Hyoid Bone Anatomy
Number of Red Blood Cells in the Blood
Number of Red Blood Cells in the Blood:
As the blood moves throughout the body, it circulates about 20 – 30 trillion red blood cells (RBCs). Even a small drop of blood (1.0 mm3) contains millions of RBCs:
- 4.2 – 5.4 million RBCs/mm3 in males
- 3.6 – 5.0 million RBCs/mm3 in females
- Because they lack a nucleus, RBCs stay viable for only about 120 days and must be replaced at the same rate as they disappear from the blood (= 2.5 million cell/second).
- A high number of RBCs per volume of blood is referred to as polycythemia. When this abnormality occurs, it can increase blood volume, pressure, and viscosity.
Learn how to identify different cells under the microscope with these interactive histology quizzes and labelling exercises.
- A low number of RBCs of blood reduces the hemoglobin concentration, which is measured in grams Hb per deciliter (100 milliliters) of whole blood:
- 14 – 18 grams/dL in males
- 12 – 16 grams/dL in females
- A low hemoglobin concentration, which is called anemia, decreases oxygen (O2) delivery to the tissues.