Blood returning to the mammalian heart in a pulmonary vein drains first into the a. left atrium. b. right atrium. c. left ventricle. d. right ventricle.

Verified step by step guidance

1. Step 1: Understand the question. The question is asking where the blood returning to the heart from the lungs first drains into.
2. Step 2: Recall the structure of the heart. The heart is divided into four chambers: the left atrium, right atrium, left ventricle, and right ventricle.
3. Step 3: Recall the flow of blood in the heart. Blood returning from the lungs, which is oxygenated, first enters the heart at the left atrium.
4. Step 4: Match the information from step 3 to the options given in the question.
5. Step 5: The correct answer is a. left atrium.

Key Concepts

Mammalian Circulatory System

The mammalian circulatory system is a closed system that consists of the heart, blood vessels, and blood. It is responsible for transporting oxygen, nutrients, and waste products throughout the body. In mammals, the heart has four chambers: two atria and two ventricles, which work together to ensure efficient blood flow and separation of oxygenated and deoxygenated blood.

Pulmonary Circulation

Pulmonary circulation is the part of the circulatory system that carries deoxygenated blood from the right side of the heart to the lungs and returns oxygenated blood to the left side of the heart. Blood enters the lungs via the pulmonary arteries, where it releases carbon dioxide and absorbs oxygen. The oxygen-rich blood then returns to the heart through the pulmonary veins, specifically draining into the left atrium.

Heart Chambers

The heart consists of four chambers: the right atrium, right ventricle, left atrium, and left ventricle. The atria receive blood returning to the heart, while the ventricles pump blood out of the heart. The left atrium receives oxygenated blood from the lungs via the pulmonary veins, while the right atrium receives deoxygenated blood from the body. Understanding the flow of blood through these chambers is crucial for comprehending the overall function of the heart.