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14 November 2012 Respiratory Physiology Lab this week: EKGs and Blood Pressure. Bring calculator and textbook to lab. Wear clothes and shoes you can run in comfortably. Work on Hemorrhage Diagram! 1QQ 27 for 8:30 • Beginning with a loss of 1 liter of blood, diagram the sequence of events that leads to a change in the frequency of action potentials in baroreceptors. (No abbreviations allowed.) 1QQ 27 for 9:30 • Beginning with a loss of 1 liter of blood, diagram the sequence of events that leads to a change in the frequency of action potentials in baroreceptors. (No abbreviations allowed.) • Respiration is the overall movement of gases between the outside environment and the internal cells. • Ventilation is the movement of air in and out of the lungs. O2 CO2 O2 CO2 • Ventilation should be matched to metabolism. Carbon Dioxide reacts with water! CO2 + H20 ↔ H2CO3 ↔ H+ + HCO3Carbonic Acid Bicarbonate So disturbances in gas exchange or ventilation are often associated with disruptions of pH. pH changes with Hypoventilation & Hyperventilation Gas Laws Dalton’s Law • Total pressure = sum of partial pressures • PATM = P N2 + P O2 + P CO2 • 100% = 79% + 21% + <1% • P O2 = 0.21 x 760mmHg = 160 • Partial pressure of Oxygen in atmosphere at sea level is 160 mmHg • Regardless of elevation, air is always 21% O2. • N2 is physiologically inert; ignore except for decompression sickness Henry’s Law • Gases dissolve in liquids in proportion to their partial pressure in the air in contact with that liquid air P O2 =160 mmHg liquid P O2 =160 mmHg Why the difference in partial pressures in Air and Alveoli? Ventilation by Bulk Flow Gas exchange by Diffusion Where should the receptors be for the negative feedback loop for homeostasis? Gas exchange Gradient for CO2 is only 6 mmHg; CO2 is more soluble and permeable than O2 Gas exchange • All gases move by diffusion. Thus limited by: – Surface area – Distance – Concentration (partial pressure) gradient • In the lung, gases must move from air to water and vice versa. The amount is proportional to – Solubility (CO2 more soluble than O2) – Temperature (colder fluids dissolve more gas) – Pressure gradient Respiratory Physiology The physics of air flow 1) Flow in tubes 2) Ventilation Poiseulle’s equation The Structure underlying the function: Upper Respiratory Tract Lower Respiratory Tract Intercostal muscles Bronchitis= infection/inflammation of conducting airways Asthma = smooth muscles contract →increase resistance to airflow in conducting airways. Pneumothorax (unilateral due to each lung having its own compartment. Visceral pleura and parietal pleura separated by fluid-filled pleural cavity which allows lung and chest wall to slide relative to each other but remain adhered unless air enters the pleural cavity (which leads to collapse of the lung and outward expansion of chest wall on that side.) Greg R. and the story of spontaneous pneumothorax Upper Tract Sleep Apnea a)obstructive, b)central & CPAP Continuous Positive Airway Pressure