Oxygen makes up 65 percent of the mass of the human body because at least 60 percent of a normal human's mass is water. Water is made of two hydrogen atoms and one oxygen atom, and the oxygen atom weighs eight times that of both hydrogen atoms combined.Know More
Most of the oxygen at any given time in the human body is bound to water, and water comprises anywhere from 60 percent to 90 percent of individual cells. Just six elements make 99 percent of a human body's weight. After oxygen, hydrogen makes up 10 percent of the human body by weight and carbon comprises 18 percent, nitrogen 3 percent, calcium 1.5 percent and phosphorus 1 percent. The rest of the body's weight is comprised of trace minerals. Carbon is responsible for the organic chemistry in the human body. Nitrogen is part of DNA, and calcium is necessary for bone growth.
Humans breathe in about 19 cubic feet of oxygen per day, which weighs about 1.43 ounces per cubic foot. On average, a human breathes less than 2 pounds of oxygen per day, so the amount of gaseous oxygen in the body at any given time is negligible compared to a 150-pound person who is comprised of nearly 98 pounds of oxygen.Learn more about Blood
There are an estimated 10 billion capillaries, measuring approximately 25,000 miles, in the average human body. Each capillary has a length of about 1.1 millimeter. Most capillaries are little more than a single cell layer thick.Full Answer >
The human body is capable of replacing the plasma from one pint of blood within 24 hours, while it takes four to six weeks for the body to completely replace the red blood cells from one pint of blood, according to the American Red Cross. For this reason, eight weeks is required between donations of blood to ensure the health and safety of the donor.Full Answer >
The five functions of the human circulatory system are the transportation of hormones, oxygen and nutrients; the removal of waste; the stabilization of the pH of bodily fluids; the maintenance of body temperature; and the fighting of infections. Fighting infections is achieved by transporting white blood cells.Full Answer >
Blood is responsible for transporting oxygen, carbon dioxide, nutrients, hormones and proteins in the body, according to KidsHealth. The blood also carries glucose, ions, amino acids and waste products, such as urea, through the body. Red blood cells carry hemoglobin, a chemical that gives blood its red color.Full Answer >