Parts Of The Digestive System

The question asks us to identify the vertebrate group of animals characterized by the presence of a crop and a gizzard in their digestive system. Let's analyze each of the given options:

• Amphibia: This group includes animals like frogs, toads, and salamanders. Amphibians usually have a simpler stomach structure and do not possess a crop and gizzard.
• Aves: This group comprises birds. Birds have a unique digestive system that includes a crop and a gizzard. The crop is a storage pouch that allows birds to store food temporarily, and the gizzard is a muscular part of the stomach that grinds food, often with the aid of ingested stones.
• Reptilia: Reptiles, like lizards and snakes, do not typically have a crop and gizzard in their digestive system. They have a different mechanism for digestion.
• Osteichthyes: This group encompasses bony fish. Fish generally do not have a crop and gizzard; instead, they have simple stomach structures.

Based on the above analysis, the correct group characterized by the presence of a crop and gizzard is Aves.

Therefore, the correct answer is:

• Aves

The question asks us to identify the type of cells whose secretions protect the lining of the gastro-intestinal tract from various enzymes.

The options provided are:

• Chief Cells
• Goblet Cells
• Oxyntic Cells
• Duodenal Cells

To determine the correct option, let's analyze each one:

1. Chief Cells: These cells are located in the stomach and are responsible for secreting pepsinogen, a precursor to the enzyme pepsin. They do not protect the lining of the gastro-intestinal tract.
2. Goblet Cells: These are specialized epithelial cells whose primary function is to secrete mucus. This mucus coats the lining of the gastro-intestinal tract, forming a protective barrier against digestive enzymes, acidic conditions, and physical damage.
3. Oxyntic Cells: Also known as parietal cells, these are found in the stomach and secrete hydrochloric acid, which aids in digestion but does not protect the lining.
4. Duodenal Cells: These cells are part of the lining of the duodenum and have various functions, but they do not specifically protect the gastro-intestinal tract with secretions.

Conclusion: Goblet Cells are the cells whose secretion, mucus, protects the lining of the gastro-intestinal tract from various enzymes and acid. Thus, the correct answer is Goblet Cells.

The question asks about the term "Succus entericus" and which option it refers to. Let us explore each option to find the correct answer:

1. Pancreatic juice: This is the digestive fluid secreted by the pancreas. It contains a range of enzymes that aid in the digestion of carbohydrates, proteins, and fats. However, pancreatic juice is not referred to as succus entericus.
2. Intestinal juice: This is indeed what the term 'Succus entericus' refers to. It is the liquid secreted by the intestinal glands located in the walls of the small intestine. Intestinal juice contains a mixture of enzymes, mucus, and hormones that aid in the final stages of digestion and nutrient absorption.
3. Gastric juice: This is the digestive fluid produced by the stomach lining, consisting primarily of hydrochloric acid and pepsin. Gastric juice assists in the digestion of proteins. It is unrelated to succus entericus.
4. Chyme: This is the semi-fluid mass of partly digested food that is passed from the stomach to the small intestine. Chyme is the result of gastric digestion and is not a juice secreted by the intestines.

From the explanations above, it is clear that "Succus entericus" is referred to as Intestinal juice. Thus, the correct answer is Intestinal juice.