Lower Respiratory System Lecture Notes PDF

(001) LOWER RESPIRATORYSYSTEM DR. GLENDA OGSIMER TAGORDA | 11/30/20 - The posterior free ends of the cartilage are connected...

(001) LOWER RESPIRATORYSYSTEM DR. GLENDA OGSIMER TAGORDA | 11/30/20 - The posterior free ends of the cartilage are connected by smooth muscle, the trachealis muscle. OUTLINE I. TRACHEA II. BRONCHI III. BRONCHIOLES IV. LUNGS V. LOBES AND FISSURE VI. BRONCHOPULMONARY SEGMENT VII. PLEURA VIII. MECHANISM OF BREATHING IX. TYPES OF RESPIRATION X. INSPIRATION vs EXPIRATION XI. TEST YOUR KNOWLEGE Figure 2. Cross section of trachea I. TRACHEA o The trachea is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus. o The cartilaginous rings are C- shaped to allow the trachea to collapse slightly at the opening so that food can pass down the esophagus. o The trachealis muscle connects the ends of the open part of the C-shaped rings and contracts during coughing, reducing the size of the lumen of the trachea to increase the air flow rate. o The esophagus lies posteriorly to the trachea. o The mucocilliary escalator helps prevent pathogens from entering the lungs. o The trachea is part of the conducting zone and contributes to anatomical dead space. B. LINING OF THE EPITHELIUM  Mucous membrane of the trachea is lined with pseudostratified ciliated columnar epithelium. Figure 1. Surface anatomy of trachea  Contains many goblet cells and tubular mucous glands. A. DESCRIPTION PSEUDOSTRATIFIED EPITHELIUM o Starts as: a continuation of the larynx at the lower border  Single layer of cells of different height, some not reaching of the cricoid cartilage at the level of the 6th cervical the free surface, nuclei seen at different levels, may contain vertebra, descends in the midline of the neck. mucus secreting goblet cells and bear cilia.  Ends at: the carina by dividing into right and left principal  Function: secretion particularly of mucus by ciliary action. (main) bronchi at the level of the sternal angle (opposite  Location: the disc between the 4th and 5th thoracic vertebrae). a. Non ciliated: male sperm carrying ducts and ducts of large glands. - During expiration, the bifurcation rises by about one b. Ciliated: respiratory tract. vertebral level - During deep inspiration may be lowered as far as the 6th thoracic vertebra  At the root of the neck, it may be palpated in the midline in the suprasternal notch.  In adults, Length is about 4 1/2 in. (11.25 cm) diameter: 1 in. (2.5 cm)  A mobile cartilaginous and membranous tube - The fibro elastic tube is kept patent by the presence of U-shaped cartilaginous bar (rings) of hyaline cartilage embedded in its wall. - There are about 15 to 20 C-shaped cartilaginous rings that reinforce the anterior and lateral sides of the trachea to protect and maintain the airway, leaving a membranous wall (pars membranacea) dorsally without cartilage where the C-shape is open. Figure 3. Pseudostratified ciliated columnar epithelium of trachea mucous membrane PREPARED BY: CMED 1A 2024 Page 1 of 13  (001) LOWER RESPIRATORYSYSTEM DR. GLENDA OGSIMER TAGORDA | 11/30/20 C. RELATIONS OF TRACHEA IN THE NECK  Anteriorly: Skin, fascia, isthmus of the thyroid gland (in front E. NERVE SUPPLY of the 2nd, 3rd 4th tracheal rings), inferior thyroid vein, jugular  The sensory nerve supply is from the vagi and the recurrent arch, thyroidea ima artery (if present). laryngeal nerves. Sympathetic nerves supply the trachealis  Posteriorly: Right and left recurrent laryngeal nerves and the muscle. esophagus.  Laterally: Lobes of the thyroid gland and the carotid sheath F. BLOOD SUPPLY and contents  The upper two thirds are supplied by the inferior thyroid arteries and the lower third is supplied by the bronchial arteries. Bronchial artery: origin is thoracic aorta.  Arterial: tracheal branches of inferior thyroid artery Venous: inferior thyroid venous plexus. G. LYMPH DRAINAGE  Into the pretracheal and paratracheal lymph nodes and the deep cervical nodes.  Pretracheal nodes Paratracheal cervical and thoracic lymph nodes II. BRONCHI  The trachea bifurcates behind the arch of the aorta into the right and left principal (primary or main) bronchi.  The bronchi divide dichotomously, giving rise to several million terminal bronchioles that terminate in one or more respiratory bronchioles. Figure 4. Relations of trachea in the neck, showing positions of  Each respiratory bronchiole divides into 2 to 11 alveolar ducts that various structures in the area enter the alveolar sacs.  