Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 23 – Anatomy of the Respiratory System Dr. Kim Wilson Introduction to the Respiratory System • • • FUNCTIONS • 1. Providing an extensive surface area for gas exchange between air and circulating blood. • 2. Moving air to and from the exchange surfaces of the lungs. • 3. Protecting respiratory surfaces from the outside environment. • 4. Producing sounds. • 5. Participating in the olfactory sense. Filters, warms, and humidifies the air we breathe The respiratory tract consists of a conducting portion (from the nasal cavity to the terminal bronchioles) and a respiratory portion (the respiratory bronchioles and alveoli). Alveoli are the air-filled pockets within the lungs where all gas exchange takes place. Introduction to the Respiratory System • • • • Divided into two divisions for purpose of study Upper respiratory tract • Composition: nose, nasopharynx, oropharynx, laryngopharynx, & larynx Lower respiratory tract • Composition: trachea, all segments of the bronchial tree, & lungs Accessory structures: • Oral cavity • Rib cage • Diaphram Upper Respiratory Tract Organs - Nose • STRUCTURE (2 portions) • Internal portion (nasal cavity) • Lies over the roof of the mouth, separated by the palatine bones • If bones fail to unit cleft palate difficulty swallowing • Cribriform plate: separates the roof of the nose from the cranial cavity • Septum: separates the nasal cavity into right and left cavities • Consists of four structures • Ethmoid bone, the vomer bone, the vomeronasal cartilages, and the septal nasal cartilage Upper Respiratory Tract Organs - Nose • Structure cont. • External portion (visible portion) • Consists of a bony and cartilaginous frame covered by skin containing sebaceous glands • The two nasal bones meet and are surrounded by the frontal bone to form the root • The nose is surrounded by the maxilla Upper Respiratory Tract Organs - Nose • PASSAGEWAYS (meati) • Superior • Middle • Inferior • The meatuses are constricted passageways that produce air turbulence, giving incoming air time to warm and humidify, and particles to be trapped. Upper Respiratory Tract Organs - Nose • OPENINGS • Anterior nares (nostrils): external openings to the nasal cavities; open into the vestibule • Posterior nares: internal openings between nasal cavities and nasopharynx • Sequence of air flow through the nose into the pharynx: anterior nares vestibule three meatuses simultaneously posterior nares Upper Respiratory Tract Organs – Nose • • • • Nasal mucosa • A mucous membrane that air passes over; it contains a rich blood supply (Figure 23-4) Olfactory epithelium: special sensory membrane containing many olfactory nerve cells and a rich lymphatic plexus MICROSCOPIC ANATOMY • Tissue Type: Pseudostratified ciliated columnar epithelium • Mucous membrane with goblet cells • Contains cilia FUNCTION of nasal mucosa • Prepares inhaled air for arrival at the lower respiratory organs (warming and humidifying). • Breathing through your mouth bypasses this important step. Upper Respiratory Tract Organs – Nose • Paranasal sinuses • Four pairs of air-containing spaces that open or drain into the nasal cavity; each is lined with respiratory mucosa (Figure 23-5) • FUNCTIONS of the nose • Provides a passageway for air traveling to and from the lungs • Filters the air, aids speech, and makes possible the sense of smell Upper Respiratory Tract Organs – Pharynx • Pharynx (throat) • Pathway for the respiratory and digestive tracts • STRUCTURE: a tubelike structure extending from the base of the skull to the esophagus • 3 parts • Nasopharynx - Extends from posterior nares to soft palate • Oropharynx - Extends from soft palate to hyoid bone • Contains: the palatine tonsils (most commonly removed) and the lingual tonsils (rarely removed) • Laryngopharynx - Extends from hyoid bone to esophagus • Pharyngeal tonsils: located in the nasopharynx, called adenoids when they become enlarged Upper Respiratory Tract Organs – Larynx • Larynx (voice box) • Air from the pharynx enters the larynx, a cartilaginous structure that surrounds the glottis. • LOCATION: positioned between the root of the tongue and the upper end of the trachea • STRUCTURE: consists of cartilages attached to each other by muscle; lined by a ciliated mucous membrane, which forms two pairs of folds • Vestibular folds (false vocal folds) • Vocal folds Upper Respiratory Tract Organs – Larynx • • • CARTILAGES (framework) of the larynx: Formed by nine cartilages Three large, unpaired cartilages form the larynx: • 1. The thyroid cartilage (Adam’s apple): • hyaline cartilage • forms anterior and lateral walls of larynx • ligaments attach to hyoid bone, epiglottis, laryngeal cartilages • 2. The cricoid cartilage: • hyaline cartilage • form posterior portion of larynx • ligaments attach to first tracheal cartilage • articulates with arytenoid cartilages • 3. The epiglottis: • elastic cartilage • ligaments attach to thyroid cartilage and hyoid bone Upper Respiratory Tract Organs – Larynx • • The thyroid and cricoid cartilages surround and protect the glottis and the entrance to the trachea. During swallowing, the larynx is elevated and the epiglottis folds back over the glottis, preventing entry of food and liquids into the respiratory tract. The larynx also contains 3 pairs of smaller hyaline cartilages: 1. the