Problem 10 - Biology E/M

Question

Match the description to the parts of the human digestive system below. (A) Small intestine (B) Stomach (C) Esophagus (D) Colon (E) Mouth Contains villi

Step-by-Step Solution

Answer

The small intestine contains villi.

Step 1: Identify the function of each part

First, let's identify the function of each part of the digestive system mentioned: - **Mouth**: Entry point for food, starts digestion with chewing and saliva. - **Esophagus**: A muscular tube that connects the mouth to the stomach. - **Stomach**: Mixes food with digestive juices and churns it into a liquid. - **Small intestine**: Main site for digestion and absorption of nutrients; contains villi. - **Colon (Large Intestine)**: Absorbs water and forms feces.

Step 2: Focus on the key term

The keyword in the question is "villi." Villi are tiny, finger-like projections that line the wall of the small intestine, increasing its surface area to allow for a larger area for nutrient absorption.

Step 3: Match the description to the part

Since the villi are associated with nutrient absorption and are present in the small intestine, we can match the description "Contains villi" to the small intestine (A).

Key Concepts

Small Intestine

The small intestine is a vital component of the human digestive system, acting as the main site for digestion and absorption of nutrients. It is a long, coiled tube that connects the stomach to the large intestine. Despite its name, the small intestine is quite extensive and can measure up to 20 feet in length in an adult. It is divided into three parts:

• Duodenum – receives partially digested food from the stomach.
• Jejunum – where most nutrient absorption occurs.
• Ileum – absorbs remaining nutrients and moves residues to the large intestine.

The small intestine is essential for breaking down food into nutrients, which are then absorbed into the bloodstream. Without it, our bodies wouldn't receive the energy and nutrients needed for survival.

Villi

Villi are tiny, finger-like projections that line the inside of the small intestine. They play a crucial role in nutrient absorption by increasing the surface area available to absorb nutrients from the digested food passing through the intestine. Each villus contains:

• Capillaries – to carry away absorbed nutrients into the bloodstream.
• Lacteals – small lymphatic vessels that absorb fats.

The presence of villi is significant because without them, the efficiency of nutrient absorption would decrease dramatically. They work by creating a brush-border effect, which allows for a much larger surface area than if the small intestine were a flat tube. This enhancement is crucial for enabling our bodies to absorb essential nutrients efficiently and effectively.

Nutrient Absorption

Nutrient absorption is a critical process in the digestive system where digested food particles are transferred from the gut into the body's circulation system. This occurs primarily in the small intestine, particularly due to the role of villi. During digestion:

• Enzymes break down food into tiny components – amino acids, fatty acids, vitamins, and minerals.
• Villi and microvilli absorb these digested nutrients efficiently.

These nutrients are then distributed throughout the body through the bloodstream, supplying cells with the energy and materials they need to perform various functions. Proper nutrient absorption is vital for maintaining health because it ensures that all body tissues receive adequate nutrients to function properly.

Digestive System Function

The human digestive system is a complex network designed to convert the food we eat into energy and nutrients. This system involves multiple organs working in concert, beginning with the mouth and ending with the anus. Its primary functions are:

• Ingestion – taking in food.
• Digestion – breaking down food into useable nutrients with acids and enzymes.
• Absorption – transferring nutrients into the bloodstream through the small intestine.
• Elimination – removing indigestible remains as waste.

Each part of the digestive system has a specialized role, ensuring that the entire process runs smoothly and efficiently. It's what allows us to utilize food to maintain bodily functions and support growth and repair processes.