Problem 122 - Objective Biology for NEET

Question

Hormonal control of the secretion of digestive juice is carried out by local, produced by \(\quad\) and \(\quad\) mucosa. (a) Neurotransmitters, liver, pancreas (b) Hormones, Liver, pancreas (c) hormones, Gastric, intestinal (d) Neurotransmitters, gastric, intestinal

Step-by-Step Solution

Answer

The correct answer is option (c). Hormones produced by the gastric and intestinal mucosa control the secretion of digestive juice locally.

Step 1: Identify the Control Mechanism

The control of the secretion of digestive juice is carried out by local hormones, which is the focus of the question.

Step 2: Choose the Correct Sources

The possible sources provided are 'liver', 'pancreas', 'gastric', and 'intestinal'. Considering it is about digestive juice secretion, the most relevant sources are the ones directly involved in digestion process, which are the gastric and intestinal mucosa.

Step 3: Match the Control Mechanism and Sources

From the options provided, it is clear that the option with both the correct control mechanism (hormones) and the correct sources (gastric and intestinal mucosa) is option (c).

Key Concepts

Hormonal Control

The digestive process is intricately managed by hormones, which act as chemical messengers. These hormones are produced by the gastric and intestinal mucosa, and play a vital role in regulating the secretion of digestive juices.

• Hormonal control ensures that digestive juices are released exactly when needed.
• Various hormones are responsible for signaling the different phases of digestion.

For example, gastrin is a hormone that stimulates the secretion of gastric acid from the stomach when food is present. In addition, secretin and cholecystokinin (CCK) are hormones released by the intestinal mucosa, which coordinate the release of digestive enzymes and bile, thus facilitating further digestion in the small intestine.

Digestive Juices

Digestive juices are critical for the breakdown of food into nutrients that the body can absorb. These juices are secreted by different glands along the digestive tract, each contributing specific enzymes or acids to aid digestion.

• The stomach produces gastric juice, which contains hydrochloric acid and pepsin, essential for the initial breakdown of proteins.
• The pancreas produces pancreatic juice, rich in digestive enzymes like amylase, lipase, and proteases.
• Bile, produced by the liver and stored in the gallbladder, emulsifies fats for easier digestion in the intestine.

Each type of digestive juice is specifically tailored to break down different types of food molecules, working in conjunction to ensure efficient nutrient absorption.

Gastric Mucosa

The gastric mucosa is the mucous membrane layer of the stomach, responsible for the secretion of gastric juices.
This layer is populated with specialized cells - parietal cells secrete hydrochloric acid, chief cells release pepsinogen, and mucous cells produce mucus to protect the stomach lining.

• The hydrochloric acid lowers the pH, making it ideal for the digestive enzymes to function.
• Pepsinogen is converted to pepsin, which digests proteins into peptides.
• Mucus forms a protective barrier against the strong acids.

The processes carried out by the gastric mucosa are crucial for starting protein digestion and protecting the stomach itself from damage by acidic conditions.

Intestinal Mucosa

The intestinal mucosa refers to the innermost layer of the intestines, vital for nutrient absorption and further digestion.
This mucous membrane lines the small intestine and contains villi and microvilli that increase surface area, optimizing nutrient absorption.

• Hormones produced here, like secretin and CCK, play an integral role in stimulating the release of enzymes and bile.
• The intestinal mucosa also secretes its own enzymes, such as lactase, maltase, and sucrase, which help break down sugars into simpler forms that can be absorbed.
• Additionally, it helps in the absorption of nutrients and electrolytes, ensuring these essential elements enter the bloodstream efficiently.

The intestinal mucosa is therefore critical for the effective digestion and absorption that sustains our body's functions.