Table of contents:
- Get to know the parts of the adrenal glands
- Functions of the outer adrenal glands (adrenal cortex)
- 1. Mineralocorticoid function
- 2. Glucocorticoid function
- 3. Gonadocorticoid function
- The function of the inner adrenal glands, medulla
- 1. Epinephrine
- 2. Norepinephrine
Did you know that there are two adrenal glands? Yes, each gland is located above the kidney and is about half a thumb in size. Even though they are small, the adrenal glands are responsible for producing various hormones in the body.
Healthy adrenal glands help the body's various functions run properly. Thus, disruption of these glands will have a major impact on the body.
Get to know the parts of the adrenal glands
The adrenal glands consist of two parts, namely the adrenal cortex (outer) and the adrenal medulla (inner). The adrenal cortex is responsible for producing three types of hormones, namely mineralocorticoids (cortisol) which regulate sodium in the body, glucocorticoids which increase blood glucose levels, and gonadocorticoids which regulate sex hormones.
If the adrenal cortex stops functioning, the metabolic processes that are essential for our life will stop and result in death. Meanwhile, the adrenal medulla secretes the hormones epinephrine (adrenaline) and norepinephrine (noradenalin) during times of stress.
Functions of the outer adrenal glands (adrenal cortex)
1. Mineralocorticoid function
Mineralocorticoids are steroid hormones that are responsible for maintaining sodium, and maintaining salt and water balance in the body. Primary mineralocorticoids are known as aldosterone, and are secreted by the zona glomerulose (outermost layer) of the adrenal cortex.
This steroid hormone is part of the renin-angiotensin system (RAS) or the renin angiotensin aldosterone-system (Raas). This is a hormonal system that regulates blood pressure and fluid balance in the body. Generally, renin is produced by the kidneys when excess salt and water are removed from the body. Renin triggers the production of angiotensin, which in turn stimulates the adrenal glands to release the hormone aldosterone. The decrease in arterial blood pressure also stimulates renin secretion.
So, together with the renin-angiotensin system, aldosterone helps the kidneys to retain important minerals like sodium. Aldosterone increases renal reabsorption of sodium and excretion of potassium. It helps constrict blood vessels by increasing sodium and water retention, which can increase blood pressure levels. So, this hormone is concerned with regulating blood pressure levels as well.
2. Glucocorticoid function
Glucocorticosteroids are another class of steroid hormones that play an important role in regulating glucose metabolism. Glucocorticosteroids are produced in the fasciculate zones of the adrenal cortex, an example is cortisol.
Cortisol is responsible for regulating carbohydrate, protein, and fat metabolism. Corticosteroids play an important role in regulating the body's inflammatory response.
Corticosteroids can affect the immune system, and can be used as immune-suppressing agents. Secretion is controlled by adrenocorticotropic hormone (ACTH) which is secreted by the pituitary gland.
3. Gonadocorticoid function
Gonadocorticoids or androgenic steroids are secreted by the reticular zone or the innermost layer of the adrenal cortex. Androgens are male sex hormones, and they facilitate the development of secondary sexual characteristics in men. They play an important role in the development of the male sex organs during embryonic development.
Small amounts of female hormones are also produced by the adrenal cortex. However, the effects of androgenic steroids secreted by the adrenal cortex can be masked by the larger amounts of testosterone and estrogen secreted by the testes and ovaries, respectively.
The function of the inner adrenal glands, medulla
The medulla is the inner part of the adrenal glands, and is associated with the production of epinephrine and norepinephrine.
1. Epinephrine
Both epinephrine and norepinephrine are called catecholamines, and they are released by the adrenal glands in response to physical or mental stress. Epinephrine, also known as adrenaline, plays an important role in the conversion of glycogen to glucose, and thus, increases blood sugar levels. This is needed by the body to maintain a smooth supply of blood to the brain and muscles.
It can also increase heart rate and blood pressure, and relax the smooth muscles of the lungs and digestive tract. This hormone dilates the small arteries of the heart, lungs, kidneys, and muscles. Excitement, physical and mental stress, and emotional distress trigger the secretion of this hormone, which prepares our bodies for a "fight or flight" response called "fight or flight."
2. Norepinephrine
Along with epinephrine, norepinephrine also activates mechanisms for the 'fight or' response, by increasing alertness and arousal. When injected as a drug, norepinephrine or noradrenaline can have a constricting effect on the coronary arteries. This causes the tiny blood vessels in the kidneys, digestive system, and skin to shrink. This facilitates the movement of food through the digestive system and increases sweating. It also stimulates glucose release and blood flow to the muscles.
In short, the adrenal glands are responsible for secreting hormones essential for carrying out several important metabolic processes. In addition, they help the body deal with physical and mental stress. Chronic stress can make the glands work so hard that they may eventually tire or become too tired to meet the needs of the adrenal hormones.
