Problem 105 - Objective Biology for NEET

Question

Enterokinase is secreted by (a) Mouth (b) Stomach (c) Small intestine (d) Large intestine

Step-by-Step Solution

Answer

The enzyme Enterokinase is secreted by the small intestine.

Step 1: Identification of the Enzyme

Firstly, identify that the enzyme in question is Enterokinase. Enterokinase is an enzyme that aids in digestion. It activates trypsinogen into trypsin, starting the process of protein digestion in the pancreas.

Step 2: Understand the Role of Enterokinase

Once the identity and function of Enterokinase are established, its role in the digestive system needs to be understood. Enterokinase is part of the process of digestion, and specifically, it is involved in the digestion of proteins.

Step 3: Identify the Organ that Secretes Enterokinase

Enterokinase is secreted in the small intestine. The small intestine releases this enzyme to assist in the breakdown and absorption of ingested proteins.

Key Concepts

Digestive Enzymes

Digestive enzymes play a crucial role in breaking down the food we eat into nutrients that our bodies can absorb and use. These enzymes are biological catalysts that speed up chemical reactions in digestion, making the process efficient and effective.

Each enzyme targets a specific type of substance: amylases break down carbohydrates, lipases break down fats, and proteases break down proteins. They are secreted by various organs of the digestive system, including the salivary glands, stomach, pancreas, and the small intestine, each adding to the digestive cocktail as food makes its way through the gastrointestinal tract.

Types and Functions of Digestive Enzymes

• Amylase: Begins carbohydrate digestion in the mouth.
• Pepsin: Starts protein digestion in the stomach.
• Lipase: Works with bile to break down fats in the small intestine.
• Enterokinase: Converts trypsinogen to trypsin for protein digestion in the small intestine.

Understanding the specificity and locale of action of these enzymes is paramount to grasping how the digestive system functions as a whole.

Protein Digestion

Protein digestion is a complex process that begins in the stomach and continues in the small intestine. Proteins, which are made up of long chains of amino acids, must be broken down into their individual amino acids or small peptides before they can be absorbed by the body.

This process starts when enzymes like pepsin in the stomach cleave the protein molecules. It progresses as the partially digested proteins enter the small intestine, where enzymes like trypsin and chymotrypsin, which have been activated from their inactive forms by enterokinase, take over.

Steps in Protein Digestion

• Denaturation: Stomach acid unfolds proteins to make them accessible to enzymes.
• Hydrolysis: Enzymatic reactions break peptide bonds between amino acids.
• Absorption: Amino acids and peptides are absorbed through the intestinal walls.

Understanding each step is essential for the study of nutrition and the diagnosis of digestive ailments.

Small Intestine Physiology

The small intestine is a sophisticated organ where the bulk of digestion and absorption takes place. It is structured with folds, villi, and microvilli, vastly increasing the surface area to optimize absorption of nutrients.

The small intestine's physiology is intricately linked to its function. It provides an environment for enzymes to act and for the majority of nutrient uptake to occur. The pH level and composition of the digestive juices, including bile and enzymes, are carefully regulated to maximize digestive efficacy.

Key Features of Small Intestine Physiology

• Length and Surface Area: Approximately 20 feet long with a high surface area.
• Segmentation and Peristalsis: Muscular contractions mix food and move it along.
• Secretions: Produces enzymes and utilizes pancreatic and biliary secretions.
• Absorption: Nutrients pass through to the bloodstream via a vast network of capillaries.

The well-coordinated physiology of the small intestine is vital for converting our dietary intake into the building blocks and energy required for the body's functions.