Physiology 206 1STedition Lecture 17Outline of Last Lecture I. Thoracic cavityII. DiaphragmIII. Intercostal musclesIV. BronchiolesV. Obstructive disordersVI. Elasticity of lungsOutline of Current Lecture I. Lung volumeII. Conducting zoneIII. Alveolar respirationIV. Pressure in alveoliV. Hemoglobin Current Lecture-ResidualoSmall amount always left in lungThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.oPrevents lungs from collapsing along with surrounding negative pressure-TidaloVolume of air normally inhaledoUsually about 500 mLoLung volume at this time is between 2200 and 2700 mL-Inspiratory ReserveoMaximum volume that can be inhaled at a time-Expiratory ReserveoMaximum volume that can be exhaled at a time-Pulmonary Ventilation = Tidal * Rate of Respirationo500 mL * 12 breaths per min = 6 L per minute-Conducting ZoneoThe first 150 mL that comes in is also the last 150 mL that previously "left"oAlso called the anatomical dead spaceoCan't attach yourself to a hose and go to the bottom of the pond and breathe because the anatomical dead space goes above tidal volume and you don’t bring in any fresh air-Alveolar Ventilationo(tidal - dead space) * respiration rateo(500 - 150) * 12 = 4,200 mLoIf you inhale 150 mL or less, you are not getting and fresh airoIncreasing Alveolar Ventilation:-Increase tidal volume-Increase respiration rate-Gas ExchangeoLungs and alveoli exist as a method for gas exchange between body and atmosphereoHappens through diffusion-Room air is at 1 atm (760 mm Hg)o80% N2o20% O2oAll gas molecules exert exactly the same pressure on their container-Therefore, 20% of pressure comes from oxygen; 150 mm Hg comes from oxygenReferred to as the partial pressure of oxygen (pO2)-About 600 mm Hg is from N2-Pressure in alveoli is much loweroOnly 2/3 of the air that gets to the alveoli is fresh airopO2 = 100 mm HgopO2 of plasma in pulmonary capillaries also is 100 mm Hg after reaching equilibrium withalveoli-Is lower before reaching itopO2 is lower than 100 mm Hg in tissue-Allows for diffusion when oxygen reaches the systemic capillaries-Oxygen is not soluble in water welloWhen pO2 = 100 mm Hg, only about 3 mL of oxygen can dissolve in 1 L of plasma-Cardiac output per minute = 5 L-Therefore, only about 15 mL of oxygen per cardiac outputoAbout 20-22 mL of oxygen is used per minute-Additional oxygen can pop off of hemoglobin and diffuse into tissue-Hemoglobin load up on oxygen in the pulmonary capillariesoWhen pO2 = 100 mm Hg, hemoglobin is 100% saturated-HemoglobinoRed proteinoLarge amount in red blood cellsoCan reversibly bind oxygen Hb+O2↔ Hb O2 K =[ Hb O2][Hb][O2] oMeans that hemoglobin can exist in 2 forms:-FreeVery small percentage is freeOtherwise, metabolic rate could not be supported in body-Oxygen-boundoTo keep constant (K) the same, change the oxygen
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