Tag: transportation in living organisms

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.

(b) To maintain electrostatic neutrality of plasma, many chloride ions diffuse from plasma into RBCs and bicarbonate ions pass out. The chloride content of RBCs increase when oxygenated blood become deoxygenated. This is termed as chloride shift or Hamburger phenomenon.