Organism level systems Study Guide

The human body maintains a constant internal environment, a process known as homeostasis. Blood glucose concentration is one such factor that needs tight regulation. The pancreas, an organ located behind the stomach, plays a central role in this control by producing two key hormones: insulin and glucagon. When blood glucose levels rise, typically after a meal high in carbohydrates, the pancreas releases insulin. Insulin acts on liver and muscle cells, allowing them to absorb glucose from the blood and convert it into glycogen for storage. This process lowers blood glucose concentrations back to a healthy range. Conversely, when blood glucose levels fall, such as during prolonged fasting or intense exercise, the pancreas releases glucagon. Glucagon signals the liver to break down stored glycogen back into glucose, which is then released into the bloodstream. This increases blood glucose concentrations. Together, insulin and glucagon act antagonistically, meaning they have opposing effects, to maintain blood glucose within a narrow, healthy range, ensuring a constant energy supply to cells while preventing harmful fluctuations.

Diabetes is a chronic condition characterised by high blood glucose (sugar) levels. The body usually controls blood sugar using a hormone called insulin, produced by the pancreas. Insulin helps glucose move from the bloodstream into cells to be used for energy. When this system malfunctions, diabetes occurs. There are two main types: Type 1 and Type 2.

Type 1 diabetes is an autoimmune condition where the body's immune system mistakenly attacks and destroys the insulin-producing cells in the pancreas. This means the pancreas produces very little or no insulin. Without insulin, glucose cannot enter the cells and builds up in the blood. Type 1 diabetes typically develops quickly, often in childhood or young adulthood. Treatment involves lifelong insulin injections to replace the insulin the body cannot produce. Regular monitoring of blood glucose levels, a carefully planned diet, and physical activity are also crucial.

Type 2 diabetes develops when the body either doesn't produce enough insulin or the body's cells don't react properly to insulin, a condition known as insulin resistance. This leads to glucose accumulating in the blood. Type 2 diabetes is often linked to lifestyle factors such as obesity, lack of physical activity, and an unhealthy diet, and it tends to develop gradually, often in older adults, though it is increasingly seen in younger people. Initial treatment often involves lifestyle changes like regular exercise and a healthy diet. If these are insufficient, medication (e.g., to increase insulin production or improve insulin sensitivity) may be prescribed. In some cases, insulin injections might also be needed as the condition progresses. Both types of diabetes, if not properly managed, can lead to serious health complications like heart disease, kidney damage, vision problems, and nerve damage.