The Respiratory System: Modified by Dr. Par Mohammadian 22 The Respiratory System: Modified by Dr. Par Mohammadian

The Respiratory System Major function-respiration Supply body with O2 for cellular respiration; dispose of CO2, a waste product of cellular respiration Its four processes involve both respiratory and circulatory systems Also functions in olfaction and speech

Processes of Respiration Pulmonary ventilation (breathing)- movement of air into and out of lungs External respiration-O2 and CO2 exchange between lungs and blood Transport-O2 and CO2 in blood Internal respiration-O2 and CO2 exchange between systemic blood vessels and tissues Respiratory system Circulatory system

Respiratory System: Functional Anatomy Major organs Nose, nasal cavity, and paranasal sinuses Pharynx Larynx Trachea Bronchi and their branches Lungs and alveoli

Nasal cavity Oral cavity Nostril Pharynx Larynx Trachea Carina of Figure 22.1 The major respiratory organs in relation to surrounding structures. Nasal cavity Oral cavity Nostril Pharynx Larynx Trachea Carina of trachea Left main (primary) bronchus Right main (primary) bronchus Left lung Right lung Diaphragm © 2013 Pearson Education, Inc.

Respiratory zone-site of gas exchange Functional Anatomy 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; cleanses, warms, humidifies air Diaphragm and other respiratory muscles promote ventilation

The Nose Functions Provides an airway for respiration Moistens and warms entering air Filters and cleans inspired air Serves as resonating chamber for speech Houses olfactory receptors

Figure 22.2a The external nose. The Nose - Two regions: external nose & nasal cavity External nose-root, bridge, dorsum nasi, and apex Philtrum-shallow vertical groove inferior to apex Nostrils (nares)-bounded laterally by alae Epicranius, frontal belly Root and bridge of nose Dorsum nasi Ala of nose Apex of nose Naris (nostril) Surface anatomy

Figure 22.2b The external nose. Frontal bone Septal cartilage Maxillary bone (frontal process) Nasal bone Lateral process of septal cartilage Minor alar cartilages Dense fibrous connective tissue Major alar cartilages External skeletal framework

Nasal cavity: Divided by midline nasal septum The Nose Nasal cavity: Divided by midline nasal septum Posterior nasal apertures (choanae=funnels) open into nasopharynx Roof of the nose: ethmoid & sphenoid bones Floor: hard (bone) & soft palates (muscle) Nasal conchae: Increase mucosal area; Enhance air turbulence) Vibrissae (hairs) filter coarse particles from inspired air

Nasal Cavity Olfactory mucosa contains olfactory epithelium Respiratory mucosa Pseudostratified ciliated columnar epithelium Mucous and serous secretions contain lysozyme and defensins Cilia move contaminated mucus posteriorly to throat Inspired air warmed by plexuses of capillaries and veins Sensory nerve endings trigger sneezing

Figure 22.3b The upper respiratory tract. Cribriform plate of ethmoid bone Frontal sinus Sphenoid sinus Nasal cavity Posterior nasal aperture Nasal conchae (superior, middle and inferior) Nasopharynx Pharyngeal tonsil Nasal meatuses (superior, middle, and inferior- grooves) Opening of pharyngotympanic tube Nasal vestibule Uvula Nostril Hard palate Soft palate Tongue Lingual tonsil Hyoid bone

Functions of the Nasal Mucosa and Conchae During inhalation, conchae and nasal mucosa Filter, heat, and moisten air During exhalation these structures Reclaim heat and moisture

Pharynx (throat) Pharynx Nasopharynx Oropharynx Laryngopharynx Muscular tube from base of skull to C6 Connects nasal cavity and mouth to larynx and esophagus Composed of skeletal muscle Three regions: Pharynx Nasopharynx Oropharynx Laryngopharynx Passageway for food and air Regions of the pharynx

Figure 22.3b The upper respiratory tract. Pharyngeal tonsil (adenoids) on posterior wall (traps & destrys pathogens) Pharyngotympanic (auditory) tubes drain and equalize pressure in middle ear Uvula: prevents food from entering the nose Nasopharynx Pharyngeal tonsil Opening of pharyngotympanic tube Uvula Tongue Isthmus of fauces-opening to oral cavity Palatine tonsils-in lateral walls of fauces Lingual tonsil-on posterior surface of tongue Oropharynx Palatine tonsil Lingual tonsil Isthmus of the fauces Hyoid bone Laryngopharynx Larynx Extends to larynx, where continuous with esophagus Epiglottis Vestibular fold Thyroid cartilage Esophagus Vocal fold Cricoid cartilage When eating and giggling, food comes out of our nose! Trachea Thyroid gland Illustration

