Transport In Mammals - Session 2

As we have studied, the pulmonary arteries take the deoxygenated blood from heart to the lungs. The pulmonary veins carry the oxygenated blood from the lungs to the heart.There are typically four pulmonary veins in the human body, two from each lung. These veins are paired, with one from each lung joining together to form a pair.

The left-lung has two pulmonary veins. These are the left superior pulmonary vein and the left inferior pulmonary vein.The right-lung also has two pulmonary veins. These are the right superior pulmonary vein and the right inferior pulmonary vein.

Each pulmonary vein collects oxygenated blood from the small capillaries within the lung tissue. This blood is rich in oxygen because it has recent undergone the process of oxygen exchange in the alveoli. The pulmonary vein collects this oxygenated blood. It then transports it again to the heart.

The aorta and the vena cava are two major blood vessels in the circulatory system. They undertake crucial roles in transporting blood throughout the body. They are part of the body's larger network of blood vessels, arteries, and veins. They serve different functions in the circulation of blood.

The aorta is the largest artery in the human body. It originates from the left-ventricle of the heart. It arches upward, then arches downward as it extends into the abdomen. It then splits into two main branches. These branches are the abdominal aorta and the thoracic aorta. The abdominal aorta supplies blood to the abdominal and pelvic organs. The thoracic aorta supplies blood to the chest and upper body.

The primary function of the aorta is to carry oxygenated blood away from the heart and distribute it to all parts of the body. It acts as a conduit for blood that is rich in oxygen and nutrients. It delivers this oxygenated blood to various organs, tissues, and cells to support their metabolic processes. As the left ventricle contracts, it pumps blood into the aorta. The aorta carries this blood under high pressure to ensure adequate perfusion throughout the body.

There are two major veins in the body known as the superior vena cava and the inferior vena cava. The superior vena cava returns the deoxygenated blood from the upper part of the body to the right-atrium of the heart. The inferior vena cava is another large vein. It returns deoxygenated blood from the lower part of the body to the right-atrium of the heart.

The aorta and the vena cava are integral components of the circulatory system. They work together to ensure that blood circulates efficiently throughout the body. The aorta carries oxygenated blood away from the heart to nourish the body's cells. The vena cava return deoxygenated blood to the heart to be reoxygenated in the lungs.

Pulmonary circulation is the portion of the circulatory system. It is responsible for transporting blood between the heart and the lungs. Its primary function is to facilitate the exchange of gases such as oxygen and carbon dioxide between the blood and the air in the lungs.

First, the deoxygenated blood from the body returns to the right-atrium of the heart via the superior vena cava and the inferior vena cava. After that, the right-atrium contracts, forcing blood into the right-ventricle. From the right-ventricle, the deoxygenated blood is pumped into the pulmonary arteries. The pulmonary arteries then carry the blood to the lungs.

Within the lungs, the pulmonary arteries branch into smaller arterioles and capillaries. In the alveoli, the oxygen diffuses from the inhaled air into the capillaries. The carbon dioxide diffuses from the capillaries into the alveoli. The blood is now oxygenated.

The oxygenated blood, now enriched with oxygen and depleted of carbon dioxide, returns to the heart through the pulmonary veins. The pulmonary veins empty into the left-atrium. The left-atrium contracts, forcing oxygenated blood into the left-ventricle. The left-ventricle then pumps this oxygenated blood into the systemic circulation.

Let us now understand the systemic circulation. The systemic circulation is responsible for delivering oxygenated blood to the body's tissues and organs. It is also responsible for transporting deoxygenated blood again to the heart. First of all, the oxygenated blood from the left ventricle is pumped into the aorta.

The aorta branches into numerous smaller arteries. These arteries carry oxygenated blood to all parts of the body, including organs, muscles, and tissues. Within the tissues, the arteries further branch into tiny capillaries. Here, the oxygen and the nutrients are exchanged for carbon dioxide and waste products.

Now the blood becomes deoxygenated and contains carbon dioxide. It is collected by small venules and then progressively larger veins. The veins ultimately merge into the superior vena cava and the inferior vena cava. The superior vena cava and the inferior vena cava return deoxygenated blood to the right-atrium of the heart. The cycle continues as this deoxygenated blood moves through the pulmonary circulation to be reoxygenated.