas the superior and middle conchae are portions of the ethmoid bone. Conchae serve to increase the surface area of the nasal cavity and to disrupt the flow of air as it enters the nose, causing air to bounce along the epithelium, where it is cleaned and warmed. The conchae and meatuses also conserve water and prevent dehydration of the nasal epithelium by trapping water during exhalation. The floor of the nasal cavity is composed of the palate. The hard palate at the anterior region of the nasal cavity is composed of bone. The soft palate at the posterior portion of the nasal cavity consists of muscle tissue. Air exits the nasal cavities via the internal nares and moves into the pharynx.

Several bones that help form the walls of the nasal cavity have air-containing spaces called the paranasal sinuses, which serve to warm and humidify incoming air. Sinuses are lined with a mucosa. Each paranasal sinus is named for its associated bone: frontal sinus, maxillary sinus, sphenoidal sinus, and ethmoidal sinus. The sinuses produce mucus and lighten the weight of the skull.

The nares and anterior portion of the nasal cavities are lined with mucous membranes, containing sebaceous glands and hair follicles that serve to prevent the passage of large debris, such as dirt, through the nasal cavity. An olfactory epithelium used to detect odors is found deeper in the nasal cavity.

The conchae, meatuses, and paranasal sinuses are lined by respiratory epithelium composed of pseudostratified ciliated columnar epithelium ( Figure 22.5 ). The epithelium contains goblet cells, one of the specialized, columnar epithelial cells that produce mucus to trap debris. The cilia of the respiratory epithelium help remove the mucus and debris from the nasal cavity with a constant beating motion, sweeping materials towards the throat to be swallowed. Interestingly, cold air slows the movement of the cilia, resulting in accumulation of mucus that may in turn lead to a runny nose during cold weather. This moist epithelium functions to warm and humidify incoming air. Capillaries located just beneath the nasal epithelium warm the air by convection. Serous and mucus-producing cells also secrete the lysozyme enzyme and proteins called defensins, which have antibacterial properties. Immune cells that patrol the connective tissue deep to the respiratory epithelium provide additional protection.

Interactive Link

View the University of Michigan WebScope to explore the tissue sample in greater detail.

The pharynx is a tube formed by skeletal muscle and lined by mucous membrane that is continuous with that of the nasal cavities (see Figure 22.4 ). The pharynx is divided into three major regions: the nasopharynx, the oropharynx, and the laryngopharynx ( Figure 22.6 ).

The nasopharynx is flanked by the conchae of the nasal cavity, and it serves only as an airway. At the top of the nasopharynx are the pharyngeal tonsils. A pharyngeal tonsil , also called an adenoid, is an aggregate of lymphoid reticular tissue similar to a lymph node that lies at the superior portion of the nasopharynx. The function of the pharyngeal tonsil is not well understood, but it contains a rich supply of lymphocytes and is covered with ciliated epithelium that traps and destroys invading pathogens that enter during inhalation. The pharyngeal tonsils are large in children, but interestingly, tend to regress with age and may even disappear. The uvula is a small bulbous, teardrop-shaped structure located at the apex of the soft palate. Both the uvula and soft palate move like a pendulum during swallowing, swinging upward to close off the nasopharynx to prevent ingested materials from entering the nasal cavity. In addition, auditory (Eustachian) tubes that connect to each middle ear cavity open into the nasopharynx. This connection is why colds often lead to ear infections.

The oropharynx is a passageway for both air and food. The oropharynx is bordered superiorly by the nasopharynx and anteriorly by the oral cavity. The fauces is the opening at the connection between the oral cavity and the oropharynx. As the nasopharynx becomes the oropharynx, the epithelium changes from pseudostratified ciliated columnar epithelium to stratified squamous epithelium. The oropharynx contains two distinct sets of tonsils, the palatine and lingual tonsils. A palatine tonsil is one of a pair of structures located laterally in the oropharynx in the area of the fauces. The lingual tonsil is located at the base of the tongue. Similar to the pharyngeal tonsil, the palatine and lingual tonsils are composed of lymphoid tissue, and trap and destroy pathogens entering the body through the oral or nasal cavities.

The laryngopharynx is inferior to the oropharynx and posterior to the larynx. It continues the route for ingested material and air until its inferior end, where the digestive and respiratory systems diverge. The stratified squamous epithelium of the oropharynx is continuous with the laryngopharynx. Anteriorly, the laryngopharynx opens into the larynx, whereas posteriorly, it enters the esophagus.

The larynx is a cartilaginous structure inferior to the laryngopharynx that connects the pharynx to the trachea and helps regulate the volume of air that enters and leaves the lungs ( Figure 22.7 ). The structure of the larynx is formed by several pieces of cartilage. Three large cartilage pieces—the thyroid cartilage (anterior), epiglottis (superior), and cricoid cartilage (inferior)—form the major structure of the larynx. The thyroid cartilage is the largest piece of cartilage that makes up the larynx. The thyroid cartilage consists of the laryngeal prominence , or “Adam’s apple,” which tends to be more prominent in males. The thick cricoid cartilage forms a ring, with a wide posterior region and a thinner anterior region. Three smaller, paired cartilages—the arytenoids, corniculates, and cuneiforms—attach to the epiglottis and the vocal cords and muscle that help move the vocal cords to produce speech.

