Question

Figure 5.5 Which of the following statements about the digestive sy stem is false? a. Chyme is a mixture of food and digestive juices that is produced in the stom a b. Food enters the large intestine before the small intestine. c. In the small intestine, chyme mixes with bile, which emulsifies fats. d. The stomach is separated from the small intestine by the pyloric sphincter.

Short answer

a) Chyme is a mixture of food and digestive juices that is produced in the stomach. b) Food enters the large intestine before the small intestine. c) In the small intestine, chyme mixes with bile, which emulsifies fats. d) The stomach is separated from the small intestine by the pyloric sphincter. Answer: b) Food enters the large intestine before the small intestine.

Step-by-step solution

Read and understand all the statements

Go through each of the given statements and make sure you comprehend them. Everything you know about the digestive system will be helpful in solving this exercise.

Verify Statement a

"Chyme is a mixture of food and digestive juices that is produced in the stomach." This statement is true. Chyme is created in the stomach through the action of stomach muscles, acid, and enzymes. The chyme is then moved further along the digestive tract for further processing.

Verify Statement b

"Food enters the large intestine before the small intestine." This statement is false. Food enters the small intestine after being processed in the stomach. The small intestine is where most digestion and nutrient absorption take place. Next, the food moves on to the large intestine for further absorption and the formation of feces.

Verify Statement c

"In the small intestine, chyme mixes with bile, which emulsifies fats." This statement is true. Bile, which is produced by the liver and stored in the gallbladder, is released into the small intestine to emulsify fats, making them easier to digest.

Verify Statement d

"The stomach is separated from the small intestine by the pyloric sphincter." This statement is true. The pyloric sphincter is a ring-like muscle that controls the passage of chyme from the stomach to the small intestine. It regulates the release of chyme into the small intestine to ensure proper digestion.

Identify the false statement

Based on the verification of all statements, the only false statement is option b: "Food enters the large intestine before the small intestine." This statement is incorrect because food actually enters the small intestine first, where most digestion and absorption processes occur, before moving on to the large intestine.

Key concepts

Chyme

Chyme plays a key role in digestion. It is the semi-liquid mixture of partially digested food and digestive juices, including hydrochloric acid and digestive enzymes. Chyme forms in the stomach by the churning action of the stomach muscles. This process breaks down the food into smaller particles making it easier to digest. After being formed, chyme slowly moves into the small intestine through a process called gastric emptying. This transfer is carefully regulated to ensure that the intestine can efficiently absorb nutrients.

Small Intestine

The small intestine is a long, muscular tube that follows the stomach. It is the site where most of the digestion and absorption of nutrients occurs. Structurally, it is divided into three segments: the duodenum, jejunum, and ileum, each serving distinct roles.

• The duodenum receives chyme and digestive juices from the liver and pancreas, initiating the breakdown of fats, proteins, and carbohydrates.
• The jejunum is where a large portion of nutrient absorption happens, thanks to its finger-like projections called villi that increase surface area.
• The ileum absorbs vitamin B12 and bile acids, crucial for overall nutrition.

In summary, the small intestine efficiently breaks down chyme, absorbing essential nutrients and water before the remaining waste moves into the large intestine.

Pyloric Sphincter

The pyloric sphincter is an essential component of the digestive system. It is a muscular valve located at the junction between the stomach and the small intestine. The primary function of the pyloric sphincter is to control the passage of chyme from the stomach into the small intestine. It acts like a gatekeeper, allowing small amounts of chyme to enter the intestine so that the digestive process can occur effectively. Additionally, the pyloric sphincter prevents the backflow of intestinal contents into the stomach, safeguarding the stomach lining from potential irritants. Proper functioning of this sphincter is crucial for maintaining a balance in the digestive process, ensuring that food is properly digested and nutrients are absorbed.

Bile

Bile is a vital digestive fluid produced by the liver and stored in the gallbladder. It is released into the small intestine in response to the presence of chyme, particularly when this mixture contains fats.

Functions of Bile

• Emulsification of Fats: Bile's primary role in digestion is to emulsify fats. This means it breaks down large fat globules into smaller droplets, making them easier for digestive enzymes to process.
• Absorption: Bile acids help in absorbing fat-soluble vitamins such as A, D, E, and K.
• Neutralization: Bile aids in neutralizing stomach acids, creating an optimal environment in the small intestine for enzyme activity.

Bile's efficient action ensures that fats are digested smoothly and nutrients are properly absorbed in the small intestine.