These hormones prepare the body for these unexpected stressful situations by meeting the needs of the intense muscular activity with increased blood flow, nutrients, and oxygen supply by mobilizing glucose and fatty acids for metabolism to produce energy, prepare heart, lungs, and muscles. The adrenal cortex is divided into three distinct zones, each specialized to secrete specific corticosteroids with distinct functions. The outer part is the zona glomerulosa, and it secretes a group of hormones called mineralocorticoids whose function is to help control water and electrolyte homeostasis, particularly the concentrations of Sodium and Potassium ions. The middle part of the adrenal cortex is the zona fasciculata which secretes a group of hormones called glucocorticoids. Their function is to regulate metabolism and resistance to chronic stress, such as long term starvation, cold, fasting, loss of blood pressure, hemorrhage, surgery, and infections.
Cortisol increases the blood glucose supply for tissues, mainly the brain and heart.
It exerts this action by promoting catabolism of proteins and by stimulating the conversion of the resultant amino acids to glucose, a process known as gluconeogenesis which principally occurs in the liver. The inner zone of the adrenal cortex is called the zona reticularis which synthesizes small amounts of sex steroids, namely androgens as well as minute amounts of estrogen and progesterone. The function of androgens in the adult male is considered to be unimportant due to the large amounts of testosterone. However, androgens are the main source of the male sex steroid in females, and some of the adrenal androgens can be converted to estrogen. The most observable effects of androgens are in children where they affect bone and muscle growth, fat accumulation and distribution during puberty.