The epiglottis , attached to the thyroid cartilage, is a very flexible piece of elastic cartilage that covers the opening of the trachea (see Figure 22.4 ). When in the “closed” position, the unattached end of the epiglottis rests on the glottis. The glottis is composed of the vestibular folds, the true vocal cords, and the space between these folds ( Figure 22.8 ). A vestibular fold , or false vocal cord, is one of a pair of folded sections of mucous membrane. A true vocal cord is one of the white, membranous folds attached by muscle to the thyroid and arytenoid cartilages of the larynx on their outer edges. The inner edges of the true vocal cords are free, allowing oscillation to produce sound. The size of the membranous folds of the true vocal cords differs between individuals, producing voices with different pitch ranges. Folds in males tend to be larger than those in females, which create a deeper voice. The act of swallowing causes the pharynx and larynx to lift upward, allowing the pharynx to expand and the epiglottis of the larynx to swing downward, closing the opening to the trachea. These movements produce a larger area for food to pass through, while preventing food and beverages from entering the trachea.

Continuous with the laryngopharynx, the superior portion of the larynx is lined with stratified squamous epithelium, transitioning into pseudostratified ciliated columnar epithelium that contains goblet cells. Similar to the nasal cavity and nasopharynx, this specialized epithelium produces mucus to trap debris and pathogens as they enter the trachea. The cilia beat the mucus upward towards the laryngopharynx, where it can be swallowed down the esophagus.

The trachea (windpipe) extends from the larynx toward the lungs ( Figure 22.9 a ). The trachea is formed by 16 to 20 stacked, C-shaped pieces of hyaline cartilage that are connected by dense connective tissue. The trachealis muscle and elastic connective tissue together form the fibroelastic membrane , a flexible membrane that closes the posterior surface of the trachea, connecting the C-shaped cartilages. The fibroelastic membrane allows the trachea to stretch and expand slightly during inhalation and exhalation, whereas the rings of cartilage provide structural support and prevent the trachea from collapsing. In addition, the trachealis muscle can be contracted to force air through the trachea during exhalation. The trachea is lined with pseudostratified ciliated columnar epithelium, which is continuous with the larynx. The esophagus borders the trachea posteriorly.

Bronchial Tree

The trachea branches into the right and left primary bronchi at the carina. These bronchi are also lined by pseudostratified ciliated columnar epithelium containing mucus-producing goblet cells ( Figure 22.9 b ). The carina is a raised structure that contains specialized nervous tissue that induces violent coughing if a foreign body, such as food, is present. Rings of cartilage, similar to those of the trachea, support the structure of the bronchi and prevent their collapse. The primary bronchi enter the lungs at the hilum, a concave region where blood vessels, lymphatic vessels, and nerves also enter the lungs. The bronchi continue to branch into a bronchial tree. A bronchial tree (or respiratory tree) is the collective term used for these multiple-branched bronchi. The main function of the bronchi, like other conducting zone structures, is to provide a passageway for air to move into and out of each lung. In addition, the mucous membrane traps debris and pathogens.

A bronchiole branches from the tertiary bronchi. Bronchioles, which are about 1 mm in diameter, further branch until they become the tiny terminal bronchioles, which lead to the structures of gas exchange. There are more than 1000 terminal bronchioles in each lung. The muscular walls of the bronchioles do not contain cartilage like those of the bronchi. This muscular wall can change the size of the tubing to increase or decrease airflow through the tube.

Respiratory Zone

In contrast to the conducting zone, the respiratory zone includes structures that are directly involved in gas exchange. The respiratory zone begins where the terminal bronchioles join a respiratory bronchiole , the smallest type of bronchiole ( Figure 22.10 ), which then leads to an alveolar duct, opening into a cluster of alveoli.

An alveolar duct is a tube composed of smooth muscle and connective tissue, which opens into a cluster of alveoli. An alveolus is one of the many small, grape-like sacs that are attached to the alveolar ducts.

An alveolar sac is a cluster of many individual alveoli that are responsible for gas exchange. An alveolus is approximately 200 μm in diameter with elastic walls that allow the alveolus to stretch during air intake, which greatly increases the surface area available for gas exchange. Alveoli are connected to their neighbors by alveolar pores , which help maintain equal air pressure throughout the alveoli and lung ( Figure 22.11 ).

The alveolar wall consists of three major cell types: type I alveolar cells, type II alveolar cells, and alveolar macrophages. A type I alveolar cell is a squamous epithelial cell of the alveoli, which constitute up to 97 percent of the alveolar surface area. These cells are about 25 nm thick and are highly permeable to gases. A type II alveolar cell is interspersed among the type I cells and secretes pulmonary surfactant , a substance composed of phospholipids and proteins that reduces the surface tension of the alveoli. Roaming around the alveolar wall is the alveolar macrophage , a phagocytic cell of the immune system that removes debris and pathogens that have reached the alveoli.

The simple squamous epithelium formed by type I alveolar cells is attached to a thin, elastic basement membrane. This epithelium is extremely thin and borders the endothelial membrane of capillaries. Taken together, the alveoli and capillary membranes form a respiratory membrane that is approximately 0.5 μm (micrometers) thick. The respiratory membrane allows gases to cross by simple diffusion, allowing oxygen to be picked up by the blood for transport and CO 2 to be released into the air of the alveoli.

Diseases of the...

Respiratory system: asthma.

Asthma is common condition that affects the lungs in both adults and children. Approximately 8.2 percent of adults (18.7 million) and 9.4 percent of children (7 million) in the United States suffer from asthma. In addition, asthma is the most frequent cause of hospitalization in children.

Asthma is a chronic disease characterized by inflammation and edema of the airway, and bronchospasms (that is, constriction of the bronchioles), which can inhibit air from entering the lungs. In addition, excessive mucus secretion can occur, which further contributes to airway occlusion ( Figure 22.12 ). Cells of the immune system, such as eosinophils and mononuclear cells, may also be involved in infiltrating the walls of the bronchi and bronchioles.