Larynx Attaches to hyoid bone; opens into laryngopharynx; continuous with trachea Functions Provides patent airway Routes air and food into proper channels Voice production Houses vocal folds Larynx Epiglottis Vestibular fold Thyroid cartilage Esophagus Vocal fold Cricoid cartilage Trachea Thyroid gland

All hyaline cartilage except epiglottis Figure 22.4a The larynx. Epiglottis Thyrohyoid membrane Body of hyoid bone Thyroid cartilage Laryngeal prominence (Adam’s apple) In men larger: due to testosterone) Cricothyroid ligament Cricoid cartilage Cricotracheal ligament Tracheal cartilages All hyaline cartilage except epiglottis Anterior superficial view

Corniculate cartilage Figure 22.4b The larynx. Epiglottis Body of hyoid bone Thyrohyoid membrane Thyrohyoid membrane Cuneiform cartilage Fatty pad Vestibular fold (false vocal cord) Corniculate cartilage Arytenoid cartilage Thyroid cartilage Arytenoid muscles Vocal fold (true vocal cord) Cricoid cartilage Cricothyroid ligament Cricotracheal ligament Tracheal cartilages Sagittal view; anterior surface to the right © 2013 Pearson Education, Inc.

Larynx (voice box) Vocal ligaments-deep to laryngeal mucosa Form core of vocal folds (true vocal cords) Glottis-opening between vocal folds Folds vibrate to produce sound as air rushes up from lungs Vestibular folds (false vocal cords) Superior to vocal folds No part in sound production Help to close glottis during swallowing Base of tongue Epiglottis Vestibular fold (false vocal cord) Vocal fold (true vocal cord) Glottis Inner lining of trachea Cuneiform cartilage Corniculate cartilage Vocal folds in closed position; closed glottis Vocal folds in open position; open glottis

Windpipe–from larynx into mediastinum Wall composed of three layers Trachea Windpipe–from larynx into mediastinum Wall composed of three layers Mucosa-ciliated pseudostratified epithelium with goblet cells Submucosa-connective tissue with seromucous glands Adventitia-outermost layer made of connective tissue; encases C-shaped rings of hyaline cartilage

Trachea Trachealis Connects posterior parts of cartilage rings Contracts during coughing to expel mucus Carina Spar of cartilage on last, expanded tracheal cartilage Point where trachea branches into two main bronchi Carina of trachea

Figure 22.6a Tissue composition of the tracheal wall. Posterior Mucosa Esophagus Submucosa Trachealis muscle Lumen of trachea Seromucous gland in submucosa Hyaline cartilage Adventitia Anterior Cross section of the trachea and esophagus

Bronchi and Subdivisions Air passages undergo 23 orders of branching  bronchial (respiratory) tree From tips of bronchial tree  conducting zone structures  respiratory zone structures © 2013 Pearson Education, Inc.

Conducting Zone Structures Trachea  right and left main (primary) bronchi Each main bronchus enters hilum of one lung Right main bronchus wider, shorter, more vertical than left Each main bronchus branches into lobar (secondary) bronchi (three on right, two on left) Each lobar bronchus supplies one lobe Each lobar bronchus branches into segmental (tertiary) bronchi Segmental bronchi divide repeatedly Branches become smaller and smaller  Bronchioles-less than 1 mm in diameter Terminal bronchioles-smallest-less than 0.5 mm diameter

Figure 22.7 Conducting zone passages. Trachea Superior lobe of left lung Left main (primary) bronchus Superior lobe of right lung Lobar (secondary) bronchus Segmental (tertiary) bronchus Middle lobe of right lung Inferior lobe of right lung Inferior lobe of left lung Left side longer; right wider traps a foreign object that has entered the passageway

Conducting Zone Structures From bronchi through bronchioles, structural changes occur Cartilage rings become irregular plates; in bronchioles elastic fibers replace cartilage Epithelium changes from pseudostratified columnar to cuboidal; cilia and goblet cells become sparse Relative amount of smooth muscle increases Allows constriction

Respiratory Zone Begins as terminal bronchioles  respiratory bronchioles  alveolar ducts  alveolar sacs Alveolar sacs contain clusters of alveoli ~300 million alveoli make up most of lung volume Sites of gas exchange Alveoli Alveolar duct Respiratory bronchioles Alveolar duct Terminal bronchiole Alveolar sac

Figure 22.8b Respiratory zone structures. bronchiole Alveolar duct Alveolar pores Alveoli Alveolar sac © 2013 Pearson Education, Inc.

