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Respiration • Major function is to supply the body with oxygen and dispose of carbon dioxide • Involves both the respiratory and the circulatory systems • Four processes that supply the body with O2 and dispose of CO2 Copyright © 2010 Pearson Education, Inc. Respiration • 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 of Gases: O2 and CO2 in the blood • Internal respiration: O2 and CO2 exchange between systemic blood vessels and tissues Copyright © 2010 Pearson Education, Inc. Circulatory system Respiratory System: Functional Anatomy Major organs include: • Nose, nasal cavity, and paranasal sinuses • Pharynx • Larynx • Trachea • Bronchi and their branches • Lungs and alveoli Copyright © 2010 Pearson Education, Inc. Nasal cavity Nostril Oral cavity Pharynx Larynx Trachea Carina of trachea Right main (primary) bronchus Right lung Copyright © 2010 Pearson Education, Inc. Left main (primary) bronchus Left lung Diaphragm Figure 22.1 Functional Anatomy– consists of 2 zones Respiratory zone: site of gas exchange • Microscopic structures: respiratory bronchioles, alveolar ducts, and alveoli Conducting zone: passageways leading to gas exchange sites • Includes all other respiratory structures Respiratory muscles: diaphragm and other muscles that promote ventilation Note: functions in respiratory system but truly part of skeletal system Copyright © 2010 Pearson Education, Inc. The Nose 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 • Useful for storing beads, corn, and other small objects…see visual aid Copyright © 2010 Pearson Education, Inc. The Nose 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 Copyright © 2010 Pearson Education, Inc. Epicranius, frontal belly Root and bridge of nose Dorsum nasi Ala of nose Apex of nose Naris (nostril) Philtrum (a) Surface anatomy Copyright © 2010 Pearson Education, Inc. Figure 22.2a 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 Copyright © 2010 Pearson Education, Inc. Figure 22.2b The Nose 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 Copyright © 2010 Pearson Education, Inc. Nasal Cavity Vestibule: nasal cavity superior to the nostrils lined with sebaceous and sweat glands and many hair follicles • Vibrissae hairs that filter coarse particles (dust, pollen) from inspired air The rest of the nasal cavity is lined with 2 types of mucous membranes Note: there is a 1. Olfactory mucosa difference between • Lines the superior nasal cavity mucous and mucus!!! • Contains smell receptors Copyright © 2010 Pearson Education, Inc. Nasal Cavity 2. 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 networks of capillaries and veins • Sensory nerve endings triggers sneezing Copyright © 2010 Pearson Education, Inc. Cribriform plate of ethmoid bone Sphenoid sinus Posterior nasal aperture Nasopharynx Pharyngeal tonsil Opening of pharyngotympanic tube Uvula Frontal sinus Nasal cavity Nasal conchae (superior, middle and inferior) Nasal meatuses (superior, middle, and inferior) Nasal vestibule Nostril Oropharynx Palatine tonsil Isthmus of the fauces Hard palate Soft palate Tongue Lingual tonsil Laryngopharynx Esophagus Trachea (c) Illustration Copyright © 2010 Pearson Education, Inc. Larynx Epiglottis Vestibular fold Thyroid cartilage Vocal fold Cricoid cartilage Thyroid gland Hyoid bone Figure 22.3c Nasal Cavity Superior, middle, and inferior nasal conchae • Protrude from the lateral walls • Increase mucosal area • Enhance air turbulence This air turbulence helps clean, moisten and warm incoming air before it reaches the throat. Copyright © 2010 Pearson Education, Inc. Functions of the Nasal Mucosa and Conchae • During inhalation, the conchae and nasal mucosa • Filter, heat, and moisten air • During exhalation these structures • Reclaim heat and moisture Bat in the Cave Cam Copyright © 2010 Pearson Education, Inc. Paranasal Sinuses • In frontal, sphenoid, ethmoid, and maxillary bones What functions do the sinuses perform? • Lighten the skull and help to warm and moisten the air Copyright © 2010 Pearson Education, Inc. Pharynx = Throat • Muscular tube that connects to the • Nasal cavity and mouth superiorly • Larynx and esophagus inferiorly • Divided into 3 regions • Nasopharynx • Oropharynx • Laryngopharynx Copyright © 2010 Pearson Education, Inc. Pharynx Nasopharynx Oropharynx Laryngopharynx (b) Regions of the pharynx Copyright © 2010 Pearson Education, Inc. Figure 22.3b Nasopharynx • Air passageway only located posterior to the nasal cavity • Soft palate and uvula