SEER Training:Bronchi, Bronchial Tree, & Lungs Bronchi, Bronchial Tree, & Lungs Bronchi, Bronchial Tree, & Lungs Bronchi and Bronchial Tree In the mediastinum , at the level of the fifth thoracic vertebra, the trachea divides into the right and left primary bronchi. The bronchi branch into smaller and smaller passageways until they terminate in tiny air sacs called alveoli. The cartilage and mucous membrane of the primary bronchi are similar to that in the trachea. As the branching continues through the bronchial tree, the amount of hyaline cartilage in the walls decreases until it is absent in the smallest bronchioles. As the cartilage decreases, the amount of smooth muscle increases. The mucous membrane also undergoes a transition from ciliated pseudostratified columnar epithelium to simple cuboidal epithelium to simple squamous epithelium. The alveolar ducts and alveoli consist primarily of simple squamous epithelium, which permits rapid diffusion of oxygen and carbon dioxide.

Exchange of gases between the air in the lungs and the blood in the capillaries occurs across the walls of the alveolar ducts and alveoli. Lungs The two lungs, which contain all the components of the bronchial tree beyond the primary bronchi, occupy most of the space in the thoracic cavity. The lungs are soft and spongy because they are mostly air spaces surrounded by the alveolar cells and elastic connective tissue. They are separated from each other by the mediastinum , which contains the heart. The only point of attachment for each lung is at the hilum, or root, on the medial side. This is where the bronchi, blood vessels, lymphatics, and nerves enter the lungs. The right lung is shorter, broader, and has a greater volume than the left lung. It is divided into three lobes and each lobe is supplied by one of the secondary bronchi. The left lung is longer and narrower than the right lung. It has an indentation, called the cardiac notch, on its medial surface for the apex of the heart. The left lung has two lobes. Each lung is enclosed by a double-layered serous membrane, called the pleura.

The visceral pleura is firmly attached to the surface of the lung. At the hilum, the visceral pleura is continuous with the parietal pleura that lines the wall of the thorax. The small space between the visceral and parietal pleurae is the pleural cavity. It contains a thin film of serous fluid that is produced by the pleura. The fluid acts as a lubricant to reduce friction as the two layers slide against each other, and it helps to hold the two layers together as the lungs inflate and deflate. Anatomy of the Respiratory System & Related Systems - Respiratory System/Pulmonary Anatomy - HealthCommunities.com Anatomy of the Respiratory System & Related Systems Print Respiratory System Anatomy The cells of the human body run on oxygen much like a car runs on gas. There are parts of the cell called mitochondria that use the oxygen to generate ATP, the energy currency of cells. How do the cells get their oxygen? The body takes in air rich in oxygen through the nose and mouth. It then travels down through the air tubes (the pharynx and larynx), through the trachea, the bronchial tubes, and into the alveolar spaces.

The alveolar spaces are millions of tiny air sacs that have a very thin wall. The alveolar capillary rests immediately on the other side of the alveolar wall. Oxygen readily transfers from the alveolar space through the thin alveolar wall into the oxygen-depleted red blood cells in the capillary. The oxygen-rich blood then returns to the heart and is pumped throughout the body. Waste in the form of carbon dioxide transfers from the blood into the alveolar space and is exhaled from the body. Lung Anatomy The lungs are the body's major organs of respiration. The two vital parts that make up the lungs are located on each side of the chest within the rib cage. They are separated by the heart and other contents of the mediastinumthe tissues and organs of the middle chest (e.g., the heart and large vessels, windpipe). The lungs are shaped rather like an upside-down butterfly. The top, or apex, of each lung extends into the lowest part of the neck, just above the level of the first rib. The bottom, or base, of each lung extends down to the diaphragm, which is the major breathing-associated muscle that separates the chest from the abdominal cavity.

Each lung is divided into upper and lower lobes, although the upper lobe of the right lung contains another triangular subdivision known as the middle lobe. The right lung is larger and heavier than the left lung, which is somewhat smaller in size because of the position of the heart. At birth, the lungs are pinkish-white in color; however, with age, the lungs darken to gray or mottled black because of deposits of carbon and other particles that are inhaled over the years. The root connects the lungs to the heart and the trachea (windpipe). Each root is made up of a main stem bronchus (large air passage connecting the windpipe to the right or left lungs), pulmonary artery (major artery that brings oxygen-poor blood back to the right or left lungs), pulmonary vein (major vein receiving oxygen-rich blood from the lobes of the right or left lungs), the bronchial arteries and veins, as well as nerves and lymphatic vessels. A clear, thin, shiny covering known as the serous coat, or pleura, covers the lungs. The inner, visceral layer of the pleura is attached to the lungs and the outer, parietal layer is attached to the chest wall.

Both layers are held in place by a film of pleural fluid in a manner similar to two glass microscope slides that are wet and stuck together. Beneath the pleura is a layer of elastic fibers that span the lung surface and extend down into its subdivisions. The trachea splits into right and left main stem bronchi. These are the major air passages from the trachea to the lungs and are similar to the trachea in tissue composition. The main stem bronchi enter each lung and progressively branch off into more than 23 paired subdivisions. At every branching, the number of airways increases greatly. The entire structure, from the trachea to the smallest bronchioles, resembles an upside-down branching tree, with the branches getting smaller and smaller as they get further from the trunk (the tracheobronchial tree). The tracheobronchial tree conducts, humidifies, and heats air that is breathed in, or inspired. At its endpoints, the tracheobronchial tree connects with the blood vessels. The lining of the tracheobronchial tree is composed of columnar epithelium (column-shaped surface cells) and glands that produce mucus and serous (clear plasma) fluid.

The cilia (hair-like projections on columnar epithelium) move in a constant, beating motion to cleanse the airways of foreign bodies and infectious organisms. A watery "mucous blanket" - a gel-like liquid - covers and is moved by the cilia and aids the lungs' self-cleaning. Coughing triggers a high-speed flow of air that mobilizes the mucous blanket. The sputum produced by such mobilization contains mucus, nasal secretions, and saliva. The essential tissue of the lunglung parenchymais made up of clusters of spongy air sacs called lobules. There are about 130,000 primary lobules in each lung. Each lobule is approximately 3.5 millimeters in diameter and contains about 2,200 alveoli (air sacs and ducts). Tracheobronchial branches that are larger than 1 millimeter in diameter and have connective tissue coverings are called segmental bronchi. The smallest subdivisions, which are less than 1 millimeter in diameter and do not have connective tissue coverings, are called bronchioles.

The final branches of the bronchioles are called terminal bronchioles. The bronchioles end in irregular, swollen projections known as alveolar ducts (terminal branches composed of special gas-exchanging tissue) and alveolar sacs (blind passages of alveolar ducts). The alveolar sacs are tiny, thin-walled, cup-shaped structures (250300 mm2) are lined with a detergent-like substance known as surfactant, which reduces surface tension and prevents them from collapsing during breathing. Another substance in the alveolar wall, elastin, applies an elastic force to "shrink" the alveoli during exhalation. There are approximately 3,000,000 alveoli in the lungs. Anatomy of the Respiratory Muscles Air is inhaled by the active contraction of the respiratory muscles. The major respiratory muscle is the diaphragm, a large muscular partition that separates the chest cavity from the abdominal cavity. It lies beneath the lungs and is dome shaped, with the apex of the dome in approximation with the lower portion of the lungs.

