Question

A pulmonary ______ carries oxygen-poor blood. a. artery b. vein

Short answer

a. artery

Step-by-step solution

Key Concepts Overview

Understand the difference between arteries and veins. Typically, arteries carry oxygen-rich blood from the heart to the body, and veins carry oxygen-poor blood back to the heart. However, the pulmonary circulation is an exception to this general rule.

Pulmonary Artery Function

The pulmonary arteries are responsible for carrying oxygen-poor blood from the right ventricle of the heart to the lungs. In the lungs, the blood gets oxygenated.

Pulmonary Vein Function

The pulmonary veins carry oxygen-rich blood from the lungs back to the left atrium of the heart. This completes the exception to the typical artery-vein oxygen carry rules.

Making the Choice

Based on the functions explained, the correct choice is the one that aligns with the pulmonary arteries, which carry oxygen-poor blood.

Key concepts

Arteries and Veins

Arteries and veins are crucial components of the cardiovascular system, each with distinct roles. Under typical circumstances, arteries transport oxygen-rich blood from the heart to various parts of the body. Once cells utilize the oxygen, veins return the oxygen-poor blood back to the heart. However, this general pattern sees a fascinating deviation in the pulmonary circulation.
In pulmonary circulation, the roles are effectively swapped. Pulmonary arteries carry oxygen-poor blood, while pulmonary veins return oxygen-rich blood to the heart. This unique system allows the exchange of gases in the lungs, ensuring the body always has fresh oxygen while efficiently removing carbon dioxide.

Oxygen Transport

Oxygen transport is the fundamental process delivering oxygen to tissues across the body while removing carbon dioxide. Hemoglobin, a protein in red blood cells, plays a critical role by binding with oxygen in the lungs. This oxygen-rich blood is then pumped through the systemic arteries to organs and tissues.
Once the oxygen is delivered, and carbon dioxide is picked up as a waste product from cellular respiration, the blood becomes oxygen-poor and is carried back to the heart through systemic veins.

• Hemoglobin binds with oxygen to transport it.
• Oxygen-rich blood flows to body tissues.
• Oxygen-poor blood returns to the heart.

In the unique pulmonary circulation, blood travels to the lungs to drop off carbon dioxide and pick up oxygen, getting ready for another trip through the body.

Pulmonary Artery Function

The pulmonary artery is quite unique compared to other arteries in the body. While most arteries carry oxygenated blood, the pulmonary artery is tasked with transporting oxygen-poor blood from the right ventricle of the heart to the lungs.
In the lungs, a critical exchange occurs. Here, blood releases carbon dioxide—a waste product of metabolism—and takes in fresh oxygen. This newly oxygenated blood is crucial for sustaining life and is prepared to nourish body tissues. The pulmonary artery becomes essential during this process as it initiates the blood's journey to refresh its oxygen content.

• Transports oxygen-poor blood from the heart to the lungs.
• Carbon dioxide is released, and oxygen is absorbed in the lungs.

Without this function, the body would quickly deplete its oxygen reserves, making it a vital part of human physiology.

Pulmonary Vein Function

Role reversal continues with the pulmonary vein, a vessel that carries oxygen-rich blood, unlike typical veins. After oxygenation in the lungs, the blood must be transported back to the heart to be pumped into systemic circulation.
The pulmonary veins complete this task by carrying freshly oxygenated blood to the left atrium of the heart. This oxygen-rich blood is then pumped through the left ventricle and out through the aorta to supply the body with essential oxygen. The function of the pulmonary veins ensures that body tissues get the oxygen necessary for all vital functions.

• Transports oxygen-rich blood back to the heart.
• Delivers it to the left atrium for distribution throughout the body.

In this way, the pulmonary veins play an indispensable role in maintaining the oxygen levels required for various cellular activities.