What physiological role does oxygen serve in the bloodstream?

Oxygen plays a crucial role in supporting cellular metabolism, which is the set of life-sustaining chemical reactions in organisms. In the bloodstream, oxygen is transported from the lungs to the tissues and organs where it is utilized by cells to produce energy through a process called aerobic respiration. This process converts glucose and oxygen into adenosine triphosphate (ATP), the energy currency of the cell, along with carbon dioxide and water as byproducts. Without a steady supply of oxygen, cells would not be able to efficiently produce the energy needed for various functions, leading to impaired cellular activity and overall organ function. This fundamental role of oxygen underscores its importance in maintaining health and energy levels in the body.