A nurse is assessing an older adult's respiratory status. Which of the following are normal age-related changes in the respiratory system? (Select all that apply.)

A. Stiffening of the chest wall: Aging causes calcification of costal cartilage and reduced flexibility of the thoracic cage. This stiffness limits chest expansion, making deep breathing more difficult and decreasing overall lung compliance. B. Increased resistance to airflow: Age-related weakening of respiratory muscles and narrowing of the airways contribute to greater airway resistance. These changes reduce the efficiency of ventilation and may cause mild shortness of breath during exertion. C. Diminished cough reflex: Degeneration of sensory receptors and weakened respiratory muscles lead to a less effective cough reflex. This increases the risk of retained secretions and respiratory infections such as pneumonia in older adults. D. Loss of elastic recoil: The lungs gradually lose elasticity with age, resulting in air trapping and decreased expiratory flow. This change reduces gas exchange efficiency and contributes to higher residual lung volumes. E. Decreased respiratory rate: Respiratory rate generally remains stable with age unless affected by illness or medication. While breathing patterns may become shallower, the rate itself does not normally decline in healthy older adults.