Question

Мышечная стенка левого предсердия наиболее тонкая, так как при его сокращении кровь движется:1) из предсердия в желудочек2) из желудочка в предсердие 3) по малому кругу кровообращения4) по большому кругу кровообращения

Answer 1

3) по малому кругу кровообращения

Answer 2

The Thinnest Muscular Wall of the Left Atrium

The muscular wall of the left atrium is the thinnest compared to other cardiac chambers. This is because the left atrium's main function is to receive oxygenated blood from the pulmonary veins and pump it into the left ventricle for distribution to the rest of the body. The left atrium does not generate as much force as the left ventricle, which is responsible for pumping blood to the entire body. Therefore, the muscular wall of the left atrium is relatively thinner.

When the left atrium contracts, blood moves in a specific direction. Let's explore the options provided:

1) From the atrium to the ventricle: This is the correct answer. When the left atrium contracts, it pushes blood into the left ventricle, which then pumps the blood out to the body.

2) From the ventricle to the atrium: This is incorrect. The left ventricle pumps blood out to the body, and the blood does not flow back into the atrium during normal cardiac function.

3) Through the pulmonary circulation: This is incorrect. The pulmonary circulation refers to the circulation of blood between the heart and the lungs. The left atrium receives oxygenated blood from the pulmonary veins, but it does not pump blood through the pulmonary circulation.

4) Through the systemic circulation: This is incorrect. The systemic circulation refers to the circulation of blood between the heart and the rest of the body. The left atrium receives blood from the pulmonary veins and pumps it into the left ventricle, which then pumps it out to the systemic circulation.

Therefore, the correct answer is that the blood moves from the left atrium to the left ventricle when the left atrium contracts.

I hope this clarifies the movement of blood in the left atrium. Let me know if you have any further questions!