Question

Given below are four statements (a-d) regarding human blood circulatory system.

(a) Arteries are thick-walled and have narrow lumen as compared to veins.
(b) Angina is acute chest pain when the blood circulation of the brain is reduced.
(c) Persons with blood group AB can donate blood to any person with any blood group under ABO system.
(d) Calcium ions play a very important role in blood clotting.

Which two of the above statements are correct?

• A. (c) and (d)
• B. (a) and (d)
• C. (a) and (b)
• D. (b) and (c)

Answer 1

The correct option is B (a) and (d)

• The walls of arteries are thicker than that of veins to withstand pulsatile flow and higher blood pressures.
• Compared to arteries, veins have larger diameters and thinner walls. They, therefore, have larger lumens and contribute capacitance to the circulation, holding approximately two-thirds of all circulating blood.
• In the blood clotting process, the presence of calcium ions and other clotting factors, factor X activates an enzyme called prothrombin activator.
• This enzyme then converts the plasma protein prothrombin into thrombin.
• Thrombin is an enzyme that, in turn, converts fibrinogen to fibrin. Angina is acute chest pain when the blood circulation of the heart muscles is reduced.
• Persons with blood group AB can receive blood from any person with any blood group under the ABO system.

So, the correct answer is option B.