Question

Unlike capillaries in the systemic circuit, in the pulmonary circuit, ___________ blood enters the capillaries from the arterioles and __________ blood leaves the capillaries for the venules. a. oxygenated ... oxygenated b. oxygenated ... deoxygenated c. deoxygenated ... oxygenated d. deoxygenated ... deoxygenated a. oxygenated ... oxygenated b. oxygenated ... deoxygenated c. deoxygenated ... oxygenated d. deoxygenated ... deoxygenated

Short answer

c. deoxygenated ... oxygenated

Step-by-step solution

Understand the pulmonary circuit

The pulmonary circuit is the part of the cardiovascular system that carries blood from the heart to the lungs and back. Its primary purpose is to exchange carbon dioxide in the blood for oxygen in the lungs.

Identify blood content entering the capillaries from arterioles

In the pulmonary circuit, blood enters the capillaries from the arterioles. This blood is deoxygenated because it has delivered oxygen to tissues and picked up carbon dioxide as a waste product in the systemic circuit.

Identify blood content leaving the capillaries for venules

After the exchange of gases in the lungs, the blood becomes oxygenated in the capillaries. Therefore, oxygenated blood leaves the capillaries to enter the venules, which then returns to the heart.

Choose the correct answer

Based on the understanding of the pulmonary circuit, the correct answer is that deoxygenated blood enters the capillaries from the arterioles and oxygenated blood leaves the capillaries for the venules. This corresponds to option c.

Key concepts

Cardiovascular System

The cardiovascular system is an essential system in the human body. It includes the heart, blood, and blood vessels. Its main function is to transport blood throughout the body. There are two main circuits:

• The systemic circuit, which carries oxygenated blood from the heart to the rest of the body.
• The pulmonary circuit, which carries deoxygenated blood from the heart to the lungs and brings oxygenated blood back to the heart.

Both circuits are crucial for sustaining life. They deliver oxygen and nutrients to cells and remove waste products like carbon dioxide.

Gas Exchange

Gas exchange is a fundamental process in the respiratory system. It occurs in the lungs, within tiny air sacs called alveoli. Here, oxygen from inhaled air passes into the blood, while carbon dioxide from the blood is expelled in exhaled air. This exchange happens through diffusion, where gases move from an area of higher concentration to one of lower concentration.

In the pulmonary circuit:

• Deoxygenated blood carries high levels of carbon dioxide to the lungs.
• At the alveoli, carbon dioxide is released from the blood, and oxygen is absorbed.
• This process converts deoxygenated blood into oxygenated blood, ready to supply the body with much-needed oxygen.

Without efficient gas exchange, cells would not receive adequate oxygen, impacting overall bodily functions.

Oxygenated Blood

Oxygenated blood is blood that has been enriched with oxygen. This occurs in the lungs, specifically in the alveoli, where oxygen from the inhaled air binds to hemoglobin in the red blood cells. This oxygen-rich blood is then transported back to the heart and pumped throughout the body via the systemic circuit. Key points about oxygenated blood include:

• It appears bright red due to the high oxygen content.
• It leaves the lungs and returns to the left side of the heart.
• Once in the systemic circuit, it delivers oxygen to tissues and organs, ensuring they function efficiently.

Oxygenated blood is crucial for cellular respiration, the process by which cells produce energy.

Deoxygenated Blood

Deoxygenated blood is blood that has delivered oxygen to tissues and taken up carbon dioxide, a waste product of cellular metabolism. This blood returns to the heart and is then pumped to the lungs for reoxygenation via the pulmonary circuit. Important aspects of deoxygenated blood include:

• It contains high levels of carbon dioxide and low levels of oxygen.
• It appears darker, almost bluish, because of the lack of oxygen.
• In the pulmonary circuit, it travels from the heart to the lungs through the pulmonary arteries.

Efficient removal of carbon dioxide and replenishment with oxygen is vital for maintaining healthy, functioning cells and overall homeostasis in the body.