Body Fluids And Circulation

Answer (a) Two times

Seventy two double circulations are normally completed by human heart in one minute.

Answer (c) Blood = Plasma + RBC + WBC + Blood platelets

During an injury, the blood platelets release thromboplastin which converts plasma protein prothrombin into thrombin in the presence of calcium ions. Thrombin then converts soluble plasma protein fibrinogen into fibrin which forms a meshwork by trapping red blood cells, thus forming a clot.

Systemic circulation is the movement of the blood between heart and rest of the body (tissues) and the back to the heart.

Heparin is an anticoagulant

The Rh-factor has great significance in child birth. An Rh- negative woman married with Rh-positive man becomes sensitised by carrying a Rh-positive child within her body.

This is because an Rh-vc person, if exposed to Rh+ve blood, will fonn specific antibodies against the Rh antigens. This is observed in case of Rh-vc blood of a pregnant mother with Rh+ve blood of the foetus. Rh antigens of the foetus do not get exposed to the Rh-ve blood of the mother in the first pregnancy as the two bloods are well separated by placenta. However, during the delivery of the first child, there is a possibility of exposure of the maternal blood to small amounts of the Rh+ve blood from the foetus. In such cases, the mother starts preparing antibodies against Rh antigen in her blood. In case of her subsequent pregnancies, the Rh antibodies from the mother (Rh-ve) can leak into the blood of the foetus (Rh+ve) and destroy the foetal RBCs. This could be fatal to the foetus or could cause severe anaemia and jaundice to the baby. This condition is called erythroblastosis foetalis.

A blood donation occurs when in a person blood is voluntarily drawn and used for transfusions or made into medications. The donor is asked about medical history and given a short physical examination to make sure that the donation is not hazardous to his or her health. India Red Cross Society has recommended guidelines for suitable persons for blood donation, a person who is immunised with live vaccines is one of them.