Endocrine System

The endocrine system is a network of glands that produce and release hormones that help to control many important body functions, especially the body’s ability to change calories into energy that powers cells and organs. 

The main function of endocrine glands is to secrete hormones directly into the bloodstream. Hormones are chemical substances that affect the activity of another part of the body (target site). In essence, hormones serve as messengers, controlling and coordinating activities throughout the body. Upon reaching a target site, a hormone binds to a receptor, much like a key fits into a lock. Once the hormone locks into its receptor, it transmits a message that causes the target site to take a specific action. Hormone receptors may be within the nucleus or on the surface of the cell. Ultimately, hormones control the function of entire organs, affecting such diverse processes as growth and development, reproduction, response to stimuli (stress and injury) and sexual characteristics. Hormones also influence the way the body uses and stores energy and control the volume of fluid and the levels of salts and sugar (glucose) in the blood. Very small amounts of hormones can trigger very large responses in the body. Although hormones circulate throughout the body, each type of hormone influences only certain organs and tissues. Some hormones affect only one or two organs, whereas others have influence throughout the body. For example, thyroid- stimulating hormone, produced in the pituitary gland, affects only the thyroid gland. In contrast, thyroid hormone, produced in the thyroid gland, affects cells throughout the body and is involved in such important functions as regulating growth of cells, controlling the heart rate, and affecting the speed at which calories are burned. Insulin, secreted by the islet cells of the pancreas, affects the processing (metabolism) of glucose, protein and fat throughout the body. Most hormones are proteins. Others are steroids, which are fatty substances derived from cholesterol. 

DIABETES MELLITUS 

Diabetes mellitus is a metabolic disorder, in which glucose level in the blood is much higher than normal (hyperglycemia) and hence this condition is also commonly referred to as sugar disease. The defect in this condition is that, either the pancreas does not produce enough insulin or it produces sufficient insulin, but the cells of the body are unable to use the insulin properly. Insulin, a hormone released from the pancreas, controls the amount of glucose in the blood. Glucose in the bloodstream stimulates the pancreas to produce insulin. Insulin allows glucose to move from the blood into the cells. Once inside the cells, glucose is converted to energy, which is used immediately, or the glucose is stored as fat or glycogen until it is needed. The levels of glucose in the blood vary normally throughout the day. They rise after a meal and return to normal within about 2 hours after eating. Once the levels of glucose in the blood return to normal, insulin production decreases. The variation in blood glucose levels is usually within a narrow range, about 70 to 110 milligrams per deciliter (mg/dL) of blood in healthy people. 

If people eat a large amount of carbohydrates, the blood glucose levels may increase more. People older than 65 years tend to have slightly higher levels, especially after eating. Insulin is like a key which opens the body cell doors to allow glucose to enter. In the absence of enough insulin, glucose cannot enter the cells and remains in the blood stream in high amounts (hyperglycemia). If the body does not produce enough insulin to move the glucose into the cells, or if the cells stop responding normally to insulin, the resulting high levels of glucose in the blood and the inadequate amount of glucose in the cells together produce the symptoms and complications of diabetes.