The diagram provided shows a
simplified view of the different circulatory pathways in the human body. Which color line represents the
hepatic portal circulatory system?
We can distinguish three different
circulatory systems in the human body: the systemic system, the pulmonary system,
and the hepatic portal system.
The word systemic is used to
describe anything relating to the entire body. The black lines on the diagram
provided by the question represent the systemic system, showing the transport of
blood from the heart to the other organs of the body, including the brain, and then
back to the heart.
The word pulmonary is used to
describe anything relating to the lungs. In the pulmonary system, the heart
pumps deoxygenated blood to the lungs where it releases carbon dioxide and takes up
inhaled oxygen. The oxygenated blood is then sent
back to the heart and pumped to the body. As the green lines on the diagram
provided by the question represent the blood flow from the heart to the lungs and
back, this color of line represents the pulmonary system.
The word hepatic is used to
describe anything relating to the liver, and the hepatic portal system forms a
special connection between the digestive system and the liver. Unlike the blood from the other
organs of the body, the blood being transported away from the organs of the
digestive system is especially rich in nutrients like glucose and amino acids that
have been absorbed from the food we eat. Since the liver has so many crucial
functions to perform, it needs a substantial supply of these nutrients, so the
hepatic portal system delivers nutrient-rich blood from the digestive system to the
The hepatic portal system has
another important function of delivering blood containing toxic molecules absorbed
by the digestive organs, like ethanol or certain medications a person might take,
via the bloodstream to the liver where they can be detoxified.
The pink line on the diagram
provided by the question represents blood flowing from the digestive system to the
liver. Therefore, we can deduce that the
pink line represents the hepatic portal system.