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The Respiratory System. ANATOMY OF THE RESPIRATORY SYSTEM

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The Respiratory System Slide 2 ANATOMY OF THE RESPIRATORY SYSTEM Slide 3 The Respiratory Tract: The Lungs Alveoli TABLE OF CONTENT Slide 4 1) Respiratory Tract : Nose through bronchi 2) The lungs. THE RESPIRATORY SYSTEM CONSISTS OF: Slide 5 The respiratory tract further divided into the upper and lower respiratory tract Slide 6 The upper respiratory tract from the nose through the pharynx Slide 7 The lower respiratory tract (The Bronchial Tree) from the larynx to tertiary bronchi Slide 8 The Bronchial Tree Slide 9 Alveoli The Bronchial Tree Extends to Bronchioles and Alveoli Slide 10 Bronchioles and Alveoli Slide 11 Cartilage Plates No Cartilage but Smooth Muscles Bronchioles Cartilage Ring asthma attack Slide 12 Cross Section Longitudinal Section Ciliary Lining of the Lower Respiratory Tract Cilia Slide 13 Electron Micrograph of Cilia Slide 14 The cilia beat upward and drive the debris-laden mucus to the pharynx, where it is swallowed. Slide 15 THE LUNGS Slide 16 The Lungs overlap with the respiratory tract. Secondary Bronchi Tertiary Bronchi Bronchioles Alveoli Bronchioles Alveoli Primary Bronchi Inside Lungs Slide 17 THE LUNGS - consist of the left and the right lungs - The left lung is divided into two lobes; the right into three. - receives the bronchus, blood and lymphatic vessels, and nerves through its hilum. - The bronchi extend into alveoli Slide 18 ALVEOLI Slide 19 ~700 SF surface area Slide 20 Alveoli consists of : 1) type I alveolar cells (95%), thin 2) type II alveolar cells (5%), secrete surfactant. 3) macrophages (dust cells), defense Slide 21 -Each alveolus is surrounded with a basket of capillaries. Slide 22 surrounded with capillaries Slide 23 The respiratory membrane: 1) the wall of the alveolus 2) the endothelial wall of the capillary 3) their fused basement membranes Slide 24 Alveoli contain elastic fibers which helps expiration. Slide 25 Low blood pressure keeps alveoli dry. Slide 26 Gas exchange occurs only in alveoli. Slide 27 Dead Space - starts from nose to terminal bronchiole - where there is no gas exchange - ~ 150 ml terminal bronchiole Slide 28 The Respiratory Tract: The Lungs Alveoli ANATOMY OF THE RESPIRATORY SYSTEM SUMMARY Slide 29 ventilation gas exchange transport by blood gas exchange Slide 30 MECHANICS OF VENTILATION Slide 31 Driving Force for Air Flow Resistance to Airflow Measurements of Ventilation Alveolar Ventilation TABLE OF CONTENTS Slide 32 Terms: inspiration or inhalation: breathing in expiration or exhalation: breathing out Slide 33 Driving Force for Air Flow Airflow driven by the pressure difference between atmosphere (barometric pressure) and inside the lungs (intrapulmonary pressure). 760 mmHg Slide 34 atmospheric pressure = 760 mmHg Before inspiration Slide 35 atmospheric pressure = 760 mmHg Slide 36 atmospheric pressure = 760 mmHg Slide 37 atmospheric pressure = 760 mmHg Slide 38 Mechanism for the Change in Intrapulmonary pressure Boyles Law: Volume x Pressure = Constant gas PV Slide 39 Volume Pressure Volume Pressure Inspiration:Expiration: Slide 40 Volume Pressure Volume Pressure Inspiration:Expiration: Can the lungs expand/shrink by themselves? Slide 41 1) The Diaphragm 2) External Intercostal Muscles 3) Internal Intercostal Muscles 4) The Abdominal Muscles - the principal muscle of inspiration - pulls the diaphragm down, increasing all three dimensions of the thoracic cage. Major Respiratory Muscles 1) The Diaphragm 2) External Intercostal Muscles - Inspiration muscles - increases the anteroposterior and transverse dimensions of the chest. 1) The Diaphragm 2) External Intercostal Muscles 3) The Abdominal Muscles - Expiration muscles - pulls the diaphragm up, reducing the vertical dimension of the thoracic cage. 1) The Diaphragm 2) External Intercostal Muscles 3) The Abdominal Muscles 4) Internal Intercostal Muscles - Extra Expiration muscles Slide 42 Coupling Between Lungs and Thoracic Cage Slide 43 Visceral pleura covers the surface of each lung; parietal pleura lines the chest cavity. - The lungs and thoracic cage are coupled by the pleurae. pleural cavity - The two pleurae form the pleural cavity. - The pleural fluid serves to reduce friction during chest expansion. - Intrapleural pressure: The pressure in the pleural cavity is negative. Slide 44 Parietal pleura visceral pleura Potential pleural cavity (negative intrapleural pressure) lung The thoracic cage is larger than the natural size of the lungs. Generation of the negative intrapleural pressure Slide 45 Parietal pleura visceral pleura Potential pleural cavity (negative intrapleural pressure) air pneumathorax lung Slide 46 Conclusion LungsThoracic Cage pleurae - pressure Slide 47 Inspiration Contraction of 1) diaphragm 2) external intercostal muscles The lungs are carried along. Lung volume pressure Air flows in. active Slide 48 passive Resting Expiration