Counter-regulatory response hypoglycemia

Despite the apparent importance of the adrenal medulla in homeostasis, particularly regulation of metabolism, the medulla in contrast to the adrenal cortex is not vital for survival. Studies in adrenalectomized subjects clearly show that both hemodynamic and glucose-counter-regulatory responses to insulin-hypoglycemia, exercise, and other manipulations remain intact despite absence of epinephrine responses. This contrasts with the severe disturbances of blood pressure regulation accompanying loss of sympathetic nerves. 

There is a hierarchy of physiological responses to hypoglycemia. Endogenous insulin secretion is reduced at a plasma glucose of about 70 mg/dL (3.9 mM) thereafter, counter-regulatory... 

Glucagon Pancreatic alpha cell, central nervous system Primary counter-regulatory hormone that restores glucose levels in hypoglycemic state (increases glycogenolysis and gluconeogenesis as well as protein-lipid flux in liver and muscle) Neural and humoral factors released in response to hypoglycemia... 

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