During inhalation, the diaphragm contracts downward and away from the lungs, creating more space in the chest cavity. This lowers the pressure in the chest cavity relative to the pressure outside the body, and air moves into the lungs. The diaphragm receives help from accessory muscles. The muscles in the neck that attach to the upper part of the sternum and clavicles, such as the sternocleidomastoid muscle, and the muscles between the ribs, called the intercostal muscles, increase the diameter of the chest wall, which helps lower the pressure in the chest. Intercostal muscles contract and shrink the chest wall during forced exhalation. Anatomy of the Blood Vessels Oxygen-poor blood is brought back to the lungs by the pulmonary artery. The pulmonary artery divides into branches that parallel the bronchial tubes and ends in a network of pulmonary capillaries (tiny blood vessels) within the walls of the small air passages and alveoli of the lungs. The pulmonary veins carry oxygen-rich blood away from the lungs. They begin in the pulmonary capillaries, unite to form larger branches (e.g., the left and right superior and inferior pulmonary veins), and eventually lead into the left atrium of the heart.

The heart then pumps the oxygenated blood out to the body via the aorta (the great artery arising from the left ventricle of the heart). The bronchial arteries are blood vessels that branch off from the aorta to supply blood and nutrition for the lung itself and the bronchial tubes. The bronchial vein begins at the root of the lung and receives blood from vessels near the bronchial arteries. Anatomy of the Lymphatic System Lymphatic vessels are structures that drain lymph, the clear, yellowish fluid containing lymphocytes (white blood cells that fight disease) from the tissues of the body. The lungs have two sets of lymphatic vessels - a surface, or superficial set, and a deep set. The surface lymphatic vessels are located beneath the pleura (thin, serous covering of the lungs), whereas the deep-set vessels follow the blood vessels and extend along the bronchi. Both sets end at the root of the lungs, within the bronchial glands. Two or three efferent (outward-leading) vessels travel up the trachea (windpipe) to the base of the neck, where they cross the trachea and esophagus (tube that passes from the mouth to the stomach).

These vessels end at either the thoracic duct (passage that empties a large amount of lymph and lymph-related compounds into the blood) on the left side or the lymphatic duct on the right. Anatomy of the Nerves The lungs receive their nerve supply from the anterior (front) and posterior (back) nerve networks, called pulmonary plexuses. These plexuses are offshoots of larger nerves - e.g., the sympathetic nerves of the trunk and the pneumogastric (tenth cranial, or vagus) nerve. The nerves of the lung contain small, knotty masses called ganglia. The diaphragm receives its nerve supply from the phrenic nerves, which descend from the upper neck. Publication Review By: the Editorial Staff at HealthCommunities.com Published: 01 Jun 2000 Chapter 22: The pleurae and lungs Chapter 22: The pleurae and lungs Pleura The two lungs and their pleural sacs are situated in the thoracic cavity (figs. 22-1 and 22-2 ). The pleura is a thin, glistening, slippery serous membrane, inflammation of which is called pleurisy.

The pleura lines the thoracic wall and diaphragm, where it is known as the parietal pleura. It is reflected onto the lung, where it is called the visceral pleura. The visceral pleura covers the lung and dips into its fissures. The facing surfaces of the parietal and visceral pleurae slide smoothly against each other during respiration. The contact between the parietal and visceral pleurae depends on the atmospheric pressure (1) on the outside of the chest wall and (2) inside the alveoli (which are connected to the exterior by the bronchial tree). On the other hand, the two pleural layers tend to be separated by the elasticity of (1) the thoracic wall (directed outward) and (2) the lungs (stretched by inspiration). The pleural cavity, which is the potential space between the two layers, contains only a thin film of fluid. Air in the pleural cavity (pneumothorax) results in collapse of the lung. The pleura is supplied by adjacent arteries and nerves and has numerous lymphatics.

Irritation of the parietal pleura causes pain referred to the thoraco-abdominal wall (intercostal nerves) or to the shoulder (phrenic nerve). The parietal pleura has costal, mediastinal, and diaphragmatic parts and a cupola (fig. 22-3 ). The costal pleura is separated from the sternum, costal cartilages, ribs, and muscles by a loose connective tissue termed endothoracic fascia, which provides a natural cleavage plane for surgical separation of the pleura from the thoracic wall. Anteriorly, the costal pleura turns sharply onto the mediastinum, and the underlying portion of the pleural cavity is called the costomediastinal recess. Inferiorly, the costal pleura is continuous with the diaphragmatic pleura, and the underlying space is termed the costodiaphragmatic recess. In the adult, the anterior borders of the right and left pleurae probably meet at or near the median plane during a part of their course. The left anterior border sometimes diverges to leave a part of the pericardium uncovered (bare area).

Posteriorly, the pleura crosses the twelfth rib. At the root of the lung, the mediastinal pleura turns laterally, enclosing the structures at the root and becoming continuous with the visceral pleura. This reflection projects downward as a tapering double fold called the pulmonary ligament. The mediastinal pleura is adherent to the pericardium except where the phrenic nerve descends between them. Above the arch of the aorta, the right and left pleurae approach each other behind the esophagus. The diaphragmatic pleura covers most of the diaphragm except the central tendon. The cupola (or cervical pleura) is the continuation of the costal and mediastinal parts of the pleura over the apex of the lung. The cupola is strengthened by a thickening of the endothoracic fascia termed the suprapleural membrane, which is attached to the inner margin of the first rib and the transverse process of the seventh cervical vertebra (C7). Some muscular fibers (scalenus minimus) may be inserted into the membrane.

Because of the slope of the first rib, the cupola of the pleura and the apex of the lung project upward into the neck, posterior to the sternomastoid, and hence may be injured in wounds of the neck. Their highest point is 2 to 3 cm or more above the level of the medial third of the clavicle. The sympathetic trunks and first thoracic nerves are found posterior to the cupola. The anterior border of the pleura extends downward from the cupola, passing posterior to the sternoclavicular joint, then to the middle of the sternal angle, and next to approximately the level of the xiphisternal joint. The inferior border of the pleura extends laterally from the xiphisternal joint, crosses rib 8 in the midclavicular line and rib 10 in the midaxillary line, and then proceeds toward the spine of the 12th thoracic vertebra (see fig. 22-2 ). Considerable individual variation occurs, but generally the pleura extends two fingerbreadths inferior to the lung. Lungs The lungs are the essential organs of respiration. The Latin word pulmo, lung, gives rise to the adjective pulmonary.

The corresponding Greek word provides pneumonia, inflammation of the lungs. Each lung is attached by its root and pulmonary ligament to the heart and trachea but is otherwise free in the thoracic cavity. The lungs are light, soft, spongy, and elastic, and, because they contain air, they float in water. If an infant has not drawn a breath, however, the lungs will not float. (From two thirds of the way through prenatal life, a fetus is viable, i.e., has sufficient pulmonary development to live ex utero.) The air in the lungs renders them translucent to x-rays. The surface of an adult lung is usually mottled, and it presents dark gray or bluish patches caused by inhalation of atmospheric dust. The main bronchus enters the hilus and subdivides within the substance of the lung to form the "bronchial tree." The tubes of the tree carry air to the alveoli, where respiratory exchanges with the blood occur. The bronchial tree elongates on deep inspiration. The right lung, which is heavier than the left, is also shorter (the right dome of the diaphragm being higher) and wider (the heart bulging more to the left).

