What is the main difference between pulmonary and systemic circulation?

Pulmonary circulation moves deoxygenated blood from the heart to the lungs for gas exchange, while systemic circulation delivers oxygenated blood from the heart to the rest of the body and returns deoxygenated blood back.

Why does blood appear red or blue in diagrams?

Blood is typically shown as red when oxygen-rich (e.g., in systemic arteries and pulmonary veins) and blue when oxygen-poor (e.g., in systemic veins and pulmonary arteries) to visually distinguish its oxygenation state.

What is portal circulation, and what are its key examples?

Portal circulation involves blood flowing through two consecutive capillary beds before entering systemic circulation. Key examples include hepatic portal circulation for nutrient processing in the liver, hypothalamo-hypophyseal portal circulation for hormone transport in the brain, and renal portal circulation for reabsorption in the kidneys.

How does blood return to the heart in systemic circulation?

Deoxygenated blood from the body's tissues returns through progressively larger veins, eventually draining into the superior and inferior venae cavae, which empty into the right atrium of the heart.

What role do capillaries play in circulation?

Capillaries are the site of exchange for oxygen, nutrients, and waste between blood and tissues. They connect arteries and veins in both pulmonary and systemic circuits.

What is the purpose of hepatic portal circulation?

Hepatic portal circulation allows venous blood from the gastrointestinal tract, spleen, and pancreas to pass through the liver via the portal vein, enabling the liver to process absorbed nutrients before they enter systemic circulation.

Blood Circulation – Pulmonary, Systemic & Portal