Chapter 3: Physiologic Changes

Structural changes often manifest in the integumentary system, resulting in fragile skin (increasing the risk for tears and infection), reduced melanocyte activity leading to paleness and sun susceptibility, and the development of benign lesions like senile lentigo and seborrheic keratoses. Musculoskeletal aging involves the predictable loss of bone density, which can progress to osteopenia and osteoporosis, causing height reduction and spinal curvature changes like kyphosis. Normal losses in muscle mass and elasticity contribute to decreased strength and mobility. Age-related respiratory changes include decreased lung elasticity and cilia function, along with chest cavity rigidity due to calcifying cartilage, impairing gas exchange and increasing the risk for infections like pneumonia and chronic obstructive pulmonary disease (COPD). The cardiovascular system experiences slight hypertrophy of the left ventricle and decreased function in the conduction system, leading to a diminished maximum cardiac output and greater susceptibility to conditions such as heart failure, hypertension, and orthostatic hypotension. In the neurological sphere, reduced brain volume and slower nerve conduction result in delayed reflexes and coordination issues; however, major cognitive decline is linked to pathologies like Alzheimer's and vascular dementia, rather than normal aging. Sensory decline includes presbyopia and increased incidence of cataracts and glaucoma in the eyes, and presbycusis (loss of high-frequency hearing) in the ears, alongside diminished taste and smell perception. Finally, gastrointestinal changes, such as slower peristalsis and decreased intrinsic factor production, increase the risk for constipation and malabsorption, while endocrine shifts, particularly reduced insulin sensitivity and lower sex hormone levels (especially post-menopause), heighten the prevalence of Type 2 Diabetes Mellitus and related metabolic disturbances.