THE RESPIRATORY SYSTEM THE RESPIRATORY SYSTEM VISCERA OF THORACIC - PowerPoint PPT Presentation

THE RESPIRATORY SYSTEM

THE RESPIRATORY SYSTEM VISCERA OF THORACIC CAVITY

VISCERA OF THORACIC CAVITY THE RESPIRATORY SYSTEM The thoracic cavity is divided into three compartments: • Right and le9 pulmonary caviBes , bilateral compartments that contain the lungs and pleurae and occupy the majority of the thoracic cavity. • A central mediasBnum , a compartment intervening between and completely separaFng the two pulmonary caviFes, which contains essenFally all other thoracic structures: the heart, thoracic parts of the great vessels, thoracic part of the trachea, esophagus, thymus, and other structures (e.g., lymph nodes).

PLEURAE THE RESPIRATORY SYSTEM Each lung is invested by and enclosed in a serous pleural sac that consists of two conBnuous membranes : the visceral pleura , which invests all surfaces of the lungs forming their shiny outer surface, and the parietal pleura , which lines the pulmonary caviFes The pleural cavity - the potenBal space between the layers of pleura - contains a capillary layer of serous pleural fluid , which lubricates the pleural surfaces and allows the layers of pleura to slide smoothly over each other during respiraFon. The visceral pleura (pulmonary pleura) closely covers the lung and adheres to all its surfaces, including those within the horizontal and oblique fissures. The visceral pleura is conFnuous with the parietal pleura at the hilum of the lung , where structures making up the root of the lung (e.g., bronchus and pulmonary vessels) enter and leave the lung.

PLEURAE THE RESPIRATORY SYSTEM The parietal pleura lines the pulmonary caviFes, thereby adhering to the thoracic wall, mediasFnum, and diaphragm. The parietal pleura consists of three parts: • costal, • mediasFnal, • diaphragmaFc • and the cervical pleura. The costal part of the parietal pleura (costovertebral or costal pleura) covers the internal surfaces of the thoracic wall. It is separated from the internal surface of the thoracic wall (sternum, ribs and costal carFlages, intercostal muscles and membranes, and sides of thoracic vertebrae) by endothoracic fascia .

PLEURAE THE RESPIRATORY SYSTEM The mediasBnal part of the parietal pleura (mediasFnal pleura) covers the lateral aspects of the mediasFnum The diaphragmaBc part of the parietal pleura (diaphragmaFc pleura) covers the superior (thoracic) surface of the diaphragm on each side of the mediasFnum, except along its costal a.achments (origins) and where the diaphragm is fused to the pericardium A thin, more elasFc layer of endothoracic fascia, the phrenicopleural fascia , connects the diaphragmaFc pleura with the muscular fibers of the diaphragm The cervical pleura covers the apex of the lung - the part of the lung extending superiorly through the superior thoracic aperture into the root of the neck.

LUNGS THE RESPIRATORY SYSTEM The lungs are the vital organs of respiraFon. Their main funcFon is to oxygenate the blood by bringing inspired air into close relaFon with the venous blood in the pulmonary capillaries. The lungs are separated from each other by the mediasBnum . Each lung has: • apex • base • two or three lobes • three surfaces • three borders

LUNGS THE RESPIRATORY SYSTEM Each lung has: an APEX , the blunt superior end of the lung ascending above the level of the 1st rib into the root of the neck; the apex is covered by cervical pleura. A BASE , the concave inferior surface of the lung, opposite the apex, resFng on and accommodaFng the ipsilateral dome of the diaphragm TWO OR THREE LOBES , created by one or two fissures. THREE SURFACES (costal, mediasFnal, and diaphragmaFc). THREE BORDERS (anterior, inferior, and posterior).

LUNGS THE RESPIRATORY SYSTEM The right lung is larger and heavier than the leQ The right lung features right oblique and horizontal fissures that divide it into three right lobes : • superior • middle • inferior. The le9 lung has a single leQ oblique fissure dividing it into two leQ lobes: • superior • inferior.

LUNGS THE RESPIRATORY SYSTEM The anterior border of the leQ lung has a deep cardiac notch The most inferior and anterior part of the superior lobe into a thin, tongue-like process, the lingula which extends below the cardiac notch The mediasBnal surface of the lung is concave because it is related to the middle mediasFnum The mediasBnal surface includes the hilum , which receives the root of the lung.

