Question

Read the following statements and choose the correct option.
Statement 1 : Atria receive blood from all parts of the body which subsequently flows to ventricles.
Statement 2 : Action potential generated at sino-atrial node passes from atria to ventricles.

• A. Action mentioned in Statement $1$ is dependent on action mentioned in Statement $2$
• B. Action mentioned in Statement $2$ is dependent on action mentioned in Statement $1$
• C. Actions mentioned in Statements $1$ and $2$ are independent of each other
• D. Actions mentioned in Statements $1$ and $2$ are synchronous

Answer 1

Answer: (A)

Human heart is a four chambered structure where t he upper 2 chambers are the atria and the lower 2 chambers are the ventricle. Atria are the chambers of the heart that receive the blood from various organs of the body. Right atria receives deoxygenated blood from the body organs other than lungs through the vena cana, where as the left atria receives blood that is oxygenated from the lungs via pulmonary vein. The blood from both the atria is to be transferred to the respective ventricles and for that the valves that guard the atrio ventricular opening should be opened and closed after the blood is transferred from one chamber to the other so as to prevent the backward flow of the blood. For this opening and closing of the valve and also for the systole and dystole movement of the chambers stimulus is required which is provided by the sino atrial node that is present at the upper right corner of the right atria. This node generates the action potential which travels from the SA node to the atrio ventricular node that is AV node which is present at the lower left corner if the right atria. From the AV node the potential travels along the Purkenej fibers in the wall of atrio ventricular septum and the potential then spreads to the cardiac muscle of the heart. Therefore the whole functioning of the heart is dependent upon the action potential that is generated from the SA node in the atria. Therefore the answer 'Action mentioned in Statement 1 is dependent on action mentioned in Statement 2' is correct.