Surfaces and borders Each lung has an apex, three surfaces (costal, medial, and diaphragmatic), and three borders (anterior, inferior, and posterior). The right lung is divided into upper, middle, and lower lobes by oblique and horizontal fissures, whereas the left lung has usually only upper and lower lobes, separated by an oblique fissure. The bronchi and pulmonary vessels, which extend from the trachea and heart, respectively, collectively form the root of the lung. The part of the medial surface where these structures enter the lung is known as the hilus (figs. 22-4 and 22-5 ). The apex is rounded and fills the cupola of the pleura. The costal surface, which is related to the sternum, costal cartilages, and ribs, joins the medial surface at the anterior and posterior borders and the diaphragmatic surface at the inferior border. The medial surface is related posteriorly to the sides of the bodies of the vertebrae. Anteriorly, the medial surface is related to the superior, middle, and posterior parts of the mediastinum and includes the hilus.

The diaphragmatic surface, or base, rests on the dome of the diaphragm, which separates the lung from the liver (on the right side) or the stomach, spleen, and sometimes liver and left colic flexure (on the left side). Rarely, the azygos vein, instead of arching over the hilus of the right lung, arches over the upper lobe so that it isolates a medial part of the lung, called the lobule of the azygos vein. The anterior border of the lung corresponds to that of the pleura, although it is uncertain whether the costomediastinal recess of the pleura is completely filled by the lung during quiet breathing, as it is in deep inspiration. The anterior border of the left lung probably deviates more to the left (cardiac notch) than does that of the pleura. The portion of the upper lobe of the left lung that lies between the cardiac notch and the oblique fissure is known as the lingula, and it corresponds to the middle lobe of the right lung. The inferior border of the lung occupies the costodiaphragmatic recess of the pleura, although it is too thin to be demonstrated by percussion during quiet breathing.

The liver, stomach, spleen, colon, kidney, and peritoneal cavity extend to a higher level than the periphery of the diaphragm and the inferior border of the lung. Hence any perforation of the lower intercostal spaces should be considered an abdominal as well as a thoracic wound. The inferior limit of the lung that can be outlined by percussion extends laterally from the xiphisternal joint and about two intercostal spaces higher than the pleura. It crosses rib 6 in the midclavicular line and rib 8 in the midaxillary line and then proceeds toward the 10th thorac vertebra. Considerable individual variation occurs, however. Lobes and fissures (see fig. 22-2 ) The right lung is divided into upper, middle, and lower lobes by an oblique and a horizontal fissure. The left lung is divided into upper and lower lobes by an oblique fissure. The oblique fissure follows approximately the line of rib 6 as far as the inferior border of the lung. When the arm is abducted and the hand placed on the back of the head, the medial border of the scapula indicates approximately the oblique fissure.

The horizontal fissure begins at the oblique fissure near the midaxillary line (of the right side), at about the level of rib 6. It extends forward to the anterior border at the level of costal cartilage 4. It may be incomplete or even absent. Root (figs. 22-4 and 22-5 ) The root of the lung consists of the structures entering and emerging at the hilus. It connects the medial surface of each lung to the heart and trachea. It is surrounded by pleura, which is prolonged below as the pulmonary ligament. The roots of the lungs descend on deep inspiration. The chief structures in the root are the bronchi and pulmonary vessels. Also included are nerves, bronchial vessels, and lymphatics and nodes. The heart and great vessels are anterior to the trachea and main bronchi, and this relationship is maintained in the root of the lung, where the anterior-posterior order, is veins, artery, and bronchus, with the artery superior to the veins. Bronchopulmonary segments (fig.

22-6 ) The main bronchus divides into lobar (second-order) bronchi, each of which then divides into segmental (third-order) bronchi. The portion of lung supplied by a third-order bronchus is known as a bronchopulmonary segment. A given segment may be located by radiography or bronchoscopy. Pulmonary disorders may be localized in a bronchopulmonary segment, and surgical removal of a segment is feasible. The segments are separated from each other by connective tissue septa. Although variations are not uncommon, the bronchopulmonary segments have been named and numbered (fig. 22-6 and table 22-1 ). There are slight differences between the right and left lungs: briefly, in the left lung, segments 1 and 2 are generally combined, and commonly segments 7 and 8 are also. The branches of the pulmonary artery accompany the bronchi but are more variable. Pulmonary veins do not accompany the bronchi, but run between the segments; hence they are guides to intersegmental planes.

Blood supply, lymphatic drainage and innervation Blood to be oxygenated is carried by the pulmonary arteries, whereas the tissue of the bronchial tree and alveoli is nourished by the bronchial arteries. The branches of the pulmonary arteries within the lungs accompany the bronchi and end in capillary networks in the alveoli. The arteries at the hilus are visible radiographically and form a pattern that extends into the lung. The pulmonary veins collect oxygenated blood from the lung and deoxygenated blood from the bronchi and visceral pleura. Pulmonary veins are intersegmental in location. Usually four pulmonary veins enter the left atrium. Bronchial arteries, usually one on the right and two on the left, arise commonly from the aorta, but variations are frequent. They supply oxygenated blood to the non-respiratory tissues of the lungs, including the visceral pleura. Bronchial veins carry deoxygenated blood from the first few bronchial divisions to the azygos system. Carbon particles in the superficial lymphatics give the lung a grayish and mottled appearance. Superficial and deep lymphatic vessels drain toward the hilus and end in pulmonary and bronchopulmonary nodes.

These in turn drain into the tracheobronchial nodes. The anterior and posterior pulmonary plexuses around the root of the lung are formed by branches of the vagi and sympathetic trunks. Parasympathetic fibers (of vagal origin) supply the smooth muscle and glands of the bronchial tree. Spasm of the bronchial musculature occurs in asthma and can be relieved by epinephrine. Sympathetic fibers supply blood vessels and probably relax bronchial smooth muscle. Afferent fibers (vagal) from the visceral pleura and bronchi are concerned with the reflex control of respiration. Irritation of endings in the bronchial mucosa provokes coughing. Physical and radiological examinations The classic methods of physical examination are inspection, palpation, percussion, and auscultation. Corresponding areas on the two sides of the chest should be compared systematically. Inspection includes examination of the scapulae, clavicles, ribs, sternal angle, subcostal angle, expansion of the chest, and movement of the abdominal wall. The rate of respiration is normally 11 to 14 per minute, i.e., about one fourth of the pulse rate.

It is higher in children, and the neonatal rate is two to three times as high as the adult rate. Palpation involves feeling the trachea and also the vibrations ("vocal fremitus") of the chest wall. Percussion produces "resonance" over air-containing organs such as the lungs and "dullness" over solid organs. Auscultation ofthe breath sounds is undertaken with a stethoscope. The chief x-ray methods used in the examination of the chest are plain films and CT scans. Bronchoscopy is used to examine the air passages and to biopsy masses and pulmonary function tests evaluate the movement of air. The most frequently employed view in radiography of the chest is the "PA" view, i.e., postero-anterior projection, in which the x-ray tube is behind the erect patient and the film is vertically in front of the chest. Other views are indicated in figure 23-15 . The bronchi and pulmonary tissue are radiolucent, but the branches of the pulmonary arteries form a visible pattern. The dense hilar shadows are produced by a combination of vascular, bronchial, lymphatic, and connective tissue components.

