1 / 21

Respiratory system L3

Respiratory system L3. Faisal I. Mohammed, MD, PhD. Terms Used to Describe Lung Volumes and Capacities. Exchange of Oxygen and Carbon Dioxide. Dalton’s Law Each gas in a mixture of gases exerts its own pressure as if no other gases were present

tavi
Download Presentation

Respiratory system L3

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Respiratory systemL3 Faisal I. Mohammed, MD, PhD University of Jordan

  2. Terms Used to Describe Lung Volumes and Capacities

  3. Exchange of Oxygen and Carbon Dioxide • Dalton’s Law • Each gas in a mixture of gases exerts its own pressure as if no other gases were present • Pressure of a specific gas is partial pressure Px • Total pressure is the sum of all the partial pressures • Atmospheric pressure (760 mmHg) = PN2 + PO2 + PH2O + PCO2 + Pother gases • Each gas diffuses across a permeable membrane from the are where its partial pressure is greater to the area where its partial pressure is less • The greater the difference, the faster the rate of diffusion University of Jordan

  4. Partial pressure of the gas - is determined by its concentration in the mixture and by the overall pressure of the gas mixture PatmO2 = Patm * FO2 PatmO2 = 760 mm Hg * 0.21 - in the liquid - partial pressure of the gas component, which is balanced with the liquid

  5. Partial Pressures of Gases in Inhaled Air University of Jordan

  6. Henry’s law • Quantity of a gas that will dissolve in a liquid is proportional to the partial pressures of the gas and its solubility • Higher partial pressure of a gas over a liquid and higher solubility, more of the gas will stay in solution • Much more CO2 is dissolved in blood than O2 because CO2 is 24 times more soluble • Even though the air we breathe is mostly N2, very little dissolves in blood due to low solubility • Decompression sickness (bends) University of Jordan

  7. External Respiration in Lungs • Oxygen • Oxygen diffuses from alveolar air (PO2 105 mmHg) into blood of pulmonary capillaries (PO2 40 mmHg) • Diffusion continues until PO2 of pulmonary capillary blood matches PO2 of alveolar air • Small amount of mixing with blood from conducting portion of respiratory system drops PO2 of blood in pulmonary veins to 100 mmHg • Carbon dioxide • Carbon dioxide diffuses from deoxygenated blood in pulmonary capillaries (PCO2 45 mmHg) into alveolar air (PCO2 40 mmHg) • Continues until of PCO2 blood reaches 40 mmHg University of Jordan

  8. Ventilation • Mechanical process that moves air in and out of the lungs. • [O2]of air is higher in the lungs than in the blood, O2 diffuses from air to the blood. • C02 moves from the blood to the air by diffusing down its concentration gradient. • Gas exchange occurs entirely by diffusion: • Diffusion is rapid because of the large surface area and the small diffusion distance. Insert 16.1

  9. Surface Tension (continued) • Law of Laplace: • Pressure in alveoli is directly proportional to surface tension; and inversely proportional to radius of alveoli. • Pressure in smaller alveolus would be greater than in larger alveolus, if surface tension were the same in both. Insert fig. 16.11

  10. Surfactant • Phospholipid produced by alveolar type II cells. • Lowers surface tension. • Reduces attractive forces of hydrogen bonding by becoming interspersed between H20 molecules. • Surface tension in alveoli is reduced. • As alveoli radius decreases, surfactant’s ability to lower surface tension increases. • Disorders: • RDS. • ARDS. Insert fig. 16.12

  11. Internal Respiration • Internal respiration – in tissues throughout body • Oxygen • Oxygen diffuses from systemic capillary blood (PO2 100 mmHg) into tissue cells (PO2 40 mmHg) – cells constantly use oxygen to make ATP • Blood O2 drops to 40 mmHg by the time blood exits the systemic capillaries • Carbon dioxide • Carbon dioxide diffuses from tissue cells (PCO2 45 mmHg) into systemic capillaries (PCO2 40 mmHg) – cells constantly make carbon dioxide • PCO2 blood reaches 45 mmHg • At rest, only about 25% of the available oxygen is used • Deoxygenated blood would retain 75% of its oxygen capacity University of Jordan

  12. Rate of Pulmonary and Systemic Gas Exchange • Depends on (D  p*S *A /  M.Wt ) • Partial pressures of gases • Alveolar PO2 must be higher than blood PO2 for diffusion to occur – problem with increasing altitude • Surface area available for gas exchange • Diffusion distance • Molecular weight and solubility of gases • O2 has a lower molecular weight and should diffuse faster than CO2 except for its low solubility - when diffusion is slow, hypoxia occurs before hypercapnia University of Jordan

  13. Internal Respiration • Factors affecting the internal respiration: • Partial pressure of gases (diffusion) • Distance between the cells and the capillary • Rate of metabolic rate: cellular oxidation that leads to formation of CO2 • Speed of the blood flow in capillary

  14. Oxygen Diffusion from the Alveoli to the Pulmonary circulation • O2 diffuses into the pulmonary capillaries because the Po2 in the alveoli is high. • Po2 in the pulmonary capillaries increased very fast (1/3 distance).

  15. Transport in arterial blood & Pulmonary shunt flow Due to the bronchial circulation the arterial Po2 fall to 95 mm Hg

  16. Po2 in systemic circulation(Diffusion from peripheral capillaries) Oxygen is always being used by the cells. Therefore, the intracellular Po2 in the peripheral tissue cells remains lower than the Po2 in the peripheral capillaries.

  17. Diffusion of CO2 from the Tissue Cells into the Capillaries

  18. Diffusion of CO2 from the Pulmonary Capillaries into the Alveoli

  19. Thank You University of Jordan

More Related