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The Respiratory System Gas Laws

The Respiratory System Gas Laws.

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The Respiratory System Gas Laws

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  1. The Respiratory SystemGas Laws Dalton's Law (also called Dalton's Law of Partial Pressures) states that the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture. This empirical law was observed by John Dalton in 1801 and is related to the ideal gas laws. Mathematically, the pressure of a mixture of gases can be defined as the summation       where P represents the partial pressure of each component.

  2. The Respiratory SystemGas Laws • Henry's Law states that at a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.

  3. The Respiratory SystemDiffusion of Gas • Movement of a gas in one direction is the effect of a concentration gradient • Direction of diffusion occurs from areas of high to low concentration • Rate of diffusion is dependant on pressure

  4. The Respiratory System A Key Factor In The Amount Of Gas Exchange Is The Partial Pressure Difference Across The Gas Exchange Barrier a.k.a. the driving pressure • Across pulmonary capillaries • O2 partial pressure gradient • from alveoli to blood = 60 mm Hg • (100 –> 40) • CO2 partial pressure gradient from • blood to alveoli = 6 mm Hg • (46 –> 40) • Across tissue capillaries • O2 partial pressure gradient from blood • to tissue= 60 mm Hg • (100 –> 40) • CO2 partial pressure gradient from • tissue cell to blood = 6 mm Hg • (46 –> 40)

  5. The Respiratory SystemAir composition Dry air is composed of a mixture of gases. • Each gas exerts a partial pressure which is the pressure it would exert if it alone occupied a given volume. • Barometric pressure [PB] is the total pressure exerted by this mixture of gases = 760 mmHg at sea level

  6. The Respiratory SystemAir composition • Nitrogen 78.08% • Oxygen 20.94% • Argon 0.93% • Carbon Dioxide 0.03% • and trace amounts of— • Neon • Methane • Helium • Krypton • Hydrogen • Xenon

  7. The Respiratory SystemAlveolar Air Composition

  8. The Respiratory System

  9. The Respiratory System

  10. The Respiratory SystemInternal Respiration

  11. Internal Respiration Gas Exchange

  12. The Respiratory SystemTransport of Gases Hemoglobin Molecule • HEME • four pyrrole rings with iron ion at each center • GLOBIN • two pairs of polypeptide chains

  13. The Respiratory SystemTransport of Gases • O2 transport • 1.5% of O2 is dissolved in Plasma • 98.5% carried bound to Hemoglobin • Approximately 250 million Hemoglobin in a Red Blood Cell

  14. The Respiratory SystemTransport of Gases • Binding Process Hb + O2 ⇌ HbO2 Deoxyhemoglobin Oxygen Hemegloblin

  15. The Respiratory SystemHypoxia • Hypoxia • Is the inadequate delivery of oxygen to body tissues. • Anemic Hypoxia • Ischemic Hypoxia • Histotoxic Hypoxia • Hypoxemic Hypoxia • Carbon Monoxide Poisoning

  16. The Respiratory SystemHypoxia • Anemic Hypoxia • Too few RBCs • Abnormal or too little Hb • Ischemic Hypoxia • When circulation is impaired • Congestive heart failure • Emboli • Thrombi

  17. The Respiratory SystemHypoxia • Histotoxic Hypoxia • When body cells are unable to use O2 even though adequate amounts are delivered. • Metabolic poisons (cyanide) • Hypoxemic Hypoxia • Indicated by reduced arterial PO2 • Low V/Q • Pulmonary diseases • Breathing air with low amounts of O2

  18. The Respiratory SystemHypoxia • Carbon Monoxide Poisoning • When Hb binds with CO instead of O2 • Hbs affinity for CO is 200 times grater than O2s • Co poisoning is the leading cause of death from fire.

  19. The Respiratory SystemTransport of Gases • CO2 Transport • 7-10% of CO2 is simply dissolved in plasma. • 20% is bound to hemoglobin. • 70% is transported as a bicarbonate ion in plasma.

  20. The Respiratory SystemTransport of Gases

  21. The Respiratory SystemTransport of Gases CO2 + H2O ⇌ H2CO3 ⇌ H+ HCO3- Carbon Water Carbonic Hydrogen Bicarbonate Dioxide Acid Ion Ion

  22. The Respiratory SystemTransport of Gases • Bicarbonate ion reaction • The bicarbonate ion reaction occurs because of Carbonic Anhydrase. • The H+ ions released by this reaction bind to hemoglobin triggering the Bohr Effect. • The Bohr Effect is that more O2 is released by the enhanced loading of CO2.

  23. The Respiratory SystemTransport of Gases • Bicarbonate ion reaction • Once generated HCO3- moves rapidly from RBC’s to the plasma. • To counter balance the influx of HCO3- ions and maintain blood pH, chloride ions (CL-) rush into the RBC’s. This is called the chloride shift. • This mix in plasma and RBC’s is then transported to the lungs, where each process reverses and releases its load of CO2.

