Question

The first organ to receive the blood-borne products of digestion is a. the liver. b. the pancreas. c. the heart. d. the brain.

Short answer

The first organ to receive the blood-borne products of digestion is the liver, as it is directly connected to the gastrointestinal tract through the hepatic portal system.

Step-by-step solution

Recall the process of digestion

During digestion, the food we eat is broken down into smaller molecules such as glucose and amino acids. The digestive system, which includes the mouth, esophagus, stomach, and intestines, is responsible for processing the food into these smaller molecules.

Understand the role of the circulatory system in transporting the products of digestion

The circulatory system, which includes the heart, arteries, veins, and capillaries, is responsible for transporting the products of digestion (nutrients) from the digestive system to other parts of the body.

Review the portal system

The portal system is a specialized part of the circulatory system that directly transports blood from one organ to another, without passing through the heart. One of the most crucial portal systems in the body is the hepatic portal system, which transports blood from the gastrointestinal tract to the liver.

Identify the first organ to receive the products of digestion

Since the hepatic portal system transports blood (and the products of digestion) from the gastrointestinal tract directly to the liver, the liver is the first organ to receive the blood-borne products of digestion. Therefore, the correct answer is: a. the liver.

Key concepts

Circulatory System

The circulatory system plays a key role in distributing nutrients and oxygen to various parts of the body. It is made up of the heart, blood vessels like arteries and veins, and capillaries.
The heart acts as a powerful pump that ensures blood moves through the system effectively. When blood circulates, it carries essential nutrients and oxygen to cells and takes away waste products.

• Arteries carry oxygen-rich blood from the heart to tissues.
• Veins transport blood back to the heart.
• Capillaries are tiny blood vessels where the exchange of gases, nutrients, and waste occurs.

By understanding this system, we can grasp how nutrients from our food, once absorbed through the intestines, are distributed effectively across the body after being processed by the liver.

Hepatic Portal System

The hepatic portal system is a fascinating component of our circulatory pathway. Unlike typical circular routes, this system forms a direct line from the gastrointestinal tract to the liver.
After digestion, the nutrients absorbed in the intestines enter the bloodstream via this system. The blood loaded with nutrients goes straight to the liver before distributing elsewhere in the body.

• Direct Route: Blood travels from the intestines to the liver.
• Function: This ensures the liver processes and detoxifies nutrients before they reach other organs.
• Importance: Protects the body by filtering toxins and storing substances like glucose as glycogen.

This system ensures that the liver is the first stop for nutrients, reflecting its role in metabolism and detoxification.

Digestion Process

The digestion process is how our bodies break down food into nutrients. It begins in the mouth and travels through a series of organs before nutrients enter the bloodstream.
Here's a simple breakdown of the process:

• Mouth: Enzymes in saliva start breaking down carbohydrates.
• Stomach: Gastric juices turn food into a semi-liquid form called chyme, digesting proteins further.
• Intestines: In the small intestine, enzymes from the pancreas and bile from the liver fully digest fats and remaining carbohydrates. Nutrient absorption occurs here.

Once digestion in the intestines is complete, nutrients are absorbed into the bloodstream, transported directly to the liver through the hepatic portal system, then distributed throughout the body. It's a seamless and efficient process that nourishes every cell.