The pancreas is both an endocrine and exocrine organ.  The endocrine portion of the pancreas makes the hormones insulin and glucagon that are distributed throughout the body by way of the bloodstream.  The cells that provide endocrine and exocrine functions are different from each other but are evenly dispersed throughout the pancreas.

What is insulin and what does it do?

Insulin is a hormone secreted by the pancreas that regulates the glucose level in the blood.  Glucose is the body's main sugar source and it is important for the body to keep the level of blood glucose steady.  When we eat a meal, glucose is rapidly absorbed by the digestive tract into the blood.  As the blood glucose level rises, the pancreas secretes more insulin.  This insulin stimulates the body's cells to absorb the glucose to provide energy.  Extra glucose is absorbed by the liver and muscle cells where it can be stored as glycogen.  Insulin also encourages the body's cells to convert extra glucose into needed fat and protein. 

What is glucagon and what does it do?

Glucagon is a hormone secreted by the pancreas that has the opposite effects of insulin.  Between meals and while we are sleeping, the blood level of glucose drops.  The pancreas secretes glucagon which encourages cells in the liver and muscle to release glucose from storage.  If necessary, fats and even proteins can be converted to sugar to keep the glucose blood level in a normal range.

What happens when the blood glucose level drops too low?

In a healthy person, the body can either release stored glucose or create new glucose when the blood glucose level drops.  This process is encouraged by the release of glucagon by the pancreas.  You may notice mild symptoms of a low blood glucose level, called hypoglycemia, when you miss a meal.  The symptoms include hunger, a growling stomach, weakness, a tired feeling, and headache.  During times of severe starvation or illness, the body may not be able to keep the blood level of glucose in a normal range.  This may lead to lethargy, seizures or coma.  Infants have only a small amount of stored glucose and are especially prone to develop hypoglycemia if they do not eat frequently.

What happens when the blood glucose level gets too high?

In a healthy person, the blood glucose level is kept in a normal range by a balance of the pancreas hormones insulin and glucagon.  When the blood sugar rises (after eating a large piece of chocolate cake, for example), the pancreas releases insulin.  In people with diabetes, either the pancreas is unable to make enough insulin (type I diabetes) or the body's cell don't respond to insulin (type II diabetes).  A high blood glucose level can cause frequent urination, a jittery feeling, headaches, and when severely elevated - seizures and coma.

What are the exocrine functions of the pancreas?

The exocrine portion of the pancreas produces digestive enzymes.  See article on the exocrine function of the pancreas.

Photo - The pancreas. Gray's Anatomy.

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