Blood glucose concentration is kept near a set point by homeostasis. Explain the principles of homeostasis.
Glycogen phosphorylase catalyses the conversion of glycogen into glucose in liver cells. The production of glycogen phosphorylase is coded for by the gene PYGL. A mutation in PYGL leads to a condition called glycogen storage disease type VI (GSDVI), in which glycogen is not broken down efficiently. Suggest and explain why glucagon cell signalling is likely to be affected in the liver cells of a person with GSDVI.
Glycogen synthase catalyses the conversion of glucose into glycogen in liver cells. The production of glycogen synthase is coded for by the gene GYS2. A mutation in GYS2 leads to a condition called glycogen storage disease type 0 (GSD0), in which glycogen is not formed efficiently. Suggest what the consequences would be if a person with GSD0 has a meal rich in glucose.