Bronchospasms occur periodically and lead to an “asthma attack.” An attack may be triggered by environmental factors such as dust, pollen, pet hair, or dander, changes in the weather, mold, tobacco smoke, and respiratory infections, or by exercise and stress.

Symptoms of an asthma attack involve coughing, shortness of breath, wheezing, and tightness of the chest. Symptoms of a severe asthma attack that requires immediate medical attention would include difficulty breathing that results in blue (cyanotic) lips or face, confusion, drowsiness, a rapid pulse, sweating, and severe anxiety. The severity of the condition, frequency of attacks, and identified triggers influence the type of medication that an individual may require. Longer-term treatments are used for those with more severe asthma. Short-term, fast-acting drugs that are used to treat an asthma attack are typically administered via an inhaler. For young children or individuals who have difficulty using an inhaler, asthma medications can be administered via a nebulizer.

In many cases, the underlying cause of the condition is unknown. However, recent research has demonstrated that certain viruses, such as human rhinovirus C (HRVC), and the bacteria Mycoplasma pneumoniae and Chlamydia pneumoniae that are contracted in infancy or early childhood, may contribute to the development of many cases of asthma.

Visit this site to learn more about what happens during an asthma attack. What are the three changes that occur inside the airways during an asthma attack?

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Respiratory System Anatomy and Physiology

Breathe life into your understanding with our guide on the respiratory system anatomy and physiology. Nursing students, immerse yourself in the intricate dance of inhalation and exhalation that fuels every living moment.

Table of Contents

Functions of the respiratory system, main bronchi, the respiratory membrane, respiration, mechanics of breathing, respiratory volumes and capacities, respiratory sounds, external respiration, gas transport, and internal respiration, control of respiration, age-related physiological changes in the respiratory system.

The functions of the respiratory system are:

• Oxygen supplier.  The job of the respiratory system is to keep the body constantly supplied with oxygen.
• Elimination.  Elimination of carbon dioxide.
• Gas exchange.  The respiratory system organs oversee the gas exchanges that occur between the blood and the external environment.
• Passageway.  Passageways that allow air to reach the lungs.
• Humidifier.  Purify, humidify, and warm incoming air.

Anatomy of the Respiratory System

The organs of the respiratory system include the nose, pharynx, larynx, trachea, bronchi, and their smaller branches, and the lungs, which contain the alveoli.

The nose is the only externally visible part of the respiratory system.

• Nostrils.  During breathing, air enters the nose by passing through the nostrils, or nares.
• Nasal cavity. The interior of the nose consists of the nasal cavity, divided by a midline nasal septum .
• Olfactory receptors. The olfactory receptors for the sense of smell are located in the mucosa in the slitlike superior part of the nasal cavity, just beneath the ethmoid bone.
• Respiratory mucosa. The rest of the mucosal lining, the nasal cavity called the respiratory mucosa, rests on a rich network of thin-walled veins that warms the air as it flows past.
• Mucus.  In addition, the sticky mucus produced by the mucosa’s glands moistens the air and traps incoming bacteria and other foreign debris, and lysozyme enzymes in the mucus destroy bacteria chemically.
• Ciliated cells. The ciliated cells of the nasal mucosa create a gentle current that moves the sheet of contaminated mucus posteriorly toward the throat, where it is swallowed and digested by stomach juices.
• Conchae.  The lateral walls of the nasal cavity are uneven owing to three mucosa-covered projections, or lobes called conchae, which greatly increase the surface area of the mucosa exposed to the air, and also increase the air turbulence in the nasal cavity.
• Palate. The nasal cavity is separated from the oral cavity below by a partition, the palate; anteriorly, where the palate is supported by bone, is the hard palate; the unsupported posterior part is the soft palate .
• Paranasal sinuses. The nasal cavity is surrounded by a ring of paranasal sinuses located in the frontal, sphenoid, ethmoid, and maxillary bones ; theses sinuses lighten the skull, and they act as a resonance chamber for speech.

• Size. The pharynx is a muscular passageway about 13 cm (5 inches) long that vaguely resembles a short length of red garden hose.
• Function.  Commonly called the throat , the pharynx serves as a common passageway for food and air.
• Portions of the pharynx. Air enters the superior portion, the nasopharynx , from the nasal cavity and then descends through the oropharynx and laryngopharynx to enter the larynx below.
• Pharyngotympanic tube. The pharyngotympanic tubes, which drain the middle ear open into the nasopharynx.
• Pharyngeal tonsil. The pharyngeal tonsil, often called adenoid is located high in the nasopharynx.
• Palatine tonsils . The palatine tonsils are in the oropharynx at the end of the soft palate.
• Lingual tonsils . The lingual tonsils lie at the base of the tongue.

The larynx or voice box routes air and food into the proper channels and plays a role in speech.

• Structure.  Located inferior to the pharynx, it is formed by eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage, the epiglottis .
• Thyroid cartilage. The largest of the hyaline cartilages is the shield-shaped thyroid cartilage, which protrudes anteriorly and is commonly called Adam’s apple .
• Epiglottis.  Sometimes referred to as the “guardian of the airways” , the epiglottis protects the superior opening of the larynx.
• Vocal folds. Part of the mucous membrane of the larynx forms a pair of folds, called the vocal folds, or true vocal cords , which vibrate with expelled air and allows us to speak.
• Glottis.  The slitlike passageway between the vocal folds is the glottis.