The bronchial tree can be outlined by a contrast medium injected by way of an intratracheal catheter introduced through the mouth or nose. This procedure is termed bronchography (fig. 22-8 ). This has largerly been replaced by fiber-optic bronchoscopy which directly visualizes the passages. Additional reading Boyden, E. A., Segmental Anatomy of the Lungs, Blakiston (McGraw-Hill), New York, 1955. A classic on the patterns of the segmental bronchi and related pulmonary vessels. Hayek, H., von, Die menschliche Lunge, 2nd ed., Springer, Berlin, 1970. The first edition (1960) is available in English (The Human Lung). Nagaishi, C., et al., Functional Anatomy and Histology of the Lung, University Park, Baltimore, 1972. A mine of pulmonary information. Questions 22-1 What are the serous membranes? 22-1 The serous membranes line the body cavities and are reflected over protruding organs as their serous coat.

The serous membranes are the pleura, pericardium, and peritoneum. The tunica vaginalis testis is a (usually) detached extension of the peritoneum. Serous membranes consist of mesothelium and connective tissue, and they secrete a film of serous exudate. 22-2 What is pneumothorax? 22-2 Pneumothorax is the presence of air in the pleural cavity. Air may enter from the lung (e.g., from ruptured alveoli) or through the chest wall (e.g., from a perforating injury). The lung then collapses. 22-3 What is the cupola? 22-3 The cupola is the cervical parietal pleura superior to the apex of the lung. 22-4 How does the right lung differ from the left? 22-4 The right lung is usually heavier, shorter, and wider than the left lung, and it generally has three rather than two lobes. 22-5 What is the inferior limit of the lung and pleura?

22-5 The lung and pleura are generally said to cross rib 6 in the midclavicular line and ribs 8 and 10, respectively, in the midaxillary line and then to proceed toward the spinous processes of T10 and T12 vertebrae, respectively. 22-6 Why is a perforating wound of the lower intercostal spaces considered to be an abdominal as well as a thoracic wound? 22-6 A perforatiing injury of the lower intercostal spaces should be considered an abdominal as well as a thoracic wound because the liver, stomach, spleen, colon, kidney, and peritoneal cavity extend to a higher level than the periphery of the diaphragm and the inferior border of the lung. 22-7 What is a bronchopulmonary segment? 22-7 A bronchopulmonary segment is the portion of lung supplied by a third-order bronchus. 22-8 What is the main constituent of the hilar shadows seen radiographically? 22-8 The hilar shadows seen on radiography are caused mainly by branches of the pulmonary arteries, although the larger bronchi can frequently be recognized.

22-9 What are the classic methods of physical examination? 22-9 The classic methods of physical examination are inspection, palpation, percussion, and auscultation. The stethoscope was invented for auscultation by Laennec in 1816. 22-10 Which is the most frequently employed view in radiography of the chest? 22-10 The PA view (postero-anterior projection of the x-rays) is the most frequently employed view in radiography of the chest. Figure legends Figure 22-1 Thorax of an adult. Note the clavicles, ribs, diaphragm, cardiovascular shadow (including the right atrium, aortic knuckle, and left ventricle), trachea, and lungs (including vascular markings). Large descending branches of the pulmonary arteries are visible on each side of the heart. Figure 22-2 The lobes and fissures of the lungs. The pleurae are shown in blue (based on Brock.) Figure 22-3 Diagrams of pleural reflections. A, Coronal section of the right lung and pleura. Lines B to E indicate the respective planes and levels of sections shown in diagrams B to E.

B, Upper horizontal section. Note the costomediastinal and retro-esophageal recesses. C, Middle horizontal section. Note that the anterior border of the pleura forms the edge of the costomediastinal recess and that the oblique fissure reaches almost to the hilus. D, Lower horizontal section, showing also relationships to the pericardium. Note that the pulmonary ligament is formed by the double reflection of the pleura below the hilus of the lung. The mediastinal pleura is adherent to the fibrous pericardium, except where the phrenic nerve descends between them (not shown). E, Sagittal section. Figure 22-4 Mirror-image views of the right lung and mediastinal structures. The line of reflection of the parietal to the visceral pleura is shown as a white line around the hilus, prolonged below as the two-layered pulmonary ligament. Impressions produced by mediastinal structures have been indicated on the medial surface of the lung as they might appear in a hardened lung.

(Based on Mainland and on Mainland and Gordon.) The inset shows the relationships at the hilus, including the eparterial (upper lobe) bronchus. Note that in this and in similar drawings, because the pulmonary veins contain oxygenated blood, they are shown in red; correspondingly, the pulmonary arteries are shown in blue. Figure 22-5 Mirror-image views of the left lung and mediastinal structures, similar to figure 22-4 . The inset shows the relationships at the hilus. Figure 22-6 The segmental bronchi and bronchopulmonary segments. See also figs. 21-4 and 22-8 and table 22-1 . Figure 22-7 The primary lung volumes. The outermost line represents the greatest size to which the lung can expand. (Based on Comroe et al.) Figure 22-8 Postero-anterior bronchograms. A, Right lung. B, Left lung. (From Medical Radiography and Photography, courtesy of J. Stauffer Lehman, M.D., and J.

Antrim Crellin, M.D., Philadelphia, Pennsylvania.) For terminology see table 22-1 . Jump to: Lungs Lungs Home > Respiratory System > Lungs and Respiratory System of the Chest > Lungs Lungs The human lungs are a pair of large, spongy organs optimized for gas exchange between our blood and the air. Our bodies require oxygen in order to survive. The lungs provide us with that vital oxygen while also removing carbon dioxide before it can reach hazardous levels. If the inner surface of the lungs could be stretched out flat, they would occupy an area of around 80 to 100 square meters – about the size of half of a tennis court! The lungs also provide us with the air we need in order to speak, laugh at jokes, and sing.... Move up/down/left/right: Click compass arrows Rotate image: Click and drag in any direction, anywhere in the frame Identify objects: Click on them in the image Anatomy of the Lungs Pleura The pleura are double-layered serous membranes that surround each lung. Attached to the wall of the thoracic cavity, the parietal pleura forms the outer layer of the membrane.

The visceral pleura forms the inner layer of the membrane covering the outside surface of the lungs. Between the parietal and visceral pleura is the pleural cavity, which creates a hollow space for the lungs to expand into during inhalation. Serous fluid secreted by the pleural membranes lubricates the inside of the pleural cavity to prevent irritation to the lungs during breathing. External Anatomy Occupying most of the space within the thoracic cavity, the lungs extend laterally from the heart to the ribs on both sides of the chest and continue posteriorly toward the spine . Each soft, spongy lung is roughly cone-shaped with the superior end of the lung forming the point of the cone and the inferior end forming the base. The superior end of the lungs narrows to a rounded tip known as the apex. The inferior end of the lungs, known as the base, rests on the dome-shaped diaphragm . The base of the lungs is concave to follow the contour of the diaphragm. The left lung is slightly smaller than the right lung because 2/3 of the heart is located on the left side of the body. The left lung contains the cardiac notch, an indentation in the lung that surrounds the apex of the heart.

