16The Lungs overlap with the respiratory tract. Inside LungsPrimaryBronchiSecondaryBronchiBronchiolesAlveoliTertiaryBronchi
17THE LUNGS- consist of the left and the right lungs- The left lung is divided into two lobes; the right into three.receives the bronchus, blood and lymphatic vessels, and nerves through its hilum.- The bronchi extend into alveoli
40Inspiration:Expiration: Volume Pressure Volume PressureCan the lungs expand/shrink by themselves?
41Major Respiratory Muscles 1) The Diaphragm2) External Intercostal Muscles3) Internal Intercostal Muscles4) The Abdominal Muscles1) The Diaphragm2) External Intercostal Muscles3) The Abdominal Muscles- Expiration muscles- pulls the diaphragm up, reducing the vertical dimension of the thoracic cage.1) The Diaphragm2) External Intercostal Muscles3) The Abdominal Muscles4) Internal Intercostal Muscles- Extra Expiration muscles1) The Diaphragm2) External Intercostal Muscles- Inspiration muscles- increases the anteroposterior and transverse dimensions of the chest.- the principal muscle of inspiration- pulls the diaphragm down, increasing all three dimensions of the thoracic cage.
42Lungs and Thoracic Cage Coupling BetweenLungs and Thoracic Cage
43- The lungs and thoracic cage are coupled by the pleurae. Visceral pleura covers the surface of each lung; parietal pleura lines the chest cavity.- The two pleurae form the pleural cavity.- The pleural fluid serves to reduce friction during chest expansion.- Intrapleural pressure: The pressure in the pleural cavity is negative.pleural cavity
44Parietal pleuravisceral pleuralungPotential pleural cavity(negative intrapleural pressure)Generation of the negative intrapleural pressureThe thoracic cage is larger than the natural size of the lungs.
53Alveolar Surface Tension - generated by a thin film of liquid over the surface of alveolar epithelium,- tends to cause a collapse of the alveoli,- Resists against inspiration.
54Alveolar surface tension is a resistance against inspiration. Alveoli
55Surface tension is reduced by surfactant. ( type II alveolar epithelial cells)Pre-term infants don't have enough surfactant.type IIsurfactant
56Resistance 1) Alveolar Surface Tension 2) Elastic Resistance Airway Resistance- Against inspiration due to elastic fibers in the lungs and chest wall,- Increases in pulmonary fibrosis.
57Resistance 1) Alveolar Surface Tension 2) Elastic Resistance Airway Resistance- Due to friction, affected by airway caliber.- Against inspiration and expiration!- Increases during asthma attack (smooth muscle contraction in bronchiole.
58Resistance Compliance 1) Alveolar Surface Tension 2) Elastic ResistanceAirway ResistanceCompliance- The reciprocal of resistance,- An indicator of ease with which the lungs expand.
69Afferent Connections to the Respiratory Centers the limbic systemHypothalamusChemoreceptorsthe lungs
70Chemoreceptor-initiated Reflexes Peripheral chemoreceptors- aortic and carotid bodies,- monitor O2, CO2 and pH of the blood.Central chemoreceptors- close to the surface of the medulla oblongata,- monitor the pH of the cerebrospinal fluid.
71stimulate chemoreceptors frequency and depth of respiration CHEMORECEPTOR-MEDIATED REFLEXO2, CO2, or pHstimulate chemoreceptorsreflexfrequency and depth of respiration
72Voluntary Control - the motor cortex, - bypass the brainstem respiratory centers,- limited voluntary control.
74ventilationgas exchangetransport by bloodgas exchange
75- Diffusion of a gas is driven by O2 and CO2 partial pressure gradient. PO2 = 40 mmHgPCO2 = 46 mmHgPO2 = 104 mmHgPCO2 = 40 mmHg- The gas exchange between alveolar air and the blood is via diffusion of O2 and CO2.
76The partial pressure of a gas refers to the share of the total pressure generated by a mixture of gases.104 mmHgO2CO2N2H2O13.6%40 mmHg5.3%Total = 760 mmHg
77Oxygen and carbon dioxide cross the respiratory membrane and the air-water interface easily. PO2 = 40 mmHgPCO2 = 46 mmHgPO2 = 104 mmHgPCO2 = 40 mmHg
91How to dissociate? O2 GAS EXCHANGE in the TISSUES 1. Carbon Dioxide Loading2. Oxygen Unloading
92O2 Dissociation of O2 from hemoglobin (HB) is affected by: PO2 dissociationPCO2 dissociationpH dissociationDPG dissociation(2,3-diphosphoglycerate)Temperature dissociationO2
93O2 100% saturated In Lungs High PO2, low PCO2 association with HG favor the loading of O2O2100% saturated
94O2 In tissues High PCO2, low PO2, low pH, DPG dissociation of O2 from HGfavor the unloadingO2
95O2 In tissues High PCO2, low PO2, low pH, DPG dissociation of O2 from HGfavor the unloadingO2
96Utilization Coefficient - The amount of oxygen uptake by tissue versus the arterial blood oxygen content20 ml O2/dL15.6 ml O2/dLblood4.4 ml O2/dLcellcellcellcellcellUtilization Coefficient = 4.4 ml / 20 ml = 22%