BIOL 112 - The Respiratory System PDF

Instructor: Pamela Paynter-  Define respiration  Describe the structure and function of the parts of the respiratory system  Explain the mechanics of breathing  Involves both the respiratory and the circulatory systems  Four processes that supply the body with...

Instructor: Pamela Paynter-  Define respiration  Describe the structure and function of the parts of the respiratory system  Explain the mechanics of breathing  Involves both the respiratory and the circulatory systems  Four processes that supply the body with O2 and dispose of CO2 ⁷  Pulmonary ventilation (breathing): movement of air into and out of the lungs Respiratory system  External respiration: O2 and CO2 exchange between the lungs and the blood  Transport: O2 and CO2 Circulatory in the blood system  Internal respiration: O2 and CO2 exchange between systemic blood vessels and tissues ⁷  Oxygen (O2) is used by the cells  O2 needed in conversion of glucose to cellular energy (ATP)  All body cells  Carbon dioxide (CO2) is produced as a waste product  The body’s cells die if either the ⁶ respiratory or cardiovascular system fails 5  Major organs › Nose, nasal cavity, and paranasal sinuses › Pharynx › Larynx › Trachea › Bronchi and their branches › Lungs and alveoli ⁷ ⁵  Respiratory zone: site of gas exchange › Microscopic structures: respiratory bronchioles, alveolar ducts, and alveoli  Conducting zone: conduits to gas exchange sites › Includes all other respiratory structures  Respiratory muscles: diaphragm and other muscles that promote ventilation (intercostal muscles etc) ¹  Functions › Provides an airway for respiration › Moistens and warms the entering air › Filters and cleans inspired air › Serves as a resonating chamber for speech › Houses olfactory receptors ¹  Two regions: external nose and nasal cavity 1.External nose: root, bridge, dorsum nasi, and apex  Philtrum: a shallow vertical groove inferior to the apex  Nostrils (nares): bounded laterally by the alae ⁷  Epicranius, frontal belly Root and bridge of nose Dorsum nasi Ala of nose Apex of nose Naris (nostril) Philtrum (a) Surface anatomy ⁷ 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 (b) External skeletal framework ⁷ 2.Nasal cavity: in and posterior to the external nose  Divided by a midline nasal septum  Posterior nasal apertures (choanae) open into the nasal pharynx  Roof: ethmoid and sphenoid bones  Floor: hard and soft palates ¹  Vestibule: nasal cavity superior to the nostrils › Vibrissae filter coarse particles from inspired air  Olfactory mucosa › Lines the superior nasal cavity › Contains smell receptors ⁷  Respiratory mucosa › Pseudostratified ciliated columnar epithelium › Mucous and serous secretions contain lysozyme and defensins › Cilia move contaminated mucus posteriorly to throat › Inspired air is warmed by plexuses of capillaries and veins › Sensory nerve endings triggers sneezing ⁷  Cribriform plate of ethmoid bone Sphenoid sinus Frontal sinus Posterior nasal Nasal cavity aperture Nasal conchae Nasopharynx (superior, middle and inferior) Pharyngeal tonsil Nasal meatuses Opening of (superior, middle, pharyngotympanic and inferior) tube Nasal vestibule Uvula Nostril Oropharynx Hard palate Palatine tonsil Soft palate Isthmus of the fauces Tongue Lingual tonsil Laryngopharynx Hyoid bone Larynx Epiglottis Esophagus Vestibular fold Thyroid cartilage Vocal fold Trachea Cricoid cartilage Thyroid gland (c) Illustration ⁷  Superior, middle, and inferior nasal conchae › Protrude from the lateral walls › Increase mucosal area › Enhance air turbulence ⁷  During inhalation, the conchae and nasal mucosa › Filter, heat, and moisten air  During exhalation these