Question

Which of these statements about hepatic portal blood is true? a. It contains absorbed fat. b. It contains ingested proteins. c. It is mixed with bile in the liver. d. It is mixed with blood from the hepatic artery in the liver.

Short answer

The correct answer is d. The hepatic portal blood is mixed with blood from the hepatic artery in the liver.

Step-by-step solution

Confirm our understanding of hepatic portal blood

The hepatic portal blood is the blood that flows through the hepatic portal system. The system transports blood from the gastrointestinal tract and spleen to the liver. This blood contains nutrients such as glucose, amino acids, and some vitamins, which have been absorbed from the intestines after the digestion process. However, absorbed fats are not transported through the portal system; they are transported via the lymphatic system. Bile is a substance produced and secreted by the liver, not mixed with the hepatic portal blood.

Evaluate Statement a

"It contains absorbed fat." This statement is not true. Fats absorbed from the intestine enter the lymphatic system rather than the hepatic portal system.

Evaluate Statement b

"It contains ingested proteins." This statement is partially true. The hepatic portal blood contains amino acids, which are the breakdown products of proteins. However, the statement might cause confusion since it wrongly implies proteins directly entering as a whole instead of their breakdown products, amino acids.

Evaluate Statement c

"It is mixed with bile in the liver." This statement is not true. Bile is produced and secreted by the liver, but not mixed with hepatic portal blood. Bile is mixed with the partially digested food in the small intestine to help digest it further.

Evaluate Statement d

"It is mixed with blood from the hepatic artery in the liver." This statement is true. The hepatic portal blood is mixed with oxygenated blood from the hepatic artery in the liver. This mixing allows the liver to process the nutrients and other materials that have been absorbed by the gastrointestinal tract. In conclusion, the correct answer is: d. It is mixed with blood from the hepatic artery in the liver.

Key concepts

Nutrient Absorption

When we eat food, our body breaks it down into essential nutrients that can be used for energy, growth, and repair. One key process in this is nutrient absorption.

• During digestion, carbohydrates break down into simple sugars like glucose.
• Proteins are broken down into amino acids.
• Vitamins and other small molecules are also absorbed.

This absorption primarily occurs in the small intestine. The nutrients are then transferred into the blood vessels of the digestive tract. Interestingly, not all fats follow this exact route. Absorbed fats bypass the hepatic portal system and reach the bloodstream via the lymphatic system. This is why, when thinking about the hepatic portal system, we need to focus on the transportation of water-soluble nutrients such as glucose and amino acids, rather than fats.

Liver Function

The liver is a vital organ with multiple functions essential for life. It acts like a processing plant of our body, taking up raw materials from nutrient-rich blood transported through the hepatic portal system.

Nutrient Storage and Conversion

When nutrients like glucose and amino acids reach the liver, some are stored for later use, while others are converted into different forms required by the body. For instance, excess glucose can be converted to glycogen, which can later be broken down into glucose when energy is needed.

Detoxification

The liver also detoxifies harmful substances that have been ingested. This includes alcohol and certain drugs. It breaks down these compounds into less harmful forms that can be eliminated from the body.

Production of Bile

The liver produces bile, a fluid important for the digestion of fats. Although bile is crucial for nutrient processing, it is not mixed with hepatic portal blood. Instead, it is stored in the gallbladder and later enters the digestive tract when needed.

Blood Circulation

Blood circulation is the body's way of ensuring nutrients, oxygen, and waste products are effectively transported to and from different cells. In the context of the hepatic portal system, we look at a unique path that connects the digestive tract to the liver.

• After nutrient absorption in the intestines, blood rich in nutrients flows through the hepatic portal vein to the liver.
• Here, the blood is mixed with oxygen-rich blood from the hepatic artery. This is an essential aspect of liver function.
• This mixing ensures that the liver cells get enough oxygen to metabolize the nutrients efficiently.

The design of this system is vital. It allows the liver to handle nutrients and detoxify substances before these components enter the general circulation. Essentially, the hepatic portal system acts as a refining station, making sure that all the materials entering our bloodstream are in their most useful form.