LOs - Pulmonary - Caroline

LOs - Pulmonary - Caroline - Structure and Function 1....

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Structure and Function 1. Explain the important physiological functions of the lungs a. Gas exchange: O2 uptake (300mL O2/min) and CO2 output (240 mLCO2/min) i. Up to 3,000mL/min during exercise 2. Apply Fick’s 1 st law of diffusion to respiratory gas transport and define convective gas transport a. b. Rate of transfer of a gas through a sheet of tissue i. Proportional to the tissue area (A) and the diff in gas partial pressure between the 2 sides (P1-P2) ii. Inversely proportional to tissue thickness (T) c. Convective gas transport: movement of molecules w/in fluids 3. Describe the different types of airways from the mouth to the alveoli and their structural/fxnal diffs a. Conducting zone i. Trachea right and left main bronchi lobar and segmental bonchi terminal bronchioles (smallest airways w/o alveoli) ii. Fxn: bring inspired air to the gas-exchanging regions of the lung iii. No alveoli=no gas exchange=anatomic dead space (150mL) b. Respiratory zone i. Terminal bronchioles respiratory bronchioles (some alveoli budding from walls) alveolar ducts (lined w/ alveoli) alveolar sacs ii. Gas exchange occurs here iii. Portion of lung distal to a terminal bronchiole=acinus 4. Diagram/name cellular structures in the pathway for diffusion of an O2 molecule from an alveolus to a hemoglobin molecule a. Alveolar walls=pulmonary capillaries; blood-gas barrier very thin b. 3 layers i. Alveolar epithelium (EP) 1
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ii. Capillary endothelium (EN) iii. Interstitium (IN) (between the above 2) iv. Usually, thin blood-gas barrier on 1 side, but a thicker barrier on the other side where the IN is widened (imp for fluid exchange) 5. Describe the structure/fxn of diff types of blood vessels in the lung a. Main pulmonary artery (receives mixed venous blood from R ventricle) branches and accompanies the bronchi down center of lobules as far as terminal bronchioles. b. Then break up to supply capillary bed in the walls of the alveoli=dense network of caps very efficient for gas exchange (sheet flow) c. O2 blood collected from cap bed by small pulmonary veins between lobules and unite to form veins into L atrium. d. T1 alveolar epithelial cell : has central nucleus and long protoplasmic extensions (fried egg). Fxn in mechanical support e. T2 alveolar epithelial cell : Globular; metabolically active contain lamellated bodies w/ phospholipid that’s extruded into the alveolar space to form surfactant 6. Bronchial arteries from aorta supply lung itself conducting upper airways diffusion into respiratory zone O2 and CO2 transport in blood 1. Gas concentrations and partial pressure in gas/liquids a. Calculate pp of a gas from its fractional concentration in a dry gas, and for a gas saturated w/ water vapor. Explain what determines vapor pressure of water i. PP in a dry gas 1. Dry air: 21% is O2; [O2]=21ml/dl; FO2 (fractional concentration)=0.21 2. Dalton’s law of PP: P B (barometric pressure)=760mmHg so PO 2 =0.21 x 760=160mmHg/ Torr ii. PP in a gas saturated w/ water vapor
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LOs - Pulmonary - Caroline - Structure and Function 1....

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