How do physiological ageing and frailty affect human body systems?

Physiological ageing leads to a progressive decline in the functional reserve of multiple organ systems, contributing to the development of frailty, a multidimensional syndrome observed by increased vulnerability to stressors and adverse health outcomes in older adults. This article explores the physiological changes across various systems, including neurological, cardiovascular, respiratory, genitourinary, gastrointestinal, endocrine, integumentary, musculoskeletal and haematological domains, and explores how these changes underpin the clinical features of frailty. By differentiating age-related decline from pathological processes, the review emphasises the importance of system specific knowledge in guiding individualised assessment, prevention and care. Understanding these correlated mechanisms is essential for healthcare professionals managing the complexities of frailty in ageing populations.