What Are the Functions of the Aorta and Pulmonary Artery?
The human heart is a muscular organ which consists of four chambers and is responsible for the pumping of blood across the whole body. The heart possesses a network of blood vessels like arteries, veins and capillaries. Two of the five blood vessels that enter or leave the heart directly are the aorta and the pulmonary artery. Aorta is the largest artery, which carries oxygenated blood from the left ventricle of the heart to other parts of the body. In contrast, the pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs with the aim of purification.
Walls of the Heart
The walls of the human heart have an important function, which is to pump blood by relaxing and contracting these walls.
The wall dividing the left and right parts of the heart is known as the septum.
The walls of the heart have three layers, namely:
Endocardium: It is the inner layer of the heart wall.
Myocardium: The middle layer of the heart wall. It is muscular.
Epicardium: The outermost protective layer of the heart wall.
Fun Fact: The endocardium is made up of one layer of the pericardium. The pericardium is the protective sac that covers the entire human heart, filled with the protective fluid for lubrication.
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Aorta
The biggest artery present in the human body is the aorta, which carries oxygenated blood from the heart to other parts of the body. High blood pressure is present within the aorta due to the transportation of oxygenated blood across the body, and thus the aorta is composed of thick walls.
The aorta is elastic and located at the top of the heart. An aortic valve is present at the entrance of the aorta from the left ventricle. The aorta is responsible for the systemic circulation of blood throughout the body.
The aorta is further composed of several arteries like the ascending and descending aorta, the aortic arch, the thoracic and the abdominal aorta. Baroreceptors and chemoreceptors are present at the aortic arch to monitor the blood pressure.
Some of the common diseases related to the aortic artery are aortic dissection, aortic aneurysm, atherosclerosis, aortic inflammation and connective tissue disorders.
Pulmonary Artery
The function of the pulmonary artery is to carry deoxygenated blood from the right ventricle of the heart to the lungs for purification. A pulmonary valve is present at the beginning of the pulmonary artery.
The pulmonary artery is located just below the aorta. It further divides into the right pulmonary artery and the left pulmonary artery, which also divide into smaller arteries, arterioles and capillaries. All of these, together with the pulmonary trunk and pulmonary aorta, form the pulmonary circulation.
Some of the frequent diseases related to the pulmonary artery include pulmonary embolisms and pulmonary hypertension.
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Aorta and pulmonary are two arteries present in the heart but have some critical differences among them. The following are some of the differences between the aorta and pulmonary artery:
Difference Between Aorta and Pulmonary Artery
Both the aorta and the pulmonary artery are important arteries of the body and are essential for the circulation of blood throughout the body. The primary difference between the aorta and pulmonary artery is that aorta carries oxygenated blood from the heart to other parts of the body while the pulmonary artery carries deoxygenated blood from the heart to the lungs to purify it.
The aorta originates from the left ventricle of the heart and branches into five other arteries. In contrast, the pulmonary artery arises from the right ventricle and branches into the left and right pulmonary arteries. The aorta has a thick wall around it as the blood pressure is high inside while the blood pressure in the pulmonary artery is lower. The aorta and pulmonary artery are located close to each other. The aorta is located at the top of the heart, while the pulmonary artery is located beneath it.
Functions of the Human Heart
There are four main functions of the human heart, and they are as follows:
The primary function of the human heart is to pump the oxygenated blood to all the parts of the body.
The human heart is also involved in pumping important nutrients and other substances to various parts of the human body.
Human hearts receive deoxygenated blood from all the parts of the body and are responsible for pumping the impure blood to the lungs for purification.
The human heart maintains blood pressure.
The human heart works with the other organs for the following:
Nervous System: The human heart coordinates with the nervous system to control the heart rate. The nervous system sends the signal to heat to beat accordingly, faster during any physical activity and slower during the rest.
Endocrine System: The hormones by the endocrine system tell the heart to contract and relax during the passage of blood, which in turn affects the blood pressure. The thyroid gland is also involved in signalling the heart to beat slower and faster.
Human Heart’s Electrical Conduction System
Just like the electrical wiring in the building, the human heart also comprises the electrical conduction system that helps in the rhythm and pace of the heart.
The Sinoatrial Node(SV): The sinoatrial node sends the signals that make the human heartbeat.
Atrioventricular Node (AV): This node carries the electrical signals from the upper chambers of the heart to its lower chambers.
