The Respiratory System

Transcription

1 PowerPoint Lecture Slides prepared by Leslie Hendon University of Alabama, Birmingham C H A P T E R 22 Part 1 The Respiratory System The Respiratory System Basic functions of the respiratory system Supplies body with oxygen Disposes of carbon dioxide Four processes involved in respiration Pulmonary ventilation External respiration Transport of respiratory gases Internal respiration Functional Anatomy of the Respiratory System Organs of the Respiratory System Respiratory organs Nose, nasal cavity, and paranasal sinuses Pharynx, larynx, and trachea Bronchi and smaller branches s and alveoli Carina of trachea Right main (primary) Right lung Parietal pleura Nasal cavity Nostril Larynx Oral cavity Pharynx Left main (primary) Bronchi Alveoli Left lung Diaphragm Figure 22.1 Organs of the Respiratory System The Nose Divided into Conducting zone Respiratory zone Provides an airway for respiration Moistens and warms air Filters inhaled air Resonating chamber for speech Houses olfactory receptors 1

2 The Nose Size variation due to differences in nasal cartilages Skin is thin contains many sebaceous glands Epicranius, frontal belly Root and bridge of nose Dorsum nasi Ala of nose Apex of nose Naris (nostril) Philtrum Frontal bone Nasal bone Septal cartilage Maxillary bone (frontal process) Lateral process of septal cartilage Minor alar cartilages Dense fibrous connective tissue Major alar cartilages The Nasal Cavity External nares nostrils Divided by nasal septum Continuous with nasopharynx Posterior nasal apertures choanae (a) Surface anatomy (b) External skeletal framework Figure 22.2 Nasal Cavity Two types of mucous membrane Olfactory mucosa Near roof of nasal cavity Houses olfactory (smell) receptors Respiratory mucosa Lines nasal cavity Epithelium is pseudostratified ciliated columnar The Upper Respiratory Tract Cribriform plate of ethmoid bone Sphenoid sinus Posterior nasal aperture Nasopharynx Pharyngeal tonsil Opening of pharyngotympanic tube Uvula Oropharynx Palatine tonsil Isthmus of the fauces Laryngopharynx Esophagus (c) Illustration Frontal sinus Nasal cavity Nasal conchae (superior, middle and inferior) Nasal meatuses (superior, middle, and inferior) Nasal vestibule Nostril Hard palate Soft palate Tongue Lingual tonsil Larynx Hyoid bone Epiglottis Vestibular fold Thyroid cartilage Vocal fold Thyroid gland Figure 22.3c Respiratory Mucosa Nasal Conchae Consists of Pseudostratified ciliated columnar epithelium Goblet cells within epithelium Underlying layer of lamina propria Cilia move contaminated mucus posteriorly Superior and middle nasal conchae Part of the ethmoid bone Inferior nasal conchae Separate bone Project medially from the lateral wall of the nasal cavity Particulate matter Deflected to mucus-coated surfaces 2

3 The Pharynx The Nasopharynx Funnel-shaped passageway Connects nasal cavity and mouth Divided into three sections by location Nasopharynx Oropharynx Laryngopharynx Type of mucosal lining changes along its length Superior to the point where food enters Only an air passageway Closed off during swallowing Pharyngeal tonsil (adenoids) Located on posterior wall Destroys entering pathogens Contains the opening to the pharyngotympanic tube (auditory tube) Tubal tonsil Provides some protection from infection The Oropharynx The Laryngopharynx Arch-like entranceway fauces Extends from soft palate to the epiglottis Epithelium Stratified squamous epithelium Two types of tonsils in the oropharynx Palatine tonsils in the lateral walls of the fauces Lingual tonsils covers the posterior surface of the tongue Passageway for both food and air Epithelium Stratified squamous epithelium Continuous with the esophagus and larynx The Larynx Nine Cartilages of the Larynx Three functions Voice production Provides an open airway Routes air and food into the proper channels Superior opening is Closed during swallowing Open during breathing Thyroid cartilage Shield-shaped, forms laryngeal prominence (Adam s apple) Three pairs of small cartilages Arytenoid cartilages Corniculate cartilages Cuneiform cartilages Epiglottis Tips inferiorly during swallowing 3

