Red Blood Cells
(Microsoft Encarta)
COMPOSITION OF BLOODAbout 55 percent of the blood is composed of a liquid known as
plasma. The rest of the blood is made of three major types of
cells: red blood cells (also known as erythrocytes), white blood cells
(leukocytes), and platelets (thrombocytes).RED BLOOD CELLS
Red blood cells make up almost 45 percent
of the blood volume. Their primary function is to carry oxygen from the lungs to
every cell in the body. Red blood cells are composed predominantly of a protein
and iron compound, called hemoglobin, that captures oxygen
molecules as the blood moves through the lungs, giving blood its red color. As
blood passes through body tissues, hemoglobin then releases the oxygen to cells
throughout the body. Red blood cells are so packed with hemoglobin that they
lack many components, including a nucleus, found in other cells.
The membrane, or outer layer, of the red
blood cell is flexible, like a soap bubble, and is able to bend in many
directions without breaking. This is important because the red blood cells must
be able to pass through the tiniest blood vessels, the capillaries, to deliver
oxygen wherever it is needed. The capillaries are so narrow that the red blood
cells, normally shaped like a disk with a concave top and bottom, must bend and
twist to maneuver single file through them.
Resumos Relacionados
- Blood Type
- Plasma
- Splenomegaly
- Pysiological Transport
- Book Of Facts
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