What is the Difference Between Aorta and Pulmonary Artery

The main difference between aorta and pulmonary artery is that the aorta carries oxygenated blood from the heart to the other parts of the body, whereas the pulmonary artery carries deoxygenated blood from the heart to the lungs.

Aorta and pulmonary artery are two arteries that carry blood from the heart. They have thick walls as they have a thick layer of muscle tissue inside.

Key Areas Covered

1. What is Aorta
– Definition, Facts, Features
2. What is Pulmonary Artery
– Definition, Facts, Features
3. Similarities Between Aorta and Pulmonary Artery
– Outline of Common Features
4. Difference Between Aorta and Pulmonary Artery
– Comparison of Key Differences
5. FAQ – Aorta and Pulmonary Artery
– Answers to frequently asked questions

Key Terms 

Aorta, Pulmonary Artery, Pulmonary Trunk, Left Pulmonary Artery, Right Pulmonary Artery

What is Aorta

The aorta is the main artery of the body, which begins at the left ventricle of the heart. The aortic valve, which composes three leaflets, separates the aorta from the heart. Further, it opens in each heartbeat, allowing a one-way flow of blood from the heart to the aorta. The aorta is about one inch in diameter. The high blood pressure in the aorta facilitates the flow of blood throughout the body. The normal systolic pressure (the amount of blood pressure during the contraction of the heart) is 120 mmHg, and the normal diastolic pressure (the amount of blood pressure when the heart is at rest) is 80 mmHg.

Figure 1: Aorta

Furthermore, the four sections of the aorta are the ascending aorta, aortic arch, descending thoracic aorta, and abdominal aorta.

• Ascending aorta – It is about 2 inches long. The coronary arteries branch off from the ascending aorta.
• Aortic arch – This covers the heart and gives rise to the artery branches that supply blood to the head, neck, and arms.
• Descending thoracic aorta – It travels down through the chest and gives rise to the arteries that supply blood to the ribs and the chest.
• Abdominal aorta – It begins at the diaphragm. The branches of the abdominal aorta supply blood to the rest of the organs in the body. In the end, it divides into a pair of iliac arteries

What is Pulmonary Artery

The pulmonary artery is the artery that carries deoxygenated blood from the right ventricle of the heart to the lungs. It originates from the heart as the main pulmonary artery, which is also called the pulmonary trunk. The main pulmonary artery divides into two at the level of the fifth thoracic vertebra. They are the left pulmonary artery (LPA) and the right pulmonary artery (RPA). The left pulmonary artery carries blood to the left lung, while the right pulmonary artery carries blood to the right lung. Here, the right pulmonary artery is the longest, and it travels through the mediastinum and enters the hilus of the right lung by sloping inferiorly. Both pulmonary arteries then divide into the segmental and subsegmental pulmonary arteries, which travel parallel to the segmental and the subsegmental bronchi of the lungs, respectively.

Figure 2: Pulmonary Artery

Moreover, pulmonary arteries and pulmonary veins make up the pulmonary circulatory system, which is one of the circulatory systems of animals with double circulation. The pulmonary circulatory system interconnects the heart to the lungs. The deoxygenated blood from the right atrium travels to the lungs through the pulmonary arteries for oxygenation, and the oxygenated blood from the lungs returns to the left atrium of the heart through four pulmonary veins. 

Similarities Between Aorta and Pulmonary Artery

• Aorta and pulmonary artery are two artery types that carry blood away from the heart.
• They have thick walls and thick muscle tissue.

Difference Between Aorta and Pulmonary Artery

Definition

The aorta refers to the main artery of the body, supplying oxygenated blood to the circulatory system. In contrast, the pulmonary artery refers to the blood vessels that carry oxygen-poor blood from the right side of your heart to your lungs.

Number

A human body contains one aorta but two pulmonary arteries.

Arises from

Moreover, the aorta arises from the left ventricles of the heart, while the pulmonary artery arises from the right ventricle.

Type of Blood

The aorta carries oxygenated blood to the organs of the body, while the pulmonary artery carries deoxygenated blood from the heart to the lungs.

Function

Besides, the aorta supplies blood to the organs while the pulmonary artery purifies deoxygenated blood.

Valves

The aorta does not contain valves, while the pulmonary artery contains valves.

FAQ: Aorta and Pulmonary Artery

What is the difference between aorta and artery?

The aorta is the largest artery of the body. It carries blood from the heart to the organs of the body. In fact, arteries are branches of the aorta. They again branch into arterioles. The size of the arteries and arterioles can change depending on the pressure.

Why is the aorta thicker than the pulmonary artery?

The wall of the aorta is thicker since it has to bear high blood pressure. However, the blood pressure of the pulmonary artery is less than that of the aorta. Therefore, the wall of the pulmonary artery is less thick than that of the aorta.

What is the relationship between the aorta and the pulmonary artery?

The right pulmonary artery courses posterior to the ascending aorta and anterior to the descending aorta. It lies anterior to the right mainstem bronchus. The left pulmonary artery passes anterior to the descending aorta and lies superior to the left mainstem bronchus.

Conclusion

In brief, the aorta and pulmonary artery are two artery types that carry blood away from the heart. The aorta arises from the left ventricle and carries oxygenated blood away from the heart. It supplies blood to the organs of the body. However, it does not contain valves. Meanwhile, the pulmonary artery arises from the right ventricle of the heart. Two pulmonary arteries carry deoxygenated blood to the lungs to purify it. Importantly, pulmonary arteries are blood vessels that carry oxygen-poor blood from the right side of your heart to your lungs. Moreover, the pulmonary artery contains valves. So, in conclusion, the main difference between aorta and pulmonary artery is the type of blood they carry.       

References:

1. The aorta. TeachMeAnatomy. (n.d.). 
2. Tucker WD, Weber C, Burns B. Anatomy, Thorax, Heart Pulmonary Arteries. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.

Image Courtesy:

1. “Aorta branches” By Mikael Häggström – Own Work (CC BY-SA 3.0) via Commons Wikimedia
2. “Diagram of the human heart (cropped)” By Wapcaplet – Own Work (CC BY-SA 3.0) via Commons Wikimedia