Question

Compare and contrast the structure and function of the digestive systems in bony fish, amphibians, and mammals.

Answer 1

ANS: For bony fish:

The esophagus in bony fishes is short and expandable so that large objects can be swallowed. The esophagus walls are layered with muscle.Most bony fishes have a stomach. Usually the stomach is a bent muscular tube in a "U" or "V" shape. Gastric glands release substances that break down food to prepare it for digestion.

At the end of the stomach, many bony fishes have blind sacs called pyloric caeca. The pyloric caeca are an adaptation for increasing the gut area; they digest food.

The pancreas secretes enzymes into the intestine for digestion.

Digestive of ambhibians: Most frog larvae are herbivores, However, adult frogs and salamanders are predators and feed on small invertebrates. After an amphibians eats, the food flows from its mouth to its esophagus to its stomach. Digestion begins in the stomach of an amphibian. Food then moves to the small intestine, where enzymes from the pancreas start the digestion process. From the small intestine, nutrients from the food are absorbed into the bloodstream and delivered to body cells. Food moves from the small intestine to the large intestine before waste is eliminated. Digestive waste enters the cloaca before it exits the body.

Digestive of mamals: The digestive system is one of the largest organ systems in the human body. It is responsible for processing ingested food and liquids. The cells of the human body all require a wide array of chemicals to support their metabolic activities, from organic nutrients .

The digestive system consists of a group of organs that form a closed tube-like structure called the gastrointestinal tract (GI tract) or the alimentary canal. For convenience, the GI tract is divided into upper GI tract and lower GI tract. The organs that make up the GI tract include the mouth, the esophagus, the stomach, the small intestine, and the large intestine. There are also several accessory organs that secrete various enzymes into the GI tract. These include the salivary glands, the liver, and the pancreas.