BCMB 230 1st Edition Lecture 19 Outline of Last Lecture I Anticlotting II Review of Vasoconstriction and Vasodilation III Respiratory System IV Lungs Outline of Current Lecture I Relation of Lungs to Chest Wall II Ventilation and Lung Mechanics III Partial Pressure of Gases Current Lecture I Relation of Lungs to Chest Wall lungs are not connected to chest wall pleural cavity space between the lungs and chest parietal pleura outer layer attached to lines the interior chest wall an diaphragm visceral pleura pleural surface coating the lung attached to lung by connective tissue lungs and chest wall are not necessarily moving at the same time however pleural cavity makes it more likely that they will move together Two opposing forces that produce slight negative pressure in pleural cavity elasticity of lung tissue oriented to that lung wants to collapse elasticity of body wall cartilage loaded to spring outward Use transpulmonary pressure to pull or push the lungs with the chest wall even though they are not connected II Ventilation and Lung Mechanics Three pressures with ventilation atmospheric pressure higher than alveolar pressure air goes in lower than alveolar pressure air goes out aveolar pressure transpulmonary pressure driving force of lung and body wall movement measure pressure across pleural cavity 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 disrupt tranpulmonary pressure break linkage can do this by putting a hole in the body wall expand thoracic cavity air goes in lung collapses because there is air where there should be liquid have to have an intact fluid filled pleural cavity in order for there to be ventilation Compliance measure of how easy it is to stretch something Big factor to influence compliance surface tension strong attractions between water molecules hydrogen bonds between water molecules powerful force Surfactant anything that s going to reduce the surface tension of water reduce interactions between water molecules specialized cells within the lungs produce surfactant increase compliance make easier for lungs to expand Neonates new borns particularly premature surfactants are very important lungs are the last thing to development if premature critical point of whether it s going to survive is if its lungs are developed if surfactant s have been produced III Partial Pressure of Gases Connection between lungs and tissues is the blood do this through diffusion and bulk flow movement of blood concentration in the gas form and dissolved gas form Dalton s Law relationship between pressure of gases and mixture of gases sum of all components of gas P atm P N2 P O2 P CO2 each gas exerts its pressure independent of the others pressure of 760 mmHg 20 O2 then 20 of total pressure partial pressure of oxygen PO2 152 0 PCO2 1 7 6 all partial pressures have to add up to total pressure Can manipulate partial pressure clinically or environmentally Air PO2 105 mmHg PCO2 40 mmHg breathing in oxygen decreases and carbon dioxide increases residual volume still air in lungs don t want lungs to completely relax mix good air from outside with residual volume a lot more oxygen in air than blood gradient for diffusion to move oxygen in carbon dioxide has a gradient to move out Carbon dioxide more soluble in water than oxygen can reach perfect equilibrium in air and blood oxygen is not as soluble still diffuses but much more slowly Carbon dioxide reacting with water the enzyme carbonic anhydrase determines the speed relative amounts of reactants and products determine the direction of the reaction dealing with oxygen dissolved in plasma can t move a whole lot of it need more mechanisms to move more oxygen these mechanisms are in the red blood cells Oxygen moves to alveolus dissolved O2 has to go into red blood cell add hemoglobin which becomes a form of oxyhemoglobin dissolved oxygen then goes out into tissues To change affinity of protein look at factors that change affinity of hemoglobin for oxygen Factors that influence hemoglobin affinity for O2 In lungs increase PO2 increase affinity decrease PCO2 decrease H concentration decrease pH increase affinity decrease temperature increase affinity decrease DPG increase affinity DPG diphosphoglycerate produced by red blood cells when under lots of stress happening in lungs In tissue Decrease PO2 decreases affinity Increase PCO2 increase H decrease pH decrease affinity Increase temperature working tissues are hot decrease affinity Increase in DPG decrease affinity Want high affinity in lungs to bind to oxygen Want low affinity in tissues for oxygen to come off Oxygen hemoblogin dissociate curve look at relative pO2 and hemoglobin saturation not linear almost exponential at first closer to saturation curve levels off Borr shift temperature DPG pH shift to right decreased affinity Oxygen diffuse to plasma some stays in plasma most goes to red blood cell shift in affinity oxygen goes out of red blood cell in dissolved state out into tissues CO2 transport have small significant amount dissolved in plasma 10 some bound to hemoglobin 30 most of it is bicarbonate 60 separate binding sites no competition but they do influence each other oxygen levels influence CO2 affinity Increase PO2 decrease CO2 affinity Increase PCO2 increase CO2 affinity temperature and DPG don t play a role in influence of CO2 Get rid of bicarbonate by moving it out of the cell using a bicarbonate transporter don t want to get move H out of cell into blood will change plasma pH significantly bind H to hemoglobin Prevent production of membrane potential have an ion exchange bicarbonate moving out and chlorine moving in both going down the gradient