LUNGS THE RESPIRATORY SYSTEM The mediasBnum of the right lung : • groove for the esophagus • cardiac impression for the heart • groove for inferior and superior vena cava • groove for azygos vein The mediasBnum of the le9 lung : • cardiac impression for the heart • groove for the arch of the aorta and the descending aorta • smaller area for the esophagus

LUNGS THE RESPIRATORY SYSTEM The diaphragmaBc surface of the lung , which is also concave, forms the base of the lung, which rests on the dome of the diaphragm. The borders of the lung : • anterior • inferior • posterior The anterior border of the lung is where the costal and mediasFnal surfaces meet anteriorly and overlap the heart. The inferior border of the lung circumscribes the diaphragmaFc surface of the lung and separates this surface from the costal and mediasFnal surfaces. The posterior border of the lung is where the costal and mediasFnal surfaces meet posteriorly

LUNGS THE RESPIRATORY SYSTEM The roots of the lungs – where the lungs are aSached to the mediasFnum. A short tubular collecFon of structures that together aSach the lung to structures in the mediasFnum. The roots of the lungs contains: • bronchi and associated bronchial vessels, • pulmonary arteries, • superior and inferior pulmonary veins, • pulmonary plexuses of nerves (sympatheFc, parasympatheFc), • lymphaFc vessels Generally, the pulmonary artery is superior at the hilum , the pulmonary veins are inferior , and the bronchi are somewhat posterior in posiFon.

THE RIGHT LUNGS THE RESPIRATORY SYSTEM The right lung has three lobes and two fissures. The oblique fissure separates the inferior lobe (lower lobe) from the superior lobe and the middle lobe of the right lung. The horizontal fissure separates the superior lobe (upper lobe) from the middle lobe.

THE LEFT LUNGS THE RESPIRATORY SYSTEM The le9 lung is smaller than the right lung and has two lobes separated by an oblique fissure. The oblique fissure of the leQ lung is slightly more oblique than the corresponding fissure of the right lung. Inferior to the root of the lung, this conFnuity between parietal and visceral pleura forms the pulmonary ligament , extending between the lung and the mediasFnum, immediately anterior to the esophagus.

LUNGS THE RESPIRATORY SYSTEM In the mediasFnum, the vagus nerves pass immediately posterior to the roots of the lungs, while the phrenic nerves pass immediately anterior to them.

TRACHEOBRONCHIAL TREE THE RESPIRATORY SYSTEM TRACHEA Is approximately 12 cm in length and has 16 to 20 incomplete hyaline carBlaginous rings that open posteriorly toward the esophagus and prevent the trachea from collapsing. Begins at the inferior border of the cricoid carBlage (C6) as a conFnuaFon of the larynx. Ends by bifurcaBng into the right and leQ main stem bronchi at the level of the sternal angle (disc between T4 and T5).

TRACHEOBRONCHIAL TREE THE RESPIRATORY SYSTEM TRACHEA Has the carina , a downward and backward projecFon of the last tracheal carFlage, which lies at the level of the sternal angle and forms a keel-like ridge separaFng the openings of the right and leQ main bronchi. Carina may be distorted, widened posteriorly, and immobile in the presence of a bronchogenic carcinoma. May be compressed by an aorFc arch aneurysm, a goiter, or thyroid tumors, causing dyspnea.

TRACHEOBRONCHIAL TREE THE RESPIRATORY SYSTEM RIGHT BRONCHUS The right main bronchus is wider, shorter, and runs more verBcally than the leQ main bronchus as it passes directly to the hilum of the lung. LEFT BRONCHUS The leQ main bronchus passes inferolaterally, inferior to the arch of the aorta and anterior to the esophagus and thoracic aorta, to reach the hilum of the lung.

TRACHEOBRONCHIAL TREE THE RESPIRATORY SYSTEM BRONCHI Each main bronchus divides into secondary lobar bronchi : • two on the leQ • three on the right Each lobar bronchus divides into several terFary segmental bronchi that supply the bronchopulmonary segments

TRACHEOBRONCHIAL TREE THE RESPIRATORY SYSTEM The bronchopulmonary segments are: • The largest subdivisions of a lobe • Pyramidal-shaped segments of the lung, with their apices facing the lung root and their bases at the pleural surface. • Separated from adjacent segments by connecFve Fssue septa. • Supplied independently by a segmental bronchus and terFary branch of the pulmonary artery. • Named according to the segmental bronchi supplying them • Drained by intersegmental parts of the pulmonary veins • Usually 18–20 in number (10 in the right lung; 8–10 in the leQ lung, depending on the combining of segments). • Surgically resectable

TRACHEOBRONCHIAL TREE THE RESPIRATORY SYSTEM LOBAR BRONCHI ê • segmental bronchi ê • terminal bronchioles ConducFng bronchioles Bronchioles lack transport air but lack • conducFng bronchioles carFlage in glands or alveoli. their walls • respiratory bronchioles ê • pulmonary alveolus The pulmonary alveolus is the basic structural • alveolar ducts unit of gas exchange in the lung. • alveolar sacs