The Respiratory System

Transcription

1 The Respiratory System Review the anatomy of the respiratory system Functions of the respiratory system gas exchange regulation of acid-base balance communication Chemistry and physics of respiration Boyle s law 1 P 1 V 1 = P 2 V 2 mechanism of inhalation role of diaphragm role of intercostal muscles mechanism of expiration role of diaphragm role of intercostal muscles respiratory volumes measurable volumes tidal volume anatomic dead space inspiratory reserve volume expiratory reserve volume residual volume calculated capacities inspiratory capacity

2 functional residual capacity vital capacity total lung capacity Charles law V 1 /T 1 = V 2 /T 2 molecular basis of gas diffusion net diffusion of a gas in one direction depends on concentration gradient gas pressures in a mixture of gases depends on partial pressures Dalton s law of partial pressures P total = P 1 + P 2 + P P n Henry s law 2 concentration of dissolved gas = pressure SC Gas Solubility coefficient O CO N vapor pressure of water: 47 mm Hg at 37 C pressure gradient for diffusion 3 D ( P A S)/(d (MW) 0.5 ) where D = diffusion rate; A = cross-sectional area; S = solubility diffusion coefficient = S/(MW) 0.5 Gas Relative diffusion coefficient O

3 CO 2 N Composition of atmospheric, humidified, alveolar, and expired air Gas Atmospheric air Humidified air Alveolar air Expired air partial pressure percent partial pressure percent partial pressure percent partial pressure percent N O CO H 2 O Diffusion of gases through the respiratory membrane factors affecting thickness of membrane [0.63 µm on average] surface area of membrane diffusion coefficient pressure difference Types of respiration internal respiration external respiration Transport of oxygen and carbon dioxide role of hemoglobin in oxygen transport Hb + 4(O 2 ) Hb(O 2 ) 4

4 heme oxygen-hemoglobin dissociation curve partial pressure of oxygen ph temperature BPG (or DPG) fetal hemoglobin hypoxia - inadequate oxygenation anemic hypoxia stagnant hypoxia hypoxic hypoxia histotoxic hypoxia carbon dioxide transport in solution as carbaminohb Hb + CO 2 HbCO 2 as bicarbonate ion H 2 O + CO 2 H 2 CO 3 H + + HCO - 3 Control of respiration brainstem centers medullary respiratory centers dorsal respiratory group pacemaker functioning for inspiration ventral respiratory group

5 mixed functioning for inspiration and expiration pontine respiratory group pneumotaxic area inhibits DRG apneustic center prevents inhibition of DRG chemoreceptors and chemosensitive area hydrogen ions aortic bodies carotid bodies Go to beginning Questions for thought 1. Explain the significance of (a) Boyle s law, (b) Dalton s law, and (c) Henry s law to the process of respiration. 2. What are the differences between pulmonary volumes and respiratory capacities? Make sure you list each, and describe how each is determined. 3. What is the functional difference between the dorsal respiratory group (DRG) and the ventral respiratory group (VRG) of the brainstem? 4. Ms Vandross is admitted to the ER after having been rescued from her closed garage where she was working on her auto, but had left the engine running. The physician in charge places her on 100% O 2. Shortly thereafter, she stops breathing and dies. What was the error? And what should have been done? 5. Discuss the effects of hyperventilation on blood oxygen, carbon dioxide, and ph. 6. Describe how oxygen and carbon dioxide are transported in the blood. Go to beginning Links Referenced sites 1 A Java applet illustrating Boyle s law in action 2 Full discussion of Henry s law

6 3 A technical sidebar with some biological problems concerning diffusion Other sites ChemTutor s overview of gases and the gas laws [ Anatomy & Physiology 3 syllabus ] [ Page created 29 April 1999 ][ Last update 05 April 2007 ] [ Questions about this lecture? me ] [ ] [ xhtml validation ]