close nasopharynx during swallowing • Pharyngeal tonsil (adenoids) on posterior wall • Pharyngotympanic (auditory) tubes open into the lateral walls Copyright © 2010 Pearson Education, Inc. Oropharynx • 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 Copyright © 2010 Pearson Education, Inc. Laryngopharynx • Passageway for food and air • Posterior to the upright epiglottis • Extends to the larynx, where it is also continuous with the esophagus Copyright © 2010 Pearson Education, Inc. Cribriform plate of ethmoid bone Sphenoid sinus Posterior nasal aperture Nasopharynx Pharyngeal tonsil Opening of pharyngotympanic tube Uvula Frontal sinus Nasal cavity Nasal conchae (superior, middle and inferior) Nasal meatuses (superior, middle, and inferior) Nasal vestibule Nostril Oropharynx Palatine tonsil Isthmus of the fauces Hard palate Soft palate Tongue Lingual tonsil Laryngopharynx Esophagus Trachea (c) Illustration Copyright © 2010 Pearson Education, Inc. Larynx Epiglottis Vestibular fold Thyroid cartilage Vocal fold Cricoid cartilage Thyroid gland Hyoid bone Figure 22.3c And Breath….. Copyright © 2010 Pearson Education, Inc. Larynx • Attaches to the hyoid bone and opens into the laryngopharynx • Continuous with the trachea • Functions 1. Provides a patent airway 2. Routes air and food into proper channels 3. Voice production Copyright © 2010 Pearson Education, Inc. Larynx 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 Copyright © 2010 Pearson Education, Inc. Epiglottis Thyrohyoid membrane Body of hyoid bone Thyroid cartilage Laryngeal prominence (Adam’s apple) Cricothyroid ligament Cricoid cartilage Cricotracheal ligament Tracheal cartilages (a) Anterior superficial view Copyright © 2010 Pearson Education, Inc. Figure 22.4a Epiglottis Body of hyoid bone Thyrohyoid membrane Cuneiform cartilage Corniculate cartilage Arytenoid cartilage Arytenoid muscles Cricoid cartilage Thyrohyoid membrane Fatty pad Vestibular fold (false vocal cord) Thyroid cartilage Vocal fold (true vocal cord) Cricothyroid ligament Cricotracheal ligament Tracheal cartilages (b) Sagittal view; anterior surface to the right Copyright © 2010 Pearson Education, Inc. Figure 22.4b Larynx • 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 Copyright © 2010 Pearson Education, Inc. Larynx • Vestibular folds (false vocal cords) • Superior to the vocal folds • No part in sound production • Help to close the glottis during swallowing Copyright © 2010 Pearson Education, Inc. 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; closed glottis Copyright © 2010 Pearson Education, Inc. (b) Vocal folds in open position; open glottis Figure 22.5 Voice Production • 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 The Larynx at Work Copyright © 2010 Pearson Education, Inc. Larynx • 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 Copyright © 2010 Pearson Education, Inc. Trachea • Windpipe: extends 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 Copyright © 2010 Pearson Education, Inc. Trachea • 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 Copyright © 2010 Pearson Education, Inc. Posterior Mucosa Submucosa Esophagus Trachealis muscle Lumen of trachea Seromucous gland in submucosa Hyaline cartilage Adventitia Anterior (a) Cross section of the trachea and esophagus Copyright © 2010 Pearson Education, Inc. Figure 22.6a Bronchi and Subdivisions • Branch off the trachea into the rt. and lt. primary bronchi • Air passages branch repeatedly • Branching pattern called the bronchial tree Copyright © 2010 Pearson Education, Inc. Conducting Zone Structures • Nose Pharynx Larynx Trachea right and left main (primary) bronchi • Right main bronchus is wider, shorter, and more vertical than the left = choking hazard • Each main bronchus branches into lobar (secondary) bronchi (three right, two left) • Each lobar bronchus supplies one lobe Copyright © 2010 Pearson Education, Inc. Conducting Zone Structures • 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 Copyright © 2010 Pearson Education, Inc. Trachea Middle lobe of right lung Superior lobe of left lung Left main (primary) bronchus Lobar (secondary) bronchus Segmental (tertiary) bronchus Inferior lobe of right lung Inferior lobe of left lung Superior lobe of right lung Copyright © 2010 Pearson Education, Inc. Figure 22.7 Conducting Zone Structures • From bronchi through bronchioles, structural changes occur • Cartilage rings give way to plates; cartilage is absent from bronchioles • cilia and goblet (mucus producing) cells become sparse • Amount