Tag: circulatory system - blood

Red blood cells-- also known as RBCs, red cells, red blood corpuscles, haematids, erythroid cells or erythrocytes (from Greek erythros for "red" and kytos for "hollow vessel", with -cyte translated as "cell" in modern usage), are the most common type of blood cell and the vertebrate's principal means of delivering.

Diameter of capillaries is 4u for RBC to pass. As RBC has diameter of 8u it experiences large deformations while passing.

Platelets are cell fragments produced from megakaryocytes (special cells in the bone marrow). They are also called as thrombocytes. An injury or a trauma stimulates the platelets in the blood to release certain factors which activate the mechanism of coagulation or blood clotting. They also change their shape from round to spiny and stick to the broken vessel wall and each other and forms net-like structure during bleeding. Hence platelets forms net-like structure during bleeding.

Hemoglobin (Hb or Hgb ) is an iron-containing protein present in erythrocytes or Red blood cells(RBC) of almost all vertebrates. Each hemoglobin is made up of 4 subunits, 2 alpha subunits and 2 beta subunits. Each subunit surrounds the central heme group that contains iron and binds to one oxygen molecule. Hence each hemoglobin molecule can bind to four oxygen molecules. It carries oxygen from lungs to tissues. It also helps in the transportation of carbon dioxide, hydrogen ions back to the lungs from the tissues. Hence haemoglobin in the RBCs helps in the transport of oxygen and carbon dioxide.