The alveoli arise from the walls of the sacs as diverticula D. RELATIONS OF TRACHEA IN SUPERIOR (outpouching). MEDIASTINUM OF THE THORAX  Anteriorly: the sternum, the thymus, the left brachiocephalic A. COMPARISON BETWEEN PRIMARY, vein, the origins of the brachiocephalic and left common carotid SECONDARY, & TERTIARY BRONCHUS arteries, and the arch of the aorta  Posteriorly: The esophagus and the left recurrent laryngeal  PRIMARY BRONCHUS (MAIN) nerve  Right side: The azygos vein, the right vagus nerve, and the  Number: R:1; L:1 pleura.  Portion of the lung supplied by each: Left lung and  Left side: The arch of the aorta, the left common carotid and Right lung left subclavian arteries, the left vagus and left phrenic nerves,  Supporting structure: Rings of cartilages just like the and the pleura. trachea  SECONDARY BRONCHUS (LOBAR)  Number: R: 3 (superior, middle, inferior) and L:2 (Superior, inferior)  Portion of the lung supplied by each: Pulmonary lobe  Supporting structure: Overlapping plates of cartilage  TERTIARY BRONCHUS (SEGMENTAL)  Number: R:10; L:10  Portion of the lung supplied by each: Bronchopulmonary segment  Supporting structure: Overlapping plates of cartilage B. BLOOD SUPPLY  Bronchial tree is nourished by the bronchial artery, which arises from the aorta and carries systemic blood. Figure 5. Superior mediastinum PREPARED BY: CMED 1A 2024 Page 2 of 13  (001) LOWER RESPIRATORYSYSTEM DR. GLENDA OGSIMER TAGORDA | 11/30/20 A. TERMINAL BRONCHIOLES C. MAIN BRONCHOPULMONARY SEGMENTS  Final branches of the conducting division 1. Right lung  Function: air conduction a. Superior lobe (3): Apical, posterior, anterior  Alveolil: absent b. Middle lobe (2): Lateral, medial  Cilia: Bronchioles have a ciliated cuboidal epithelium. Cilia c. Inferior lobe (5): Superior (apical), medial basal, anterior basal, lateral basal, posterior basal allows the mucus draining into the terminal bronchioles from 2. Left lung the higher passages be driven back by the mucociliary a. Superior lobe (5): Apical, posterior, anterior, superior escalator, preventing congestion of the terminal bronchioles lingular, inferior lingular and alveoli. b. Inferior lobe (5): Superior (apical), medial basal,  Smooth muscle: Thin, incomplete circular layer of smooth anterior basal, lateral basal, posterior basal muscle; well-developed layer of smooth muscle in their walls enabling them to dilate or constrict. D. PRIMARY BRONCHI  Smaller division: Each terminal bronchiole gives off two or more smaller respiratory bronchioles. RIGHT PRINCIPAL (MAIN) BRONCHUS  It is wider, shorter, and more vertical. B. RESPIRATORY BRONCHIOLES  Its length is about 2.5 cm (1in)  It has three branches -  It marks the beginning of the respiratory division about 0.5 mm A. Before entering the Hilum of the right lung, gives off: in diameter. o Superior lobar bronchus  Function: Gas exchange - Gaseous exchange takes place B. On entering the hilum, it divides into a: between the air in the alveolar lumen through the alveolar wall o Middle lobar bronchus into the blood within the surrounding capillaries. o Inferior lobar bronchus  Alveoli: Defined by the presence of alveoli. Alveolus is surrounded by a rich network of blood capillaries. LEFT PRINCIPAL (MAIN) BRONCHUS  Cilia: Alveolar ducts and smaller divisions have nonciliated  It is narrower, wider, and more horizontal. simple squamous epithelia.  Its length is about 5 cm (2in).  Smooth muscle: Fewer smooth muscle fibers, mostly around  It has two branches alveolar openings. Their walls have scanty smooth muscle. o Superior lobar bronchus  Smaller division: Each divide into 2 to 10 elongated alveolar o Inferior lobar bronchus ducts 1. Alveolar ducts: thin-walled tubular passages that end in alveolar sacs. 2. Tubular passages with alveolar sacs: consist of several alveoli opening into a single chamber numerous thin-walled outpouchings grapelike clusters of alveoli. C. CLINICAL SIGNIFICANCE Diseases of the bronchioles include asthma, bronchiolitis obliterans, respiratory syncytial virus infections, and influenza. Figure 6. Different lobes of bronchi E. CLINICAL SIGNIFICANCE Because the right bronchus is the wider and more direct continuation of the trachea, foreign bodies tend to enter the right instead of the left bronchus. From there, they usually pass into the middle or lower lobe bronchi III. BRONCHIOLES  The smallest bronchi divide and give rise to bronchioles.  Airways of bronchioles are 1mm