Assignment task:
The cardiovascular system in humans and our close relatives is comprised of the heart and blood vessels. Our hearts are powerful muscles that provide the force needed to push blood through the body in our blood vessels which are a network of conduits that allows blood to reach every part of the body. The joint action of our heart and blood vessels provides cells with oxygen and nutrients and moves away cellular waste and CO2. We can consider two primary goals of the cardiovascular system: 1. Provide all cells of the body with O2 and nutrients and 2. remove CO2 and wastes from all cells of the body. Meeting these goals requires three processes to occur: 1. Moving blood to all parts of the body, 2. oxygenating the blood, and 3. ridding blood of CO2. The cardiovascular system accomplishes these goals as the heart pumps blood through 2 circuits: the pulmonary and systemic circuits. CV3.jpg In the pulmonary circuit, blood returning from body is rich in CO2 and low in O2. Deoxygenated blood returns to right side of heart and chambers on the right side of heart pump deoxygenated blood to the lungs. In the lungs, blood releases CO2 and picks up O2 (more on this when we get to the respiratory system). Finally, oxygenated blood returns to left side of heart.
In the systemic circuit, oxygen rich blood returning from the lungs is pumped from chambers on the left side of the heart to the rest of the body.
Let's consider the structure of portions of the heart and consider how they predict function. Your heart has two atria and two ventricles. The atria are the top, thin-walled chambers and the ventricles are the bottom, thick, muscular chambers. The right and left sides of your heart are fully separated with no blood exchange between the sides.
Your right atrium receives deoxygenated blood from the superior and inferior vena cava. When this atrium contracts, it pumps the blood through your right atrioventricular valve into the right ventricle. The right ventricle contracts and sends oxygen-poor, CO2-rich blood through the pulmonary trunk to the lungs.
Once the blood is oxygenated in the lungs, it returns to the heart through the pulmonary veins (more on arteries and veins in a bit!). The oxygen-rich blood first enters the left atrium. When the left atrium contracts, it pumps the blood to the left ventricle. Extremely powerful contraction of this ventricle sends blood to the aorta, which is the largest diameter blood vessel in your body. From there, the blood must travel to the entire rest of your body to supply your cells with oxygen!
Considering the function of each portion of the cardiovascular system described above, answer the following questions about the structure of these parts.
Select the statement that is consistent with the depicted structure and function of each part.
Group of answer choices
A. The atria are thinner and less muscular than the ventricles as they do not require as much force to move the blood to the ventricles as the ventricles require to push blood to their respective next locations.
B. The right atrium is much thinner than the left atrium because the left atrium must pump blood to the rest of the body.
C. There is not relevant difference in wall thickness between the atria and ventricles as muscle strength is not related to the ability to forcefully move blood through the body.