Question

300 WORDS, MUST BE detailed on the answer.

Identify one specific cell type found anywhere along the digestive tract. What is their function? Why is the function of the cell you identified important?

Answer 1

The digestive tract starts from the mouth. It consists of oesophagus, pharynx, stomach digestive tube and ends at the anus. Different types of cells are found in different areas of the tract with specific functions. Some cells have protective fuction, some have secretory function, some have absorptive function. It depends on the site of its action.

The gastric glands are composed of four types of epithelial cell:

(1) mucous neck cells, which have protective function.It protect the organ from the secretory products of stomach glands.

(2) chief cells, with secretory function.It produce and secrete the enzyme pepsin.

(3) parietal cells. It secrete hydrochloric acid; and

(4) argentaffin cells,They are endocrine glands.

Parietal cells:

They are also known as oxyntic cell or delomorphous cells.

FUNCTION

They are the epithelial cells which secrete hydrochloric acid .They produce it in response to

histamine (via H2 receptors),

acetylcholine (M3 receptors)

and gastrin (gastrin receptors).Parietal cells bear receptors for three stimulators of acid secretion, reflecting a triumverate of neural, paracrine and endocrine control.

They also secrete intrinsic factors. The intrinsic factor (IF) is a glycoprotein produced by the parietal cells (oxyntic cells) located at the gastric body and fundus. Intrinsic factor plays a crucial role in the transportation and absorption of the vital micronutrient vitamin B12 (cobalamin, Cbl) by the terminal ileum.

LOCATION

These parietal cells are located in the gastric glands. They are found in the lining of the fundus and in the cardia of the stomach.

These cells contain canaliculi which is an extensive secretory network . With the help of these canaliculi the hydrochloric acid is secreted by active transport into the stomach.

STRUCTURE

The parietal cell is usually depicted in a triangular shape with the apical region of the cell forming the apex of the triangle, which borders the lumen of the gastric gland. In stimulated parietal cells, the canaliculi are stylistically represented as simple bifurcations of microvillar membrane that extend partway into the cell.

IMPORTANCE

Parietal cells play an important role in gastric homeostasis, as well as in the absorption of vitamin B12 (cobalamin) due to the release of intrinsic factor.The damaged parietal cells are unable to produce the required amount of gastric acid. This leads to an increase in gastric pH, impaired digestion of food and increased risk of gastroenteritis.