BSC 2086 01 Anatomy and Physiology II Spring 2013 14 The Respiratory System Part 2 2012 Pearson Education Inc An Introduction to the Respiratory System Learning Outcomes 23 6 Define and compare the processes of external respiration and internal respiration 23 7 Summarize the physical principles governing the movement of air into the lungs and describe the origins and actions of the muscles responsible for respiratory movements 23 8 Summarize the physical principles governing the diffusion of gases into and out of the blood and body tissues 2012 Pearson Education Inc An Introduction to the Respiratory System Learning Outcomes 23 9 Describe the structure and function of hemoglobin and the transport of oxygen and carbon dioxide in the blood 23 10 List the factors that influence respiration rate and discuss reflex respiratory activity and the brain centers involved in the control of respiration 23 11 Describe age related changes in the respiratory system 2012 Pearson Education Inc 23 6 Introduction to Gas Exchange Respiration Refers to two integrated processes 1 External respiration Includes all processes involved in exchanging O2 and CO2 with the environment 1 Internal respiration Result of cellular respiration Involves the uptake of O2 and production of CO2 within individual cells mitochondria uses O2 and generates CO2 2012 Pearson Education Inc 23 6 Introduction to Gas Exchange Three Processes of External Respiration 1 Pulmonary ventilation breathing 2 Gas diffusion Across membranes and capillaries 3 Transport of O2 and CO2 Between alveolar capillaries Between capillary beds in other tissues Abnormal External Respiration Is Dangerous Hypoxia Low tissue oxygen levels Anoxia Complete lack of oxygen quickly kills cells 2012 Pearson Education Inc Figure 23 12 An Overview of the Key Steps in Respiration Respiration External Respiration Pulmonary ventilation Internal Respiration O2 transport Tissues Gas diffusion Gas diffusion Lungs Gas diffusion Gas diffusion CO2 transport 2012 Pearson Education Inc 23 7 Pulmonary Ventilation Pulmonary Ventilation Is the physical movement of air in and out of Provides alveolar ventilation air movement into out of respiratory tract alveoli The Movement of Air Atmospheric pressure The weight of air compresses our bodies Has several important physiological effects 2012 Pearson Education Inc 23 7 Pulmonary Ventilation Gas Pressure and Volume Boyle s Law volume Defines the relationship between gas pressure and P 1 V In a contained gas External pressure forces molecules closer together Movement of gas molecules exerts pressure on container 2012 Pearson Education Inc Figure 23 13 Gas Pressure and Volume Relationships If you decrease the volume of the container collisions occur more frequently per unit time elevating the pressure of the gas If you increase the volume fewer collisions occur per unit time because it takes longer for a gas molecule to travel from one wall to another As a result the gas pressure inside the container declines 2012 Pearson Education Inc 23 7 Pulmonary Ventilation Pressure and Airflow to the Lungs Air flows from area of higher pressure to area of lower pressure concept similar to diffusion Pulmonary Ventilation Causes volume changes that create changes in pressure Volume of thoracic cavity changes with expansion or contraction of diaphragm or rib cage A Respiratory Cycle consists of 1 An inspiration inhalation 2 An expiration exhalation 2012 Pearson Education Inc Figure 23 14a Mechanisms of Pulmonary Ventilation Ribs and sternum elevate Diaphragm contracts As the rib cage is elevated or the diaphragm is depressed the volume of the thoracic cavity increases 2012 Pearson Education Inc Figure 23 14b Mechanisms of Pulmonary Ventilation Pleural cavity Cardiac notch Diaphragm 2012 Pearson Education Inc Poutside Pinside Pressure outside and inside are equal so no air movement occurs At rest Figure 23 14c Mechanisms of Pulmonary Ventilation Volume increases Poutside Pinside Pressure inside falls so air flows in Inhalation Elevation of the rib cage and contraction of the diaphragm increase the size of the thoracic cavity Pressure within the thoracic cavity decreases and air flows into the lungs 2012 Pearson Education Inc Figure 23 14d Mechanisms of Pulmonary Ventilation Volume decreases Poutside Pinside Pressure inside rises so air flows out Exhalation When the rib cage returns to its original position and the diaphragm relaxes the volume of the thoracic cavity decreases Pressure rises and air moves out of the lungs 2012 Pearson Education Inc 23 7 Pulmonary Ventilation Pressure Changes during Inhalation and Exhalation Can be measured inside or outside the lungs Normal atmospheric pressure 1 atm 760 mm Hg ANIMATION Respiration Pressure Gradients 2012 Pearson Education Inc 23 7 Pulmonary Ventilation The Intrapulmonary Pressure Also called intra alveolar pressure air pressure inside the alveolus Is relative to atmospheric pressure In relaxed breathing the difference between atmospheric pressure and intrapulmonary pressure is small About 1 mm Hg on inhalation or 1 mm Hg on exhalation Maximum Intrapulmonary Pressure Maximum straining a dangerous activity can increase range from 30 mm Hg to 100 mm Hg 2012 Pearson Education Inc If too high can cause alveolar rupture or hernia 23 7 Pulmonary Ventilation The Intrapleural Pressure Pressure in space between parietal and visceral pleura Averages 4 mm Hg Maximum of 18 mm Hg during powerful inhalation Remains below atmospheric pressure throughout respiratory cycle chest wall Caused by elastic recoil of lung tissue pulling on the 2012 Pearson Education Inc 23 7 Pulmonary Ventilation Injury to the Chest Wall Pneumothorax allows air into pleural cavity Breaks the fluid bond between the pleurae Atelectasis also called a collapsed lung is a result of pneumothorax 2012 Pearson Education Inc Table 23 1 The Four Most Common Methods of Reporting Gas Pressures 2012 Pearson Education Inc 23 7 Pulmonary Ventilation The Respiratory Cycle Cyclical changes in intrapleural pressure operate the respiratory pump Which aids in venous return to heart Tidal Volume VT Approximately 500 mL Amount of air moved in and out of lungs in a single respiratory cycle 2012 Pearson Education Inc Figure 23 15 Pressure and Volume Changes during Inhalation and Exhalation INHALATION EXHALATION Intrapulmonary pressure mm Hg Trachea Bronchi Lung Intrapleural pressure mm Hg Tidal volume mL Diaphragm Right pleural cavity Left pleural cavity Note
View Full Document
Unlocking...