Question

Which of the following choices correctly illustrates the course that a piece of bread takes through the digestive tract? A. Mouth \(\rightarrow\) trachea \(\rightarrow\) esophagus \(\rightarrow\) cardiac sphincter \(\rightarrow\) stomach \(\rightarrow\) pyloric sphincter \(\rightarrow\) small intestine \(\rightarrow\) large intestine \(>\) rectum \(\rightarrow\) anus B. Mouth \(\rightarrow\) pharynx \(\rightarrow\) esophagus \(\rightarrow\) cardiac sphincter \(\rightarrow\) stomach \(\rightarrow\) pyloric sphincter \(\rightarrow\) small intestine \(\rightarrow\) large intestine \(\rightarrow\) rectum \(\rightarrow\) anus C. Mouth \(\rightarrow\) pharynx \(\rightarrow\) esophagus \(\rightarrow\) pyloric sphincter \(\rightarrow\) stomach \(\rightarrow\) cardiac sphincter \(\rightarrow\) small intestine \(\rightarrow\) large intestine \(\rightarrow\) rectum \(\rightarrow\) anus D. Mouth \(\rightarrow\) pharynx \(\rightarrow\) esophagus \(\rightarrow\) cardiac sphincter \(\rightarrow\) stomach \(\rightarrow\) pyloric sphincter \(\rightarrow\) small intestine \(\rightarrow\) large intestine \(\rightarrow\) anus \(\rightarrow\) rectum

Short answer

The correct choice is B.

Step-by-step solution

Identify the Starting Point

The digestive process begins in the mouth, where the bread is chewed and mixed with saliva.

Determine the Path through the Pharynx

After being chewed, the bread passes through the pharynx and then moves to the next part of the digestive tract.

Check the Connection to the Esophagus

The next step involves the bread moving from the pharynx into the esophagus.

Passage Through the Cardiac Sphincter

From the esophagus, the bread must pass through the cardiac sphincter to enter the stomach.

Entry into the Stomach

Once past the cardiac sphincter, the bread enters the stomach, where it's further broken down.

Move through the Pyloric Sphincter

The broken-down food then moves through the pyloric sphincter to enter the small intestine.

Small Intestine to Large Intestine

In the small intestine, nutrients are absorbed, and then the remaining material moves to the large intestine.

Final Passage to Rectum and Anus

Finally, the waste moves from the large intestine to the rectum and then exits the body through the anus.

Verify the Correct Answer

Compare the path taken by the bread piece to the provided choices to find the correct sequence.

Key concepts

digestive tract

The digestive tract, also known as the gastrointestinal (GI) tract, is a long, winding tube that starts at the mouth and ends at the anus. It consists of several key organs that work together to digest food, absorb nutrients, and expel waste. Understanding the journey that food, like a piece of bread, takes through the digestive tract can help us appreciate the complexity and efficiency of our digestive system. Here’s the typical path:

• Mouth: Chewing and saliva begin the digestion process.
• Pharynx: The area where the throat and esophagus meet.
• Esophagus: A muscular tube that transports food to the stomach.
• Stomach: Food is churned and mixed with gastric juices to break it down further.
• Small Intestine: Nutrient absorption occurs here.
• Large Intestine: Absorbs water and forms stool.
• Rectum: Stores stool until excretion.
• Anus: Final exit point of digestive waste.

This coordinated sequence ensures that the food you eat is efficiently converted into energy and necessary nutrients.

digestive sphincters

Digestive sphincters are muscle valves that play a crucial role in controlling the passage of food through different parts of the digestive tract. They ensure that the food moves in a one-way direction. Two main sphincters are involved in the bread's journey: the cardiac sphincter and the pyloric sphincter.
The cardiac sphincter, located between the esophagus and the stomach, prevents the acidic contents of the stomach from flowing back into the esophagus. This ensures that food progresses to the stomach for further digestion.
The pyloric sphincter, found between the stomach and the small intestine, regulates the flow of partially digested food (chyme) from the stomach into the small intestine. This controlled release ensures maximum nutrient absorption in the small intestine.

nutrient absorption

Nutrient absorption primarily takes place in the small intestine, a lengthy and highly folded tube that provides a large surface area for the digestion and absorption of nutrients. The inner walls of the small intestine have finger-like projections called villi, which further increase the surface area.
The bread’s journey through the digestive tract allows enzymes and digestive juices to break down carbohydrates into simpler sugars, proteins into amino acids, and fats into fatty acids and glycerol. These nutrients are then absorbed by the cells lining the small intestine and transported into the bloodstream to be used by the body.

• Carbohydrates: Broken down into simple sugars like glucose.
• Proteins: Broken down into amino acids.
• Fats: Broken down into fatty acids and glycerol.

Efficient nutrient absorption is vital for maintaining the body's energy levels and supporting various bodily functions.

anatomy of the digestive system

The anatomy of the digestive system is fascinating, with each organ performing distinct functions that contribute to the overall digestion process. Let’s break down the anatomy:

• Mouth: Where digestion begins. Saliva contains enzymes that start breaking down carbohydrates.
• Pharynx and esophagus: Food travels through these structures to the stomach.
• Stomach: A muscular sac that uses acids and enzymes to break down food into chyme.
• Small Intestine: Consists of three parts - the duodenum, jejunum, and ileum. Most of the digestion and absorption occur here.
• Large Intestine: Absorbs water and salts, forming solid waste.
• Rectum and Anus: Final segments where waste is stored and eventually expelled.

Each part of this system plays a specific role, ensuring that digestion is a smooth and efficient process.

food digestion process

The entire food digestion process is a complex but well-coordinated series of steps that convert food into usable nutrients and energy. Here’s a simple breakdown of this intricate process, using bread as an example:

• Ingestion: Bread enters the mouth, where it is chewed and mixed with saliva.
• Propulsion: Swallowing moves the chewed bread through the pharynx and into the esophagus.
• Mechanical digestion: In the stomach, bread is churned and mixed with gastric juices.
• Chemical digestion: Enzymes and acids break down carbohydrates, proteins, and fats into smaller molecules.
• Absorption: Nutrients pass through the lining of the small intestine into the bloodstream.
• Defecation: Waste products are expelled from the body through the rectum and anus.

Understanding these steps can help you grasp how the digestive system transforms food into essential nutrients, making it easier to appreciate the efficiency of this biological process.