4 The Larynx Anatomy of the Larynx Vocal ligaments of the larynx Vocal folds (true vocal cords) Act in sound production Vestibular folds (false vocal cords) No role in sound production Epithelium of the larynx Stratified squamous superior portion Pseudostratified ciliated columnar inferior portion (a) Surface view Body of hyoid bone Thyroid cartilage Laryngeal prominence (Adam s apple) Cricothyroid ligament Body of hyoid bone Laryngeal prominence (Adam s apple) Sternal head Clavicular head Sternocleidomastoid Clavicle Jugular notch Epiglottis Thyrohyoid membrane Cricotracheal ligament l cartilages (b) Anterior view Figure 22.5a, b Anatomy of the Larynx Epiglottis Hyoid bone Thyrohyoid membrane Corniculate cartilage Thyroid Arytenoid cartilage cartilage Glottis l cartilages (c) Photograph of cartilaginous framework of the larynx, posterior view Movements of the Vocal Folds Anterior Thyroid cartilage Vocal ligaments of vocal cords Glottis Lateral cricoarytenoid muscle Arytenoid cartilage Corniculate cartilage Posterior cricoarytenoid muscle Posterior Epiglottis Thyrohyoid membrane Cuneiform cartilage Corniculate cartilage Arytenoid cartilage Arytenoid muscle l cartilages Body of hyoid bone Thyrohyoid membrane Fatty pad Vestibular fold (false vocal cord) Thyroid cartilage Vocal fold (true vocal cord) Cricothyroid ligament Cricotracheal ligament Base of tongue Epiglottis Vestibular fold (false vocal cord) Vocal fold (true vocal cord) Glottis Inner lining of trachea Cuneiform cartilage Corniculate cartilage (d) Sagittal section (anterior on the right) Figure 22.5c, d (a) Vocal folds in closed position; closed glottis (b) Vocal folds in open position; open glottis Figure 22.6 The Larynx The Voice production Length of the vocal folds changes with pitch Loudness depends on the force of air across the vocal folds Sphincter function of the larynx Valsalva s maneuver straining Innervation of the larynx Recurrent laryngeal nerves (branch of vagus) Descends into the mediastinum C-shaped cartilage rings keep airway open Carina Marks where trachea divides into two primary bronchi Epithelium Pseudostratified ciliated columnar 4

5 The Bronchi in the Conducting Zone Mucosa Pseudostratified ciliated columnar epithelium Lamina propria (connective tissue) Bronchial tree Submucosa Seromucous gland in submucosa Posterior Hyaline cartilage Mucosa Esophagus (b) Photomicrograph of the tracheal wall (250 ) Submucosa lis muscle Lumen of trachea Seromucous gland in submucosa Hyaline cartilage Adventitia Anterior (a) Cross section of the trachea and esophagus Figure 22.7 Bronchi in the Conducting Zone Superior lobe of right lung Extensively branching respiratory passageways Primary bronchi (main bronchi) Largest bronchi Right main bronchi Wider and shorter than the left Bronchi in the Conducting Zone Mucosa Pseudostratified epithelium Lamina propria Superior lobe of left lung Left main (primary) Lobar (secondary) Segmental (tertiary) Inferior lobe of left lung Lumen Cartilage plate Smooth muscle Middle lobe Inferior lobe of right lung of right lung (a) The branching of the bronchial tree Fibromusculocartilaginous layer (b) Photomicrograph of a (13 ) Figure 22.8a Bronchi in the Conducting Zone Changes in Tissue Composition along Conducting Pathways Secondary (lobar) bronchi Supportive connective tissues change Three on the right Two on the left Tertiary (segmental) bronchi Branch into each lung segment Bronchioles Little bronchi, less than 1 mm in diameter Terminal bronchioles Less than 0.5 mm in diameter Figure 22.8b C-shaped rings replaced by cartilage plates Epithelium changes First, pseudostratified ciliated columnar Replaced by simple columnar, then simple cuboidal epithelium Smooth muscle becomes important Airways widen with sympathetic stimulation Airways constrict under parasympathetic direction 5

6 Structures of the Respiratory Zone Structures of the Respiratory Zone Consists of air-exchanging structures Respiratory bronchioles branch from terminal bronchioles Lead to alveolar ducts Lead to alveolar sacs Respiratory bronchioles Terminal bronchiole Alveolar duct Alveoli Alveolar duct Alveolar sac (a) Figure 22.9a Structures of the Respiratory Zone Structures of the Respiratory Zone Respiratory bronchiole Alveolar duct Alveolar pores Alveoli ~300 million alveoli account for tremendous surface area of the lungs Surface area of alveoli is 140 square meters Alveoli (b) Alveolar sac Figure 22.9b Structures of the Respiratory Zone Structures of the Respiratory Zone Structure of alveoli Type I cells single layer of simple squamous epithelial cells Surrounded by basal lamina Alveolar and capillary walls plus their basal lamina form the... Respiratory membrane Structures of alveoli (continued) Type II cells scattered among type I cells Are cuboidal epithelial cells Secrete surfactant Reduces surface tension within alveoli keeps alveoli from collapsing when we exhale Alveolar macrophages 6

