Blood: What It Does Do?

Humans need blood to live. Blood carries oxygen and nutrients that the different organs of the body need to survive. Blood also enables us to regulate our body temperature, fight infections, or eliminate our own waste products.

Our blood actually contains three types of blood cells:

Red blood cells

RBCs or erythrocytes can be distinguished through their indented, flattened disk shape. They contain the iron-rich protein hemoglobin. The bright red color of blood is created when hemoglobin picks up oxygen in the lungs. As blood courses through the body, hemoglobin releases oxygen to our tissues. There are more RBCs in the human body than any other type of cell. Each one has a lifespan of about 4 months. The body produces new RBCs everyday to replace the ones that die or are lost from the body.

White blood cells

WBCs or leukocytes are an important part of the body’s defense system against infection. WBCs travel in and out of the bloodstream to get to infected tissues. There are a lot less WBCs in the body than RBCs, though if there is an infection, the body increases its WBC production. There are several types of WBCs. Their lifespan varies from a few days to a few months. WBCs are also manufactured in the bone marrow everyday.


Platelets or thrombocytes, are necessary for clotting.

Aside from these three cells, the blood also contains other important substances, such as nutrients from food. Blood also carries hormones to various body parts that need them.

Blood is necessary in maintaining good health because it carries the fuel and oxygen that the body constantly needs to nourish its billions of cells.

Blood also carries carbon dioxide and other waste products to the lungs, kidneys, and digestive system to be eliminated by the body.

Two types of vessels transport blood throughout the body:

Arteries – carry blood that had received oxygen from the lungs (oxygenated blood).

Veins – carry blood back to the lungs to receive more oxygen.

Blood is manufactured mostly in the bone marrow, particularly in the marrow of the vertebrae, ribs, pelvis, skull, and sternum (breastbone).

Blood, and the special proteins it contains, can be replaced or supplemented through blood transfusion – giving a person blood from another. Aside from whole-blood transfusions, people can also receive just the specific blood cells (platelets, WBCs, RBCs), or clotting factor.  This is important for when a person losses blood or is ill.

Source: MSN Health