1. What is Boyle's Law? Describe ventilation
2. When the diapharam contracts what happens to intrathoracic pressure? What nerve controls the diaphram?
3. When the external intercoastal muscles contract what happens to the rib cage? internal intercoastals?
4. Does breathing consume a lot of ATP?
5. What are the pressure difference with inspiration & expiration?
6. What are the accessory muscles of inspiration? What is dyspnea? Apnea? Hyperventillation?
1. Boyle's Law = Pressure is inversely related to volume. Inspiration and Expiration are driven by differences in pressure. Gas flows from high → low pressure.
2. When the diaphram contracts (flattens) the volume in the thoracic cavity ↑. Pressure in the cavity ↓ to 758 mmHg. Intrathoracic (intrapleural) pressure ↓ to 756 mmHg. Atmospheric pressure is 760 mmHg so air flows down the pressure gradient into the lungs. This is known as inspiration or inhalation. (75% of ↑ from diaphram). The diaphram is innervated by the phrenic nerve which comes off the spinal cord at C3, C4, & C%.
- 3. The external intercoastal muscles contract and cause the rib cage to move superiorly and anteriorly (25% of volume increase).
- The internal intercoastal contract on forced exhalation and move the inferior ribs downward and compresses the abdominal viscera
4. Inhalation uses ATP (muscles contract) however exhalation is a passive process and does not use ATP normally.
- 5. Atmospheric pressure = 760 mmHg
- - Intrathoracic pressure = 756 mmHg
- - - Inhallation - Interpulmonic pressure = 758mmHg & intrathoracic (intrpleural) is 754 mmHg
- - - Exhalaiton - Interpulmonic pressure = 762 mmHg & intrathoracic = 758 mmHg
- 6. Accessory muscles of inspiration = scalenes, sternocledomastoid, serratus, pectoralis minor
- - Accessory mucles of expiration - internal intercoastals and abdominal muscles
Dyspnea = difficulty breathing
Apnes = no breathing
Hyperventillation = fast breathing