of smooth muscle increases Copyright © 2010 Pearson Education, Inc. Respiratory Zone • This zone includes the 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 Copyright © 2010 Pearson Education, Inc. Alveoli Alveolar duct Respiratory bronchioles Terminal bronchiole Alveolar duct Alveolar sac (a) Copyright © 2010 Pearson Education, Inc. Figure 22.8a Respiratory Membrane of Alveoli • Extremely thin air-blood barrier that has are on one side and blood on the other • Alveolar walls • Single layer of type I and type II cells surrounded by a flimsy basement membrane and covered in a cobweb of capillaries • Scattered type II cells secrete surfactant and antimicrobial proteins Copyright © 2010 Pearson Education, Inc. Terminal bronchiole Respiratory bronchiole Smooth muscle Elastic fibers Alveolus Capillaries (a) Diagrammatic view of capillary-alveoli relationships Copyright © 2010 Pearson Education, Inc. Figure 22.9a Copyright © 2010 Pearson Education, Inc. Figure 22.9b Alveoli • 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 Fun Fact: we swallow over 2 million old and dead macrophages per hour!!!! Copyright © 2010 Pearson Education, Inc. Red blood cell Nucleus of type I (squamous epithelial) cell Alveolar pores Capillary O2 Capillary CO2 Alveolus Alveolus Type I cell of alveolar wall Macrophage Endothelial cell nucleus Alveolar epithelium Fused basement membranes of the Respiratory alveolar epithelium membrane and the capillary Red blood cell endothelium Alveoli (gas-filled in capillary Type II (surfactantCapillary air spaces) secreting) cell endothelium (c) Detailed anatomy of the respiratory membrane Copyright © 2010 Pearson Education, Inc. Figure 22.9c Lungs • Occupy all of the thoracic cavity except the mediastinum • Costal surface: anterior, lateral, and posterior surfaces • Apex: superior tip • Base: inferior surface that rests on the diaphragm Copyright © 2010 Pearson Education, Inc. Lungs Right lung has 3 lobes separated by oblique and horizontal fissures Left lung is smaller, separated into 2 lobes by an oblique fissure • Cardiac notch of left lung: concavity that accommodates the heart Copyright © 2010 Pearson Education, Inc. Trachea Thymus Lung Intercostal muscle Rib Parietal pleura Pleural cavity Visceral pleura Apex of lung Right superior lobe Horizontal fissure Heart (in mediastinum) Right middle lobe Oblique fissure Right inferior lobe Diaphragm Base of lung Left superior lobe Oblique fissure Left inferior lobe Cardiac notch (a) Anterior view. The lungs flank mediastinal structures laterally. Copyright © 2010 Pearson Education, Inc. Figure 22.10a Right lung Right superior lobe (3 segments) Left lung Left superior lobe (4 segments) Right middle lobe (2 segments) Right inferior lobe (5 segments) Copyright © 2010 Pearson Education, Inc. Left inferior lobe (5 segments) Figure 22.11 Blood Supply 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 Copyright © 2010 Pearson Education, Inc. Blood Supply Systemic circulation (high pressure, low volume) • Bronchial arteries provide oxygenated blood to lung tissue • Arise from aorta and enter the lungs • Supply all lung tissue except the alveoli • Bronchial veins anastomose with pulmonary veins • Pulmonary veins carry most venous blood back to the heart Copyright © 2010 Pearson Education, Inc. Pleurae • Thin, double-layered membrane • Parietal pleura on thoracic wall and superior face of diaphragm • Visceral pleura on external lung surface • Pleural fluid fills the slit-like pleural cavity • Provides lubrication and surface tension See Visual Aid Copyright © 2010 Pearson Education, Inc. Vertebra Right lung Parietal pleura Visceral pleura Pleural cavity Pericardial membranes Sternum Posterior Esophagus (in mediastinum) Root of lung at hilum • Left main bronchus • Left pulmonary artery • Left pulmonary vein Left lung Thoracic wall Pulmonary trunk Heart (in mediastinum) Anterior mediastinum Anterior (c) Transverse section through the thorax, viewed from above. Lungs, pleural membranes, and major organs in the mediastinum are shown. Copyright © 2010 Pearson Education, Inc. Figure 22.10c Mechanics of Breathing Under Pressure • Pulmonary ventilation consists of two phases 1.Inspiration: air flow into the lungs 2.Expiration: air exits the lungs Average respiratory rate in an adult is 12-18 breaths per minute Copyright © 2010 Pearson Education, Inc. Pressure Relationships in the Thoracic Cavity 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 Copyright © 2010 Pearson Education, Inc. Intrapulmonary Pressure