Physiological functions refer to the various processes and activities that occur within living organisms to maintain life. These functions include essential activities such as respiration, digestion, and circulation, which help provide energy, nutrients, and oxygen to cells. Each function is crucial for sustaining overall health and well-being. These processes are regulated by complex systems, including the nervous system and endocrine system, which coordinate responses to internal and external changes. For example, when the body is under stress, the nervous system triggers a response that can increase heart rate and blood flow, ensuring that vital organs receive the necessary resources.