Respiratory lecture 2 Gas Exchange and the transport of gases in blood Samantha Franklin Learning objectives . Describe the processes of oxygen and carbon dioxide exchange between the alveoli and the blood. . Describe the factors influencing the rate of gas exchange (Fick's Law) · List the normal partial pressures of oxygen (PO2) and carbon dioxide (PCO2) in the pulmonary artery, alveoli and pulmonary vein, and explain how they contribute to the exchange of gasses (Dalton and Henry's Law) . Define specific terms associated with respiratory physiology . Explain how oxygen and carbon dioxide are transported in the blood. . Draw the haemoglobin/oxygen dissociation curve, identify its various phases, and the biochemical events occurring in each phase. What are the effects of pH and temperature? Gas exchange · Oxygen (02) & carbon dioxide (CO2) are respiratory gases. . Gas Exchange = the transport of 02 and CO2 between the lungs and the cells of the body · Respiratory gas exchanges are the most urgent physiological exchanges Respiratory gas exchanges are the most urgent physiological exchanges occurring in the body. For example, animals will die within minutes of being deprived of oxygen, but can live for days without food or water, avoiding nitrogenous waste. Oxygen is used in the final steps of energy production, and without it, ATP production cannot continue beyond a few minutes. Carbon dioxide is a waste product. Exchange of this gas is less urgent but can cause problems, but not if it can build up in the body. Distribution Lung ventilation Perfusion Diffusion Modification of rhythm 02, CO2 sensors 02 CO2 Muscle O2, CO2 carriers in blood Acid-base balance The interchange of gases between the atmosphere and the cells of the body involved two steps. The first external respiration occurs in the lungs and is the exchange of oxygen and carbon dioxide between the inhaled air and the blood flowing through the pulmonary capillaries within the lungs. The second step, internal or cellular respiration, involves the exchange of oxygen and carbon dioxide between the blood and the systemic capillaries and all the cells and tissues of the body. Respiration External Respiration Pulmonary ventilation Gas diffusion Gas diffusion O2 transport CO2 transport Internal Respiration Tissues Gas diffusion Gas diffusion
Gas exchange within the lungs (external respiration) External respiration Diffusion O2 Diffusion or convection CO2< > 02 Diffusion or convection CO2 Diffusion Environmental medium Internal tissues Some form of gas- exchange membrane is universal in animals Usually a thin layer of tissue consisting or one or two layers of simple epithelia Gas-exchange membrane When oxygen and carbon dioxide moved between the environment and the internal tissues, they must cross a barrier or gas exchange membrane. In this case, gas exchange occurs within the lungs at the blood gas interface here. Oxygen needs from the air into the venous blood and carbon dioxide moves out the oxygen and carbon dioxide molecules move between the air and blood by simple diffusion. And so, the gas exchange membrane needs to be extremely