Each lung consists of several distinct lobes. The right lung (the larger of the two) has 3 lobes – the superior, middle, and inferior lobes. The horizontal fissure separates the superior lobe from the middle lobe, while the right oblique fissure separates the middle and inferior lobes. The smaller left lung only has 2 lobes – superior and inferior – separated by the left oblique fissure. Bronchi Air enters the body through the nose or mouth and passes through the pharynx, larynx , and trachea . Just before reaching the lungs, the trachea then splits into the left and right bronchi – large, hollow tubes made of hyaline cartilage and lined with ciliated pseudostratified epithelium. The hyaline cartilage of the bronchi forms incomplete rings shaped like the letter “C” with the open part of the ring facing toward the posterior end of the bronchi. The rigid hyaline cartilage prevents the bronchi from collapsing and blocking airflow to the lungs.

Pseudostratified epithelium lines the inside of the hyaline ring and connects the unfinished ends of the ring to form a hollow tube shaped like the letter “D” with the flat part of the tube facing the posterior direction. Each lung receives air from a single, large primary bronchus. As the primary bronchi enter the lungs, they branch off into smaller secondary bronchi that carry air to each lobe of the lung. Thus, the right bronchus branches off into 3 secondary bronchi while the left lung branches off into 2 secondary bronchi. The secondary bronchi further branch into many smaller tertiary bronchi within each lobe. The secondary and tertiary bronchi improve the efficiency of the lungs by distributing air evenly within each lobe of the lungs. The pseudostratified epithelium that lines the bronchi contains many cilia and goblet cells. Cilia are small hair-like cellular projections that extend from the surface of the cells. Goblet cells are specialized epithelial cells that secrete mucus to coat the lining of the bronchi. Cilia move together to push mucus secreted by the goblet cells away from the lungs.

Particles of dust and even pathogens like viruses, bacteria and fungi in the air entering the lungs stick to the mucus and are carried out of the respiratory tract. In this way mucus helps to keep the lungs clean and free of disease. Bronchioles Many small bronchioles branch off from the tertiary bronchi. Bronchioles differ from bronchi both in size (they are smaller) and in the composition of their walls. While bronchi have hyaline cartilage rings in their walls, bronchioles are made of elastin fibers and smooth muscle tissue. The tissue of the bronchiole walls allows the diameter of bronchioles to change to a significant degree. When the body requires greater volumes of air entering the lungs, such as during exercise, the bronchioles dilate to permit greater airflow. In response to dust or other environmental pollutants, the bronchioles can constrict to prevent the pollution of the lungs. The bronchioles further branch off into many tiny terminal bronchioles. Terminal bronchioles are the smallest air tubes in the lungs and terminate at the alveoli of the lungs. Like bronchioles, the terminal bronchioles are elastic, capable of dilating or contracting to control airflow into the alveoli.

Alveoli Alveoli are the functional units of the lungs that permit gas exchange between the air in the lungs and the blood in the capillaries of the lungs. Alveoli are found in small clusters called alveolar sacs at the end of the terminal bronchiole. Each alveolus is a hollow, cup-shaped cavity surrounded by many tiny capillaries. The walls of the alveolus are lined with simple squamous epithelial cells known as alveolar cells. A thin layer of connective tissue underlies and supports the alveolar cells. Capillaries surround the connective tissue on the outer border of the alveolus. The respiratory membrane is formed where the walls of a capillary touch the walls of an alveolus. At the respiratory membrane, gas exchange occurs freely between the air and blood through the extremely thin walls of the alveolus and capillary. Septal cells and macrophages are also found inside the alveoli. Septal cells produce alveolar fluid that coats the inner surface of the alveoli.

Alveolar fluid is extremely important to lung function, as it is a surfactant that moistens the alveoli, helps maintain the elasticity of the lungs, and prevents the thin alveolar walls from collapsing. Macrophages in the alveoli keep the lungs clean and free of infections by capturing and phagocytizing pathogens and other foreign matter that enter the alveoli along with inhaled air. Physiology of the Lungs Pulmonary Ventilation Our lungs receive air from the external environment through the process of negative pressure breathing. Negative pressure breathing requires a pressure differential between the air inside the alveoli and atmospheric air. Muscles surrounding the lungs, such as the diaphragm, intercostal muscles , and abdominal muscles, expand and contract to change the volume of the thoracic cavity. Muscles expand the thoracic cavity and decrease the pressure inside the alveoli to draw atmospheric air into the lungs. This process of drawing air into the lungs is known as inhalation or inspiration. Muscles can also contract the size of the thoracic cavity to increase the pressure inside of the alveoli and force air out of the lungs. This process of pushing air out of the lungs is known as exhalation or expiration.

Normal breathing involves several different mechanisms. Shallow breathing is accomplished by the contraction of the diaphragm and the external intercostal muscles for inhalation. During exhalation, the muscles relaxing and the elasticity of the lungs returning to their resting volume expels air out of the lungs. Our bodies accomplish deep breathing by a pronounced inferior movement of the diaphragm towards the abdomen. The external intercostal muscles along with the sternocleidomastoid and scalene muscles in the neck expand the space between the ribs, increasing the volume of the chest. During deep exhalation, the internal intercostal muscles and abdominal muscles contract to decrease the volume of the thoracic cavity, forcing air out of the lungs. Eupnea is the quiet breathing that happens when the body is at rest. During eupnea, the body mostly depends on shallow breathing with occasional deep breaths as the body needs slightly higher levels of gas exchange. Lung Volume The total air volume of the lungs is about 4 to 6 liters and varies with a person’s size, age, gender, and respiratory health. Lung volumes are measured clinically by a device known as a spirometer.

Normal shallow breathing only moves a small fraction of the lungs’ total volume into and out of the body with each breath. This volume of air, known as tidal volume, usually measures only around 0.5 liters. Deep breathing can force more air into and out of the lungs than during shallow breathing. The volume of air exchanged during deep breathing is known as vital capacity and ranges between 3 to 5 liters, depending on the lung capacity of the individual. There is a residual volume of around 1 liter of air that remains in the lungs at all times, even during a deep exhalation. Fresh air entering the lungs with each breath mixes with the residual air in the lungs so that the residual air is slowly exchanged over time even at rest. External Respiration External respiration is the process of exchanging oxygen and carbon dioxide between the air inside the alveoli and the blood in the capillaries of the lungs. Air inside the alveoli contains a higher partial pressure of oxygen compared to the blood in the capillaries. Conversely, blood in the lungs' capillaries contains a higher partial pressure of carbon dioxide compared to the air in the alveoli.

These partial pressures cause oxygen to diffuse out of the air and into the blood through the respiratory membrane. At the same time, carbon dioxide diffuses out of the blood and into the air through the respiratory membrane. The exchange of oxygen into the blood and carbon dioxide into the air allows the blood leaving the lungs to provide oxygen to the body’s cells, while depositing carbon dioxide waste into the air. Control of Breathing Breathing is controlled by the brain and may be controlled both consciously and unconsciously. Unconscious control of breathing is maintained by the respiratory center of the brainstem . The respiratory center monitors the concentration of gases in the blood and adjusts the rate and depth of breathing as needed. During exercise or other exertion, the respiratory center automatically increases the breathing rate to provide constant levels of oxygen to the blood. During rest, the respiratory center reduces the breathing rate to prevent hyperventilation and maintain healthy oxygen and carbon dioxide levels in the blood. Conscious control of breathing is maintained by the cerebral cortex of the brain . The cerebral cortex may override the respiratory center and often does so during activities such as speaking, laughing, and singing.

