Freshly oxygenated blood is first received by the a. atrium, b.atrium, c. right ventricle, d. left ventricle.

Video transcript

Hi, everybody. Let's look at our next question, which of the following is responsible for the circulation of blood from left the left atrium to the right atrium. A systemic circulation. B pulmonary circulation, C coronary circulation or D renal circulation. Well, since we're talking about chambers of the heart and the circulation of blood leading to it going from one atrium to the other, we can eliminate choice D renal circulation right away, renal circulation refers to circulation of blood through the kidneys. So obviously, that's not what we're talking about. So let's move on to thinking about how blood moves through the body and through the heart. So I'm just going to put up a really crude diagram to help us remember how blood is moving through the body and into and out of the heart. So that we can think about which type of circulation will ultimately move blood from the left atrium to the right atrium. Well, choice D or excuse me, choice C, coronary circulation would refer to circulation of the blood just within the heart and blood does not go directly from left atrium to right atrium. So choice C is crossed out. So Now, we just need to figure out whether it travels in this way through pulmonary circulation, through the lungs or systemic circulation through the rest of the body. So for that, I'm going to use a little highlighting and we'll look at this extremely rough diagram. We've got the heart in the middle with R A R V L A and L V labeling right atrium, right ventricle, left atrium, left ventricle, uh blue lines symbolizing deoxygenated blood and red lines symbolizing oxygenated blood, my two little lungs up at the top and my little stick figure at the bottom, symbolizing the entire rest of the body and where blood is being distributed. So we want to know how does blood circulate starting from the left atrium and ending up in the right atrium. So we'll start with our left atrium here and blood goes from the left atrium to the left ventricle and from there exits the heart. This is oxygenated blood exits the heart through the aorta and then on to the smaller arteries into the rest of the body. In the capillary beds, oxygen is distributed to the tissues and now the blood is deoxygenated, traveling from the capillary beds through the veins up into the superior and inferior vena cava and into the right atrium. So we can see that to go from the left atrium to the right atrium, the only pathway to do that is through the systemic circulation through the entire body. So our answer is going to be choice, a systemic circulation. Let's just look at the pulmonary circulation to understand why that's not the right choice in pulmonary circulation. The deoxygenated blood leaves the right ventricle. It's come there from the right atrium. So that would be starting from the right atrium. Going to right ventricle up through the pulmonary arteries and into the lungs, picks up oxygen in the lungs and then through the pulmonary veins back into the left atrium. So pulmonary circulation will result in blood circulating from the right atrium starting point to the left atrium. But our question is asking us to go the other direction from left atrium to right atrium. So pulmonary circulation is not correct. And our answer choice is choice. A systemic circulation being responsible for the circulation of blood from the left atrium to the right atrium. See you in the next video.