RBC stands for Red Blood Cell, which is also known as Red Blood Corpuscles or Erythrocytes. RBCs are human biconcave and nucleus-free cells that carry oxygen and carbon dioxide through the blood. They are the most abundant blood cells formed in the bone marrow, and they make up 40-45% of the overall blood volume. The iron-rich protein called hemoglobin is found in RBCs, giving the blood its red color. RBCs are constantly produced in the bone marrow and remain in the bloodstream for about 120 days before being eliminated by the spleen or liver.

Some key points about RBCs include:

• The blood volume proportion that includes all red blood cells is named hematocrit.
• Roughly 0.5 billion RBCs contain in a single blood drop.
• For each 600 RBCs, there are about 40 platelets and one WBC (white blood cell).
• A tiny, round, disc-shaped cell that does not comprise a nucleus is a mature human RBC. On a peripheral blood smear, it ranges about 7-8 microns in diameter.
• To move via the smallest blood vessels or blood capillaries, they have a flexible membrane that enables them to change their appearance.
• In an adult human being, there are around 4.5 to 6 million RBCs per cubic millimeter of blood volume.

RBCs are an essential component of blood, and they play a crucial role in carrying oxygen and carbon dioxide throughout the body.