Unconscious control of breathing resumes as soon as conscious control of breathing ends, preventing the body from suffocating from lack of breathing. Prepared by Tim Taylor, Anatomy and Physiology Instructor Bronchus - Structure, Function, and Conditions Updated November 13, 2016 Definition: Bronchus A bronchus is either of the two major branches of the trachea that lead to the lungs. The bronchi begin when the trachea divides to form the right and left main bronchi (pleural of bronchus.) These bronchi, in turn, travel to each of the lungs. The bronchi divide first into lobar bronchi and then tertiary bronchi. These vessels become progressively smaller as they divide into bronchioles, terminal bronchioles, respiratory bronchioles, alveolar sacs, and finally into the alveoli where the exchange of oxygen and carbon dioxide takes place. The bronchi are made up of smooth muscles with walls of cartilage giving them stability. Structure of the Bronchi Right main bronchus - The right main bronchus is shorter and more vertical than the left, approximately 2.5 m (around 1 inch) in length.

It divides into smaller bronchi to enter the 3 lobes of the right lung. Left main bronchus - The left bronchus is smaller and longer than the right main bronchus (approximately 5 cm or 1.5 inches.) It, in turn, divides into 2 lobar bronchi which enter the 2 lobes of the left lung. Bronchial Function The bronchi function as a passageway for air to travel from the mouth and trachea, down to the alveoli, and back out to the environment. Conditions Involving the Bronchi Some medical conditions which can involve the bronchi include: Bronchitis - Both acute bronchitis and chronic bronchitis are an inflammation of the tissue of the bronchi. Chronic is one form of chronic obstructive pulmonary disease (COPD) a condition which is the 4th leading cause of death in the United States. Aspiration - If a foreign object is accidentally inhaled, it often becomes lodged in one of the bronchi. Aspiration may be suspected on an x-ray by the appearance of the lung beyond the obstruction. A bronchoscopy is often needed to remove a foreign body in these airways.

Lung cancer - Some lung cancers arise in the walls of the bronchi, especially tumors such as small cell lung cancer and squamous cell lung cancer . In the past, these types of cancer were the most common type. In recent years, lung adenocarcinoma, a tumor that usually grows in the periphery of the lungs away from the airways is the most common form of lung cancer. It's thought by some that cancers near the airways were more common before cigarettes were filtered, and residue would lodge in these first airways. In contrast, with the addition of filters, toxins may be inhaled deeper into the lungs where adenocarcinomas occur. Asthma - Asthma is an illness characterized by constriction of the bronchi , which in turn interferes with the passage of air from the environment to the alveoli of the lungs. Among other treatments, asthma is often treated with bronchodilators - medications used to dilate the bronchi and relieve the constriction. Procedures Involving the Bronchus and Bronchi Bronchoscopy - A bronchoscopy is a procedure in which a tube (called a bronchoscope) is inserted through the mouth and into the bronchi.

A bronchoscopy may be performed in order to evaluate symptoms such as a persistent cough or coughing up blood, but can also be used to treat some conditions, such as bleeding in the airways, or removal of a foreign body. Pronunciation: bron-kus Examples: Jim was told that his lung cancer was located near his right main stem bronchus. Sources: Qureshi, A. and A. Behzadi. Foreign-body aspiration in an adult . Canadian Journal of Surgery. 2008. 51(3):E69-E70. U.S. National Library of Medicine. MedlinePlus. Chronic Bronchitis. Updated 05/11/16. Continue Reading Respiratory System Respiratory System Pulmonary ventilation (air in/out, gas exchanged in lungs) External respiration (gas exchanged between blood and alveoli in lungs) Transport of respiratory gases (transport of oxygen and carbon dioxide) Internal respiration (gas exchange between blood and tissues) II.

Functional Anatomy of Respiratory System (Nose, pharynx, larynx, trachea, bronchi, lungs, and alveoli ) Diagram Consists of two zones: Respiratory zone - actual site of gas exchange (bronchioles, a;veolar ducts, alveoli) Conducting zones - all other respiratory passageways A. Nose Moistens and warms entering air Filters inspired air and cleanses it Serves as resonating chamber for speech Houses the olfactory (smell) receptors ii.

Nose structure Diagram External nose composed of dense fibrous connective tissue and cartilage attached to nasal, frontal, and maxillary bone External nares (nostrils) lead into nasal cavity which is divided by the nasal septum (composed of hyaline cartilage and vomer bone) Nasal cavity entrance contains vestibule with vibrissae Nasal cavity lined with olfactory mucosa and respiratory mucosa (mucous and serous glands) and contains lateral projections (superior, middle, inferior nasal conchae) Internal nares in posterior nasa cavity lead into the nasopharynx Connects nasal cavity and mouth to larynx and esophagus (throat) Three regions: Nasopharynx - lined with pseudostratified epithelium and houses the pharyngeal tonsil (adenoids) Oropharynx - lined with stratified squamous epithelium, located posterior to oral cavity, include archway (fauces) between uvula and epiglottis, and contain palantine and lingual tonsils Laryngopharynx - lined with stratified squamous epithelium, common passageway for food and air, posterior to epiglottis Voice box attached to

 hyoid superiorly and inferiorly with trachea Composed of corniculate, arytenoid, cricoid, and thyroid cartilage Functions: Act as switching mechanism (epiglottis) to route air and food Voice production (vestibular fold or false vocal chord and vocal fold or true vocal cord) D.

Trachea Diagram Windpipe Descends from larynx through neck into mediastinum and ends by dividing (at carina) into two primary bronchi Walls (mucosa, submucosa, hyaline cartilage and adventitia) lined with pseudostratified epithelium E. Bronchi and Subdivisions (bronchial tree) Conducting zone structures - right and left primary (principle) bronchi branch into: Secondary bronchi (3 on right 2 on left) which branch into Tertiary (segmental) bronchi which branch into 4th, 5th, etc...

23 orders Until bronchioles then terminal bronchioles Tissue composition of walls of primary bronchi is same as trachea but decreases in size of conducting tubes, then increase in change in composition with each subsequent subdivision: Cartilage rings replaced by irregular plates of cartilage Epithelium: Pseudostratified, then columnar, then cuboidal; cilia and mucus producing cells only in upper bronchioles Diagram Smooth muscle increases with decreasing size of bronchioles Respiratory zone structures - terminal bronchioles divide into respiratory bronchioles with scattered air sac outpocketing from walls, branch into Alveolar ducts with sacs called alveoli (chambers where bulk gas exchange occurs) Alveolar sacs open into a common chamber called an atrium Air sacs (alveoli) provide surface area for gas exchange Diagram Respiratory membrane - Diagram single layer of squamous epithelium (Type I pneumocytes) with pulmonary capillaries Respiratory membrane (air-blood barrier) site of gas exchange (by diffusion) Diffusion requires moist membrane, therefore there are cuboidal epithelium (Type II pneumocytes) that secretes surfactant, coating gas-exposed alveolar surfaces Alveoli

 contain alveolar macrophages that provide an immunologic defense.

F. Lungs and Plurae Air (gases) flows out of lungs down its pressure gradient until intrapulmonary pressure is zero Ribs and sternum depressed as external intercostals relax; diaphragm moves superiorly as it relaxes C. Respiratory Status i. Respiratory Volumes: (measured by spirometer) Diagram (TV) tidal volume - amount of air inhaled or exhaled with each breath under resting conditions (IRV) inspiratory reserve volume - amount of air that can be forcefully inhaled after a normal tidal volume inhalation (ERV) expiratory reserve volume - amount of air that can be forcefully exhaled after a normal tidal volume exhalation (RV) residual volume - amount of air remaining in the lungs after a forced exhalation ii.

