Final answer:
Decreased lung elasticity, compliance, respiratory muscle strength, and alveolar surface area can all impair an older adult's chest expansion and thus decrease tissue oxygenation.
Step-by-step explanation:
The age-related changes in the older adult that may result in decreased tissue oxygenation due to impaired chest expansion include: decreased lung elasticity, decreased respiratory muscle strength, decreased lung compliance, and decreased alveolar surface area. Each of these changes can impact the lungs' ability to fill with air and impair gas exchange. Decreased lung elasticity and compliance both lead to stiffer lungs that do not expand as easily, decreasing the volume of air that can be inhaled.
Weakened respiratory muscles make it hard to generate the force needed for inhalation, also contributing to less air being taken in. Finally, a decreased alveolar surface area, as seen in conditions like emphysema, directly affects gas exchange by reducing the available space for oxygen to enter the blood and carbon dioxide to be released.