Problem 34 - Objective Biology for NEET

Question

A muscular sphincter that regulates the opening of stomach into duodenum is (a) Pyloric sphincter (b) Gastroesophageal sphincter (c) Sphincter of Oddi (d) Cervical sphincter

Step-by-Step Solution

Answer

The muscular sphincter that regulates the opening of the stomach into the duodenum is the pyloric sphincter.

Step 1: Understanding the anatomy of the digestive system

Firstly, there is a need to have a knowledge of the structure of the human digestive system. The stomach is connected to the duodenum (the first part of the small intestine) through a valve-like structure, which is a muscular sphincter.

Step 2: Identifying the sphincter

The task is to identify which among the four options given is the specific sphincter that controls the opening of the stomach into the duodenum.

Step 3: Selecting the correct sphincter

Among the options, the pyloric sphincter is the right answer. The pyloric sphincter is a band of smooth muscle at the junction between the pylorus of the stomach and the duodenum of the small intestine. It plays an important role in digestion, as it controls the passage of partially digested food from the stomach to the small intestine.

Key Concepts

Digestive System

The digestive system is a complex network of organs that collaborate to break down food, absorb nutrients, and eliminate waste. It starts from the mouth, where food is mechanically broken down and mixed with saliva, beginning the digestion process. As food travels down the esophagus, it reaches the stomach where acids and enzymes further digest it.
At the end of the stomach, a muscular sphincter controls the flow of this partially digested food into the small intestine. The digestive system consists of several major organs including:

• Mouth
• Esophagus
• Stomach
• Intestines (small and large)
• Liver
• Pancreas
• Gallbladder

Each plays a crucial role in digestion, with the duodenum being the site where most nutrient absorption begins. Understanding the sequence of food digestion and the function of each organ helps in comprehending how the digestive system efficiently processes food.

Muscular Sphincter

A muscular sphincter is a ring-like muscle that opens and closes to regulate the passage of substances through the body's different pathways. These sphincters are essential in ensuring that the digestive process occurs in a controlled and efficient manner.
The pyloric sphincter, for instance, manages the passage of food from the stomach into the duodenum. It functions by relaxing at intervals to allow the chyme, or semi-liquid food mass, to enter the small intestine. Below are some key attributes of muscular sphincters:

• Control the flow of digested food
• Prevent the backflow of contents
• Made of smooth muscle tissue for involuntary control
• Located at critical points of the digestive tract such as the pyloric region and anus

Proper function of these sphincters is critical to maintaining an orderly digestive process.

Duodenum

The duodenum is the initial section of the small intestine and is named for its approximate length, which is about twelve finger-widths. It plays a significant role in the digestive process by continuing the breakdown of food using enzymes released from the pancreas and bile from the liver.
This part of the digestive tract is where the most vigorous digestion occurs, allowing nutrients to be absorbed efficiently. The duodenum's functions are supported by the:

• Secretion of digestive enzymes and bicarbonate to neutralize stomach acid
• Coordination with the pyloric sphincter to regulate food entry
• Facilitation of absorption and regulation of gastric emptying

Understanding the role of the duodenum helps in appreciating how digestive health and nutrient absorption are maintained. Proper functioning of the pyloric sphincter is crucial for allowing luminal contents to enter the duodenum at the right pace.