Blood is a combination of plasma and cells that circulate through the entire body. It is a specialized bodily fluid that supplies essential substances around the body, such as sugars, oxygen, and hormones.
It also removes waste from the cells in the body.
Hematologists work to identify and prevent blood and bone marrow diseases, as well as studying and treating the immune system, blood clotting, and the veins and arteries.
In the United States (U.S.), blood diseases accounted for between 9,000 and 10,000 annual deaths from 1999 to 2010. This constitutes less than one percent of total deaths from disease.
Fast facts on blood
Blood transports oxygen and nutrients around the body and removes cellular waste, among a range of other vital functions.
Plasma makes up 55 percent of blood content. The other 45 percent consists mainly of red blood cells and platelets.
Blood groups are categorized based on the antibodies and antigens in the cell. Receiving an incompatible blood donation can lead to fatal complications.
Anemia, blood cancer, and clots are all potential disorders of the blood.
Blood travels along vessels to reach every system of the body and carry out its crucial functions.
Blood consists of plasma, red and white blood cells, and platelets.
Plasma: This constitutes approximately 55 percent of blood fluid in humans.
Plasma is 92 percent water, and the contents of the remaining 8 percent include:
The remaining 45 percent of the blood mainly consists of red and white blood cells and platelets. Each of these has a vital role to play in keeping the blood functioning effectively.
Blood mainly consists of plasma, red and white blood cells, and platelets.
Red blood cells (RBCs), or erythrocytes: They are shaped like slightly indented, flattened disks and transport oxygen to and from the lungs. Hemoglobin is a protein that contains iron and retains the oxygen until its destination. The life span of an RBC is 4 months, and the body replaces them regularly. Amazingly, our body produces around 2 million blood cells every second.
The expected number of RBCs in a single drop, or microliter, of blood is 4.5 to 6.2 million in men and 4.0 to 5.2 million in women.
White blood cells, or leukocytes: White blood cells make up less than 1 percent of blood content, and they form vital defenses against disease and infection. The normal range of the number of white blood cells in a microliter of blood is between 3,700 and 10,500. Higher and lower levels of white blood cells can indicate disease.
Platelets, or thrombocytes: These interact with clotting proteins to prevent or stop bleeding. There should be between 150,000 and 400,000 platelets per microliter of blood.
RBCs, white blood cells, and platelets are produced in the bone marrow before entering the bloodstream. Plasma is mostly water that is absorbed from ingested food and drink by the intestines. Combined, these are propelled around the entire body by the heart and carried by the blood vessels.