structures › Reclaim heat and moisture ⁷  In frontal  Sphenoid,  Ethmoid, and  Maxillary bones ⁷  Act as resonance chambers for speech Mucosa warms and moistens the incoming air Lightens facial bones (University of Hawaii,  Muscular tube that connects to the › Nasal cavity and mouth superiorly › Larynx and esophagus inferiorly  From the base of the skull to the level of the sixth cervical vertebra ⁷  It is divided into three regions › Nasopharynx › Oropharynx › Laryngopharynx ¹  Pharynx Nasopharynx Oropharynx Laryngopharynx (b) Regions of the pharynx ⁷  Air passageway posterior to the nasal cavity  Lining: pseudostratified columnar epithelium  Soft palate and uvula close nasopharynx during swallowing  Pharyngeal tonsil (adenoids) on posterior wall  Pharyngotympanic (auditory) tubes open into the lateral walls ⁷  Passageway for food and air from the level of the soft palate to the epiglottis  Lining of stratified squamous epithelium  Isthmus of the fauces: opening to the oral cavity  Palatine tonsils in the lateral walls of fauces  Lingual tonsil on the posterior surface of the tongue ⁷  Passageway for food and air  Posterior to the upright epiglottis  Extends to the larynx, where the respiratory and digestive pathways diverge  Hence it is also continuous with the esophagus ¹  Cribriform plate of ethmoid bone Sphenoid sinus Frontal sinus Posterior nasal Nasal cavity aperture Nasal conchae Nasopharynx (superior, middle and inferior) Pharyngeal tonsil Nasal meatuses Opening of (superior, middle, pharyngotympanic and inferior) tube Nasal vestibule Uvula Nostril Oropharynx Hard palate Palatine tonsil Soft palate Isthmus of the fauces Tongue Lingual tonsil Laryngopharynx Hyoid bone Larynx Epiglottis Esophagus Vestibular fold Thyroid cartilage Vocal fold Trachea Cricoid cartilage Thyroid gland (c) Illustration ⁷  Attaches to the hyoid bone and opens into the laryngopharynx  Continuous with the trachea  Functions 1. Provides a patent airway 2. To act as a switching mechanism to route air and food into the proper channels 3. Voice production ¹  Cartilages of the larynx › Hyaline cartilage except for the epiglottis › Thyroid cartilage with laryngeal prominence (Adam’s apple) › Ring-shaped cricoid cartilage › Paired arytenoid, cuneiform, and corniculate cartilages  Epiglottis: elastic cartilage; covers the laryngeal inlet during swallowing ⁷  Epiglottis Body of hyoid bone Thyrohyoid membrane Thyroid cartilage Laryngeal prominence (Adam’s apple) Cricothyroid ligament Cricoid cartilage Cricotracheal ligament Tracheal cartilages (a) Anterior superficial view ⁷  Epiglottis Body of hyoid bone Thyrohyoid Thyrohyoid membrane membrane Fatty pad Cuneiform cartilage Vestibular fold Corniculate cartilage (false vocal cord) Arytenoid cartilage Thyroid cartilage Arytenoid muscles Vocal fold (true vocal cord) Cricoid cartilage Cricothyroid ligament Cricotracheal ligament Tracheal cartilages (b) Sagittal view; anterior surface to the right ⁷  Vocal ligaments › Attach the arytenoid cartilages to the thyroid cartilage › Contain elastic fibers › Form core of vocal folds (true vocal cords)  Opening between them is the glottis  Folds vibrate to produce sound as air rushes up from the lungs ⁷  Vestibular folds (false vocal cords) › Superior to the vocal folds › No part in sound production › Help to close the glottis during swallowing ⁷  Base of tongue Epiglottis Vestibular fold (false vocal cord) Vocal fold (true vocal cord) Glottis Inner lining of trachea Cuneiform cartilage Corniculate cartilage (a) Vocal folds in closed position; (b) Vocal folds in open position; closed glottis open glottis ⁷  Speech: intermittent release of expired air while opening and closing the