Final answer:
The hypothalamus and pancreas respond to low blood sugar levels. The hypothalamus activates the hypophyseal portal system, and the pancreas secretes glucagon to increase blood glucose through glycogenolysis and gluconeogenesis.
Step-by-step explanation:
When Lonnie, who is diabetic, experiences low blood sugar levels, her body responds to maintain homeostasis. The part of the brain that is triggered by a low blood sugar level is the hypothalamus, which can activate the hypophyseal portal system. However, the primary response to hypoglycemia involves the pancreas. The pancreas detects the drop in blood glucose and the alpha cells of the pancreas secrete the hormone glucagon. Glucagon works to increase blood sugar by promoting the conversion of glycogen to glucose in the liver—an effect called hyperglycemia—through a process known as glycogenolysis. Additionally, glucagon promotes gluconeogenesis, which is the synthesis of glucose from amino acids and glycerol in order to raise blood glucose levels back to a normal range.