BIO 311D 2nd Edition Lecture 27 Outline of Last Lecture I Hormones influence excretory tubules II Where is the respiratory epithelium III Principles of Diffusion IV Counter Current Exchange Outline of Current Lecture I Counter Current Exchange II Partial Pressure Differences Affect Diffusion III Hemoglobin in red blood cells binds O2 IV Clicker quiz questions about hemoglobin V Circulatory system Current Lecture I II III Counter Current Exchange A Birds 1 First inhalation posterior air sacs First exhalation push through lungs in one direction second inhalation anterior air sacs second exhalation 2 Helps them fly stay in the air Partial Pressure Differences Affect Diffusion A The mount of O2 is measured as a partial pressure which includes both the total atmospheric pressure 760 mm Hg at sea level and the of total air each individual gas comprises O2 is about 21 a Amount of oxygen available affected by the amount available in the air room filled with people working out B Gases diffuse across membranes from regions of higher partial pressure to lower partial pressure gradient P1 P2 C Oxygen diffuses to equilibrium in the lung alveoli Hemoglobin in red blood cells binds O2 A An example of a respiratory pigment Respiratory proteins bind O2 molecule reversibly B There s a net transfer of O2 a Into blood near the lungs where inhaled b Out of blood at metabolizing cells where oxygen is being used up c O2 loads in the lungs unloads in the tissues C Hemoglobin exhibits cooperativity i e if O2 binds to one subunit this increases the affinity of the other subunits for O2 The S shaped curve reflects this acceleration a Myoglobin has only one globin unit so has no cooperativity no S shaped curve b The oxygen binding curve of hemoglobin 1 Blood near respiring cells P O2 about 40 2 Oxygenated blood in lungs P O2 about 100 VI Clicker quiz questions about hemoglobin A When hemoglobin in red blood cells is in an area where the PO2 is 40 mm Hg about what percent of that hemoglobin is bound with O2 75 B In lung alveoli hemoglobin will load up on O2 until it s about what saturated 100 C Blood hemoglobin that has just been in lung capillaries P O2 100 is next in a capillary in the liver P O2 40 When it arrives at the liver capillaries that hemoglobin will give up unbind O2 Behaves this way because of its quaternary structure D Conditions a Low pH b More CO2 c Higher temperature the oxygen binding curve of hemoglobin shifts to the right d These conditions are likely when cells are doing what e This shift Bohr shift means that in cells the hemoglobin will release Give up more O2 under which conditions 1 pH 7 6 2 pH 7 2 correct E Fetal hemoglobin binds O2 molecules differently than adult hemoglobin curve is left shifted a Placenta p O2 30 mm Hg O2 diffuses between maternal and fetal blood b Advantage binds more to the fetal than to the mother
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