8.1 An Introduction to the Digestive Sytsem

What is the digestive tract, and what are its other names?

The digestive tract is a tube in which digestion occurs. It is also known as the alimentary canal or the gastrointestinal (GI) tract.

What are the two types of digestive tract designs in animals?

• Incomplete digestive tract: Has a single opening that serves as both mouth and anus (e.g., sea anemone).

• Complete digestive tract: Has two openings, a mouth at one end and an anus at the other (e.g., humans).

What is the function of the digestive system?

The digestive system mechanically and chemically breaks down food into small particles and molecules that can be absorbed into the internal environment. It also expels unabsorbed residues and helps maintain homeostasis in the body.

What is homeostasis and how is the digestive system involved?

Homeostasis is the maintenance of a stable internal environment. The digestive system contributes by providing nutrients and energy to all other organ systems.

Why is the digestive system considered a body cavity or tube?

Because food enters through one end (mouth), travels through a muscular tube about 7 metres long, and exits through the anus after being digested and absorbed.

What role do bacteria play in the digestive system?

Bacteria in the digestive tract, known as the microbiome, live in a symbiotic relationship with the body and help in digesting food and processing nutrients.

What are the three main advantages of having a tube-like digestive tract?

1. Allows animals to eat large pieces of food.

2. Enables separation and sequencing of chemical and physical digestion processes.

3. Supports continuous digestion due to one-way flow of food and waste.

Why do all organ systems depend on the digestive system?

Because it provides the nutrients and chemical substances required for energy and proper functioning of all other systems.

What is meant by mechanical and chemical digestion?

• Mechanical digestion involves the physical breakdown of food (e.g., chewing).

• Chemical digestion involves the use of enzymes and acids to break down food into molecules.

What is meant by “symbiotic relationship” in the context of the microbiome?

A symbiotic relationship is a mutually beneficial interaction. In this case, bacteria help us digest food, and in return, they gain a habitat and nutrients.