Blood

 Part 3

Cellular Content of Blood

There are three types of blood cells__

1. Erthrocytes or red blood cells ( RBC )

2. Leucocytes or white blood cells ( WBC )

3. Thrombocytes or Platelets

@ All blood cells originates from pluripotent stem cell and go through several development stages, byere entering the blood.

@ The process of blood  cell formation is called haemopoeisis and takes place  within red bone marrow. Haemopoeisis in the skeletons is confined to flat bone irregular bones and the ends of long bones, the main sites are skull,ribs, sternum and pelvis. Lymphocytes are produced in lymphoid tissues.

# Erythrocytes or RBC

These are circular , by concave and non- nucleated disc. They have no nucleus and their diameter is about 7micro meter . There main function is in gas transport mainly of oxygen but they also carry some carbon dioxide.

              The by concavity increases their surface area for gas exchange, and the thinest of the central portion allows fast and exist of gases.

#  Life Span and function of Erythrocytes (RBC)

Erythrocytes are present in red bone marrow which is present in the ends of long bones.

$ their life span is about 120 days

$ the process of development of RBC from pluripotent stem cells takes about 7day, and is called erythropoiesis.

$ the immature cells are released in the blood stream as reticulocytes and then mature into erythrocytes during this time they looses their nuclease and therefore become incapable of division.

$ Both vitamin B12 and frolic acid are required for red blood synthesis.