Anatomy and Physiology 1 Final Exam Figueroa Respiratory System Major Functions provide blood with oxygen O2 and to get rid of dispose of carbon dioxide CO2 gas exchange is simple diffusion In order for respiration to occur 4 processes must happen 1 Pulmonary ventilation aka breathing the moving of air into and out of the lungs see pulmonary think lungs 2 External respiration gas exchange between the lungs and blood 3 Transport of respiratory gases 4 Internal respirations movement of O2 from the blood to the tissue cells AND the movement of CO2 from the tissue cells to the blood Respiratory membrane has 3 main parts 1 wall of the capillary 2 wall of the alveolus 3 the space between these two walls Conducting Zone the function is to conduct air to the respiratory zone considered conducting zone because NO alveoli so no actual gas exchange occurs in the conducting zone Bronchi subdivided into Secondary Bronchi each supplying a lobe of the lungs there are 23 orders of branching in the lungs that air must pass through contain cartilage Bronchial Tree Bronchi split into Bronchioles bronchioles contain a layer of smooth muscle and lack cartilage support NOTE big tubes of the conducting zone contain cartilage small tubes lack cartilage Bronchi Secondary Bronchi Tertiary Bronchi Bronchioles Terminal Bronchioles Respiratory Zone begins as the terminal bronchioles feed into Respiratory bronchioles alveoli are present Terminal bronchioles start Respiratory bronchioles Alveolar ducts Alveolar sacs Alveoli alveoli are the smallest alveolar sacs are made up of alveoli etc O2 goes from high low so if take a deep breath have high O2 in lungs tubes which then travels to the blood where O2 levels are low hence simple diffusion There are 300 million alveoli this makes up most of the lungs volume there are tiny sacs on alveoli don t confuse with with alveolar sacs which account for a greater surface area for gas exchange capillaries cover alveoli 6 capillaries cover the alveoli Air Blood Barrier The Alveolar walls and Capillary walls are fused at their basal laminas making the Air Blood Barrier there is fluid between the lungs and the blood capillaries O2 diffuses into the cells and CO2 diffuses out of the cells Alveolar wall made up of a single layer epithelial cells allows gas exchange to occur via simple diffusion secretes ACE angiotensin converting enzyme Blood Circulations to the Lungs two circulations Pulmonary and Bronchial Pulmonary arteries supply systemic blood to be oxygenated Pulmonary veins carry oxygenated blood from respiratory zones to the heart Breathing aka Pulmonary Ventilation different than respiration Ventilation breathing Respiration the gas exchange aspect two phases 1 Inspiration air flows into the lungs 2 Expiration gases exit the lungs aka inhalation exhalation Mechanical process that depends on volume changes in the thoracic cavity by moving the diaphragm the pressure in the cavity changes the lower the volume higher pressure pressure and volume are INVERSELY related Inspiration diaphragm diaphragm contracts moves DOWN during inspiration changes in the anterior posterior and superior inferior dimensions ribs elevated and sternum expands as external intercostals contract diaphragm and abdomen contract at OPPOSITE times Expiration abdominal muscle abdomen contracts during expiration diaphragm relaxes moves UP and the rib cage descends due to gravity Thoracic cavity volume decreases lungs recoil passively and intrapulmonary volume decreases Ppul rises above Patm 1mm causing air to leave the lungs hence why expiration gas flows out of the lungs until Ppul is ZERO 0 During normal quiet inhalation the diaphragm and external intercostals contract During labored inhalation sternocleidomastoid scalenes and pectoralis minor ALSO contract During normal exhalation the diaphragm and external intercostals relax During forceful exhalation abdominal and internal intercostal muscles contract Pressure Relationships Respiratory pressure is measured relative to Atmospheric pressure Patm Atmospheric pressure Patm 760mm at sea level this is the pressure exerted by the air surrounding the body negative respiratory pressure less than Patm leads to inhalation so that air can go from high pressure outside the body to low pressure inside the body positive respiratory pressure greater than Patm leads to exhalation so that air can go from high pressure inside the body to low pressure outside the body Ppul intrapulmonary pressure and Pip intrapleural pressure pul PULmonary Ppul and Pip fluctuate with the phases of breathing Ppul always will eventually equalize with Patm Pip is always LESS than Ppul and Patm if the pressure INSIDE falls air flows IN inhalation volume increases NEED a difference of 3mm 3mm compared to Patm in order to inhale ex Outside 760mm Inside 757mm if the pressure INSIDE rises air flows OUT exhalation volume decreases NEED a positive difference of 3mm 3mm compared to Patm in order to exhale ex Outside 760mm Inside 763mm Two forces act to pull lungs away from the thoracic wall promoting the lung collapse Elasticity of the lungs causes them to assume smallest possible size Surface tension of alveolar fluid draws alveoli to their smallest size possible Opposing force elasticity of the chest wall pulls the thorax outward to enlarge the lungs Lung Collapse caused by the equalization of the Pip with the Ppul Transpulmonary pressure keeps the airways open Transpulmonary pressure difference btwn the intrapulmonary and intrapleural pressures Ppul Pip Physical Factors Influencing Ventilation Airway Resistance Air flow is directly related to the difference in pressure Air flow is inversely related to the tube resistance diameter accounts for this the smaller the diameter the bigger the resistance can NOT change the diameter of the BIG tubes with cartilage SMALLER tubes have smooth muscle so you CAN change the diameter of those tubes bronchial dilation Friction is the major NONelastic source of resistance to airflow F delta P R F flow P pressure R resistance delta P the amount of gas flowing into and out of the alveoli is directly proportional to the delta P the pressure gradient btwn the atmosphere and alveoli the greatest resistance is in the medium sized bronchi as airway resistance increases breathing becomes more strenuous severely constricted or obstructed bronchioles can prevent life sustaining ventilation can occur during acute asthma Know difference in images of a normal airway one
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