The heart also consists of a bundle of electrical bundles and fibres. This electrical bundle includes the following:
Left Bundle Branch: This bundle sends the electric impulses to the left ventricle of the heart.
Right Bundle Branch: This bundle sends the electric impulses to the right ventricle of the human heart.
Purkinje Fibres: These fibres help in making the ventricles of the heart contract and pump the blood out.
Bundle of his: This particular bundle sends out the impulses from the AV node to the Purkinje fibres.
Commonly Known Heart Disorders
Heart conditions are a common kind of disease affecting the majority of people today. Here are the following:
Cardiomyopathy: The condition in which there is an unusual thickening and stiffening of the heart muscle is defined as cardiomyopathy.
Coronary Artery Disease: The condition in which the building up of plaque results in narrow coronary arteries is known as coronary artery disease.
Heart Attack: This condition is a common disease in India today. In this condition, there is a sudden blockage in the coronary artery that cuts off the oxygen supply to the heart muscle.
Pericarditis: The condition in which there is an inflammation in the heart lining is called pericarditis.
Arrhythmia: The condition in which the heartbeat is too fast or too low or has irregular beating is called arrhythmia.
Atrial Fibrillation: The condition in which there is the signalling of irregular electric impulses in the atrium is known as atrial fibrillation.
Did You Know?
Usually, arteries carry oxygenated blood to various parts of the body. However, the pulmonary artery is the only artery which carries deoxygenated blood. This is the major difference between arteries and pulmonary arteries.
FAQs on Difference Between Aorta and Pulmonary Artery
1. What is the main difference between the aorta and the pulmonary artery?
The main difference lies in the type of blood they carry and their destination. The aorta, the largest artery in the body, carries oxygenated blood from the left ventricle to the entire body (systemic circulation). In contrast, the pulmonary artery carries deoxygenated blood from the right ventricle to the lungs for oxygenation (pulmonary circulation).
2. Which is structurally thicker and larger, the aorta or the pulmonary artery, and why?
The aorta is structurally thicker and has a larger diameter than the pulmonary artery. This is because the aorta must withstand extremely high pressure as it pumps oxygenated blood from the left ventricle to every part of the body. The pulmonary artery faces much lower pressure as it only needs to pump deoxygenated blood a short distance to the lungs.
3. Why does the pulmonary artery carry deoxygenated blood, unlike other arteries?
This is a key exception in the circulatory system. Arteries are defined by the direction of blood flow—away from the heart—not by the oxygen content of the blood they carry. The pulmonary artery follows this rule by carrying blood away from the heart's right ventricle. Its specific function is to transport this used, deoxygenated blood to the lungs, which is the only place it can be replenished with oxygen.
4. How does the origin of the aorta and pulmonary artery affect blood pressure within them?
The origin point directly determines the pressure. The aorta arises from the powerful left ventricle, which must contract forcefully to push blood throughout the entire body, resulting in high systolic blood pressure (around 120 mm Hg). The pulmonary artery arises from the right ventricle, which has a thinner muscular wall because it only needs to pump blood to the nearby lungs. This results in a much lower pressure system (around 25 mm Hg).
5. What are the primary functions of the aorta and pulmonary artery in circulation?
Their primary functions are distinct and complementary:
Aorta's Function: To distribute oxygen-rich blood and nutrients to all body tissues and organs, supporting cellular respiration and function. This is the starting point of systemic circulation.
Pulmonary Artery's Function: To transport oxygen-poor blood, which is high in carbon dioxide, from the heart to the lungs. This is the crucial first step of pulmonary circulation, where gas exchange occurs.
6. Besides their differences, what are the key similarities between the aorta and pulmonary artery?
Despite their different roles, they share several key features as major arteries:
Both originate directly from the ventricles of the heart.
Both carry blood away from the heart.
Both are vital for the continuous flow of blood in the double circulatory system.
Both are equipped with semilunar valves (aortic and pulmonary valves) at their base to prevent the backflow of blood into the ventricles.
7. What is the clinical significance of the difference between the aorta and pulmonary artery?
Understanding the difference is critical for diagnosing and treating congenital heart defects. For instance, in a condition called Transposition of the Great Arteries (TGA), the aorta and pulmonary artery are swapped. This means deoxygenated blood from the body returns to the heart and is pumped back to the body via the aorta, while oxygenated blood from the lungs returns to the heart and is sent back to the lungs. This condition is life-threatening and requires immediate surgical intervention to correct the circulatory pathways.
