Blood volume refers to the total amount of blood circulating within the body. In an average adult, this volume is approximately 5 to 6 liters, which accounts for about 7-8% of total body weight. Blood volume is essential for maintaining proper circulation, delivering oxygen and nutrients to tissues, and removing waste products. Several factors can influence blood volume, including hydration levels, body size, and altitude. For instance, dehydration can lead to a decrease in blood volume, while increased fluid intake can raise it. Understanding blood volume is crucial for diagnosing and managing various medical conditions, such as heart failure and shock.