What are the Adrenal Glands?

The adrenal glands are paired organs that rest on top of the kidneys and consist of two parts the cortex, and medulla. This is a important gland in the endocrine system that helps maintain many systems, and protect life by engaging fight or flight responses. The adrenal cortex has three parts the zona glomerulose, the zona fasciculata, and the Zona reticularis. These areas assist in regulating blood sugar levels (glucose), blood pressure, and developing and maintaining male characteristics. The Adrenal Medulla is responsible for providing fight and flight hormones like adrenaline, and pain regulating hormones.
The Adrenal Cortex hormones: The cortex sits around the medulla of the adrenal glands and produces hormones from cholesterol synthesizing (creates) and secreting (releases) three types of steroidal hormones; Glucocorticoids, Mineralocortioids, and androgens.

Glucocorticoids: Produced in the Zona fasciculata and reticularis cells, these steroidal hormones affect these systems:

• Immune: This hormone has a dramatic effect on the inflammatory process, by both suppressing pro-inflammatory proteins, and increasing anti-inflammatory proteins.
• Metabolic: During a fasted state these hormones will cause the production of glucose from non traditional substrates like amino acids and glycerol gained from tissues outside the liver (extrahepatic) and fat from adipose tissue. It as well inhibits the uptake of glucose by muscle and adipose tissues.
• Developmental: During fetal development glucocorticoids have a critical role in lung, brain, and cell development.
• Arousal and cognition: These hormone levels affect recalling and making long term memories in relation to strong emotions. During periods of high or low glucocorticoid levels it is harder to develop or recall memories, though during moderate levels it is very easy to develop and recall them.

Mineralocortioids: Produced in the Zona Glomerulosa, these steroidal hormones help maintain blood pressure by instructing the kidneys to reabsorb sodium and water into the blood. It as well stimulates potassium secretion in the liver.

Androgens: Produced in the Zona reticularis and fasciculata cells (as well in greater amounts and effect in the testes), these hormones like DHEA and testosterone, affect male characteristics development and maintenance including fetal development.
Adrenal Medulla hormones: The medulla is located in the center of the adrenal glands, surrounded by the cortex. Using primarily the amino acid tyrosine, the medulla will synthesize and secrete the hormones adrenaline, noradrenaline, dopamine and enkephaline in the chromaffin cells.

Adrenaline (epinephrine): This hormone is released in response to stress, and acts in part with our fight or flight response. When released it affects almost every cell in the body in different ways. It will increase respiration, heart rate, glucose levels (raw energy) in the muscles and brain, and stimulates glycogenolysis (turning sugar substrate glycogen into glucose). Adrenaline will also suppress non-emergency systems like digestion and the immune system, and will constrict blood vessels.

Noradrenaline (norepinephrine):This hormone is released in response to stress, and acts in part with our fight or flight response. It will increase heart rate and blood flow to skeletal muscle, will release glucose stores (energy). It will also act as anti-inflammatory agent in the brain.

Dopamine: Increases heart rate and blood pressure.

Enkephaline: A class of endorphin that regulates pain responses.