7 Anatomy of Alveoli and the Respiratory Membrane Anatomy of Alveoli and the Respiratory Membrane Red blood cell Nucleus of type I (squamous epithelial) cell Alveolar pores Terminal bronchiole Respiratory bronchiole Capillary O2 Smooth muscle Capillary CO2 Alveolus Macrophage Endothelial cell nucleus Elastic fibers Alveolus Alveolus Respiratory membrane Capillaries (a) Diagrammatic view of capillary-alveoli relationships Red blood cell Type I cell in capillary of alveolar wall Alveoli (gas-filled Type II (surfactantair spaces) secreting) cell Alveolar epithelium Fused basement membranes of the alveolar epithelium and the capillary endothelium Capillary endothelium (c) Detailed anatomy of the respiratory membrane Figure 22.10a, b Figure 22.10c The Respiratory Zone Gross Anatomy of the s Features of alveoli Major landmarks of the lungs Surrounded by elastic fibers Interconnect by way of alveolar pores Internal surfaces A site for free movement of alveolar macrophages Apex, base, hilum, and root Left lung Superior and inferior lobes Fissure oblique Right lung Superior, middle, and inferior lobes Fissures oblique and horizontal Gross Anatomy of the s Bronchopulmonary Segments Right lung Anterior View of Thoracic Structures Right superior lobe (3 segments) Left lung Left superior lobe (4 segments) Intercostal muscle Rib Parietal pleura Pleural cavity Visceral pleura Apex of lung Right superior lobe Horizontal fissure Right middle lobe Oblique fissure Left superior lobe Oblique fissure Left inferior lobe Right inferior lobe Heart (in mediastinum) Diaphragm Cardiac notch Base of lung (a) Anterior view. The lungs flank mediastinal structures laterally. Apex of lung Pulmonary artery Thymus Left superior lobe Left main Oblique fissure Pulmonary vein Impression of heart Oblique fissure Left inferior lobe Hilum Aortic impression Lobules (b) Photograph of medial view of the left lung Figure 22.11a, b Right middle lobe (2 segments) Right inferior lobe (5 segments) Left inferior lobe (5 segments) Figure

8 Blood Supply and Innervation of the s Pulmonary arteries Deliver oxygen-poor blood to the lungs Pulmonary veins Carry oxygenated blood to the heart Bronchial arteries (2 on left, 1 on right) Supply systemic (oxygenated) blood to the lung structures (enter lung s medial surface along with the large pulmonary vessels) Innervation Sympathetic, parasympathetic, and visceral sensory fibers Parasympathetic constrict airways Sympathetic dilate airways Transverse Cut through the Superior Thorax Right lung Parietal pleura Visceral pleura Pleural cavity Pericardial membranes Sternum Vertebra Posterior Esophagus (in mediastinum) Root of lung at hilum Left main Left pulmonary artery Left pulmonary vein Left lung Thoracic wall Pulmonary trunk Heart (in mediastinum) Anterior mediastinum Anterior (d) Transverse section through the thorax, viewed from above. s, pleural membranes, and major organs in the mediastinum are shown. Figure 22.11d The Pleurae Diagram of the Pleurae and Pleural Cavities A double-layered sac surrounding each lung Parietal pleura Visceral pleura Pleural cavity Potential space between the visceral and parietal pleurae Pleurae help divide the thoracic cavity Central mediastinum Two lateral pleural compartments Apex of lung Right superior lobe Horizontal fissure Right middle lobe Oblique fissure Right inferior lobe Thymus Heart (in mediastinum) Diaphragm Cardiac notch Base of lung (a) Anterior view. The lungs flank mediastinal structures laterally. Intercostal muscle Rib Parietal pleura Pleural cavity Visceral pleura Left superior lobe Oblique fissure Left inferior lobe Figure 22.11a Location of s in Thoracic Cavity The Mechanisms of Ventilation Rib 8 9 Clavicle Nipple Rib Two phases of pulmonary ventilation Inspiration inhalation Expiration exhalation (a) Posterior view Parietal pleura 8 Midaxillary line 9 10 Midclavicular line (b) Anterior view Infrasternal angle at the xiphisternal joint Costal margin Parietal pleura Figure

