Red blood cells: shape, cell size, count | Biology Hubspot - Definition and Examples of Biology Terms


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Saturday, February 23, 2019

Red blood cells: shape, cell size, count

Red blood cells

Red blood cells are also known by the other two names namely erythrocytes and RBCs.Red blood cells lack a nucleus (enucleated) and other cellular organelles but contain an important pigment called hemoglobin.

Red blood shape, cell size, count

These are biconcave or dumbbell-shaped measuring about 7-8 mm in length and 1-2 micrometers in thickness.
The number of Red blood cells per microliter or mm3 is called total red blood cell count and is measured by an instrument called hemocytometer.
The number of red blood cells in a healthy adult male is about 5.4 million per microliter of blood, and a healthy adult female has about 4.8 million per microlitre of blood.

Diseases caused by up or down RBC count

The red blood cells constitute 98% of the cells in the blood. The increase in the number of RBCs causes a disease called Polycythemia while a decrease in the number of RBCs causes a disease called Erythrocytopenia.
RBC Physiology
The red blood cells contain respiratory pigment called hemoglobin. The hemoglobin contains four atoms of iron in its heme portion each of which is capable of binding to the O2 molecule in a reversible form of reaction to form Oxyhaemoglobin.
The quantity of hemoglobin is measured in per hundred ml of blood by an instrument called Haemometer or haemoglobinometer. The normal value of hemoglobin is 14-16 grams per hundred ml of blood in males and 12-14 grams per hundred ml of blood in females.
The normal life span of red blood cells is 120 days. The aged or dead Red blood cells are destroyed in the spleen, thus it is called graveyard of RBCs. At any time 2.5 million red blood cells are destroyed per second and the same number is formed also.
The red blood cells are formed in the bone marrow under the influence of hormone erythropoietin secreted by kidneys the process called erythropoiesis.

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