Relaxation of 1) diaphragm 2) external intercostal muscles The lungs shrink. Lung volume pressure Air flows out. Slide 49 Forced Expiration Relaxation of 1) diaphragm 2) external intercostal muscles and Contraction of abdominal, internal intercostal and other accessory respiratory muscles. Lung volume pressure Air flows out. active Slide 50 Driving Force for Air Flow Atmosphere-lung pressure gradient Major respiratory muscles Coupling between lungs and thoracic cage SUMMARY Slide 51 Resistance to Airflow Slide 52 TABLE OF CONTENTS Resistance 1) Alveolar Surface Tension 2) Elastic Resistance 3)Airway Resistance Compliance Slide 53 1)Alveolar Surface Tension - generated by a thin film of liquid over the surface of alveolar epithelium, - tends to cause a collapse of the alveoli, -Resists against inspiration. Slide 54 Alveoli Alveolar surface tension is a resistance against inspiration. Slide 55 -Surface tension is reduced by surfactant. ( type II alveolar epithelial cells) Pre-term infants don't have enough surfactant. type II surfactant Slide 56 Resistance 1) Alveolar Surface Tension 2) Elastic Resistance 3)Airway Resistance - Against inspiration due to elastic fibers in the lungs and chest wall, - Increases in pulmonary fibrosis. Slide 57 Resistance 1) Alveolar Surface Tension 2) Elastic Resistance 3)Airway Resistance - Due to friction, affected by airway caliber. - Against inspiration and expiration! - Increases during asthma attack (smooth muscle contraction in bronchiole. Slide 58 Resistance 1) Alveolar Surface Tension 2) Elastic Resistance 3)Airway Resistance Compliance - The reciprocal of resistance, - An indicator of ease with which the lungs expand. Slide 59 Measurements of Ventilation using Spirometer Slide 60 Slide 61 Dead Space inspirationexpiration Alveolar ventilation rate = (tidal volume dead space) x resp freq (/min) Slide 62 Restrictive disorders - (pulmonary fibrosis) - compliance & vital capacity. Changes in Spirometric Measures Slide 63 - No change in respiratory volumes - FEV1. one-second forced expiratory volume Obstructive disorders Changes in Spirometric Measures Slide 64 MECHANICS OF VENTILATION SUMMARY Driving Force for Air Flow Resistance to Airflow Measurements of Ventilation Alveolar Ventilation Slide 65 NEURAL CONTROL OF VENTILATION Slide 66 Rhythm? Slide 67 1) inspiratory center - stimulates inspiration muscles. 2) expiratory center -inhibits the inspiratory center, -stimulates expiration muscles. Center in the medulla oblongata Slide 68 The pons fine-tunes ventilation. Slide 69 Afferent Connections to the Respiratory Centers the limbic system Hypothalamus Chemoreceptors the lungs Slide 70 Chemoreceptor-initiated Reflexes Peripheral chemoreceptors - aortic and carotid bodies, - monitor O 2, CO 2 and pH of the blood. Central chemoreceptors - close to the surface of the medulla oblongata, - monitor the pH of the cerebrospinal fluid. Slide 71 O 2, CO 2, or pH stimulate chemoreceptors reflex frequency and depth of respiration CHEMORECEPTOR-MEDIATED REFLEX Slide 72 Voluntary Control - the motor cortex, - bypass the brainstem respiratory centers, - limited voluntary control. Slide 73 GAS EXCHANGE in the LUNGS Slide 74 ventilation gas exchange transport by blood gas exchange Slide 75 - The gas exchange between alveolar air and the blood is via diffusion of O 2 and CO 2. - Diffusion of a gas is driven by O 2 and CO 2 partial pressure gradient. P O2 = 40 mmHg P CO2 = 46 mmHg P O2 = 104 mmHg P CO2 = 40 mmHg Slide 76 The partial pressure of a gas refers to the share of the total pressure generated by a mixture of gases. O2O2 CO 2 N2N2 H2OH2O Total = 760 mmHg 5.3% 40 mmHg 13.6% 104 mmHg Slide 77 P O2 = 40 mmHg P CO2 = 46 mmHg P O2 = 104 mmHg P CO2 = 40 mmHg Oxygen and carbon dioxide cross the respiratory membrane and the air-water interface easily. Slide 78 Overview of Gas Exchange in the Lungs Slide 79 Factors That Affect the Efficiency of Alveolar Gas Exchange 1. partial pressure 2.solubility 3.respiratory membrane thickness/area 4.ventilation-perfusion coupling Slide 80 O2O2 CO 2 N2N2 O2O2 N2N2 H2OH2O Total = 760 mmHg Air a) High altitude b) Hyperbaric chamber c) Obstructive disease P O2 104 mmHg P CO2 40 mmHg 1) Partial pressure Slide 81 CO2 has a higher solubility than O 2. CO 2 O 2 Pressure Gradient6 mmHg 64 mmHg P O2 104 mmHg P CO2 40 mmHg 2) Solubility P O2 40 mmHg P CO2 46 mmHg 1) Partial pressure Slide 82 2) Solubility 1) Partial pressure 3) Respiratory membrane thickness/area Slide 83 4) Ventilation-perfusion Coupling - average V-P ratio = 0.8 - autoregulated by: 2) Solubility 1) Partial pressure 3) Respiratory membrane thickness/area P O2 and P CO2 causes: 1)vasoconstriction of pulmonary arterioles 2)dilation of bronchioles Slide 84 summary 1) Driving force for gas exchange 2) Factors that affect the efficiency of alveolar gas exchange Slide 85 Gas transport by the blood Slide 86 TABLE OF CONTENT 1) Carbon Dioxide Transport 2) Oxygen Transport Slide 87 7% disso

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