Respiratory Capacities: (TLC) total lung capacity - maximum amount of air contained in lungs after a maximum inspiratory effort (TLC = TV + IRV + ERV + RV) (VC) vital capacity - maximum amount of air that can be expired after a maximum inspiratory effort (VC = TV + IRV + ERV) (IC) inspiratory capacity - maximum amount of air that can be inspired after a normal expiration (IC = TV + IRV) (FRC) functional residual capacity - volume of air remaining in the lungs after a normal tidal volume expiration (FRC = ERV + RV) IV. Transport of Respiratory Gases by Blood A. Oxygen Oxyhemoglobin (HbO2) / doexyhemoglon (Hhb) Hemoglobin - composed of four polypeptide chains each containing and iron (heme) group; Oxygen binding is result of "cooperation"; first oxygen bound to one heme causing change in shape of hemoglobin so that the other peptides will bind more oxygen affinity for oxygen increases with each oxygen bound until saturation; conversely, release of oxygen from hemoglobin increases with each oxygen released B.

Carbon Dioxide Active body cells produce about 200ml of carbon dioxide/minute(released by lungs) Carbon dioxide is transported in blood in three forms: Dissolved in plasma (7% to 10%), remainder enter RBCs Chemically bound to hemoglobin in RBCs (20% to 30%); carried within RBCs as carboaminohemoglobin; carbon dioxide binds to amino acids not heme, therefore does not compete with the oxyhemoglobin transport As a bicarbonate ion in plasma (60% to 70%), carbon dioxide is converted to bicarbonate ions and transported in plasma C.

Respiratory Center Atelectasis - collapse or incomplete expansion of lungs Cheyne-Stokes respiration - irregular breathing (increase/decrease in depth and rapidity) Laryngitis - inflammation of the vocal cords Pleurisy - inflammation of the pleura Infant respiratory distress syndrome (IRDS) - insufficient surfactant produced, surface tension forces collapse of the alveoli Hypoxia - inadequate amount of oxygen circulated to no oxygen delivered to body cells Hypoxic - lack of oxyen getting from lungs to heart Anemic - to few RBCs, or RBCs with inadequate hemoglobin Ischemic (stagnant) - blood circulation is impaired or blocked Histotoxic - interference with gas exchange betweem capillaries and target tissue/organ Hypercapnia - increase in carbondioxide levels in cerebrospinal fluid, causing pH to decrease, exciting chemoreceptors to make synapses with respiratory centers; depth and rate of breath increases (hyperventilation) Hypocapnia - apnea (breathing cessation) Chronic Obstructive Pulmonary Disease (COPD), common features: Patients with history of smoking Dyspnea - difficult or labored breathing Coughing and frequent pulmonary infection Will develop respiratory failure Obstructive

 emphysema - permanent enlargement of the alveoli, deterioration of alveolar walls Chronic inflammation leads to lung fibrosis (lungs lose their elasticity) Victims sometimes called "pink puffers" - breathing is labored, but doesn't become cyanotic because gas exchange remains adequate until late in the disease Chronic bronchitis - inhaled irratants lead to chronic excessive mucus production by the mucosa of lower respiratory passageways and inflammation and fibrosis of that mucosa Victims sometimes called "blue bloaters" - hypoxia and cabon dioxide retention occur Respiratory System ANAT.

502.001, Dr. A.K. Szakal Function: To conduct air to and from the lungs. Function: To provide for the exchange of CO2 & O2 in the blood . C. GROSS RELATIONSHIP: Fig. 1 & Fig. 2. Figure 1. Depicts general gross organization of the respiratory system. Figure 2. Frontal sections depicting orientation of lab slides. II. HISTOLOGY OF THE CONDUCTING SYSTEM A. THE NOSE -- a hollow organ, covered with skin, provided with muscles, supported by cartilage and bone and lined with a mucous membrane. B. THE NASAL CAVITIES -- (separated by the cartilaginous and bony parts of the nasal septum). 1. The vestibule -- opens to the outside at the anterior nares. The integument continues into the vestibule; Changes from cornified stratified squamous epithelium (associated with hairs, sebaceous and sweat glands) gradually to pseudostratified, ciliated, columnar epithelium in the rest of the nasal cavities (i.e. atrium, superior-, middle-, and inferior meatus; the surface of conchae). 2.

The respiratory region -- includes nearly all of the septum and lateral walls. The surface area of the lateral walls is increased by shelf-like projections (supported by bone) called conchae (Figure 3). a. Epithelium: pseudostratified, ciliated columnar with goblet cells; Cilia beatsbackwards, toward the pharynx; Goblet cells sometimes are concentrated in intraepithelial pits; The basement membrane varies from thin to very thick. b. Lamina propria: of loose FECT; i. contains: mixed sero-mucous glands (comp. tubuloalveolar); ii. contains: a rich cavernous venous plexus, which serves to warm the passing air; upon irritation the plexus can be distended by blood and reduces air flow. c. Submucosa: lacking, the deepest layer of the lamina propria fuses with the periosteum below; 3. The olfactory region -- located on the superior concha and adjacent septum (dime-size areas). a. Epithelium: pseudostratified ciliated columnar; composed of olfactory cells, supporting cells, and basal cells. (Figure 4).

i. Olfactory cells: spindle shaped, with round nuclei; (Nuclei are in the middle and deep zone of the epithelium.) the apical part extends to the epithelial surface, ends in a bulbous knob which bears 6-8 olfactory hairs; these hairs or cilia are non-motile, sensory and serve as dendrons; they are embedded in a thick layer of mucus and parallel the surface of the olfactory epithelium. The proximal (basal) part of the cells form a long thin axonal process, which constitute the olfactory nerve fibers; these unmyelinated fibers are connected to the olfactory center of the brain (in the olfactory bulbs). Olfactory cells are modified bipolar neurons. Functions: the olfactory cilia are stimulated by gaseous, odori-ferous substances dissolved in the secretion of serous glands moistening the epithelium. ii. Supporting cells: tall slender cells make up the upper third of the pseudostratified epithelium (nuclei in top 2-3 rows).

They are attached to the sensory (olf.) cells at the surface of the epithelium by zonula adherens (junctional complex with terminal web). Have a small Golgi complex in the apical cytoplasm and pigment granules (brown). There are numerous slender villi on their apical surface. iii. Basal cells: constitute a single layer of conical elements a the base of supporting cells (bottom layer of nuclei); have dark nuclei and branching processes. b. Lamina propria: continuous with the dense connective tissue of the underlying periosteum in the adult or with the perichondrium in the fetus. The venous plexus in the lamina propria is continuous with that of the respiratory regions. A group of branched, tubuloalveolar (mainly serous) olfactory glands called Bowman's glands present in the lamina propria supply the necessary solvents to trap odoriferous substances. The continuous replacement of secretion keeps the receptors ready for new stimuli. ************************************************************************* LABORATORY EXERCISE: Nasal Cavity -- Fetal. Go to the Digital Histology CD then examine the virtual slide entitled nose, olfactory epithelium.

