Blood serves several critical functions including: 

• Absorbing oxygen from the lungs and transporting it to various tissues and organs in the body
• Gathering waste carbon dioxide from all parts of the body and transporting it to the lungs to be exhaled 
• Regulating internal body temperature by absorbing or releasing heat
• Absorbing digested nutrients and transporting them to various parts of the body
• Transporting hormones secreted by the endocrine glands to the different organs and tissues
• Forming blood clots at injury sites to prevent excess blood loss
• Facilitating the movement of cells and antibodies that fight infection and protect the body against pathogens
• Transporting waste products to the kidney and liver, which filter and clean the blood by removing nitrogenous waste and toxins