Chapter 17: Mechanics of Breathing (PDF)

**[Chapter 17 \~ Mechanics of Breathing]** 1. List four major functions of the respiratory system. - Exchange of gases between atmosphere and blood - Homeostatic regulation of body pH - Protection from inhaled pathogens - vocalization 2. Define and describe the lung volumes and lung...

**[Chapter 17 \~ Mechanics of Breathing]** 1. List four major functions of the respiratory system. - Exchange of gases between atmosphere and blood - Homeostatic regulation of body pH - Protection from inhaled pathogens - vocalization 2. Define and describe the lung volumes and lung capacities. **[Tidal volume: (VT)]** normal volume breathing at rest   **[Inspiratory reserve volume]**: amount you breath beyond the tidal volume... DEEP BREATH (large capacity beyond tidal volume   **[Expiratory reserve volume]**: Extra you exhale beyond the tidal volume   **[Residual volume:]** remaining volume because you can\'t exhale all air out **Capacities are combinations of 2 or more volumes**   **Functional residual capacity**: what is left normally after an exhale Combo of expiratory reserve + residual volume   **Total lung capacity \--** Combo of all volumes combined   **Vital capacity \--** everything beside residual volume A diagram of a normal capacitors Description automatically generated 3. Explain how pressures and lung volumes change during normal breathing, and how that affects airflow in the respiratory system. Inspiration: alveolar pressure decreases & thoracic volume increases due to contracted diaphragm Expiration: Diaphragm relaxes, thoracic volume decreases, alveolar pressure increases  4. Explain sub-atmospheric intrapleural pressure and the role it plays in normal breathing. - Intrapleural pressures are sub atmospheric because the pleural cavity is a sealed compartment - Normally negative pressure at -3 mm Hg - Keeps lungs inflated 5. Graph the alveolar and intrapleural pressure changes that occur during one respiratory cycle. - Alveolar pressure is always greater than intrapleural to keep lungs inflated - Intrapleural pressure has greater oscillation - Lowest pressure point in alveoli: halfway through inspiration - Highest pressure point in alveolar: halfway through inspiration - Lowest pressure point in intrapleural: end of inspiration - Highest pressure point in intrapleural: end of expiration A graph of different types of pressure Description automatically generated INSPIRATION = PRESSURE DROP EXPIRATION = PRESSURE RETURN TO NORMAL VALUE 6. Compare and contrast compliance and elastance in respiratory physiology, ~~giving examples of disease states that demonstrate changes in compliance and/or elastance.~~ Compliance = ability to stretch Elastance = ability to return to normal RECOIL 7. Explain the role of surface tension and surfactants in respiratory physiology. **Surface tension** is due to water lining the alveoli surface **Surfactants**: reduce surface tension ensuring alveoli stability 8. Map the factors affecting airway resistance, with emphasis on local and reflex control mechanisms involved in bronchodilation and bronchoconstriction. **Keep local and reflex separate.** **\*\*\***Radius has the largest effect on resistance **Bronchoconstriction** increases resistance - Caused by parasympathetic Ach binding to muscarinic receptors - Closes airway **Bronchodilation** decreases resistance - Causes by sympathetic Epinephrine binding to B2 receptors - Opens airway up **Total pulmonary ventilation** (whole system) = ventilation rate x tidal volume **Alveolar ventilation (lungs)** = ventilation rate x (tidal volume -- dead space volume) - Typical dead space volume is 150 ml  \***PRACTICE MATH** 9. Explain the local control mechanisms by which ventilation and alveolar blood flow are matched. - Normally the perfusion of blood past alveoli is matched to alveolar ventilation to maximize gas exchange - If ventilation decreases in a group of alveoli, pCO2 increases and pO2 decreases. Blood flowing past those alveoli don't get oxygenated - We don't want to these areas... so there will be vasoconstriction upstream to avoid this - LOCAL CONTROL Diagram of a diagram showing the flow of ventilators Description automatically generated  **\*I GOT MUNCHED ON THIS ON THE TEST\ ** \*\*\*Opposite of systemic arteries