• Length.  Air entering the trachea or windpipe from the larynx travels down its length (10 to 12 cm or about 4 inches) to the level of the fifth thoracic vertebra , which is approximately midchest.
• Structure.  The trachea is fairly rigid because its walls are reinforced with C-shaped rings of hyaline cartilage; the open parts of the rings abut the esophagus and allow it to expand anteriorly when we swallow a large piece of food, while the solid portions support the trachea walls and keep it patent, or open, in spite of the pressure changes that occur during breathing.
• Cilia.  The trachea is lined with ciliated mucosa that beat continuously and in a direction opposite to that of the incoming air as they propel mucus, loaded with dust particles and other debris away from the lungs to the throat, where it can be swallowed or spat out.
• Structure.  The right and left main (primary) bronchi are formed by the division of the trachea.
• Location.  Each main bronchus runs obliquely before it plunges into the medial depression of the lung on its own side.
• Size.  The right main bronchus is wider, shorter, and straighter than the left.

• Location.  The lungs occupy the entire thoracic cavity except for the most central area, the mediastinum , which houses the heart, the great blood vessels, bronchi, esophagus, and other organs.
• Apex.  The narrow, superior portion of each lung, the apex, is just deep into the clavicle.
• Base.  The broad lung area resting on the diaphragm is the base.
• Division.  Each lung is divided into lobes by fissures; the left lung has two lobes , and the right lung has three .
• Pleura.  The surface of each lung is covered with a visceral serosa called the pulmonary , or visceral pleura, and the walls of the thoracic cavity are lined by the parietal pleura .
• Pleural fluid. The pleural membranes produce pleural fluid, a slippery serous secretion that allows the lungs to glide easily over the thorax wall during breathing movements and causes the two pleural layers to cling together.
• Pleural space. The lungs are held tightly to the thorax wall, and the pleural space is more of a potential space than an actual one.
• Bronchioles .  The smallest of the conducting passageways are the bronchioles.
• Alveoli.  The terminal bronchioles lead to the respiratory zone structures, even smaller conduits that eventually terminate in alveoli or air sacs.
• Respiratory zone. The respiratory zone, which includes the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, is the only site of gas exchange .
• Conducting zone structures. All other respiratory passages are conducting zone structures that serve as conduits to and from the respiratory zone.
• Stroma.  The balance of the lung tissue, its stroma, is mainly elastic connective tissue that allows the lungs to recoil passively as we exhale.
• Wall structure. The walls of the alveoli are composed largely of a single, thin layer of squamous epithelial cells.
• Alveolar pores. Alveolar pores connect neighboring air sacs and provide alternative routes for air to reach alveoli whose feeder bronchioles have been clogged by mucus or otherwise blocked.
• Respiratory membrane. Together, the alveolar and capillary walls, their fused basement membranes, and occasional elastic fibers construct the respiratory membrane (air-blood barrier), which has gas (air) flowing past on one side and blood flowing past on the other.
• Alveolar macrophages. Remarkably efficient alveolar macrophages sometimes called “dust cells” , wander in and out of the alveoli picking up bacteria, carbon particles, and other debris.
• Cuboidal cells. Also scattered amid the epithelial cells that form most of the alveolar walls are chunky cuboidal cells, which produce a lipid (fat) molecule called surfactant , which coats the gas-exposed alveolar surfaces and is very important in lung function.

Physiology of the Respiratory System

The major function of the respiratory system is to supply the body with oxygen and to dispose of carbon dioxide. To do this, at least four distinct events, collectively called respiration, must occur.

• Pulmonary ventilation . Air must move into and out of the lungs so that gasses in the air sacs are continuously refreshed, and this process is commonly called breathing.
• External respiration. Gas exchange between the pulmonary blood and alveoli must take place.
• Respiratory gas transport. Oxygen and carbon dioxide must be transported to and from the lungs and tissue cells of the body via the bloodstream.
• Internal respiration. At systemic capillaries, gas exchanges must be made between the blood and tissue cells.
• Rule.  Volume changes lead to pressure changes, which lead to the flow of gasses to equalize pressure.
• Inspiration.  Air is flowing into the lungs; the chest is expanded laterally, the rib cage is elevated, and the diaphragm is depressed and flattened; lungs are stretched to the larger thoracic volume, causing the intrapulmonary pressure to fall and air to flow into the lungs.
• Expiration.  Air is leaving the lungs; the chest is depressed and the lateral dimension is reduced, the rib cage is descended, and the diaphragm is elevated and dome-shaped; lungs recoil to a smaller volume, intrapulmonary pressure rises, and air flows out of the lung.
• Intrapulmonary volume. Intrapulmonary volume is the volume within the lungs.
• Intrapleural pressure. The normal pressure within the pleural space, the intrapleural pressure, is always negative, and this is the major factor preventing the collapse of the lungs.
• Nonrespiratory air movements. Nonrespiratory movements are a result of reflex activity, but some may be produced voluntarily such as coughing , sneezing, crying, laughing, hiccups, and yawning.

