High blood glucose levels.
When blood sugar levels rises, like after a meal, insulin is secreted by the beta cells in the islets of Langerhans in primary response to decrease the blood concentration of glucose. As seen in diagram 2. The beta cells act as the receptor and the control. The beta cells detect a rise in glucose and in response secretes insulin.
The islets of Langerhans do not depend on the nervous system for their output of insulin. As a result the beta cells respond directly to blood glucose levels. When there is a rise in blood glucose, glucose is transported into the beta cell by facilitated diffusion through a glucose transporter. Elevated concentrations of glucose within the beta cells leads to membrane depolarization …show more content…
This is called hypoglycaemia and stops further insulin release from the beta cells through a negative feedback loop. Glycogen synthesis in the liver diminishes and the enzymes responsible for breakdown of glycogen become active. Glycogen does not breakdown just because insulin secretion stops but also because of the presence of glucagon, which is secreted when blood glucose levels fall.
Low blood glucose levels
When blood glucose levels fall, from lack of food intake or exercise, the hormone glucagon is released by the alpha cells and acts as an antagonist to insulin. As seen in diagram 1. The alpha cells act as the receptor and the control. The alpha cell detects the lack of glucose in the blood and activates the enzymes to release glucagon into the bloodstream. Just like beta cells, alpha cells respond directly to the glucose concentration of the blood.
The secretion of glucagon is triggered by elevated blood levels of amino acids and exercise.
Low blood glucose levels means that the body isn’t getting enough energy. The brain in particular has a great need for glucose as a fuel, because neurons cannot use alternative energy sources like fatty acids to the same