Biological responses refer to the reactions of living organisms to various stimuli in their environment. These responses can be physical, such as changes in heart rate or hormone levels, or behavioral, like fleeing from danger or seeking food. They are essential for survival and help organisms adapt to changing conditions. These responses are often regulated by the nervous system and endocrine system, which work together to process information and trigger appropriate actions. For example, when faced with a threat, the body may release adrenaline, preparing it for a "fight or flight" response. Understanding these mechanisms is crucial in fields like medicine and psychology.