• Tidal volume. Normal quiet breathing moves approximately 500 ml of air into and out of the lungs with each breath.
• Inspiratory reserve volume. The amount of air that can be taken in forcibly over the tidal volume is the inspiratory reserve volume, which is normally between 2100 ml to 3200 ml.
• Expiratory reserve volume. The amount of air that can be forcibly exhaled after a tidal expiration, the expiratory reserve volume, is approximately 1200 ml.
• Residual volume. Even after the most strenuous expiration, about 1200 ml of air still remains in the lungs and it cannot be voluntarily expelled; this is called residual volume, and it is important because it allows gas exchange to go on continuously even between breaths and helps to keep the alveoli inflated.
• Vital capacity. The total amount of exchangeable air is typically around 4800 ml in healthy young men, and this respiratory capacity is the vital capacity, which is the sum of the tidal volume, inspiratory reserve volume, and expiratory reserve volume.
• Dead space volume. Much of the air that enters the respiratory tract remains in the conducting zone passageways and never reaches the alveoli; this is called the dead space volume and during a normal tidal breath, it amounts to about 150 ml.
• Functional volume. The functional volume, which is the air that actually reaches the respiratory zone and contributes to gas exchange, is about 350 ml.
• Spirometer.  Respiratory capacities are measured with a spirometer, wherein as a person breathes, the volumes of air exhaled can be read on an indicator, which shows the changes in air volume inside the apparatus.
• Bronchial sounds. Bronchial sounds are produced by air rushing through the large respiratory passageways (trachea and bronchi).
• Vesicular breathing sounds. Vesicular breathing sounds occur as air fills the alveoli, and they are soft and resemble a muffled breeze.
• External respiration. External respiration or pulmonary gas exchange involves oxygen being loaded and carbon dioxide being unloaded from the blood.
• Internal respiration. In internal respiration or systemic capillary gas exchange, oxygen is unloaded and carbon dioxide is loaded into the blood.
• Gas transport. Oxygen is transported in the blood in two ways: most attaches to hemoglobin molecules inside the RBCs to form oxyhemoglobin, or a very small amount of oxygen is carried dissolved in the plasma; while carbon dioxide is transported in plasma as bicarbonate ion, or a smaller amount (between 20 to 30 percent of the transported carbon dioxide) is carried inside the RBCs bound to hemoglobin.

Neural Regulation

• Phrenic and intercostal nerves. These two nerves regulate the activity of the respiratory muscles, the diaphragm, and external intercostals.
• Medulla and pons. Neural centers that control respiratory rhythm and depth are located mainly in the medulla and pons; the medulla, which sets the basic rhythm of breathing, contains a pacemaker , or self-exciting inspiratory center, and an expiratory center that inhibits the pacemaker in a rhythmic way; pons centers appear to smooth out the basic rhythm of inspiration and expiration set by the medulla.
• Eupnea.  The normal respiratory rate is referred to as eupnea, and it is maintained at a rate of 12 to 15 respirations/minute .
• Hyperpnea.  During exercise, we breathe more vigorously and deeply because the brain centers send more impulses to the respiratory muscles, and this respiratory pattern is called hyperpnea.

Non-neural Factors Influencing Respiratory Rate and Depth

• Physical factors. Although the medulla’s respiratory centers set the basic rhythm of breathing, there is no question that physical factors such as talking, coughing, and exercising can modify both the rate and depth of breathing, as well as an increased body temperature, which increases the rate of breathing.
• Volition (conscious control). Voluntary control of breathing is limited, and the respiratory centers will simply ignore messages from the cortex (our wishes) when the oxygen supply in the blood is getting low or blood pH is falling .
• Emotional factors. Emotional factors also modify the rate and depth of breathing through reflexes initiated by emotional stimuli acting through centers in the hypothalamus .
• Chemical factors. The most important factors that modify respiratory rate and depth are chemical- the levels of carbon dioxide and oxygen in the blood; increased levels of carbon dioxide and decreased blood pH are the most important stimuli leading to an increase in the rate and depth of breathing, while a decrease in oxygen levels become important stimuli when the levels are dangerously low.
• Hyperventilation.  Hyperventilation blows off more carbon dioxide and decreases the amount of carbonic acid, which returns blood pH to the normal range when carbon dioxide or other sources of acids begin to accumulate in the blood.
• Hypoventilation.  Hypoventilation or extremely slow or shallow breathing allows carbon dioxide to accumulate in the blood and brings blood pH back into normal range when blood starts to become slightly alkaline.

Respiratory efficiency is reduced with age. They are unable to compensate for increased oxygen need and are significantly increasing the amount of air inspired. Therefore, difficulty in breathing is usually common especially during activities.  Expiratory muscles become weaker so their cough efficiency is reduced and the amount of air left in the lungs is increased. Health promotion teaching can include smoking cessation, preventing respiratory infections through handwashing , and ensuring up to date influenza and pneumonia vaccinations.

Craving more insights? Dive into these related materials to enhance your study journey!

• Anatomy and Physiology Nursing Test Banks . This nursing test bank includes questions about Anatomy and Physiology and its related concepts such as: structure and functions of the human body, nursing care management of patients with conditions related to the different body systems.

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Respiratory System

Jan 01, 2020

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Respiratory System. Parts. The respiratory system is divided into two parts: Upper respiratory tract Lower respiratory tract. Major Organs and Functions. Nose: The only Externally visible part of the respiratory system.

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• carbon dioxide
• respiratory tract
• intrapulmonary pressure
• expiration letting air
• alveoli tiny air sacs

Presentation Transcript

Parts • The respiratory system is divided into two parts: • Upper respiratory tract • Lowerrespiratory tract

Major Organs and Functions • Nose:The only Externally visible part of the respiratory system. • During the process of breathing, air passes through the external nares (nostrils) • The interior of the nose is called the nasal cavity, which is divided by the midline/nasal septum. • The Respiratory Mucosa lining the nasal cavity contains olfactory receptors which provide for the sense of smell. • Beneath the mucosa lies a network of thin walled veins, which function to warm and moisten air as it enters the nose. Also the mucosa traps incoming bacteria which prevents colds and sicknesses.

