Problem 103 - Objective Biology for NEET

Question

Which of the following is correct about human heart? (a) The volume of both atria \(>\) the volume of both ventricles (b) The volume of both ventricle \(>\) the volume of both atria (c) The volume of both atria \(=\) the volume of both ventricles (d) Ventricles are upper chambers and atria are lower chambers in our heart.

Step-by-Step Solution

Answer

(b) The volume of both ventricle \(>\) the volume of both atria

Step 1: Understand the structure of heart

The human heart is comprised of four chambers: two upper ones called atria and two lower ones called ventricles. The primary role of atria is to receive blood returning to the heart, while the ventricles pump blood out from the heart.

Step 2: Evaluate the options

Now, one-by-one evaluate the options. For option (a) and (b), it is known that the ventricles are larger in size than atria because they need more muscle power to pump blood out from the heart, hence option (b) seems plausible. Option (c) is also incorrect as the ventricles have to pump blood to the whole body while atria just receive blood, they can't be equal in size. Regarding option (d), it is incorrect based on the position of atria and ventricles. Atria are the upper chambers while ventricles are the lower chambers of the heart.

Key Concepts

Atria and Ventricles

The human heart is a complex organ made up of four main chambers, divided into two types: atria and ventricles.

• Atria: These are the two upper chambers of the heart. The right and left atrium act as receiving chambers for blood coming into the heart. They are smaller and have thinner walls compared to ventricles. Atria don’t need to pump blood far—just from the atria to the ventricles—hence they require less muscle.


• Ventricles: These are the two lower chambers of the heart, known as the powerhouse of the heart. The function of these chambers is primarily to pump blood out of the heart. The right ventricle sends blood to the lungs for oxygenation, while the left ventricle pumps oxygenated blood to the entire body. This exhaustive task requires more muscle power, making ventricles larger and stronger than atria.

Understanding this fundamental difference helps explain why the volumes of the ventricles are greater than those of the atria.

Heart Chambers

The human heart is structured into four chambers: two atria and two ventricles. This structured division plays a pivotal role in how blood flows through the heart.

• Right Atrium: This chamber collects deoxygenated blood from the body through veins known as the superior and inferior vena cava.


• Left Atrium: It receives oxygen-rich blood from the lungs through the pulmonary veins.


• Right Ventricle: This chamber takes deoxygenated blood from the right atrium and pumps it to the lungs for oxygenation through the pulmonary arteries.


• Left Ventricle: The strongest chamber, it receives oxygenated blood from the left atrium and pumps it to the rest of the body through the aorta.

Understanding the function of each chamber is crucial to comprehending how the heart operates efficiently to sustain life.

Blood Circulation in Heart

Blood circulation within the heart is a vital process essential for maintaining the body’s functions. The heart facilitates the circulation of blood in two main loops—pulmonary and systemic circulation.

• Pulmonary Circulation: This part of circulation involves the movement of blood from the heart to the lungs and back. Deoxygenated blood from the right atrium moves into the right ventricle and is then pumped to the lungs through the pulmonary artery. Here, carbon dioxide is exchanged for oxygen before the blood returns to the left atrium of the heart via the pulmonary veins.


• Systemic Circulation: Following pulmonary circulation, oxygen-rich blood is pumped from the left atrium into the left ventricle and then distributed throughout the body through the aorta. The body’s tissues absorb oxygen and nutrients from the blood and, in return, release waste products and carbon dioxide into the blood. This now deoxygenated blood returns to the right atrium via veins, completing the cycle.

This circular flow ensures that each cell in the body receives the oxygen and nutrients it needs, making the heart the key driver of life-sustaining blood circulation.