arytenoid cartilages 2. the corniculate cartilages 3. the cuneiform cartilages Upper Respiratory Tract Organs – Glottis • • FUNCTION – sound production (air passing through the glottis vibrates the vocal folds and produces sound waves) • The corniculate and arytenoid cartilages function in the opening and closing of the glottis and the production of sound. LOCATION – space between the vocal folds Source: http://www.aboutcancer.com/anatomy_glottis.gif Upper Respiratory Tract Organs – Larynx • MUSCLES • Intrinsic muscles both insert and originate within the larynx • Extrinsic muscles insert in the larynx but originate on some other structure • FUNCTION: forms part of the airway to the lungs and produces the voice Upper Respiratory Tract Organs – Trachea (Windpipe) • • • • • LOCATION - Extends from the larynx to the primary bronchi • Extends from the cricoid cartilage into the mediastinum where it branches into the right and left pulmonary bronchi. Furnishes part of the open airway to the lungs; obstruction causes death Mucous coat = beneath the mucosa, the trachea has a submucosa that contains the mucous glands. The trachea has 15-20 tracheal cartilages that strengthen and protect the airway. The tracheal cartilages are discontinuous on the posterior side, where the trachea contacts the esophagus. An elastic ligament and the trachealis muscle connect the ends of each tracheal cartilage. Upper Respiratory Tract Organs – Bronchi • • FUNCTION • Distribute air to the lung’s interior STRUCTURE OF BRONCHI • Lower end of the trachea divides into two primary bronchi (right and left) • Separated by an internal ridge called the carina. • The primary bronchi enter the lung and divide into secondary bronchi, which branch into bronchioles and eventually divide into alveolar ducts and alveoli • The right primary bronchus is larger in diameter than the left, and descends at a steeper angle. • Each primary bronchus travels to a groove (the hilus) along the medial surface of its lung, where pulmonary nerves, blood vessels and lymphatics enter, anchored in a meshwork of connective tissue. This complex, called the root of the lung, is anchored to the mediastinum. Upper Respiratory Tract Organs – Alveoli • • • • • • FUNCTION - Primary gas exchange structures STRUCTURE OF ALVEOLI Microscopic grapelike sacs located Within the alveolar sacs Respiratory membrane: the barrier between which gases are exchanged by alveolar air and blood (Figure 23-15) Respiratory membrane components: • alveolar epithelium • capillary endothelium • their joined basement membranes Surfactant: a component of the fluid coating the respiratory membrane that reduces surface tension; produced by type II cells Upper Respiratory Tract Organs – Alveoli Lower Respiratory Tract Organs – Lungs • • • FUNCTIONS: air distribution and gas exchange LOCATION – in the left and right pleural cavities The inferior portion of each lung (the base) rests on the superior surface of the diaphragm. • STRUCTURE: cone-shaped organs extending from the diaphragm to above the clavicles (Figure 23-17) • Hilum: slit on the lung’s medial surface where the primary bronchi and pulmonary blood vessels enter • Base: the inferior surface of the lung that rests on the diaphragm • Costal surface: lies against the ribs Lower Respiratory Tract Organs – Lungs • • • Lobes are further divided into functional units (bronchopulmonary segments) Right lung = 10 segments Left lung = 8 segments • Left lung is divided into 2 lobes: superior and inferior • Right lung is divided into 3 lobes: superior, middle, and inferior Lower Respiratory Tract Organs – Lungs • COVERING – visceral pleural Lower Respiratory Tract Organs – Thorax (Thoracic Cavity) • • • • FUNCTION: brings about inspiration and expiration in respiration by generating pressure changes STRUCTURE: • Pleural divisions: the part occupied by the lungs Parietal pleura – lines the entire thoracic cavity; adheres to the internal surface of the ribs and superior surface of the diaphragm; partitions the mediastinum • Mediastinum: part occupied by the esophagus, trachea, large blood vessels, and heart Visceral pleura • Lies against the parietal pleura Parts of the parietal pleura (parietal pleura in blue; visceral pleura in purple): 1. costal 2. mediastinal Image source: http://home.comcast.net/~wnor/thoraxlesson2.htm Clinical Correlations • Pharyngitis – inflammation or infection of the pharynx (“sore throat” • Laryngitis – inflammation of the mucous lining of the larynx, characterized by edema of the vocal cords • “croup” in children under age 5 • Epiglottitis – rare, severe and rapidly progressing form of laryngitis (swollen larynx) • Medical emergency – can cause airway obstruction • Tonsillitis – inflammation of one of more of the masses of lymphatic tissue embedded in the mucous membrane of the pharynx Image source: http://www.aic.cuhk.edu.hk/web8/epiglottitis %20picture.htm Image source: http://bryanking.net/tonsillitis/ Clinical Correlations – Anatomical Disorders • Deviated septum – nasal obstruction caused by displacement of the nasal septum from the midline of the nasal cavity • Sleep apnea • Epistaxis – nosebleed • Causes - nose blowing, chronic infection, inflammation, hypertension, blow to the nose Resources • Excellent resource for the thoracic cavity and lungs • http://home.comcast.net/~wnor/thoraxlesson2.htm