Pharynx:A muscular passageway for food and air, which is often referred to as the throat. • The air enters thenasopharynxfrom the nasal cavity and continues through theoropharynxand laryngopharynxto enter the esophagus below. The tonsils are located in the pharynx and are just clusters of lymphatic tissues • Larynx:Voice box which conducts air and food into proper pathways and plays an important role in speech. • It is made up of eight hyaline cartilages, thethyroid cartilagebeing the largest. It protrudes anteriorly and is called the Adams Apple. The epiglottis guides the air throughout the superior opening of the larynx.

-Bronchi: Two air tubes that branch off of the trachea enter the lungs and spread into treelike fashion into smaller tubes called bronchial tubes. -Alveoli: Tiny air sacs within the lungs where the exchange of oxygen and carbon dioxide takes place. -They are at the end of the bronchioles, running from the bronchi into the lobes of the lung.

Diaphragm: is a shelf of muscle extending across the bottom of the ribcage. • In order to draw air into the lungs, the diaphragm contracts, thus enlarging the thoracic cavity and reducing intra-thoracic pressure. When the diaphragm relaxes, air is exhaled.

Trachea:(Also called windpipe), is an important part of the vertebrate respiratory system. It is a bony tube that connects the nose and mouth to the lungs. • When an individual breathes, air is taken into the lungs for respiration. The air flows through the windpipe. Because of its primary function, any damage incurred to the trachea can be potentially life-threatening.

Lungs: main organs of the respiratory system. In the lungs oxygen is transported to the body and carbon dioxide is removed. • Structure: • Each lung is between 10 and 12 inches long. The left lung is divided into two sections, or lobes: superior and inferior. The right lung is somewhat larger than the left lung and is divided into three lobes: superior, middle, and inferior. The lungs are covered by a protective membrane called the pulmonary pleura. • The walls of the thoracic cavity are lined with parietal pleura. The pleural membranes function to produce pleural fluid, which is a slippery secretion which permits the lungs to glide easily over the thorax during breathing movements and allow the two pleural layers to cling to one and other. The pleurae have the ability to slide across each other, but resist being pulled apart. The position of tightly adhering pleural membranes is essential for normal breathing.

Lungs • Function: The main function of your lungs is respiration. • Each day, you take about 23,000 breaths, which bring almost 10,000 quarts of air into your lungs. The air that you breathe in contains several gases, including oxygen that your cells need to function. With each breath, your lungs add fresh oxygen to your blood, which then carries it to your cells.

How do you breathe? Breathing: • a mechanical process that depends on volume changes that occur in the thoracic cavity • breathing works by making the rib cage bigger, the pleural layers slide over each other and the pressure in the lung is decreased, so air is sucked in. • Breathing out does the reverse, the cage collapses and air is expelled. • The diaphragm is the main component. • When is contracts, it flattens and increases the space above it. • During relaxation, the abdominal contents push it up again. Voice Production: • Air pressure from the lungs travels up through the trachea, larynx, and pharynx. • The vocal folds in the larynx vibrate, which creates fluctuations in air pressure called sounds waves. • The vocal tract resonates and modifies the waves to match the shape of the jaw, lips, tongue, soft palate, and other vocal organs. This creates regions and differentiation in sound. • The openings of the mouth and nose release the sound to the external environment,

Oxygen and Carbon Dioxide transportation in the blood The Major function of Respiratory system is to supply the body with oxygen and to dispose of Carbon Dioxide.  • The walls of alveoli are a single, thin layer of squamous epithelial cells (a sheet of tissue paper is much thicker) • Alveolar Pores connect neighboring air sacs and provide alternate routes for air to reach alveoli. • External surfaces of alveoli are covered with pulmonary capillaries. • Together, alveolar and capillary walls and their fused basement membranes construct the respiratory membrane (air-blood barrier), which has gas (air) flowing past on one side and blood flowing past on the other side. ** • Gas exchanges occur by a simple diffusion through the respiratory membrane- oxygen passing from the alveolar air into the capillary blood and carbon dioxide leaving the blood to enter the gas-filled alveolus. • Total gas exchange surface provided by the alveolar walls estimated = 50-70 square meters. (40 times greater than surface area of skin.)

Respiratory Volume • There are many factors that influence lung capcity. • Size, age, sex, physical condition, ect. • Tidal Volume (TV) is the amount of quiet breathing into and out of the lungs with each breath (500mL normally) • Inspiratory Reserve Volume (IRV): The amount of air that can be taken in forcibly over the tidal volume. (2100-3200mL normally) • Expiratory Reserve Volume (ERV): The amount of air that can be forcibly exhaled after a tidal expiration. (1200mL normally) • Residual Volume: The amount of air still remaining in the lungs that cannot be voluntarily expelled (1200mL normally) It is important because it permits gas exchange to continue between breaths and keeps alveoli open. .

Lung Capacities • Respiratory Volumes are measured with a spirometer. • Vital Capacity (VC): The total amount of exchangeable air. It is the sum of the TV, IRV, and ERV. (4800 in healthy young males) • Dead Space Volume: The air that enters the respiratory tract but does not reach the alveoli. (Usually about 150mL, the other 350 reaches the alveoli)

External v Internal Respiration • External Respiration is the exchange of gases between the alveoli and the blood, while internal respiration is gas exchange between the systemic capillaries and he tissue cells.

