The Respiratory System Study Guide for Exam 4 The Respiratory System controls the exchange of gases to provide O2 for the body and expel CO2 Pulmonary ventilation moving air into and out of the lungs External Respiration gas exchange between the lungs and the blood Conducting zones do NOT have alveoli bronchi and terminal bronchioles are the conducting zone o Alveoli are where gas exchange occurs because there are over 300 million alveoli in the lungs there is a much larger area for gas exchange to take place Respiratory zones DO have alveoli respiratory bronchioles are a respiratory zone o Begins at terminal bronchioles and feeds into the respiratory bronchioles H2CO3 HCO3 Buffer System functions to regulate blood pH levels o If H concentration increases excess H removed by combining with HCO3 o If H concentration decreases carbonic acid dissociates releasing H Mechanics of breathing aka Pulmonary ventilation Breathing is different than respiration Respiration is the gas exchange aspect ventilation is breathing 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 the higher the pressure pressure volume inversely related Breathing or pulmonary ventilation consists of 2 phases o Inspiration air flows into lungs inhalation diaphragm Diaphragm contracts moves down normal inhalation Ribs elevated sternum expands as external intercostals contract forced inhalation o Expiration gases exit the lungs exhalation abdominal muscle Abdomen contracts during expiration forceful exhalation Diaphragm relaxes move up and the rib cage descends due to gravity normal exhalation Thoracic cavity volume decreases Lungs recoil passively and intrapulmonary volume decreases Ppul rises about 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 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 in the thoracic cavity Atmospheric pressure 760 mmHg it takes greater than the atmospheric pressure to move air from inside the lungs to the outside air expiration Direction of airflow is determined by changing pressures air flows from high to low pressure Pressure can be altered by changing the volume less volume higher pressure Pressure Volume Relationships o Changing the relative pressure in the compartment can control the direction of airflow between compartments o In a close compartment pressure and volume are inversely related Reducing the volume will increase the pressure Increasing the volume will decrease the pressure Normal Inspiration o Prior to normal inspiration atmospheric and alveolar pressure are equal o During inspiration the diaphragm flattens increasing the volume of the thoracic cavity by increasing the length Diaphragm comes down contraction pressure decreases The external intercostals elevate the ribs and increase the volume of the thoracic cavity by increasing the width This causes the lungs and visceral pleura to be pulled outward and lung volume increases Normal Expiration o Prior to normal expiration atmospheric and alveolar pressures are equal o Is a passive event does not involve muscle activity o Two factors decease the thoracic cavity and lung volume Relaxation of inspiratory muscles Elastic recoil of lungs o Decrease in lung volume causes increase in alveolar pressure o When alveolar pressure rises above atmospheric pressure air moves out of the lungs o Diaphragm moves up relaxation pressure increases Contraction of the abdomen increases pressure and pushes the diaphragm up causing expiration Relaxing these muscle causes a decrease in pressure Pulmonary Ventilation Respiratory system is responsible for the movement of gases involved in cellular metabolism O2 is used up and CO2 is generated during the aerobic breakdown of glucose and other fuel molecules in order to produce ATP Pulmonary ventilation is the process of bringing air into and out of the lungs o Inspiration air moves into the lungs o Expiration air moves out of the lungs Proper ventilation is important to promote airflow which enhances gas exchange Physical Factors Influencing Pulmonary Ventilation Airway resistance o Airflow is directly related to the difference in pressure o Airflow is inversely related to the tube resistance diameter The smaller the diameter the larger the resistance Can not change the diameter of big tubes with cartilage Can change the diameter of smaller tubes because they have smooth muscle Bronchial dilation o As airway resistance rises breathing becomes more strenuous o Constricted or obstructed bronchioles can prevent life sustaining ventilation and can occur during acute asthma attacks which stops ventilation Friction major non elastic source of resistance to airflow F P R o F flow o P pressure o R resistance to the air flow negatively related to air flow o The amount of gas flowing into and out of the alveoli is directly proportional to the P P the pressure gradient between the atmosphere and alveoli positively related to air flow Greatest resistance medium sized bronchi Amount of gas flowing into and out of the alveoli is directly proportional to the pressure gradient between the atmosphere and the alveoli Know difference in images of normal airway one with Asthma inflammation or Bronchoconstriction o Asthma is produced by contraction of smooth muscle in bronchioles o Bronchoconstriction air flow decreases Epinephrine release via the Sympathetic nervous system dilates makes bigger bronchioles and reduces air resistance PNS activity increases air resistance Dead space and alveolar ventilation Tidal Volume 500 mL this is the volume of air moving in and out of the lungs during normal inspiration expiration o Ventilation is what is occurring inside of the lungs Anatomical Dead Space 150 mL volume of the conducting respiratory passages o Air that does not reach alveoli no function besides to push air into alveoli Alveolar air 350 mL air per breath that is needed from the tidal volume AVR Alveolar Ventilation Rate measures flow of gases into and out of alveoli o AVR frequency tidal volume dead space o Frequency how many breaths for exam this is however many breaths
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