The aorta and the pulmonary artery are the two most important arteries in the human body. The aorta is the biggest artery and channels oxygenated blood to the rest of the body. The pulmonary artery carries deoxygenated blood to the lungs for purification.
The aorta supplies oxygenated blood from the heart's pumping chamber to the rest of the body.
Pulmonary artery carries deoxygenated or unaerated blood from the heart to the lungs.Like all arteries, the pulmonary artery carries blood away from the heart. However, the pulmonary artery is the only artery that carries deoxygenated blood from the heart to the lungs.
Structure of the aorta
The aorta is divided into 5 main sections:
- Aortic root - This is the base of the aorta where it connects to the heart's pumping chamber. It gives rise to two coronary arteries which are responsible for carrying oxygenated blood to the heart muscles. The two coronary arteries end at the beginning of ascending aorta.
- Ascending aorta - This section of the aorta begins from the aortic root and ascends upwards to the point where the aorta forms an arch. Due to very little support of the surrounding tissue and handling the complete output volume of the cardiac, it is considered one of the most vulnerable parts of the aorta.
- Aortic arch - This is the curved section of the aorta. Along with brachiocephalic (aka. innominate), left common carotid and left subcalvian arteries it supplies blood to the upper body including the head.
- Descending aorta - Beginning from the arch it descends downwards into the body and ends at diaphragm. It supplies oxygenated blood to the spinal cord.
- Thoracoabdominal aorta - This section begins at the diaphragm and ends at the celiac, superior mesenteric and the visceral vessels.
- Abdominal aorta – This section begins below the renal arteries and ends at the two iliac arteries. It also contains a small artery named the inferior mesenteric artery. This section supplies blood to the kidneys.
Structure of the Pulmonary Artery
The pulmonary artery is divided into 2 main sections:
- Pulmonary trunk: Also known as pulmonary artery or main pulmonary artery, this section originates at the right ventricle and further branches into left and right pulmonary arteries.
- Left and Right Pulmonary arteries: Branching from the pulmonary trunk, the left and right pulmonary arteries supply deoxygenated blood to the left and right lung respectively.
Aortic and pulmonary diseases are often diagnosed with MRA or MRI scans.
Since the aorta is the primary artery which supplies oxygenated blood to the rest of the body, a disease in the aorta can prove fatal. Some of the aortic diseases include:
- Aortic Dissection, where the inner layer of the aortic walls tears causing blood to leak into the wall.
- Aortic Aneurysm, where due to an abnormal bulge in the aortic wall the aorta may rupture causing internal bleeding. The major causes of Aortic Aneurysm known are hypertension, smoking, and family history.
- Atherosclerosis, where the arteries harden due to high blood pressure, and buildup of fat and cholesterol causing reduced blood supply to the rest of the body.
- Aortic inflammation, where the aortic wall weakens due to inflammation.
- Connective tissue disorders, where due to weak aortic walls, a rupture or tear can occur. Usually seen in patients with Marfan Syndrome, Ehler-Danlos syndrome, and other connective tissue disorders, with early detection and proper treatment, patients can continue to enjoy a normal life.
Pulmonary heart diseases can be acute or chronic in nature.
- Pulmonary embolisms, the acute form, is when there is a sudden obstruction to the blood flow causing disruptions to the blood supply to the lungs.
- Pulmonary hypertension (PAH) is considered chronic when high blood pressure causes poor circulation of blood and an increase in arterial pressure which can be damaging to the heart, lungs and as well as liver. Factors that can cause PAH vary from the inflammation of the arteries to the tighteing of the aortic wall, etc. 
Did You Know?
American Heart Association Reports the following findings based on 2005-2006 data analysis:
- In the United States, someone has a heart attack every 40 seconds.
- Nearly 2400 Americans die of Cardio vascular disease each day—an average of 1 death every 37 seconds.
- Each year, about 795 000 people experience a new or recurrent stroke in America.
- Approximately 65% of men and 70% of women had been screened for high cholesterol in the previous 5 years.
- From 1971–1974 to 2003–2006, Overweight (body mass index–for–age values at or above the 95th percentile) percentage in,
- Infants and Toddlers (between the ages of 6 and 23 months), increased from 7.2% to 11.5%.
- Children (6 to11 years of age) increased from 4.0% to 17.0%.
- Adolescents (12 to 19 years of age) increased from 6.1% to 17.6%.
- Over 12% of preschool children 2 to 5 years of age are overweight in 2003–2006.
Video explaining the differences