Inspiration v Expiration • Inspiration, or inhalation, is the process by which air flows into the lungs. It involves the contraction of the diaphragm and external intercostals, which in turn increases the volume of the thoracic cavity. Consequently, the lungs and the gases within the lungs, expand to fill the new space. This effect produces a partial vacuum that sucks the air into the lungs until the intrapulmonary pressure is equal to atmospheric pressure. • Expiration, or exhalation, is the process that expels air out of the lungs. In healthy people, this process is very passive and relies mostly on the elasticity of the lungs rather than muscle contractions. After inspiration takes place, the muscles resume their original positions, forcing the ribcage to descend and the lungs to recoil. This causes the thoracic and intrapulmonary volumes decrease. As a result, the gases inside the lungs are forced more closely together and the intrapulmonary pressure rises to a point higher than atmospheric pressure, The gases then flow out of the lungs to stabilize pressures inside and outside of the lungs.

Nervous Control of Respiration • Voluntary • Phrenic and Intercostal Nerves • In the brain, breathing is controlled by neural centers called the ponsand medulla • Medulla- sets basic rhythm; contains a self-exciting inspiratory center as well as other respiratory centers • Pons- smoothes out basic rhythm of inspiration and expiration set by medulla • Impulses go back and forth b/w the two • Normal breathing rate = 12-15 respirations/min. (eupnea) • In case of overinflation of bronchioles and alveoli, impulses are sent from the stretch receptors to the medulla by the vagus nerves (inspiration ends, expiration occurs) • Hyperpnea-brain sends more impulses to resp. muscles to breathe (exercise, etc.) • Volition- conscious control • Emotional factors(fear, love, etc.) • Chemical factors- • Levels of co2 and o2 in blood (medulla)

Pressure Relationship of Breathing • Inspiration- taking in air (inhalation) • As the diaphragmand external intercostals contract, thoracic cavity gets bigger from top to bottom (diaphragm flattens out=bottom down, external intercostals contract= top up) • Sternum thrusted forward (increases front to back) • Lungs expand with thoracic cavity • Gas has more room to move; PRESSURE DECREASES • Body seeks to make intrapulmonary pressure equal to atmospheric pressure by inhaling more gas until lungs are full • Expiration- letting air out (exhalation) • Inspiratory muscles relax; thoracic and intrapulmonary volume decreases • Gases in lungs are forced more closely together; intrapulmonary pressure is greater than atmospheric pressure • Gases flow out to equalize pressure • Usually effortless unless resp. passages are narrowed (asthma, pneumonia, bronchitis, etc.); in forced expiration, internal intercostals muscles depress rib cage and abs contract to force air out by squeezing abdominal organs against diaphragm • The intrapleural pressure is always negative; prevents collapse of lungs • Protective Mechanisms • cilia and mucous to trap dust, bacteria, etc. • coughing (clears lower respiratory passageways), sneezing (clears upper respiratory passageways) • movement of larynx blocks food from entering trachea and directs it to esophagus

Respiratory Diseases • Infectionby viruses and bacteria: range from the common cold to the flu virus and Streptococcus(strep throat) • Many upper respiratory tract problems: • Epistaxis • Laryngitis • Pharyngitis • Rhinitis • Sinusitis • Sleep apnea • tonsilitis

Respiratory Diseases • Emphysema: usuallycaused by smoking • Can also be inherited (deficiency of alpha-I antitrypsin [AAT] protein) • Fourth leading cause of death in U.S. • How it works: • Damage to alveoli- Over-inflated alveoli fuse to become an enlarged alveoli. This results in less surface area for the normal gas exchange and blood oxygenation. Damage to the surfactant coating the alveoli causes a loss of elasticity. “Stale” air is never replaced by fresh air, and eventually alveoli can collapse, trapping the air. • Symptoms: breathlessness, barrel chest, weight loss, problems with breathing out

Respiratory Diseases • Emphysema(cont): • Treatment: • 1. surfactants to replace those lost • 2. oxygen therapy to oxygenate tissues • 3. treatment of symptoms • Pneumonia: an inflammation of the lungs caused by an infection or an injury in which the alveoli fill with fluid • Two to three million people affected in U.S. each year; out of these, about 40,000 to 70,000 people die • Proper gas exchange can not occur when fluid such as mucus or pus is present • Causes? • Bacteria, viruses, mycoplasmas, fungi, and various chemicals • Lead to a variety of types and strengths of pneumonia

Respiratory Diseases (cont) • Pneumonia (cont): • Symptoms: • severe shaking chill, high fever, cough, shortness of breath, rapid breathing, chest pains • Treatment: • antibiotics for the bacterial form; rest, drink fluids; anti-inflammatory meds • Preventative measures: • good hygiene, flu vaccination, don’t smoke tobacco Normal lungs Lungs with pneumonia

Respiratory Diseases (cont) • Tuberculosis: a bacterial infection of the lungs caused by the Myobacterium tuberculosis bacteria • Over-stimulates the inflammatory immune response, destroying lung tissue • Symptoms: a cough lasting 3 or more weeks, coughing up blood or mucus, fever and chills, night sweats; can be very deadly • Treatments: • Active: antibiotic treatment over a period of 6-12 months; if second occurrence (MDR-TB), requires special drugs that often have extreme side effects • Latent: isoniazid can prevent TB from becoming active • A vaccine for specifically Bacille Calmette-Guerin (BCG) strain

