Ventilation for review session

Ventilation for review session - Ventilation: Recommended...

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Ventilation: Recommended Reading Chapter 17 Topics: The Respiratory System: Bones and muscles of the thorax surround the lungs Pleural sacs enclose the lungs Airways connect lungs to the external environment The Airways warm, humidify and filter inspired air Alveoli are the site of gas exchange Pulmonary circulation is high flow, low pressure Gas Laws: Air is a mixture of gasses Gasses move down pressure gradients Boyle’s Law Ventilation: Lung volumes change during ventilation During ventilation, air flows because of pressure gradients Inspiration occurs when alveolar pressure decreases Expiration occurs when alveolar pressure increases Intraplueral pressure changes during ventilation Lung compliance and elastance may change in disease state Surfactant decreases the work of breathing Airway diameter determines airway resistance Rate and depth of breathing determine the efficiency of breathing Gas Composition in the alveoli varies little during normal breathing Ventilation and alveolar blood flow are matched
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Auscultation and spirometry assess pulmonary function There are three exchanges in the respiratory system:
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Anatomy Summary
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The airway humidifies, warms and cleans the air Ciliated respiratory epithelium in the trachea helps mucous that has trapped dirt move to the pharynx. The goblet cells in the trachea produce the mucous. Also, the air is humidified close to 100 percent, which will affect the partial pressures of gasses in the lungs. Pulmonary Circulation: At any given moment, about .5L of blood are running through the pulmonary circulation The lungs receive the entire cardiac output: ~5L/min The blood pressure is around 28/5
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Gas Laws: The partial pressure of a gas is: Pressure (atm) x % of gas in atmosphere Gasses move from areas of high pressure to low pressure Boyle’s Law: P1V1=P2V2 This implies the relationship that pressure and volume are inversely proportional If pressure increases, the volume will decrease Pressure of alveolar oxygen P alverloar O2 = P O2(inspired air in trachea) – (P alveolar CO2 )/ R P A is alveolar pressure; P a is arteriole pressure R is the respiratory quotient, which varies on what is being metabolized R = (rate of CO 2 production)/ rate of oxygen consumption R = 1 for a diet of only carbohydrates R = .7 for a diet of mainly fatty acids (causes more oxygen consumption that carbon dioxide production) Proteins have an intermediate R R = .8 for a mixed diet Dalton’s Law: P tot = (P N2 ) + (P O2 ) + (P CO2 ) + (P H2O ) N 2 = 79% of air O 2 = 21 % of air 760 mmHg = P O2 + P N2 Partial pressure of oxygen gas: (.21) (atmospheric) ~ 160 mmHg Partial pressure of nitrogen gas: (.79) (atmospheric) ~ 500 mmHg At 100% humidity, 37 ° C, P H2O is 47mmHg
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This means that the partial pressures of the other gasses will decrease P IO2 = (Patm-47 mmHg) x .21 ~ 150 mmHg Alveoloar ventilation (analogous to cardiac output) V tot (L/min) Total ventilation = Vtid x respiratory frequency Tidal volume x respiratory frequency At rest, .5L x 10-12 breaths per minute = 5-6 L/min
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This note was uploaded on 03/12/2010 for the course BIPN BIPN 102 taught by Professor Fortes during the Fall '09 term at UCSD.

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Ventilation for review session - Ventilation: Recommended...

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