Human Immunity and Blood

Leukaemia is cancer of blood-forming cells. Leukaemia usually causes large numbers of white blood cells to be made. These abnormal cells usually can't carry out the normal functions of white blood cells. They crowd the bone marrow and spill into the blood and may then spread into organs such as the liver, spleen, lungs and kidneys. Sometimes, they may also spread into the fluid around the brain and spinal cord. Because there are so many abnormal white cells crowded into the bone marrow, the marrow sometimes can't make enough normal red blood cells, white blood cells and platelets. Thus, option B is correct.

Leukaemia is cancer of blood-forming cells. Leukaemia usually causes large numbers of white blood cells to be made. These abnormal cells usually can't carry out the normal functions of white blood cells. They crowd the bone marrow and spill into the blood and may then spread into organs such as the liver, spleen, lungs and kidneys. Sometimes, they may also spread into the fluid around the brain and spinal cord. Because, there are so many abnormal white cells crowded into the bone marrow, the marrow sometimes can't make enough normal red blood cells, white blood cells and platelets.

Out of all other leucocytes, the neutrophils (60-65%) are most abundant and the least are basophils (0.5-1%). Platelets are cell fragments produced from megakaryocytes. During the blood clotting, the enzyme thrombin converts inactive fibrinogens into active fibrins.. 

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. 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 RBC helps in transportation of gases while WBC takes parts in immune function and protects the body from infectious diseases and foreign invaders(bacteria, viruses other pathogens) and platelets in blood coagulation.

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. This prevents the loss of hemoglobin through bleeding.

The process of making blood cells is called haemopoiesis. Blood cells are made in the bone marrow. That's a spongy tissue located inside some bones. It contains young parent cells called stem cells. These blood-forming stem cells can grow into all 3 types of blood cells – red cells, white cells, and platelets. These blood-forming stem cells make copies of themselves, and they also produce mature blood cells. When blood cells are fully mature and functional, they leave the bone marrow and enter the blood. Healthy people have enough stem cells to keep making all the blood cells they need every day.

Blood platelets or thrombocyte is another word for platelet, the blood cell that is responsible for normal blood clotting. The root "thrombo" means clot, and you will see it used with diseases and conditions that affect the platelets and blood clotting.

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.

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.

Haemoglobin synthesis begins during the early stages of erythropoiesis. It is first detectable in the intermediate normoblast stage.

The presence of haemoglobin, the red pigment in the red blood cells (RBCs) makes blood appear red in colour. The haemoglobin carries oxygen and transports it to all the parts of the body.