For example, in individuals with pernicious anemia, red blood cells appear oval-shaped; and in sickle-cell anemia, crescent-shaped. A red blood cell count , also known as an erythrocyte count , calculates the number of red blood cells in your blood.
It is typically measured as part of a complete blood count CBC. A high red blood cell count is a condition called polycythemia vera. If you have this medical condition, it means that your bone marrow is producing too many red blood cells. This can result in thickening of the blood, slow flow of blood, and eventually blood clots. There are two types of polycythemia vera [3] :. Various medical conditions associated with generalized hypoxia or overproduction of red blood cells typically cause a high red blood cell count , including:.
People with polycythemia vera may not show any symptoms. It takes about 7 days for a stem cell to fully mature into a red blood cell that is prepared to be released into the bloodstream. During this process, the stem cell becomes an immature red blood cell called an erythroblast.
Then, the nucleus and mitochondria of the erythroblast disappear, and the immature cell is gradually filled with hemoglobin. At this point, the cell is called a reticulocyte. Finally, the cell becomes a full mature red blood cell and enters the blood, ready to transport oxygen throughout the body.
The life of a red blood cell is short due to its lack of nucleus; human red blood cells only survive for about days. When red blood cells are old or damage, they are ready to be eliminated from the bloodstream.
Red blood cell removal is controlled by specialized cells called macrophages in the spleen part of the lymphatic system and the liver. The spleen disposes of worn-out red blood cells and controls the amount of blood cells at work in the body. Additionally, the liver recycles iron from damaged red blood cells.
Together, the macrophages in the spleen and liver remove old red blood cells from the body. Red blood cell count can also be reduced by certain drug interactions or nutritional deficiencies iron, copper, vitamin B-6, vitamin B, or folate. While some red blood cell diseases can be caused by illnesses or nutritional deficiencies, others are inherited. Diseases involving red blood cells include anemia low red blood cell count or low hemoglobin , thalassemia inherited blood disorders , and polycythemia vera or other blood cancers.
Bone marrow disease and hypoxia low blood oxygen levels are also possibilities. A red blood cell isolation protocol is a critical part of preparing a blood sample for analysis. Blood loss anemias are fairly straightforward. In addition to bleeding from wounds or other lesions, these forms of anemia may be due to ulcers, hemorrhoids, inflammation of the stomach gastritis , and some cancers of the gastrointestinal tract. The excessive use of aspirin or other nonsteroidal anti-inflammatory drugs such as ibuprofen can trigger ulceration and gastritis.
Excessive menstruation and loss of blood during childbirth are also potential causes. Anemias caused by faulty or decreased RBC production include sickle cell anemia, iron deficiency anemia, vitamin deficiency anemia, and diseases of the bone marrow and stem cells. Figure 5. Sickle Cells Sickle cell anemia is caused by a mutation in one of the hemoglobin genes.
Erythrocytes produce an abnormal type of hemoglobin, which causes the cell to take on a sickle or crescent shape. It can occur transiently in a person who is dehydrated; when water intake is inadequate or water losses are excessive, the plasma volume falls.
As a result, the hematocrit rises. For reasons mentioned earlier, a mild form of polycythemia is chronic but normal in people living at high altitudes.
Some elite athletes train at high elevations specifically to induce this phenomenon. Polycythemia vera can dangerously elevate the viscosity of blood, raising blood pressure and making it more difficult for the heart to pump blood throughout the body. It is a relatively rare disease that occurs more often in men than women, and is more likely to be present in elderly patients those over 60 years of age.
The most abundant formed elements in blood, erythrocytes are red, biconcave disks packed with an oxygen-carrying compound called hemoglobin. The hemoglobin molecule contains four globin proteins bound to a pigment molecule called heme, which contains an ion of iron. In the bloodstream, iron picks up oxygen in the lungs and drops it off in the tissues; the amino acids in hemoglobin then transport carbon dioxide from the tissues back to the lungs.
Erythrocytes live only days on average, and thus must be continually replaced. Worn-out erythrocytes are phagocytized by macrophages and their hemoglobin is broken down. The breakdown products are recycled or removed as wastes: Globin is broken down into amino acids for synthesis of new proteins; iron is stored in the liver or spleen or used by the bone marrow for production of new erythrocytes; and the remnants of heme are converted into bilirubin, or other waste products that are taken up by the liver and excreted in the bile or removed by the kidneys.
Answer the question s below to see how well you understand the topics covered in the previous section. Show Answers. Skip to main content. Module 2: The Cardiovascular System: Blood. Search for:. Erythrocytes Learning Objectives By the end of this section, you will be able to: Describe the anatomy of erythrocytes Discuss the various steps in the lifecycle of an erythrocyte Explain the composition and function of hemoglobin.
Figure 1. Summary of Formed Elements in Blood. Critical Thinking Questions young woman has been experiencing unusually heavy menstrual bleeding for several years. She follows a strict vegan diet no animal foods. She is at risk for what disorder, and why? A patient has thalassemia, a genetic disorder characterized by abnormal synthesis of globin proteins and excessive destruction of erythrocytes. This patient is jaundiced and is found to have an excessive level of bilirubin in his blood. Explain the connection.
Show Answers She is at risk for anemia, because her unusually heavy menstrual bleeding results in excessive loss of erythrocytes each month. At the same time, her vegan diet means that she does not have dietary sources of heme iron. The non-heme iron she consumes in plant foods is not as well absorbed as heme iron.
Bilirubin is a breakdown product of the non-iron component of heme, which is cleaved from globin when erythrocytes are degraded. Excessive erythrocyte destruction would deposit excessive bilirubin in the blood. Bilirubin is a yellowish pigment, and high blood levels can manifest as yellowed skin. Licenses and Attributions.
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