Pancreas: Exocrine or endocrine gland?

key points: pancreas, exocrine gland, endocrine gland, pancreatic enzymes, islets of Langerhans, glucose, glucagon etc.

Do you remember studying different types of glands? Some of them were endocrine while some of them were exocrine. Before we go to Pancreas, let us first understand what are endocrine and exocrine glands?

What are endocrine glands?

Our nervous system controls and co ordinates with different organs as well as try to responds with the external environment. But human body carries several activities in various organ systems at the same time, Therefore nervous system has to maintain a balance and regulates each activity at certain time. Endocrine system brings all the co ordination and balance the activities with the help of chemical messengers called as ‘hormones’. But what does the endocrine system do? (Endo- inside and crine- separate) The system literally means secrete internally. The endocrine system consists of certain endocrine glands which perform the function of secreting hormones. They are also known as ductless glands since they release the hormones into bloodstream and not via any specialized ducts. For example, Pituitary gland- oxytocin, ADH and thyroid gland- thyroxine etc.

What are exocrine glands?

Exocrine glands require the ducts to transport the secreted substance at target site. They can not release the substance directly into bloodstream and also the substance which are produced by them shows the action at nearby areas. There are several exocrine glands such as lacrimal glands which produce tears or sweat gland for production of sweat or salivary gland for producing saliva. If you notice their function of these glands their action is restricted to certain area and shows effect around the area where they are located.

Pancreas as endocrine and exocrine glands

Liver and pancreas are the only glands in human body which act as both endocrine and exocrine glands. Let us first understand the endocrine function of pancreas.

Pancreas are located in the abdominal cavity close to duodenum and behind the stomach. They are mainly responsible for two functions are as follows:

  1. Secreting of hormones for controlling glucose (Insulin and Glucagon).
  2. Secreting digestive enzymes.

Pancreas as an endocrine gland:

Pancreas has a region called as “Islets of Langerhans” which typically consists of four cells

  1. Alpha cells
  2. Beta cells
  3. Delta cells
  4. F cells

Beta cells are responsible for producing insulin whereas alpha cells produce glucagon. Both the hormones carry the function of maintaining glucose balance inside the blood stream. The delta cells produce a hormone known as somatostatin which restrains the secretion of insulin and glucagon.

Brief mechanism of insulin and glucagon

Case I: Consider that a person had carbohydrate diet which means he is now having a lots of sugar inside the body. This is sensed by pancreas and it stimulates the beta cells to produce glucose controlling hormone called as “Insulin”.  This insulin gets released into the blood stream and bind to the glucose. This glucose is stored in the liver in the form of glycogen.

Case II: Now consider that the same person is starving and has no food to eat. In this case the pancreas stimulate alpha cells to produce “Glucagon”. Many times people get confused between glycogen and glucagon. Let’s fix this mind, glycogen is a complex form of sugar while glucagon is a hormone to break that sugar into glucose i.e. simple sugar. Hence the stored glycogen is now broken by glucagon and free glucose is released into the blood stream.

Pancreas as exocrine gland

As a duct gland it secrets digestive juices which break down the nutrients. These juices are then poured to the duodenum which is the beginning of small intestine. These enzymes travel through series of ducts and meets the pancreatic duct. The pancreatic duct meets the common bile duct and it carries bile to duodenum.

Conclusion

Pancreas secrete several enzymes which helps in the digestion. The enzymes are transported via certain ducts. Therefore Pancreas are said to have an exocrine function. Also to maintain blood sugar level it secretes hormones (insulin and glucagon) which defines its endocrine function. Hence pancreas act as both endocrine and exocrine system.

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