GSU BIOL 2240 - Respiratory (26 pages)

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Respiratory



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Respiratory

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Pages:
26
School:
Georgia State University
Course:
Biol 2240 - Intro to Human Physiology
Intro to Human Physiology Documents
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Respiratory system Respiratory System Ventilation Movement of air in out of lungs External respiration Gas exchange oxygen and carbon dioxide between air in lungs and blood Internal respiration Gas exchange between the blood and tissues Anatomy of Respiratory System Upper tract nose pharynx and associated structures Lower tract larynx trachea bronchi lungs and the tubing within the lungs Trachea Windpipe from the larynx into the mediastinum Wall composed of C shaped rings of hyaline cartilage Respiratory zone respiratory bronchioles to alveoli Alveoli Nucleus of type I cell Surrounded by fine elastic fibers Alveolar pores contribute to recoil Contain open pores that connect adjacent alveoli Allow air pressure throughout the lung to be equalized Capillary Alveolus Type I cell of alveolar wall Macrophage Endothelial cell nucleus Red blood cell Alveoli gas filled in capillary Type II surfactantair spaces secreting cell 23 4 The Respiratory Membrane Three types of cells in membrane Type I pneumocytes 90 of surface of alveolus Gas exchange Type II pneumocytes Produce surfactant Dust cells phagocytes Nucleus of type I cell Alveolar pores Capillary Alveolus Type I cell of alveolar wall Macrophage Endothelial cell nucleus Respiratory Membrane Red blood cell Alveoli gas filled in capillary Type II surfactantair spaces secreting cell Layers of respiratory membrane 23 5 The Respiratory Membrane Layers of respiratory membrane Alveolar fluid w surfactant Alveolar epithelium Thin interstitial space Capillary endothelium Red blood cell Nucleus of type I cell O2 CO2 Capillary Alveolus Endothelial cell nucleus Alveolar epithelium Fused basement membranes of the alveolar epithelium and the capillary endothelium Capillary endothelium 23 6 Lungs Two lungs Thoracic cavity w in ribcage Base sits on diaphragm Right lung three lobes Lobes separated by fissures Left lung Two lobes and an indentation called the cardiac notch Covered by pleural membrane Pleura Muscles of Ventilation Inspiration diaphragm external intercostals pectoralis minor scalenes Abdominal muscles relax Other muscles to help elevate ribs and costal cartilages allow lateral rib movement Expiration muscles that depress the ribs and sternum abdominal muscles and internal intercostals relaxation of diaphragm and external intercostals with contraction of abdominal muscles Ventilation Movement of air into and out of lungs Air moves from area of higher pressure to area of lower pressure down gradient Boyle s Law P k V where P gas pressure V volume k constant at a given temperature Atmospheric P Patm If Patm Palv alveolar pressure air flows into alveoli insprn thorax expands V alveoli size Palv air flows in Alveolar Volume Lung recoil drives alveoli to collapse resulting from Elastic recoil elastic fibers in the alveolar walls Surface tension H bonds of water molecules of fluids in lungs drives alveoli to collapse Surfactant Produced by type II pneumocytes Reduces tendency of lungs to collapse by reducing surface tension Pleural Pressure Negative pressure can cause alveoli to expand inflated Alveoli expand when pleural pressure is low negative enough to overcome lung recoil Pleural fluid Measurement of Lung Function Measurement of Lung Function Spirometer measures volumes of air that move into and out of respiratory system Tidal volume amount of air inspired or expired with each breath At rest 500 mL Inspiratory reserve volume amount that can be inspired forcefully after inspiration of the tidal volume At rest 3000 mL Expiratory reserve volume amount that can be forcefully expired after expiration of the tidal volume At rest 100 mL Residual volume volume still remaining in respiratory passages and lungs after most forceful expiration At rest 1200 mL Physical Principles of Gas Exchange Diffusion of gases thru respiratory membrane depends on 4 factors Surface area Diffusion coefficient of gas measure of how easily a gas diffuses through a liquid or tissue CO2 O2 N2 Membrane thickness The thicker the lower the diffusion rate Partial pressure differences Gas moves from area of higher partial pressure to area of lower partial pressure Membrane thickness Cardiac pulmonary edema aka congestive heart failure occurs when left ventricle isn t able to pump out enough of the blood it receives from your lungs pressure increases inside the left atrium and then in the veins and capillaries in your lungs fluid pushed through the capillary walls into the air sacs edema gasping wheezing decreased gas exchange Gas Exchange Oxygen Moves from alveoli into blood Blood is almost completely saturated with oxygen when it leaves the pulmonary capillary PO2 in blood decreases because of mixing with deoxygnt d blood Oxygen moves from tissue capillaries into the tissues Carbon dioxide Moves from tissues into tissue capillaries Moves from pulmonary capillaries into alveoli Test yourself Gas exchange at pulmonary capillaries is a Internal respiration b External respiration c ventilation Respiratory gas exchange is a two way process CO2 diffuses out of the body as O2 diffuses in The concentration gradient of CO2 from air breathers to the environment is always large Oxygen is transported by hemoglobin Hb 98 5 and is in plasma 1 5 hemoglobin a protein with four polypeptide subunits tetramer Each polypeptide surrounds a heme group that can bind a molecule of O2 One molecule of hemoglobin can bind up to four molecules of O2 b Globin chains a Globin chains Heme group Hemoglobin will pick up or release O2 depending on the PO2 of the environment If PO2 is high as in the lungs hemoglobin will pick up its maximum of four O2 molecules As blood circulates through tissues with lower PO2 hemoglobin will release some O2 The relationship between PO2 and the O2 binding is S shaped Oxyhemoglobin dissociation curve Low PO2 one subunit binds O2 Positive cooperativity one subunit binds and changes shape making it easier for the next one to bind the affinity for O2 is increased When three subunits are bound a larger increase in PO2 is needed Bohr Effect Effect of pH on oxygenhemoglobin dissociation curve as pH of blood declines amount of oxygen bound to hemoglobin at any given PO2 declines H that combines with hemoglobin changes its shape st oxygen cannot bind to hemoglobin Transport of Carbon Dioxide CO2 is transported away from tissues in blood Carbon dioxide is transported as bicarbonate ions HCO3 70 bound to proteins 23 primarily hemoglobin and in solution with plasma 7 CO2Transport


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