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RESPIRATION

RESPIRATION. INTERNAL AND EXTERNAL. INTERNAL RESPIRATION. CELLULAR METABOLISM ANAEROBIC GLYCOLYSIS AEROBIC OXIDATIVE METABOLISM IN THE MITOCHONDRIA. EXTERNAL RESPIRATION. Ventilation or breathing: air moved in and out of lungs Oxygen and Carbon Dioxide exchange in the lungs

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RESPIRATION

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  1. RESPIRATION INTERNAL AND EXTERNAL

  2. INTERNAL RESPIRATION • CELLULAR METABOLISM • ANAEROBIC GLYCOLYSIS • AEROBIC OXIDATIVE METABOLISM IN THE MITOCHONDRIA

  3. EXTERNAL RESPIRATION • Ventilation or breathing: air moved in and out of lungs • Oxygen and Carbon Dioxide exchange in the lungs • Oxygen and Carbon Dioxide transported by blood to and from tissues • Exchange of Oxygen and Carbon Dioxide between tissue and blood

  4. EXTERNAL AND INTERNAL RESPIRATION TISSUE CELL O2 + FOOD ATMOSPHERE SYSTEMIC CIRCULATION HEART PULMONARY CIRULATION LUNGS CO2 + H2O + ATP

  5. THE RESPIRATORY SYSTEM • Nasal Passages • Mouth • Pharynx • Larynx • Trachea • Bronchi • Alveoli • Lung

  6. Alveoli • Small, thin walled, inflatable sacs at end of bronchioles • Surrounded by jacket of pulmonary capillaries • Provide thin barrier and enormous surface area for gas exchange by diffusion • Type II secrete surfactant

  7. Alveoli and Pulmonary Capillaries

  8. RESPIRATION The Mechanics of Breathing

  9. PRESSURES AT REST • Atmospheric pressure: 760 mm Hg • Intra-alveolar pressure: 760 mm Hg • Intrapleural pressure: 756 mm Hg

  10. BAROMETRIC PRESSURE VACUUM 760 mm WEIGHT OF COLUMN OF AIR = FORCE FORCE/AREA = PRESSURE Sea Level Mercury Hg

  11. REST PRESSURES Atmosphere Airways 760 MM Hg Intrapleural pressure Pleural Sac 756 mmHg Thoracic Wall Lungs

  12. THE TRANSMURAL PRESSURE GRADIENT INFLATES THE LUNGS • Thoracic cavity larger than lungs • Transmural (Across Lung Wall) pressure gradient holds thoracic wall and lungs in close apposition • This pressure gradient is balanced by the elastic forces in the alveoli producing equilibrium

  13. REST PRESSURES Atmosphere Airways 760 MM Hg Intrapleural pressure Pleural Sac 756 mmHg Thoracic Wall Lungs

  14. AIR IS A COMPRESSABLE GAS WHICH OBEYS BOYLE’S LAW • P1V1 = P2V2 • If Volume increases, Pressure must decrease • As lungs expand, pressure inside falls

  15. INSPIRATION • Elevation of ribs expands lungs • Lowering of diaphragm by contraction also expands lungs • Expansion of lungs causes pressure inside to drop below atmospheric pressure • Air rushes in to fill the expanded lungs

  16. INSPIRATION Atmosphere Airways 760 mm Hg 759mm Hg Intrapleural pressure Pleural Sac 754 mmHg Thoracic Wall Lungs

  17. EXPIRATION • Return of ribs to rest position causes diminishing of lung volume • Return of diaphragm to rest position also causes diminishing of lung volume • Diminishing of lung volume causes pressure in lung to raise to a higher value than atmospheric pressure • Air flows out of the lungs

  18. EXPIRATION Atmosphere 760 mm Hg Airways 761 mm Hg Intrapleural pressure Pleural Sac 756 mmHg Thoracic Wall Lungs

  19. MUSCLES OF INSPIRATION • Sternocleidomastoid • Scalenus • External Intercostals • Diaphragm

  20. MUSCLES OF EXPIRATION • Internal intercostals • Abdominals

  21. AIRWAY RESISTANCE • Flow of air depends on the pressure gradient (atmospheric, Pa, and intra-alveolar, Pi) and the airway resistance, R • F = (Pa - Pi)/R • Resistance depends primarily on the radius of the conducting airways • Parasympathetic stimulation constricts, while sympathetic dilates

  22. Resistance and Disease • Colds • Asthma: Constriction of small airways, excess mucus, and histamine-induced edema • Bronchitis:Long term inflamitory response causing thickened walls and overproduction of mucous • Emphysema: Collapse of smaller airways and breakdown of alveolar walls • Alveolar surface tension

  23. LUNG VOLUMES • Tidal Volume (TV): 500 ml • Inspiratory reserve volume (IRV): 3 liters • Inspiratory capacity (IC): 3.5 liters • Expiratory reserve volume (ERV): 1 liter • Residual volume (RV): 1.2 liters • Functional Residual Capacity (FRC): 2.2 l • Vital Capacity (VC): 4.5 liters • Total Lung Capacity (TLC): 5.7 liters

  24. LUNG VOLUMES

  25. LUNG VOLUMES: RELATIONSHIPS • IC = IRV + TV • FRC = ERV + RV • VC = IRV + TV + ERV • TLC = VC + RV

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