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Ventilation

Ventilation. Thorax. Thorax – Chest Thoracic Cavity Boundaries: ribs, spine, sternum and diaphram . contains: heart and lungs Pleural Membrane Lines the thoracic cavity and the lungs (slimy to prevent friction). Inhalation and Exhalation. Inhalation:

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Ventilation

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  1. Ventilation

  2. Thorax • Thorax – Chest • Thoracic Cavity • Boundaries: ribs, spine, sternum and diaphram. • contains: heart and lungs • Pleural Membrane • Lines the thoracic cavity and the lungs (slimy to prevent friction)

  3. Inhalation and Exhalation • Inhalation: • Diaphragm and intercostal muscles contract expanding thoracic cavity (ribs and sternum move up and out) • Air pressure inside the lungs decreases • Atmospheric air pressure > internal air pressure thus vacuum like suction draws air into lungs to equalize the pressure Diaphragm: primary muscle in breathing, located beneath the lungs Intercostal muscles: muscles between the ribs that aid in breathing

  4. Exhalation: • Diaphragm and intercostal muscles relax decreasing the size of thoracic cavity (ribs and sternum in and down) • Air pressure in the chest cavity increases • Atmospheric air pressure < internal air pressure thus air is pushed out of the lungs to equalize the pressure

  5. TLC: Total Lung Capacity • Maximum air in lungs after maximum inspiration • TV: Tidal Volume • Amt of air in and out in a normal breath

  6. ERV: Expiratory Reserve Volume • Air that can be forcibly expelled AFTER a normal breath • IRV: Inspiratory Reserve Volume • Air that can be forcibly inhaled AFTER a normal breath

  7. VC: Vital Capacity • Maximum amt of air that can be expired after a maximum inspiration • RV: Residual Volume • Air remaining in lungs after forcible exhaling

  8. Factors that Affect Respiration • High Altitude • Low pressure, thus less O2 in same volume of air • Less [O2] gradient from alveoli to blood, thus less O2 in blood Fix? Body increases production of EPO (erythropoietin) from kidneys, which increases r.b.c. production, thus increases amt of O2taken from the air. This is why some athlete train at high altitudes!

  9. Factors that Affect Respiration • Asthma • Swelling of bronchi and bronchioles, thus less air to lungs • COPD • Swelling of bronchi and bronchioles, and emphysema  loss of elasticity in alveoli thus can not get air in and out

  10. Chemistry of Respiration

  11. O2 Transport in the Blood • Most 02 is transported by hemeglobin (oxyhemeglobin) • With hemeglobin ~ 20 mL of O2 in 100 mL of blood • Without hemeglobin ~ 0.3 mL O2 in 100 mL of blood • O2 in blood plasma  cells • Thus, decreases the O2 in the plasma • Thus, O2 from oxyhemeglobin  blood plasma • Hemeglobin never completely looses O2 (Why we can hold our breath!)

  12. Transport of CO2 in Blood • 7% dissolved in plasma • 20% attaches to hemeglobin (carbaminohemeglobin) • 73% reacts with H2O  H2CO3 • H2CO3 is very acidic thus hemeglobin takes outH+ and bicarbonate ions are dissolved in the plasma • H2CO3  H+ + HCO3- • At lungs H+ is released by hemeglobin and H2O and CO2 are expelled by lungs • H+ + HCO3-  H2O + CO2

  13. Respiration Control • Controlled by medulla oblongata in the brain stem • Stretch receptors in lungs send message to the brain • When lungs are stretched – relax diaphragm and intercostal muscles to exhale • When lungs are relaxed – contract diaphragm and intercostal muscles to inhale

  14. Respiration Control Levels of CO2 (and pH) are monitored by the chemical receptors in the brain High CO2 increase breathing rate to get rid of it Low CO2  decrease breathing rate

  15. HWK Pg 446 #5,8,9 Pg 451 #1,a,b,2-6

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