Identify the nasal cavity, nasal septum and conchae on CD. What type of cartilage is present? What type of epithelia lines the nasal cavity? Can you identify areas lined with olfactory epithelium on both CD and VS? How can olfactory epithelium be distinguishes from respiratory epithelium? compare the epithelial lining of the developing oral cavity to the epithelium of nasal cavities. Identify olfactory epithelium. Identify the venous plexus in the lamina propria on CD and VS. ************************************************************************* C. THE PHARYNX -- is a flattened conical chamber through which air and food pass. It is divided partly by the soft palate into: 1. Naso-pharynx -- lined with ciliated columnar epithelium with goblets cells; 2. Oro-pharynx -- lined with moist stratified squamous epithelium. D. THE LARYNX -- is interposed between the pharynx and the trachea. It is supported by cartilages and muscles; and contains the vocal folds (cords). Figure 5. 1. Epithelium -- varies according to wear and tear in the different regions of the larynx.

a. The epiglottis -- which closes that laryngeal aperture like a lid, is covered by moist stratified squamous epithelium; b. The false vocal cords - (located above the true vocal cords) are covered with pseudostratified, ciliated columnar epithelium with goblet cells. c. The true vocal cords - are covered with moist stratified squamous epithelium. d. The rest of the larynx is covered with pseudostratified, ciliated columnar epithelium with goblet cells (including the lateral walls of the laryngeal ventricles between the false and true vocal cords), resting on a thin basement membrane. The cilia beat toward the mouth, moving the mucus and attached particles or bacteria toward the exterior. Figure 7. Illustrates the microanatomy of bronchioles and alveolar sacs. A. RESPIRATORY BRONCHIOLE -- in adult man they begin with a 0.5mm diameter. A few alveoli bud from their walls. 1.

Epithelium -- starts with a simple ciliated columnar epithelium which is reduced in a short distance to a simple (non-ciliated) low cuboidal epithelium. 2. Wall -- composed of collagenous C.T. interlaced with bundles of smooth muscle. (The few alveoli associated with the wall are responsible for the term "respiratory bronchiole.") B. ALVEOLAR DUCTS -- are the branches (2 to 11) of respiratory bronchioles. These are thin walled tubules. Their wall is interrupted by the opening of many thin walled outpouchings, the alveoli. 1. Epithelium -- not distinguishable. 2. Wall -- composed of strands of elastic and collagenous fibers, and a few smooth muscle cells which are visible around the mouth of alveolar sacks. C. ALVEOLAR SACKS -- are composed of 2 to 4 or more alveoli. Alveolar sacks open only into the alveolar ducts. The space into which alveolar sacks open in the alveolar duct is called the atrium. D.

THE ALVEOLUS -- is a thin walled polyhedral sack which opens on one side only into the alveolar sack or individually into an alveolar duct ( Figure 8.) Pulmonary cavity, Pleurae, and Lungs at Pacific Northwest University of Health Sciences - StudyBlue StudyBlue Pulmonary cavity, Pleurae, and Lungs Anonymous What are the boundaries of the thoracic cavity vertebral bodies and discs, sternum, ribs and costal cartilages What do the 2 pulmonary cavities house lungs and pleura What does the mediastinum contain heart and great vessels, trachea and esophagus What are the two openings at top and bottom of thorax called thoracic inlet and thoracic outlet What is the route air takes on way to lungs nose or mouth-> pharynx-> larynx-> trachea-> R or L main bronchi-> bronchiole-> alveoli What vertebral level does the trachea divide into L or R bronchi T4 Where does gas exchange take place alveoli continuous invigilated mesothelial sac that lines the pulmonary cavity and covers the lungs How far does cervical pleura extend above clavicle and first rib into thoracic inlet What

 reinforces the cervical pleura suprapleural membrane (Sibson's fascia) What lines the superior diaphragm?

What ligament attaches the the diaphragmatic pleura to the superior part of the diaphragm? What fascia is this a part of? diaphragmatic pleura Phrenicopleura ligament, a part of endothoracic fascia. Name two pleural recesses?

I don’t know look in the mirror and tell me what you see What covers and adheres to the surface of the lung visceral pleura What makes the pleural cavity the space b/t the parietal and visceral pleura Advertisement What does the pleural cavity normally contain small amount of serous fluid Learn the reflections conically shaped, apex and base, 3 surfaces and 3 borders What are the borders of the lung anterior posterior and inferior Visualize how the lung is shaped in the thorax Remember it for the test What portion of the lung is concave mediastinal surface(contains root) and diaphragmatic surface What part of the lung is convex lateral costal surface What enters and leaves the hilum of the lung (hint Root) bronchus, arteries, veins, nerves, lymphatic's What are the fissures of right lung oblique (major) and horizontal (minor) How many lobes does right lung have and names 3 superior, middle and inferior What are the fissures of left lung only one Oblique fissure How many and names of left lung lobes 2 superior and inferior How far does apex of lung extend above first rib Where does the inferior margin of each lung stop 2 intercostal spaces higher than inferior

 margin of pleural cavity Where do the oblique fissures run rib 4 posteriorly to rib 6 near sternum Where does the horizontal fissure run in relation to thorax ICS 4 anterior to midaxillary line What bronchus is wider, shorter and more vertical right Which bronchus passes more horizontally left and close to great vessels of heart What marks the bifurcation of the trachea into R and L Main bronchi Carina What does a Main bronchi give rise to Lobar (secondary) bronchi What do Lobar bronchi give rise to several segmental (tertiary) bronchi What is the smallest subdivision of a lung bronchopulmonary segment Bronchopulmonary characteristics conic or pyramidal shape, aerated by one segmental bronchus, gets 1 branch of pulm.

Artery, has CT septa, venous drainage b/t septa How many bronchopulmonary segments in each lung 10.0 Where do pulmonary arteries enter hilum ->Lobar -> segmental-> similar to bronchus branching How many arteries supply a bronchopulmonary segment 1 non overlapping segmental branch What is end point of pulmonary arterial system capillary network that surrounds alveoli What is return route for blood from capillaries cap.-> two pulmonary veins-> through hilum-> dump in left atrium Where does left bronchial artery arise from thoracic aorta Where does right bronchial artery arise from intercostal artery, direct branch of aorta, or left bronchial artery Do bronchial and pulmonary arteries anastomose Oh yeah What are the 2 routes for lymph drainage superficial and deep routes What does superficial lymph plexus drain visceral pleura and lung tissue to the Hilar lymph nodes What does the deep lymph plexus drain along bronchial tree to Hilar nodes at root of lung Do Hilar lymph nodes drain to separate places yes Right bronchopulmonary nodes drain to right superior tracheobronchial lymph nodes and channels Left bronchopulmonary nodes

 drain to left superior lobe to left superior tracheobronchial nodes Where does left inferior lobe drain to right tracheobronchial nodes and channels Pulmonary plexus contains sympathetic, parasympathetic, and sensory fibers Actions of sympathetics constrict pulmonary vessels, inhibit bronchial smooth muscle, inhibit secretion by alveolar glands Where are sympathetic preganglionic cell bodies upper thoracic level of spinal cord Where are parasympathetic preganglionic cell bodies in brain stem axons travel via vagus Where are parasympathetic postganglionic cell bodies in small ganglia scattered within pulmonary plexus Actions of parasympathetics inhibit vasoconstriction, produce bronchoconstriction, stimulate mucous secretion in airway Where are sensory cell bodies found in ganglia near base of skull How do the sensory fibers distribute to the pulmonary plexus as components of vagus nerve What causes cough reflex

Question: Where are the pleurae, bronchi and alveoli?
Answer: Lungs