Digestive system 2

Question 1

What is the adventitia or serosa in the GI tract?

Answer 1

• The adventitia or serosa is the outermost layer of the GI tract.
• In the thorax, it consists of loose fibrous tissue, while in the abdomen, the organs are covered by a serous membrane called the peritoneum.

Question 2

What is the muscularis in the GI tract?

Answer 2

• The muscularis consists of smooth muscle found in two sheets:
• An inner sheet of circular fibers and
• An outer sheet of longitudinal fibers. Involuntary contractions of these muscles assist in the mechanical breakdown of food, mixing it with digestive secretions, and propelling it along the tract.

Question 3

What is the mucosa in the GI tract?

Answer 3

The mucosa outlines the lumen of the GI tract and functions as both an absorptive and a secretory layer.

Question 3

What is the submucosa in the GI tract?

Answer 3

The submucosa is a fairly thick, highly vascular layer of connective tissue that serves the mucosa.

Question 4

What are the three portions of the pharynx?

Answer 4

• The nasopharynx,
• Oropharynx,
• Laryngopharynx.

Only the oropharynx and laryngopharynx are involved in the digestive system.

Question 5

What is the esophagus and its function?

Answer 5

The esophagus is about 25 cm in length, extending from the pharynx to the stomach.

• It functions as a conduit for food and liquids swallowed into the pharynx to reach the stomach.

Question 6

What is the structure and function of the stomach?

Answer 6

• The stomach is the most dilated portion of the alimentary canal, J-shaped, and continuous with the esophagus superiorly and the duodenum inferiorly.
• It stores food, mixes it with gastric juices (which include digestive enzymes and hydrochloric acid), and breaks down food while killing potentially harmful microbes.

Question 7

What are the layers of the stomach wall?

Answer 7

• Outer serous coat (provided by the peritoneum)
• Muscular coat (outer layer of longitudinal smooth muscle fibers, middle layer of circular smooth muscle fibers, and inner layer of obliquely arranged smooth muscle fibers)

*Submucous coat (loose areolar tissue)

Question 7

What are the four parts of the stomach?

Answer 7

• Cardia - receives swallowed food and contains the esophagogastric sphincter.
• Fundus - lies above and to the left of the cardiac orifice.
• Body - lies below the fundus and above the pyloric antrum.
• Pyloric antrum - lies between the body of the stomach and the pyloric orifice.

Question 8

What is the small intestine and its function?

Answer 8

The small intestine is the portion of the GI tract between the pyloric sphincter of the stomach and the ileocecal valve that opens into the large intestine

Question 9

What is the function of small intestine.

Answer 9

It absorbs nutrients, such as carbohydrates, proteins, fats, vitamins, and minerals, from the digested food into the bloodstream.

Question 10

What are the three parts of the small intestine?

Answer 10

• Duodenum,
• Jejunum,
• Ileum.

Question 11

Describe the duodenum

Answer 11

• The duodenum is the shortest and widest part of the small intestine, about 25 cm (10 inches) long.
• It is divided into four parts: superior, descending, horizontal, and ascending.

Question 12

What is the large intestine and its function?

Answer 12

• The large intestine is about 1.5 meters (5 feet) long, beginning at the caecum and ending at the rectum and anal canal.
• It forms an arch around the small intestine and has a sacculated appearance. It absorbs water and forms feces.

Question 13

What are the parts of the large intestine?

Answer 13

• Caecum
• Colon
• Rectum
• Anal canal.

Question 14

What is the function of the pancreas?

Answer 14

The pancreas functions as both an exocrine and endocrine gland. It produces and secretes digestive enzymes (exocrine) and hormones like glucagon and insulin (endocrine).

Question 15

Describe the structure of the pancreas

Answer 15

• The pancreas is composed of lobules surrounded by areolar tissue.
• Each lobule contains tubular alveoli lined by columnar epithelial cells that secrete pancreatic juice, which drains into ducts forming the main pancreatic duct.

Question 16

What is the biliary apparatus?

Answer 16

the right and left hepatic ducts, which unite to form the common hepatic duct. The common bile duct passes behind the duodenum and enters a groove on the posterior surface of the pancreas, draining bile from the liver.