glottis  Pitch is determined by the length and tension of the vocal cords  Loudness depends upon the force of air  Chambers of pharynx, oral, nasal, and sinus cavities amplify and enhance sound quality  Sound is “shaped” into language by muscles of the pharynx, tongue, soft palate, and lips ⁷  Vocal folds may act as a sphincter to prevent air passage  Example: Valsalva’s maneuver › Glottis closes to prevent exhalation › Abdominal muscles contract › Intra-abdominal pressure rises › Helps to empty the rectum or stabilizes the trunk during heavy lifting ⁷  Windpipe: from the larynx into the mediastinum  Wall composed of three layers 1.Mucosa: ciliated pseudostratified epithelium with goblet cells 2.Submucosa: connective tissue with seromucous glands 3.Adventitia: outermost layer made of connective tissue that encases the C- shaped rings of hyaline cartilage ⁷  Trachealis muscle › Connects posterior parts of cartilage rings › Contracts during coughing to expel mucus  Carina › Last tracheal cartilage › Point where trachea branches into two bronchi ⁷  Posterior Mucosa Esophagus Submucosa Trachealis Lumen of Seromucous gland muscle trachea in submucosa Hyaline cartilage Adventitia Anterior (a) Cross section of the trachea and esophagus ⁷ Mucosa Pseudostratified ciliated columnar epithelium Lamina propria (connective tissue) Submucosa Seromucous gland in submucosa Hyaline cartilage (b) Photomicrograph of the tracheal wall (320x) ⁷  Air passages undergo 23 orders of branching  Branching pattern called the bronchial (respiratory) tree ⁷ (University of Hawaii, n.d.).  Trachea right and left main (primary) bronchi  Each main bronchus enters the hilum of one lung › Right main bronchus is wider, shorter, and more vertical than the left  Each main bronchus branches into lobar (secondary) bronchi (three right, two left) › Each lobar bronchus supplies one lobe ⁷  Each lobar bronchus branches into segmental (tertiary) bronchi › Segmental bronchi divide repeatedly  Bronchioles are less than 1 mm in diameter  Terminal bronchioles are the smallest, less than 0.5 mm diameter ⁷  Trachea Superior lobe of left lung Left main (primary) Superior lobe bronchus of right lung Lobar (secondary) bronchus Segmental Middle lobe (tertiary) of right lung bronchus Inferior lobe Inferior lobe of right lung of left lung ⁷  From bronchi through bronchioles, structural changes occur › Cartilage rings give way to plates; cartilage is absent from bronchioles › Epithelium changes from pseudostratified columnar to cuboidal; cilia and goblet cells become sparse › Relative amount of smooth muscle increases ⁷  Respiratory bronchioles, alveolar ducts, alveolar sacs (clusters of alveoli)  ~300 million alveoli account for most of the lungs’ volume and are the main site for gas exchange ⁷  Alveoli Alveolar duct Respiratory Alveolar duct bronchioles Terminal Alveolar bronchiole sac (a) ⁷  Respiratory bronchiole Alveolar Alveolar duct pores Alveoli Alveolar sac (b) ⁷  ~0.5-m-thick air-blood barrier  Alveolar and capillary walls and their fused basement membranes  Alveolar walls › Single layer of squamous epithelium (type I cells)  Scattered type II cuboidal cells secrete surfactant and antimicrobial proteins ⁷ ⁷  Surrounded by fine elastic fibers  Contain open pores that › Connect adjacent alveoli › Allow air pressure throughout the lung to be equalized  House alveolar macrophages that keep alveolar surfaces sterile ⁷ (University of Hawaii, n.d.). ⁶  Occupy all of the thoracic cavity except the mediastinum  Root: site of vascular and bronchial attachments  Costal surface: anterior, lateral, and posterior surfaces ⁷  Posterior Esophagus Vertebra (in mediastinum) Root of lung Right lung at hilum