Homeostasis (Blood Glucose Regulatory System)

Re-establishment of Homeostasis (Blood glucose regulatory system).

When consuming food, there are certain factors which can lead to an increase in blood glucose levels such as excess food intake, particularly of carbohydrates. Carbohydrates are the main cause of rising blood glucose levels in relation to food consumption as digestible carbohydrates are broken down directly into sugar which enters the blood. Liquids high in carbohydrates such as milk or juice, are also absorbed much faster than solid carbohydrates like bread. When a carbohydrate-rich meal is consumed, the digestive carbohydrates are broken down directly into glucose which is absorbed into the bloodstream through the walls of the small intestine. This increases blood glucose

However, the beta cells will detect the surplus of blood glucose causing the blood glucose regulatory system to react and lower the levels of blood glucose, in order to maintain a normal equilibrium and keep the body in homeostasis. This prevents the short-term effects of high blood glucose such as hyperglycaemia. Hyperglycaemia occurs when blood glucose concentration exceeds 7mM. The main symptoms of hyperglycaemia are frequent urination and increased thirst. Although, these may also be accompanied by headaches, tiredness, blurred vision, hunger, and difficulty with thinking or concentrating. Extreme highs in blood glucose levels can result in a medical emergency (diabetic coma). If present for a prolonged amount of time, hyperglycaemia can lead to damage to organs and tissues. Long-term hyperglycaemia can even impair the immune response, leading to poor healing of cuts/wounds. It can also cause nerve damage, vision problems, and damage to the blood vessels and kidneys. Therefore, there is a need to counteract hyperglycaemia, which is achieved

When glucose levels in the blood are at a stable equilibrium, the potassium ion channels are open, allowing potassium ions to move freely out of the cell. If glucose concentration in the blood rises, the glucose molecules move into the cell. Inside the cell, the glucose is then metabolised into ATP , which then has the effect of closing the potassium ion channels. This then has the further effect of changing the potential difference across the membrane, becoming less negative inside the cell. This causes the calcium ion channels to open allowing calcium ions to move in. This then results in vesicles containing insulin to attach to the cell membrane, diffusing insulin by the process of exocytosis . The release of stored insulin from the endocrine tissue of the pancreas is a controller of this homeostatic system. When insulin is diffused into the bloodstream through exocytosis, it is released to the hepatic portal vein. The hepatic portal vein drains blood from the gastrointestinal tract and spleen to the liver which therefore allows insulin to reach the liver, the effector of the blood glucose regulatory system. Processes in the liver stimulated by the release of insulin, work to counteract rising blood sugar levels which take place after consumption of