Alveolar and capillary walls and their fused basement membranes Respiratory Membrane Alveolar and capillary walls and their fused basement membranes ~0.5-µm-thick; gas exchange across membrane by simple diffusion Alveolar walls Single layer of squamous epithelium (type I alveolar cells) Scattered cuboidal type II alveolar cells secrete surfactant and antimicrobial proteins

Figure 22.9a Alveoli and the respiratory membrane. Terminal bronchiole Respiratory bronchiole Smooth muscle Scanning electron micrograph of pulmonary capillary casts (70x) Elastic fibers Alveolus Capillaries Diagrammatic view of capillary-alveoli relationships

Surrounded by fine elastic fibers and pulmonary capillaries Alveoli Surrounded by fine elastic fibers and pulmonary capillaries Alveolar pores connect adjacent alveoli Equalize air pressure throughout lung Alveolar macrophages keep alveolar surfaces sterile 2 million dead macrophages/hour carried by cilia  throat  swallowed

Figure 22.9c Alveoli and the respiratory membrane. Red blood cell Nucleus of type I alveolar cell Alveolar pores Capillary Capillary Macrophage Alveolus Endothelial cell nucleus Alveolus Alveolar epithelium Respiratory membrane Fused basement membranes of alveolar epithelium and capillary endothelium Alveoli (gas-filled air spaces) Red blood cell in capillary Type II alveolar cell Type I alveolar cell Capillary endothelium Detailed anatomy of the respiratory membrane © 2013 Pearson Education, Inc.

Lungs Occupy all thoracic cavity except mediastinum Root-site of vascular and bronchial attachment to mediastinum Costal surface-anterior, lateral, and posterior surfaces Composed primarily of alveoli Balance–stroma-elastic connective tissue  elasticity

Heart (in mediastinum) Anterior mediastinum Sternum Anterior Figure 22.10c Anatomical relationships of organs in the thoracic cavity. Esophagus (in mediastinum) Posterior Vertebra Root of lung at hilum • Left main bronchus Right lung • Left pulmonary artery Parietal pleura • Left pulmonary vein Visceral pleura Left lung Pleural cavity Thoracic wall Pulmonary trunk Pericardial membranes Heart (in mediastinum) Anterior mediastinum Sternum Anterior Transverse section through the thorax, viewed from above. Lungs, pleural membranes, and major organs in the mediastinum are shown. © 2013 Pearson Education, Inc.

Apex-superior tip; deep to clavicle Lungs Apex-superior tip; deep to clavicle Base-inferior surface; rests on diaphragm Hilum-on mediastinal surface; site for entry/exit of blood vessels, bronchi, lymphatic vessels, and nerves Left lung smaller than right Cardiac notch-concavity to accommodate the heart Separated into superior and inferior lobes by oblique fissure

Lungs Right lung Superior, middle, inferior lobes separated by oblique and horizontal fissures Bronchopulmonary segments (10 right lung, 8–10 left lung) separated by connective tissue septa If diseased can be individually removed Lobules-smallest subdivisions visible to naked eye; served by bronchioles and their branches

Anterior view. The lungs flank mediastinal structures laterally. Figure 22.10a Anatomical relationships of organs in the thoracic cavity. Intercostal muscle Rib Parietal pleura Lung Pleural cavity Visceral pleura Trachea Thymus Apex of lung Left superior lobe Right superior lobe Oblique fissure Horizontal fissure Right middle lobe Left inferior lobe Oblique fissure Right inferior lobe Heart (in mediastinum) Diaphragm Cardiac notch Base of lung Anterior view. The lungs flank mediastinal structures laterally.

Photograph of medial view of the left lung. Figure 22.10b Anatomical relationships of organs in the thoracic cavity. Apex of lung Pulmonary artery Left main bronchus Left superior lobe Oblique fissure Pulmonary vein Left inferior lobe Cardiac impression Hilum of lung Oblique fissure Aortic impression Lobules Photograph of medial view of the left lung.

Figure 22.11 A cast of the bronchial tree (segments). Right lung Left lung Right superior lobe (3 segments) Left superior lobe (4 segments) Right middle lobe (2 segments) Right inferior lobe (5 segments) Left inferior lobe (5 segments)

Pleurae Thin, double-layered serosa: Parietal pleura Visceral pleura Covers the thoracic wall and superior face of the diaphragm Continues around heart and between lungs Visceral pleura Covers the external lung surface Divides the thoracic cavity into three chambers The central mediastinum Two lateral compartments, each containing a lung