  24. Hb + O2 ⇌ HbO2 CO2 O2 O2 CO2 CO2 + Hb ⇌ HbCO2 CO2 + H2O ⇌ H2CO3 ⇌ H+ HCO3-

  25. The Respiratory SystemNeural Control • Respiratory Center located in the medulla oblongata • Receives input from peripheral and central chemoreceptors

  26. The Respiratory SystemNeural Control

  27. The Respiratory SystemNeural Control

  28. The Respiratory SystemNeural Control • CENTRAL RECEPTORS • When CO2 chronically elevated, pH returns to normal • Central receptors exhibit a decreased sensitivity to CO2 changes

  29. The Respiratory SystemNeural Control • PERIPHERAL RECEPTORS • Primarily affected by oxygen • maximum stimulation when PaO2 decreases to 40 - 60 mm Hg

  30. The Respiratory SystemNeural Control • PERIPHERAL RECEPTORS • with a chronically elevated CO2, organism functions on the hypoxic drive • primary stimulus to breathe is a reduced partial pressure of oxygen

  31. The Respiratory SystemHomeostatic Imbalances • COPD • COPD consists of two diseases Emphysema and Chronic Bronchitis. • More than 80% of patients have a history of Smoking. • Coughing and frequent pulmonary infections are common. • Most COPD victims develop respiratory failure which is manifested as Hypoventilation.

  32. The Respiratory SystemHomeostatic Imbalances • Emphysema (structural changes) • Permanent enlargement and destruction of the air spaces distal to the terminal bronchioles. • Destruction of pulmonary capillaries. • Weakening of the distal airways, primarily the respiratory bronchioles. • Bronchospasm ( with concomitant bronchitis). • Hyperinflation of the alveoli (air trapping).

  33. The Respiratory SystemHomeostatic Imbalances • Emphysema • The structural changes lead to increased reliance on accessory muscles of inspiration. • This leads to perpetual exhaustion as 15-20% of total body energy is used to breathe. • Damage to terminal bronchioles leads to gas trapping, which in turn leads to a permanently expanded “barrel chest”. • The damage to the pulmonary capillaries increases resistance in the pulmonary circuit causing a greater work load for the right heart.

  34. The Respiratory SystemHomeostatic Imbalances • Emphysema

  35. The Respiratory SystemHomeostatic Imbalances • Chronic Bronchitis (structural changes) • Chronic inflammation and swelling of the peripheral airways. • Excessive mucus production and accumulation. • Partial or total mucus plugging. • Hyperinflation of alveoli (air trapping). • Smooth muscle constriction of bronchial airways (bronchospasm).

  36. The Respiratory SystemHomeostatic Imbalances • Chronic Bronchitis • The structural changes lead to increased reliance on accessory muscles of inspiration. • This leads to perpetual exhaustion as 15-20% of total body energy is used to breathe. • Mucus plugging leads to gas trapping, which in turn leads to a permanently expanded “barrel chest”.

  37. The Respiratory SystemHomeostatic Imbalances • Chronic Bronchitis • Is defined as a daily productive cough for at least 3 consecutive months each year for 2 years in a row.

  38. The Respiratory SystemHomeostatic Imbalances Chronic Bronchitis

  39. The Respiratory SystemHomeostatic Imbalances • Chronic Bronchitis

  40. The Respiratory SystemHomeostatic Imbalances • Asthma • Asthma is characterized by episodes of coughing, dyspnea, wheezing, and chest tightness. • These symptoms can be felt alone or in combination. • One good thing it is reversible, with good drugs.

  41. The Respiratory SystemHomeostatic Imbalances • Asthma comes in two forms. • Allergic Asthma • Hypersensitivity reaction to environmental agents. • Nonallergic Asthma • Nonspecific stimuli cause inflammatory response. • About one in ten people in North America suffer from Asthma.

  42. The Respiratory SystemHomeostatic Imbalances • Asthma (structural changes) • Bronchospasm • Mucosal Edema • Excessive production of thick, whitish, tenacious bronchial secretions • Mucus plugging

  43. The Respiratory SystemHomeostatic Imbalances • Asthma

  44. The Respiratory SystemHomeostatic Imbalances Asthma

  45. The Respiratory SystemHomeostatic Imbalances Asthma

  46. The Respiratory SystemHomeostatic Imbalances • Lung Cancer • Lung Cancer is the leading cause of death among cancers in North America. • The “cocktail” of free radicals and other carcinogens in tobacco smoke eventually translates into Lung Cancer.

  47. The Respiratory SystemHomeostatic Imbalances • Lung Cancer’s three most common types. • Squamous Cell Carcinoma • 25-30% of cases • Adenocarcinoma • 40% of cases • Small Cell Carcinoma • 20% of cases

  48. The Respiratory SystemHomeostatic Imbalances • Lung Cancer (structural changes) • Inflammation, swelling, and destruction of the bronchial airways and alveoli. • Excessive mucus production. • Tracheobronchial mucus accumulation and plugging. • Airway obstruction ( either from blood, from mucus accumulation, of from a tumor projecting into a bronchus).

  49. The Respiratory SystemHomeostatic Imbalances • Lung Cancer (structural changes) • Atelectasis • Alveolar consolidation • Cavity formation • Pleural effusion ( when a tumor invades the parietal pleura and mediastinum).

  50. The Respiratory SystemHomeostatic Imbalances Lung Cancer

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