Iron deficiency; Pernicious anemia
Anemia is an abnormal reduction in red blood cells.
Anemia is not a single disease but a condition, like fever, with many possible causes and many forms. Causes of anemia include nutritional deficiencies, inherited genetic defects, medication-related side effects, and chronic disease. It can also occur because of blood loss from injury or internal bleeding, the destruction of red blood cells, or insufficient red blood cell production. The condition may be temporary or long-term, and can manifest in mild or severe forms.
This report focuses on three of the most common forms of anemia:
Some less common causes and types of anemia are included in a table in this report.
Blood has two major components:
Red blood cells (RBCs), also known as erythrocytes, carry oxygen throughout the body to nourish tissues and sustain life. Red blood cells are the most abundant cells in our bodies. Men have about 5.2 million red blood cells per cubic millimeter of blood, and women have about 4.7 million per cubic millimeter of blood.
Hemoglobin and Iron
Each red blood cell contains 280 million hemoglobin molecules. Hemoglobin is a complex molecule, and it is the most important component of red blood cells. It is composed of protein (globulin) and a molecule (heme), which binds to iron.
In the lungs, the heme component binds to oxygen in exchange for carbon dioxide. The oxygenated red blood cells are then transported to the body's tissues, where the hemoglobin releases the oxygen in exchange for carbon dioxide, and the cycle repeats. The oxygen is used in the mitochondria, the power source within all cells.
Red blood cells typically circulate for about 120 days before they are broken down in the spleen. Most of the iron used in hemoglobin can be recycled from there and reused.
Structure and Shape of Red Blood Cells
Red blood cells -- the erythrocytes -- are extremely small and look something like tiny, flexible inner tubes. This unique shape offers many advantages:
Abnormally shaped or sized erythrocytes are typically destroyed and eliminated.
Blood Cell Production (Erythropoiesis)
The actual process of making red blood cells is called erythropoiesis. (In Greek, erythro means "red," and poiesis means "the making of things.") The process of manufacturing, recycling, and regulating the number of red blood cells is complex and involves many parts of the body:
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