Problem 8 - Biology

Question

Pepsin is produced by the (a) liver (b) stomach (c) pancreas (d) duodenum (e) salivary glands

Step-by-Step Solution

Answer

Stomach (b).

Step 1: Understanding the question

We need to identify which organ in the human body produces pepsin, an enzyme that plays a role in digestion.

Step 2: Reviewing enzyme functions

Pepsin is an enzyme that breaks down proteins into smaller peptides. It is active in the digestive tract where it aids in digestion.

Step 3: Recall pepsin's production site

Pepsin is not produced by the liver, pancreas, duodenum, or salivary glands. It is produced by the gastric glands within the stomach lining.

Step 4: Finalizing the answer

Based on the knowledge that pepsin is produced and secreted by the stomach, we determine that the correct answer is (b) stomach.

Key Concepts

Stomach

The stomach is a crucial organ in the digestive system. Located in the upper part of the abdomen, it is responsible for churning and mixing the food we eat. This muscular sac produces gastric juices, which are a mixture of hydrochloric acid and enzymes. These juices play a significant role in breaking down the food into a semi-liquid form called chyme.

• Functions as a storage unit: It holds food while the digestion process begins.
• Muscle contractions: These mix the food with gastric juices thoroughly.
• Protection: The acidic environment kills most of the bacteria present in the food.

Understanding the stomach's environment and its functions helps us appreciate the complexities involved in the digestive processes.

Digestive Enzymes

Digestive enzymes are vital for breaking down the complex molecules found in food into simpler ones. They help convert foods into nutrients that the body can absorb and use. These enzymes work at different locations in the digestive tract, each specific to the type of nutrient they break down. For instance:

• Amylase breaks down carbohydrates.
• Lipase handles fats.
• Proteases like pepsin are responsible for proteins.

These enzymes are produced by various glands and organs, including the salivary glands, stomach, pancreas, and small intestine, providing a comprehensive system for efficient digestion.

Protein Digestion

Protein digestion is a vital process that begins in the stomach. Proteins, which are large and complex molecules, need to be broken down into amino acids before the body can utilize them. The primary enzyme responsible for this initial step in the stomach is pepsin.

• Activated in the stomach: Pepsinogen is converted into pepsin in the acidic environment of the stomach.
• Breaks down proteins into peptides, which are smaller chains of amino acids.
• Continues in the small intestine: Further digestion occurs with other enzymes like trypsin and chymotrypsin.

This multistage breakdown ensures that the body effectively absorbs proteins, which are essential for building and repairing tissues.

Gastric Glands

Gastric glands are embedded within the lining of the stomach and are integral to the digestive process. They play a pivotal role in producing the substances that create the stomach's acidic environment. Each gland is made up of different cell types that secrete distinct components.

• Parietal cells secrete hydrochloric acid (HCl), crucial for creating a low pH.
• Chief cells produce pepsinogen, the inactive form of pepsin.
• Mucous cells release mucus to coat and protect the stomach lining from being digested by its own acid.

The coordinated activity of these cells ensures that the stomach maintains the right balance of acidity and digestive enzymes, fostering an efficient breakdown of food.