Red blood cell
Red blood cells (also known as RBCs, red blood corpuscles or erythrocytes) are cells in the blood which transport oxygen.[1][2] Red blood cells are very large in number; in women, there are 4.8 million red blood cells per microliter of blood. In men, there are 5.4 million red blood cells per microliter of blood[3]. Red blood cells are red because they have hemoglobin in them.
[change] Function
The most important function of red blood cells is the transport of oxygen. The hemoglobin absorbs oxygen in the lungs, travels through blood vessels and brings oxygen to all other cells via the heart. A fact which makes human red blood cells different to all other cells is that red blood cells do not have a nucleus, since they need lots of room for hemoglobin. However, bird red blood cells have nucleus. Since the blood cells go through both the lungs (to collect oxygen), through the heart (to be pumped around the rest of the body to give all cells oxygen) and back to the heart to be re-pumped to the lungs (to again collect oxygen), it is said that the blood in your body travels in a double circuit, going through your heart twice before it completes one full circulation of the body.
Red blood cells are doughnut (without the hole) shaped. However, hereditary diseases such as sickle-cell disease can cause them to change shapes and stop blood flow in capillaries and veins. Red blood cells do not have some parts that normal cells have, such as the nucleus, which makes the doughnut shape we see. Plasma is obtained from whole blood. To prevent clotting, an anticoagulant such as citrate is added to the blood specimen immediately after it is obtained.
[change] Development
Like all cells in the body, red blood cells begin as a stem cell. This is called a hematopoietic stem cell. This cell can form lots of cell types that make up the blood. The red cell is only one of the possibilities. Although red cells are small cells, they are very big when they are young cells. Just like people, cells must mature. Blood cells get smaller as they get older. When they grow, they have to cut themselves in half to reproduce. They start off with a nucleus and are called erythroblasts. A "blast" is a baby cell. Erythroblasts are much bigger than red blood cells. These become polychromatophilic red blood cells. They are named that because they are seen with many colors when stained. After this, they eject their nucleus and change shape to become a red blood cell. [4]
[change] References
- ↑ Bradfield, Phil; Potter, Steve (2009). Edexcel IGCSE Biology Student Book. Pearson Education. ISBN 9780435966881.
- ↑ Liang, Barbara. "General Anatomy & Physiology: Red Blood Cells". Wisc-Online. http://www.wisc-online.com/objects/ViewObject.aspx?ID=ap14604. Retrieved 2011-03-22.
- ↑ http://www.webmd.com/a-to-z-guides/complete-blood-count-cbc?page=3
- ↑ http://www.som.tulane.edu/classware/pathology/Krause/Blood/EP.html
