Question

Describe exocrine secretory cells and discuss its function within the body. Talk about common locations for the type of cell and discuss the clinical significance of the cell.

Answer 1

• The two main types of exocrine secretory cells of the stomach are parietal cells and chief cells. Parietal cells secrete hydrochloric acid and chief cells secrete digestive enzymes such as pepsin. These cells secrete their products when activated by signals from the body such as hormones and neurotransmitters.

• The pancreas is composed of endocrine cells that secrete hormones, exocrine cells that make digestive enzymes, and duct cells that secrete bicarbonate and water. The exocrine pancreas consists of cells organized into acini and a duct system that leads to the small intestine

  Exocrine Function of the Pancreas
  When we consider the functions of the pancreas, it is simpler to view it as a mix of two glands. We can divide the pancreas into an exocrine gland, containing the acinar and duct tissue, and the endocrine gland containing the islets of Langerhans.

  The majority of the pancreas is made up of the exocrine portion (85% by mass) and secretes digestive enzymes, water and bicarbonate to assist in digestion.

  The bicarbonate helps in neutralising the stomach acid. This is a vital part of digestion as the small intestine is not specialised to withstand the strong acids from the stomach. This is because the small intestine, unlike the stomach, lacks a thick protective mucous layer. Additionally, the digestive enzymes secreted by the pancreas reach their optimum function at a basic pH. This is achieved by the bicarbonate secretions of the pancreas.

  Exocrine Pancreas – The Functional Unit
  The functional unit of the exocrine pancreas includes the Acinus and its duct system. The word acinus is from the Latin term for “berry in a cluster”. These acinar cells are specialised in enzyme synthesis, storage and secretion. The duct system modifies the aqueous secretions. This mechanism is stimulated by the parasympathetic system and inhibited by the sympathetic system
  Digestive Enzyme Secretion
  The acinar cells produce digestive enzymes on the rough endoplasmic reticulum.
  Bicarbonate Secretion
  Water and carbon dioxide combine in a reaction catalysed by the enzyme carbonic anhydrase.
  Regulation of Pancreatic Secretions
  There are a number of factors involved in triggering the pancreas to release its secretions. Vagal innervation to the pancreas stimulates the secretion of enzymes. This stimulation occurs when we see, smell or taste food, or when the stomach wall is stretched.

• The cells of exocrine glands are generally arranged into secretory units in the form of acini or tubules (although the liver has a remarkable arrangement of cords). The product of endocrine glands is secreted into interstitial fluid and hence into capillaries and general circulation.

  The stomach is an organ of the digestive system. The inner wall of the stomach contains small pores called gastric pits. These pits contain cells that secrete chemicals that digest food. The two main types of exocrine secretory cells of the stomach are parietal cells and chief cells.
  Parietal cells -also known as oxyntic or delomorphous cells) are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and in the cardia of the stomach.

  Gastric chief cells are generally located deep in the mucosal layer of the stomach lining

• Clinical Significance
  Exocrine glands can be found in everything from the skin to the pancreas, and provide the body with a method to release secretions containing proteins, mucus, and other products to epithelial surfaces around the body.