9 Inspiration Inspiration Volume of thoracic cavity increases Decreases internal gas pressure Action of the diaphragm Diaphragm flattens Action of intercostal muscles Contraction raises the ribs Deep inspiration requires Scalenes Sternocleidomastoid Pectoralis minor Erector spinae extends the back Expiration Quiet expiration chiefly a passive process Inspiratory muscles relax Diaphragm moves superiorly Volume of thoracic cavity decreases Forced expiration an active process Produced by contraction of Internal and external oblique muscles Transverse abdominis muscles Changes in Thoracic Volume (a) Inspiration (b) Expiration Diaphragm and intercostal muscles Inspiratory muscles relax (diaphragm rises and contract (diaphragm descends and rib cage descends due to recoil of the costal rib cage rises). Thoracic cavity cartilages). Thoracic cavity volume decreases. volume increases. Ribs are Ribs and elevated and sternum are Changes in sternum flares depressed as superior- as external inferior and intercostals external anterior- contract. intercostals posterior relax. dimensions Diaphragm moves inferiorly during Diaphragm moves contraction. superiorly as it relaxes. Changes in lateral External External dimensions intercostals intercostals (superior contract. relax. view) Figure Changes in Thoracic Volume 1 At rest, no air movement: Air pressure in lungs is equal to atmospheric (air) pressure. Pressure in the pleural cavity is less than pressure in the lungs. This pressure difference keeps the lungs inflated. 2 Inspiration: Inspiratory muscles contract and increase the volume of the thoracic and pleural cavities. Pleural fluid in the pleural cavity holds the parietal and visceral pleura close together, causing the lungs to expand. As volume increases, pressure decreases and air flows into the lungs. Main bronchi Diaphragm Air Air Thoracic wall Pleural cavity At rest Expanded V P Parietal Visceral pleura pleura Air flows in Pleural cavity V P Thoracic wall Neural Control of Ventilation Most important respiratory center VRG ventral respiratory group Located in reticular formation in the medulla oblongata Neurons generate respiratory rhythm 3 Expiration: Inspiratory muscles relax, reducing thoracic volume, and the lungs recoil. Simultaneously, volumes of the pleural cavity and the lungs decrease, causing pressure to increase in the lungs, and air flows out. Resting state is reestablished. V V P P Air flows out Figure

10 Respiratory Centers in the Brain Stem Neural Control of Ventilation Ventral respiratory group (VRG) contains rhythm generators whose output drives respiration. Pons Medulla Pons Medulla To inspiratory muscles Pontine respiratory centers interact with the medullary respiratory centers to smooth the respiratory pattern. Dorsal respiratory group (DRG) integrates peripheral sensory input and modifies the rhythms generated by the VRG. Respiratory center Generates baseline respiration rate In the reticular formation of the medulla oblongata Chemoreceptors Sensitive to rising and falling oxygen levels Central chemoreceptors located in medulla Peripheral chemoreceptors Aortic bodies Carotid bodies External intercostal muscles Diaphragm Figure Location of Peripheral Chemoreceptors Disorders of Lower Respiratory Structures Brain Sensory nerve fiber in cranial nerve IX (pharyngeal branch of glossopharyngeal) External carotid artery Internal carotid artery Carotid body Common carotid artery Cranial nerve X (vagus nerve) Sensory nerve fiber in cranial nerve X Aortic bodies in aortic arch Aorta Bronchial asthma A type of allergic inflammation Hypersensitivity to irritants in the air or to stress Asthma attacks characterized by Contraction of bronchiole smooth muscle Secretion of mucus in airways Heart Figure Disorders of Lower Respiratory Structures Disorders of Lower Respiratory Structures Cystic fibrosis (CF) inherited disease Exocrine gland function is disrupted Respiratory system affected by Oversecretion of viscous mucus Chronic obstructive pulmonary disease (COPD) Airflow into and out of the lungs is difficult Obstructive emphysema Chronic bronchitis History of smoking 10

11 Disorders of Lower Respiratory Structures Alveolar Changes in Emphysema Figure Figure Disorders of Upper Respiratory Structures Epistaxis nosebleed The Respiratory System Throughout Life By week 4 of development Olfactory placodes appear Invaginate to form olfactory pits Laryngotracheal bud Forms trachea, bronchi, and bronchi subdivisions Reaches functional maturity late in development At birth, only one-sixth of alveoli are present Those who begin smoking as teenagers s never fully develop Additional alveoli never form The Respiratory System Throughout Life Aging of the Respiratory System (a) 4 weeks: anterior superficial view of the embryo s head Frontonasal elevation Olfactory placode Stomodeum (future mouth) Laryngotracheal bud Future mouth Eye Bronchial buds (b) 5 weeks: left lateral view of the developing lower respiratory passageway mucosae Pharynx Foregut Olfactory placode Esophagus Liver Number of glands in the nasal mucosa declines Nose dries Produces thickened mucus Thoracic wall becomes more rigid s lose elasticity Oxygen levels in the blood may fall Figure