Presentation on theme: "Chapter 6 The Respiratory System and Its Regulation."— Presentation transcript:
1 chapter6The Respiratory System and Its Regulation
2 Learning ObjectivesFind out how the respiratory system brings oxygen to muscles and tissues and rids the body of carbon dioxideLearn the steps involved in respiration and gas exchangeDiscover how your respiratory system regulates your breathing and gas exchange
4 Transportation of Oxygen and Carbon Dioxide Pulmonary ventilation (breathing): movement of air into and out of the lungsPulmonary diffusion: the exchange of O2 and CO2 between the lungs and the bloodTransport of O2 and CO2 via the bloodCapillary diffusion: the exchange of O2 and CO2 between the capillary blood and the metabolically active tissue
5 Pressure1 x Volume1 = Pressure2 x Volume2 Boyle’s LawIf temperature is constant:Pressure1 x Volume1 = Pressure2 x Volume2
6 Pulmonary Ventilation Inspiration: active process involving the diaphragm and the external intercostal musclesPressure in the lung is less than the air pressure outside the body, air following the pressure gradient coming into the lungExpiration: usually a passive process involving relaxation of the inspiratory muscles; pressure increases in the lungs and air is forced outActive process during forced breathing
8 Lung Volumes Measured by Spirometry Reprinted, by permission, from J. West, 2000, Respiratory physiology: The essentials (Baltimore, MD: Lippincott, Williams, and Wilkins), 14.
9 Pulmonary Ventilation Key PointsPulmonary ventilation is the process by which air is moved into and out of the lung (inspiration, expiration)Inspiration is an active process in which the diaphragm and intercostal muscles contract, increasing dimensions and volume of the thoracic cageExpiration at rest is normally passive; the inspiratory muscles relax, decreasing the thoracic cageForced inspiration and expiration are active processes involving accessory musclesLung volumes and capacities are measured by spirometry
10 Pulmonary DiffusionReplenishes blood's oxygen supply that has been depleted for oxidative energy productionRemoves carbon dioxide from returning venous blood
11 Blood Flow to the Lungs at Rest: Pulmonary Hemodynamics Low pressure and resistance circulation compared to the systemic circulationLungs receive 4-6 L/min of blood flowPulmonary artery mean pressure = 15 mmHg (aortic pressure = 95 mmHg)Left atrial pressure = 5 mmHgPulmonary vessels are thin walled
12 Pressures in the Pulmonary and Systemic Circulations Reprinted, by permission, from J. West, 2000, Respiratory physiology: The essentials (Baltimore, MD: Lippincott, Williams, and Wilkins), 36.
13 Respiratory Membrane: Gas Exchange Alveolar wallCapillary wallBasement membranes ( mm)Gases will move along a concentration gradient based on partial pressures
19 Uneven Distribution of Blood Flow in the Lung Reprinted, by permission, from J. West, 2000, Respiratory physiology: The essentials (Baltimore, MD: Lippincott, Williams, and Wilkins), 44.
20 Pulmonary Diffusion Key Points Pulmonary diffusion is the process by which gases are exchanged across the respiratory membrane in the alveoliThe amount and rate of gas exchange depends on the partial pressure of each gasGases diffuse along a pressure gradient, moving from an area of higher pressure to lower pressureVgas A / T x D x (P1 - P2)(continued).
21 Pulmonary Diffusion (continued) Key PointsOxygen diffusion rate increases as you move from rest to exerciseExercising muscle requires more oxygen for metabolism; when venous oxygen is depleted, oxygen exchange at the alveoli is facilitated due to an increased pressure gradientThe pressure gradient for carbon dioxide exchange is less than for oxygen exchange, but carbon dioxide’s membrane solubility is 20 times greater than oxygen, so CO2 crosses the membrane readily
22 Oxygen TransportOxygen is transported bound to hemoglobin (>98%) or dissolved in plasma (<2%)Hemoglobin concentration largely determines the oxygen-carrying capacity of bloodIncreased H+ (acidity) and temperature of a muscle favors oxygen unloading in the muscleOxygen carrying capacity seldom limits performance in healthy individuals
23 Oxyhemoglobin Dissociation Curve Reprinted, by permission, from S.K. Powers and E.T. Howley, 2004, Exercise physiology: Theory and application to fitness and performance, 5th ed. (New York: McGraw-Hill Companies), 205. With permission from The McGraw-Hill Companies.
24 Effects of pH and Temperature on the Oxyhemoglobin Dissociation Curve Reprinted, by permission, from S.K. Powers and E.T. Howley, 2004, Exercise physiology: Theory and application to fitness and performance, 5th ed. (New York: McGraw-Hill Companies), 206. With permission from The McGraw-Hill Companies.
25 Carbon Dioxide Transport Bicarbonate ionsMuscle: CO2 + H2O → H2CO3 → H+ + HCO3-Lung: H+ + HCO3- → H2CO3 → CO2 + H2ODissolved in blood plasmaBound to hemoglobin (carbaminohemoglobin)
26 Gas Exchange Key Points O2 is transported in the blood primarily bound to hemoglobinHemoglobin unloading of O2 in tissues is enhanced by:Decreased PO2Decreased pHIncreased temperatureHemoglobin is ~98% saturated with oxygen, and O2 carrying capacity typically does not limit performanceCO2 is primarily transported as bicarbonate ion in the blood
27 Gas Exchange at the Muscles: Arterial–Venous Oxygen Difference
28 Oxygen Transport in the Muscle: Myoglobin Reprinted, by permission, from S.K. Powers and E.T. Howley, 2004, Exercise physiology: Theory and application to fitness and performance, 5th ed. (New York: McGraw-Hill Companies), 207. With permission from The McGraw-Hill Companies.
29 Factors Affecting Oxygen Uptake and Delivery 1. Oxygen content of blood2. Amount of blood flow3. Local conditions within the muscle
30 Gas Exchange at the Muscle Key Points(a-v)O2 difference is the difference in the oxygen content of the arterial and mixed venous blood throughout the bodyO2 delivery to the tissues depends on the O2 content in the blood, blood flow to the tissues, and local conditionsCO2 exchange at the tissues is similar to O2 exchange except CO2 leaves the muscle to be transported to the lungs-
31 Regulation of Pulmonary Ventilation Higher brain centersExpiratory centersInspiratory centersChemoreceptorsMechanoreceptors in the active muscles and the lung musclesHypothalamic inputConscious control
32 Central and Peripheral Regulators of Respiration