Intrapulmonary pressure (Ppul) • Pressure in the alveoli • Fluctuates with breathing • Always eventually equalizes with Patm (0 respiratory pressure) Copyright © 2010 Pearson Education, Inc. Intrapleural Pressure Intrapleural pressure (Pip): • Pressure in the pleural cavity • Fluctuates with breathing • Always a negative pressure Copyright © 2010 Pearson Education, Inc. Intrapleural Pressure Negative Pip is caused by opposing forces • Two inward forces promote lung collapse • Elastic recoil of lungs decreases lung size • Surface tension of alveolar fluid reduces alveolar size • One outward force tends to enlarge the lungs • Elasticity of the chest wall pulls the thorax outward Copyright © 2010 Pearson Education, Inc. Pressure Relationships • If Pip = Ppul the lungs collapse • The difference in these pressures = transpulmonary pressure • Keeps the airways open • The greater the transpulmonary pressure, the larger the lungs Copyright © 2010 Pearson Education, Inc. Atmospheric pressure Parietal pleura Thoracic wall Visceral pleura Pleural cavity Transpulmonary pressure 760 mm Hg –756 mm Hg = 4 mm Hg 756 760 Lung Diaphragm Copyright © 2010 Pearson Education, Inc. Intrapleural pressure 756 mm Hg (–4 mm Hg) Intrapulmonary pressure 760 mm Hg (0 mm Hg) Figure 22.12 Homeostatic Imbalance • Atelectasis (lung collapse) is due to • Plugged bronchioles collapse of alveoli • Wound that admits air into pleural cavity (pneumothorax) Copyright © 2010 Pearson Education, Inc. Pulmonary Ventilation • Inspiration and expiration • Mechanical processes that depend on volume changes in the thoracic cavity • Volume changes pressure changes • Pressure changes gases flow to equalize pressure Copyright © 2010 Pearson Education, Inc. Boyle’s Law • The relationship between the pressure and volume of a gas • Pressure varies inversely with volume As we decrease volume, we increase pressure As we increase volume, we decrease pressure Who likes marshmallows? Copyright © 2010 Pearson Education, Inc. Inspiration • An active process • Inspiratory muscles contract • Thoracic volume increases • Lungs are stretched and intrapulmonary volume increases • Intrapulmonary pressure drops (to 1 mm Hg) • Air flows into the lungs, down its pressure gradient, until Ppul = Patm Copyright © 2010 Pearson Education, Inc. Expiration • Quiet expiration is normally a passive process • Inspiratory muscles relax • Thoracic cavity volume decreases • Elastic lungs recoil and intrapulmonary volume decreases • Intrapulmonary pressure increases (to +1 mm Hg) • Air flows out of the lungs down its pressure gradient until pulmonary pressure (Ppul) = 0 • Note: forced expiration is an active process: it uses abdominal and internal intercostal muscles Copyright © 2010 Pearson Education, Inc. Physical Factors Influencing Pulmonary Ventilation • 3 factors hinder air passage and pulmonary ventilation 1. Airway resistance 2. Alveolar surface tension 3. Lung compliance Copyright © 2010 Pearson Education, Inc. Airway Resistance • As airway resistance rises, breathing movements become more strenuous • Severely constricted or obstructed bronchioles • Can prevent life-sustaining ventilation • Can occur during acute asthma attacks and stop ventilation • Epinephrine dilates bronchioles and reduces air resistance Copyright © 2010 Pearson Education, Inc. Alveolar Surface Tension Surface tension • Attracts liquid molecules to one another at a gas-liquid interface • Resists any force that tends to increase the surface area of the liquid Copyright © 2010 Pearson Education, Inc. Alveolar Surface Tension • Surfactant • Detergent-like lipid and protein complex produced by type II alveolar cells • Reduces surface tension of alveolar fluid and discourages alveolar collapse • Insufficient quantity in premature infants causes infant respiratory distress syndrome Want to see a magic trick? Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Lung Compliance • A measure of the change in lung volume that occurs with a given change in transpulmonary pressure • Normally high due to • Elasticity of the lung tissue • Alveolar surface tension Copyright © 2010 Pearson Education, Inc. Lung Compliance • Diminished by • Nonelastic scar tissue (fibrosis) • Reduced production of surfactant • Decreased flexibility of the thoracic cage Copyright © 2010 Pearson Education, Inc. Lung Compliance • Homeostatic imbalances that reduce compliance • Deformities of thorax • Ossification of the costal cartilage • Paralysis of intercostal muscles Copyright © 2010 Pearson Education, Inc.