Physiology 206 1STedition Lecture 17 Outline of Last Lecture I Thoracic cavity II Diaphragm III Intercostal muscles IV Bronchioles V Obstructive disorders VI Elasticity of lungs Outline of Current Lecture I Lung volume II Conducting zone III Alveolar respiration IV Pressure in alveoli V Hemoglobin Current Lecture Residual o Small amount always left in lung These 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 o Tidal o o o Prevents lungs from collapsing along with surrounding negative pressure Volume of air normally inhaled Usually about 500 mL Lung volume at this time is between 2200 and 2700 mL Inspiratory Reserve o Maximum volume that can be inhaled at a time Expiratory Reserve o Maximum volume that can be exhaled at a time Pulmonary Ventilation Tidal Rate of Respiration o 500 mL 12 breaths per min 6 L per minute Conducting Zone o The first 150 mL that comes in is also the last 150 mL that previously left o Also called the anatomical dead space o Can 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 Ventilation o tidal dead space respiration rate o 500 150 12 4 200 mL o If you inhale 150 mL or less you are not getting and fresh air o Increasing Alveolar Ventilation Increase tidal volume Increase respiration rate Gas Exchange o Lungs and alveoli exist as a method for gas exchange between body and atmosphere o Happens through diffusion Room air is at 1 atm 760 mm Hg o 80 N2 o 20 O2 o All gas molecules exert exactly the same pressure on their container Therefore 20 of pressure comes from oxygen 150 mm Hg comes from oxygen Referred to as the partial pressure of oxygen pO 2 About 600 mm Hg is from N2 Pressure in alveoli is much lower o Only 2 3 of the air that gets to the alveoli is fresh air o pO2 100 mm Hg o pO2 of plasma in pulmonary capillaries also is 100 mm Hg after reaching equilibrium with alveoli Is lower before reaching it o pO2 is lower than 100 mm Hg in tissue Allows for diffusion when oxygen reaches the systemic capillaries Oxygen is not soluble in water well o When 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 output o About 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 capillaries When pO2 100 mm Hg hemoglobin is 100 saturated Hemoglobin o Red protein o Large amount in red blood cells o Can reversibly bind oxygen o Hb O2 Hb O2 K o o HbO2 Hb O2 Means that hemoglobin can exist in 2 forms Free Very small percentage is free Otherwise metabolic rate could not be supported in body Oxygen bound To keep constant K the same change the oxygen content
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