Explain how insulin and glucagon maintain blood glucose homeostasis. What are the two types of diabetes mellitus, and what are the major symptoms? (pages \(341-44\) )

Insulin and glucagon are two hormones produced by the pancreas. Insulin is produced by the beta cells, while glucagon is produced by the alpha cells. These hormones play crucial roles in maintaining the proper blood glucose (sugar) concentration.

The main function of insulin and glucagon is to keep the blood sugar level within an appropriate range, known as glucose homeostasis. Insulin and glucagon work together to achieve this. - Insulin helps lower blood sugar levels when they are too high, which usually occurs after a meal. It does this by promoting the uptake of glucose into the cells and stimulating the liver and muscles to store glucose as glycogen. - Glucagon increases blood sugar levels when they are too low, such as when the body needs more glucose for energy during fasting or intensive physical activity. It promotes the breakdown of glycogen stored in the liver and muscles into glucose, thus raising blood glucose levels. Through this continuous interaction, insulin and glucagon maintain a stable blood glucose level.

Diabetes mellitus is a chronic disease characterized by high blood sugar levels due to insufficient insulin production or resistance to its action. There are mainly two types of diabetes: 1. Type 1 Diabetes Mellitus: This type occurs when the body's immune system destroys the beta cells responsible for producing insulin. As a result, those affected have little or no insulin production. Type 1 diabetes is typically diagnosed during childhood or adolescence, but it can also occur later in life. 2. Type 2 Diabetes Mellitus: In this type, the body either resists the effects of insulin or does not produce enough insulin to maintain normal glucose levels. Type 2 diabetes is more common and often associated with lifestyle factors like obesity, physical inactivity, and aging. Major symptoms of diabetes mellitus include: - Frequent urination (polyuria) - Excessive thirst (polydipsia) - Unintended weight loss - Fatigue - Blurry vision - Slow-healing sores In conclusion, insulin and glucagon work together to maintain blood glucose homeostasis, which ensures that our body functions properly. Diabetes occurs when this balance is disrupted, leading to either insufficient insulin production or resistance to insulin's actions.