Explain how blood sugar levels are regulated using hormones (insulin and glucagon). Include an explanation of as to why regulating blood sugar levels through homeostatic mechanisms is significant

Question

Can someone help me understand this

Answer 1

I'm not sure how much detail you want, so please let me know if this is good.

Insulin and glucagon are two hormones released by the pancreas (at different times). Insulin has a transmembrane receptor with 2 alpha subunits that are extracellular, and 2 beta subunits that go through the membrane and into the cell cytosol. Insulin is released from the pancreas when glucose levels are high, and can bind to the alpha subunits thereby triggering a cascade of reactions, starting with insulin phosphorylating itself on tyrosines. These reactions lead to the activation and movement of glucose transporters, GLUT4 to the plasma membrane. These transporters can then take the glucose into the cell, removing it from the bloodstream, and utilizing it for other purposes such as glycogen synthesis.

When blood sugar is low, however, this stimulates the release of glucagon from the pancreas. Glucagon activates a transmembrane GPCR which also induces a cascade of reactions including, the activation of cAMP which ultimately leads to the breakdown of glycogen and the release of glucose.

Regulating blood sugar homeostatically is critical due to the fact that glucose is central to many of the reactions within our body, including the brain (which cannot itself synthesize glucose). Homeostasis and the regulation of these hormones, ensures that there is a balance, and that the 2 are not counteracting each other. If one hormone is working, the other is usually not, and vice versa, to enable the maintenance of proper glucose levels.