Animal Biology: Homeostasis - Control of Blood Glucose

Animal Biology: Homeostasis - Control of Blood Glucose

• Homeostasis is the maintenance of a constant internal environment in organisms.
• Blood glucose levels are controlled through homeostasis - a process that involves the hormones insulin and glucagon.
• These hormones are produced in the pancreas, specifically in the Islets of Langerhans.
• If the glucose level in the blood is too high, beta cells in the Islets of Langerhans release insulin.
• Insulin facilitates the uptake of glucose into liver and muscle cells.
• In these cells, glucose is converted into glycogen, a storage carbohydrate, through a process called glycogenesis.
• This process decreases blood glucose levels.
• If blood glucose levels fall too low, alpha cells in the Islets of Langerhans release glucagon.
• Glucagon triggers the conversion of stored glycogen back into glucose in the liver, through a process called glycogenolysis.
• Additionally, if glucose levels are very low, a process called gluconeogenesis can occur where the liver synthesises glucose from non-carbohydrate sources, like amino acids and glycerol.
• This boosts blood glucose levels back to the normal range.
• The conversion of glucose into glycogen and vice versa is a good example of a negative feedback system. When blood glucose rises, insulin reduces it; when it falls, glucagon increases it.
• Diabetes is a condition where the body cannot maintain its blood glucose levels. Type 1 diabetes is characterised by a lack of insulin production, while type 2 diabetes involves insulin resistance of cells.