Parietal Left main bronchus pleura Left pulmonary artery Visceral Left pulmonary vein pleura Left lung Pleural Thoracic wall cavity Pulmonary trunk Pericardial membranes Heart (in mediastinum) Sternum Anterior mediastinum Anterior (c) Transverse section through the thorax, viewed from above. Lungs, pleural membranes, and major organs in the mediastinum are shown. ⁷  Apex: superior tip  Base: inferior surface that rests on the diaphragm  Hilum: on mediastinal surface; site for attachment of blood vessels, bronchi, lymphatic vessels, and nerves  Cardiac notch of left lung: concavity that accommodates the heart ⁷  Left lung is smaller, separated into two lobes by an oblique fissure  Right lung has three lobes separated by oblique and horizontal fissures  Bronchopulmonary segments (10 right, 8–9 left)  Lobules are the smallest subdivisions; served by bronchioles and their branches ⁷  Intercostal muscle Rib Parietal pleura Trachea Lung Pleural cavity Thymus Visceral pleura Apex of lung Right superior lobe Left Horizontal fissure superior lobe Heart Oblique (in mediastinum) fissure Right middle lobe Left inferior Oblique fissure lobe Right inferior lobe Diaphragm Base of lung Cardiac notch (a) Anterior view. The lungs flank mediastinal structures laterally. ⁷  Right lung Left lung Right superior Left superior lobe (3 lobe segments) (4 segments) Right middle lobe (2 segments) Right Left inferior inferior lobe (5 segments) lobe (5 segments) ⁷  Pulmonary circulation (low pressure, high volume) › Pulmonary arteries deliver systemic venous blood  Branch profusely, along with bronchi  Feed into the pulmonary capillary networks › Pulmonary veins carry oxygenated blood from respiratory zones to the heart ⁷  Systemic circulation (high pressure, low volume) › Bronchial arteries provide oxygenated blood to lung tissue  Arise from aorta and enter the lungs at the hilum  Supply all lung tissue except the alveoli › Bronchial veins anastomose with pulmonary veins › Pulmonary veins carry most venous blood back to the heart ⁷  Thin, double-layered serosa  Parietal pleura on thoracic wall and superior face of diaphragm  Visceral pleura on external lung surface  Pleural fluid fills the slitlike pleural cavity › Provides lubrication and surface tension ⁷ ⁵  Posterior Esophagus Vertebra (in mediastinum) Root of lung Right lung at hilum Parietal Left main bronchus pleura Left pulmonary artery Visceral Left pulmonary vein pleura Left lung Pleural Thoracic wall cavity Pulmonary trunk Pericardial membranes Heart (in mediastinum) Sternum Anterior mediastinum Anterior (c) Transverse section through the thorax, viewed from above. Lungs, pleural membranes, and major organs in the mediastinum are shown. ⁷  Pulmonary ventilation consists of two phases 1.Inspiration: gases flow into the lungs 2.Expiration: gases exit the lungs ⁷  Volume of thoracic cavity increases › Decreases internal gas pressure › Action of the diaphragm  Diaphragm flattens › Action of intercostal muscles  Contraction raises the ribs ⁵  Deep inspiration requires › Scalenes › Sternocleidomastoid › Pectoralis minor › Erector spinae – extends the back ⁵  Atmospheric pressure (Patm) › Pressure exerted by the air surrounding the body › 760 mm Hg at sea level  Respiratory pressures are described relative to Patm › Negative respiratory pressure is less than Patm › Positive respiratory pressure is greater than Patm › Zero respiratory pressure = Patm ⁷  Intrapulmonary (intra-alveolar) pressure (Ppul) › Pressure in the alveoli › Fluctuates with breathing › Always eventually equalizes with Patm ⁷  Intrapleural pressure (Pip): › Pressure in the pleural cavity › Fluctuates with breathing › Always a negative pressure (