PHIS 206 1st Edition Lecture 17 Outline of Last Lecture I Respiratory System Functions II Respiration III Respiratory System Organization IV Mechanics of Respiration V Inspiration Expiration in Thorax VI How To Change Volume VII Pipes VIII Categories of Pulmonary Disorders IX La Passe s Law Outline of Current Lecture I Thoracic Cavity II Volume in Lungs III Gas Exchange IV Blood V How Things Work Current Lecture I II Thoracic Cavity always at a slightly pressure prevents lungs from collapsing pneumothorax condition where the lungs collapse pulmonary surfactant reduces tension b w lining of lungs and air in the alveoli results in low surface tension so there is a lower tendency of the alveoli to collapse Volume in Lungs 5700 mm when you take a breath 1200 mm when you exhale air left in alveoli residual Amt we breathe 500 mL Tidal volume Normally operating b w 2200 2700 mL You can increase by nearly 10 fold inspiratory expiratory reserves Capacitors sums of volumes Total Lung Capacity sum of all 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 III Vital Capacity sum of all except residual volume FEV1 force expiratory volume in 1 sec inspire and expire at maximum will exhale 80 of vital capacity in 1 sec If obstructive pulmonary disorder airway resistance increases FEV1 will be less than 80 vital capacity same EX asthma If restrictive pulmonary disorder vital capacity decreases but still exhale 80 vital capacity down EX pneumonia conducting zone no gas exchange volume 150 mL ANATOMICAL DEAD SPACE 1st breathe taken already in alveoli trachea and bronchioles 1st breathe taken out ends up in alveoli trachea and bronchioles anatomical dead space alveoli only gets 350 500 mL fresh air o alveoli ventilation rate TITLE VOLUME DEAD SPACE RATE rate at which you get fresh air can increase or decrease by changing title volume or rate if TV gets small enough alveoli ventilation rate will fall to 0 and you DIE no fresh air same thing will happen if dead space gets changed Gas Exchange In alveoli gas exchange going from gas to liquid phases Air 80 N and 20 O 760 mmHg Pressure exerted on a gas mixture is independent of what gas it is pressure result of molecules banging against beaker O and H same pressure o driven by thermal agitation larger molecule larger velocity PO2 150 mmHg pressure exerted on O2 o insoluble in water molar conc is relatively small o P unit used to show direction of diffusion Alveoli only comes out w less PO2 in mmHg Capillaries 150 mmHg of PO2 b c O2 diffuses into them IV Blood circulates in systemic capillaries and alveoli systemic capillaries low PO2 40 mmHg using up O2 and entering 100 mmHg o net diffusion out of capillaries and into cells capillaries ONLY place things can change pulmonary capillaries PO2 enter HOW WE GET OXYGEN starts at 150 mmHg to 100 mmHg in alveoli to 200 mmHg pulmonary blood to systemic capillaries oxygen diffuses out V How Things Work PO2 100 mmHG O2 in water 3 mL L 15 mL min in plasma cardiac output is 5L min not enough to live most O2 is not in plasma o in a red protein hemoglobin reversibly binds O2 can bind 4 molecules of O2 when hemoglobin put in low PO2 O2 comes off unloads most O2 in hemoglobin in red cells o myoglobin in muscles can also bind O2 Hemoglobin 40 mmHg Saturated PO2 100 by 100 mmHg PO2 hemoglobin is 99 saturated 5700 Inspiratory Reserve increase 3 L when you breathe Total Lung Capacity Lung 2700 Tidal 2200 Expiratory Reserve extra L you can force out 1200 Residual 0
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