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Respiratory System

Respiratory System. Breathing Mechanism: Respiratory Volumes and Capacity, Alveolar Ventilation, and Nonrespiratory Movements. Respiratory Volumes. The different volumes of air that enter or leave the lungs Can be divided into four different volumes: Resting tidal volume

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Respiratory System

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  1. Respiratory System Breathing Mechanism: Respiratory Volumes and Capacity, Alveolar Ventilation, and Nonrespiratory Movements

  2. Respiratory Volumes • The different volumes of air that enter or leave the lungs • Can be divided into four different volumes: • Resting tidal volume • Inspiratory reserve volume • Expiratory reserve volume • Residual volume

  3. Spirometry • Study of respiratory volumes

  4. Spirometer • Used to measure respiratory air volumes (except residual volume) • These volumes can then be used in the evaluation of respiratory illnesses

  5. Respiratory Cycle • One inspiration and one expiration

  6. Tidal Volume • Volume of air that enters or leaves during a respiratory cycle

  7. Resting Tidal Volume • Volume of air that enters or leaves during normal, resting inspiration and expiration • About 500 mL

  8. Inspiratory Reserve Volume • Volume of air taken in during forced maximal inspiration in addition to the resting tidal volume • Equals about 3,000 mL

  9. Expiratory Reserve Volume • Volume of air expelled from the lungs during maximal forced expiration in addition to the resting tidal volume • About 1,100 mL

  10. Residual Volume • Air that remains in the lungs • (About 1,200 mL even after the most forceful expiration) • Mixes with newly inhaled air • Prevents the CO2/O2 concentrations from fluctuating greatly with each breath

  11. Vital Capacity • The maximum volume of air a person can exhale after taking the deepest breath possible • Equal to tidal volume plus inspiratory reserve volume plus expiratory reserve volume • About 4,600 mL

  12. Inspiratory Capacity • Maximum volume of air a person can inhale following a resting expiration • Equal to the tidal volume plus the inspiratory reserve • About 3,500 mL

  13. Functional Residual Capacity • Volume of air that remains in the lungs following a resting expiration • Equal to the expiratory reserve volume plus the residual volume • About 2,300 mL

  14. Total Lung Capacity • Equal to the vital capacity plus the residual volume • About 5,800 mL • Total varies with gender, age, and body size

  15. Anatomic Dead Space • Created by air that is inspired (about 150 mL) but remains in the trachea, bronchi, and bronchioles where gas exchange does not occur

  16. Alveolar Dead Space • Created by nonfunctional air sacs (due to poor blood flow in adjacent capillaries)

  17. Physiological Dead Space • Total volume of the anatomical dead space and the alveolar dead space • Volume is essentially the same as the volume of the anatomical dead space (about 150 mL)

  18. Minute Ventilation • Volume of air moves into the respiratory passages each minute • Equal to the tidal volume multiplied by the breathing rate • Much of this new air remains in physiological dead space

  19. Alveolar Ventilation Rate • Volume of new air that reaches the alveoli and is available for gas exchange • Equal to (the tidal volume minus the physiological dead space) multiplied by the breathing rate • (500 mL – 150 mL) x 12 breaths/min = 4,200 mL/min

  20. Nonrespiratory Air Movements • Air movements that occur in addition to breathing • Used to clear air passages or to express emotions • Usually result from reflexes but can also be triggered through conscious effort

  21. Coughing • Used to clear the lower respiratory passages • Involves: • Taking a deep breath • Closing the glottis • Forcing air upward from the lungs against closure • Suddenly opening the glottis • And forcing a blast of air upward from the lower respiratory tract

  22. Sneezing • Clears the upper respiratory passages • Usually triggered by an irritant in the lining of the nasal cavity • Similar to a cough but in the process of sneezing the uvula is depressed directing the upward forced air to enter the nasal passages

  23. Laughing • Involves a person taking a breath and releasing it in a series of short expirations

  24. Crying • Works through the same process as laughing

  25. Hicupping • Caused by a sudden inspiration due to a spasmodic contraction of the diaphragm while the glottis is closed • Associated noise is caused by air striking the vocal cords • Function of hiccups is not known

  26. Yawning • A deep inspiration that involves the glottis and mouth being open • Why we yawn and why it is “contagious” are not understood

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