question_answer 30)

  Read the following statements and choose the correct option. Statement I Atria receive blood from all parts of the body which subsequently flows to ventricles. Statement II Action potential generated at sino-atrial node passes from atria to ventricles. (a) Action mentioned is statement I is dependent on action mentioned in Statement II (b) Action mentioned in statement II is dependent on action mentioned in Statement I (c) Action mentioned in statement I and II are independent of each other. (d) Action mentioned in statement I and II are synchronous.

Answer:

                (d) The superior vena cava pours venous blood into right atria and left atria receive blood from lungs. This then flows into ventricles. The contraction of muscles of atria arise from SA nodes and passes to AV node and then to the Purkinje fibres. Therefore, action mentioned in statement I and II are synchronous, while the other options are wrong.