'Respiratory system," Hillendale Health. May 3, 2007. <http://hes.ucf.k12.pa.us/gclaypo/repiratorysys.html#Lungs> • "Anatomy of Respiratory System," Ohio State University Medical Center. May 3, 2007 <http://medicalcenter.osu.edu/patientcare/healthinformation/diseasesandconditions/respiratory/about/anatomy/> • "Oxygen Delivery System," The Franklin Institute. May 3, 2007. <http://www.fi.edu/biosci/systems/respiration.html> • "How the Lungs Work," National Heart Lung and Blood Institute. May 3, 2007. <http://www.nhlbi.nih.gov/health/dci/Diseases/Copd/Copd_HowLungsWork.html> • Ballard, Dr. Carol. The Lungs and Breathing. Farmington Hills, MI: Kidhaven Press, 2005. • Marieb, Elanie N. Essentials of Human Anatomy & Physiology. San Francisco, CA: Daryl Fox, 2003. • "Lung Toxicology Problem Set," The University of Arizona. 1997. May 7, 2007. http://www.biology.arizona.edu/chh/problem_sets/lung_toxicology/03t.html

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Respiratory System!!! . By Hannah Brock . Organs. Lungs Nose Trachea Larynx. This is a healthy lung . . This is a unhealthy lung. Important to Body. http :// www.neok12.com/php/watch.php?v=zX7a51620305036844477802&amp;t=Respiratory-System Brings Air to the body. How It Works.

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Respiratory System. Brings O2 in and lets CO2 out of the body. What does the RS do?. Respiration The process of bringing O2 in the body from outside and getting rid of CO2 – waste product made by cells Lungs Main organ of the gas exchange in the RS. Path air takes to enter body.

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Respiratory System. Introduction. Functions. Provide for gas exchange Intake of O2 Removal of CO2 Regulate blood pH Sense of smell Produces sounds Filters, warms, moistens air Water, heat balance. 3 Major Steps. Pulmonary Ventilation Moving air in and out of lungs

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Respiratory System. By: Jenna Constantino. What is in the Respiratory System?. The respiratory system consists of these parts: Lungs, Trachea, Bronchi, Diaphragm, and the Bronchioles, alveoli, and the capillaries. . .

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Respiratory system

By: D alton M cBride. Respiratory system. VIDEO. http://www.youtube.com/watch?v=sU_8juD3YzQ. MAJOR ORGANS . The nose, trachea, larynx, lungs, epiglottis, and the diaphragm are the major organs of the respiratory system. MAJOR FUNCTIONS. Supplies body with O2 and disposes of Co2

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RESPIRATORY SYSTEM. Pathway of inhaled air: nasal cavity  pharynx  larynx  trachea  bronchi  bronchioles  alveoli Nasal cavity Hairs and mucus filter particles, pathogens Warms and moistens inhaled air Contains olfactory bulb Pharynx

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RESPIRATORY SYSTEM . LUNGS &amp; AIR PASSAGES. WHY ARE THEY NEEDED. TAKE IN OXYGEN GAS NEEDED BY ALL BODY CELLS REMOVING CARBON DIOXIDE GAS THAT IS A WASTE PRODUCT PRODCUED BY THE CELLS. HOW MUCH O2 DO WE HAVE?. FOUR TO SIX MINUTES SUPPLY. RESPIRATORY SYSTEM.

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Respiratory System. Respiration. a single complete act of breathing in and out; &quot;thirty respirations per minute&quot; breathing the bodily process of inhalation and exhalation; the process of taking in oxygen from inhaled air and releasing carbon dioxide by exhalation .

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Respiratory System. GAS EXCHANGE!!! The path air takes: Mouth or nose → pharynx (throat) → larynx → trachea (windpipe) → 2 bronchi → lungs Epiglottis The air must be cleaned: Lungs, nasal cavity, trachea, and bronchi are lined with ciliated cells that secrete mucus. Respiratory System.

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Respiratory system. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD). DEFINITION.

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RESPIRATORY SYSTEM. by Harry Carter, Ian Cooper, Kazuki Moriguchi, and John Su. The Structure of the Respiratory System. The respiratory system consists of the mouth, epiglottis, larynx and trachea leading to the lungs.

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Respiratory System. HST I . Includes:. Nasal cavity Sinuses Pharynx Larynx Epiglottis Trachea . Bronchi Bronchioles Alveoli Lungs Pleura Mediastinum. Main organs involved in the respiratory system:. Nose/mouth Pharynx Larynx Trachea Bronchi Alveoli (within lungs) Lungs.

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Respiratory system!

Respiratory system!. parts. Parts 2. Definitions. Disorders. Homeostasis. 10. 10. 10. 10. 10. 20. 20. 20. 20. 20. 30. 30. 30. 30. 30. 40. 40. 40. 40. 40. 50. 50. 50. 50. 50. Topic 1 – 10 Points. QUESTION: What is the beginning of the respiratory tract? ANSWER:

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Respiratory System. Respiratory Functions. I.  Provide surface area for the diffusion of gasses A.  Oxygen (To be transported to the cells for aerobic respiration) B.  Excrete carbon dioxide II. Warm, moisten, and filter inspired air. Respiratory Organs. Breathing structures

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Respiratory system. ا.م.د.بيداء حميد عبدالله. Pulmonary infection. It can be caused by : Viral, bacterial, fungal and mycoplasma infection. Bacterial infection: Bacterial invasion of the lung parenchyma will cause an exudative solidification (consolidation) of the lung tissue.

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RESPIRATORY SYSTEM. Organs of the Respiratory System. Nose Pharynx Larynx Trachea Bronchi Lungs—alveoli. Respiratory System Anatomy. Structurally divided into Upper respiratory system Above the larynx Nose, pharynx and associated structures Lower respiratory system Below the larynx

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