Facts About Blood
What is blood?
Blood is the life-maintaining fluid that flows through the body's blood vessels:
What is the function of blood?
Blood carries the following to the body tissues:
Blood carries the following away from the body tissues:
What is blood made up of?
The different parts of human blood include:
Where are blood cells made?
Blood cells are made in the bone marrow. The bone marrow is the soft, spongy material
in the center of the bones. It makes about 95% of the body's blood cells. Most of
the adult body's bone marrow is in the pelvic bones, breastbone, and the bones of
There are other organs and systems in our bodies that help regulate blood cells. The
lymph nodes, spleen, and liver help regulate the production, destruction, and differentiation
(developing a specific function) of cells.
Blood cells formed in the bone marrow start out as a stem cell. A stem cell is the
first phase of all blood cells. As the stem cell matures, several distinct cells evolve.
These include the red blood cells, white blood cells, and platelets. Immature blood
cells are also called blasts. Some blasts stay in the marrow to mature. Others travel
to other parts of the body to develop into mature, functioning blood cells.
What do blood cells do?
The main function of red blood cells, or erythrocytes, is to carry oxygen from the
lungs to the body tissues. And to carry carbon dioxide as a waste product away from
the tissues and back to the lungs. Hemoglobin is an important protein in red blood
cells that carries oxygen from the lungs to all parts of the body.
The main function of white blood cells, or leukocytes, is to fight infection. There
are several types of white blood cells. Each has its own role in fighting bacterial,
viral, fungal, and parasitic infections. Types of white blood cells that are most
important for helping protect the body from infection and foreign cells include:
White blood cells:
Help heal wounds. They do this by fighting infection, and also by taking in matter.
This includes dead cells, tissue debris, and old red blood cells.
Are our protection from foreign bodies that enter the blood, such as allergens.
Help to protect against changed (mutated) cells, such as cancer.
The main function of platelets is blood clotting. Platelets are much smaller than
the other blood cells. They group together to form clumps, or a plug, in the hole
of a vessel to stop bleeding.
What is a complete blood cell count (CBC)?
A complete blood cell count (CBC) is a blood test that measures the size, number,
and maturity of the different blood cells in a specific volume of blood. A small sample
of blood is taken from a vein in your hand or arm and studied in a lab. A CBC can
be used to find many abnormalities with either the production or destruction of blood
cells. Changes from the normal number, size, or maturity of the blood cells can be
used to show an infection or disease process. Often with an infection, there is a
higher number of white blood cells. Many forms of cancer can affect the bone marrow
production of blood cells. An increase in the immature white blood cells in a CBC
can be linked to leukemia. Anemia and sickle cell disease will have abnormally low
Common blood tests
Some common blood tests include the following:
Complete blood count (CBC), which includes:
White blood cell count (WBC)
Red blood cell count (RBC)
Hematocrit red blood cell volume (HCT)
Differential blood count
To help diagnose anemia and other blood disorders and certain cancers of the blood.
To watch for blood loss and infection.
To watch a person's response to cancer treatment, such as chemotherapy and radiation.
To diagnose or monitor bleeding and clotting disorders.
Prothrombin time (PT) and partial thromboplastin time (PTT)
To evaluate bleeding and clotting disorders and to monitor anticoagulation (anticlotting)
Your healthcare provider will explain the purpose and results of any blood tests with
Blood production is very complex. And so is blood's role in supporting the entire
body. So there are many blood diseases that can happen. These include bleeding disorders,
anemias, and blood cancers called leukemias.