Adrenal Cortex - Functions & Details

The adrenal cortex develops in the early weeks of gestation. At this period, the adrenal gland has two sections, such as the foetal and adult definitive zones. This foetal layer compresses and disappears when we are born. The developing gland is mainly responsible for producing adrenal cortex hormones and connects to nerves nearby.

The treatments available for adrenal cortex diseases are:

• Change in lifestyle - Practising healthy habits can reduce stress and strain on the adrenal glands.

• Hormone replacement therapy - This is the case in which the identical hormone is replaced to restore the proper functioning of hormones to a satisfactory level.

• Medication - If the body is producing more hormones than it needs, then medication such as drugs and medicines, is used to avoid that.

• Tumour and cancer treatments - This treatment is used to remove the tumours that are producing the high hormones.

Plastic surgery - This treatment repairs the structures affected by the excess hormonal levels.

We have to take good care of the adrenal cortex in the following ways:

• Taking food that is rich in nutrients

• Following a healthy lifestyle

• Doing meditation and yoga daily

• Taking prevention by practising regular checkups

The adrenal cortex is divided into three distinct zones, each producing different hormones: the zona glomerulosa (outermost), zona fasciculata (middle), and zona reticularis (innermost). This structural organization allows for the efficient production of specific hormones in each zone.

The zona reticularis is the innermost layer of the adrenal cortex and is primarily responsible for producing adrenal androgens like DHEA and androstenedione. These hormones are particularly important during adrenarche (adrenal maturation) in childhood.

Aldosterone, produced in the adrenal cortex, plays a crucial role in water balance by promoting sodium reabsorption in the kidneys. This leads to water retention, helping to maintain blood volume and pressure.

The adrenal cortex produces small amounts of sex hormones (androgens and estrogens). In women, these adrenal androgens can be significant contributors to overall androgen levels. Additionally, excessive cortisol can interfere with reproductive function in both sexes.

Adrenal hyperplasia refers to an increase in the number of cells in the adrenal cortex, while adrenal hypertrophy refers to an increase in the size of existing cells. Both can result in enlarged adrenal glands but occur through different cellular mechanisms.

Glucocorticoids like cortisol can have negative effects on bone metabolism when present in excess. They inhibit bone formation by suppressing osteoblast activity and increase bone resorption, potentially leading to osteoporosis with long-term exposure.

Cortisol promotes lipolysis (breakdown of fat) in adipose tissue, releasing fatty acids into the bloodstream. It also stimulates fat redistribution, which can lead to characteristic fat deposits in conditions like Cushing's syndrome.

In acute stress, the adrenal cortex rapidly increases cortisol production to help the body cope. In chronic stress, there's sustained activation of the HPA axis, which can lead to dysregulation of cortisol production and potentially adrenal fatigue over time.

Cortisol production follows a circadian rhythm, with levels highest in the early morning and lowest at night. This rhythm is controlled by the suprachiasmatic nucleus in the brain, which regulates the release of CRH and ACTH throughout the day.

Addison's disease is a condition where the adrenal cortex doesn't produce enough hormones, particularly cortisol and aldosterone. This can result from autoimmune destruction of the adrenal cortex or other causes of adrenal insufficiency.

Cushing's syndrome results from excessive cortisol in the body, which can be caused by overproduction in the adrenal cortex or by taking glucocorticoid medications. Symptoms include weight gain, thinning skin, easy bruising, and muscle weakness.

CAH is a group of genetic disorders affecting enzyme production in the adrenal cortex. This leads to imbalances in hormone production, often resulting in decreased cortisol and increased androgen levels, which can cause various symptoms depending on the specific enzyme deficiency.

Chronic stress can lead to prolonged activation of the HPA axis, resulting in sustained high levels of cortisol. Over time, this can lead to dysregulation of the axis, potentially causing problems like adrenal fatigue or resistance to cortisol's effects.

Adrenal insufficiency is a broader term referring to inadequate production of adrenal hormones. While Addison's disease specifically refers to primary adrenal insufficiency (problem in the adrenal glands themselves), secondary adrenal insufficiency can occur due to problems in the pituitary or hypothalamus.

The adrenal cortex produces three main types of hormones: mineralocorticoids (primarily aldosterone), glucocorticoids (primarily cortisol), and androgens (such as DHEA and androstenedione).

The adrenal cortex produces aldosterone, which regulates sodium and potassium balance in the body. Aldosterone increases sodium reabsorption and potassium excretion in the kidneys, helping maintain proper electrolyte levels and blood pressure.

Adrenal androgens, like DHEA and androstenedione, are considered weak because they have less potent androgenic effects than testosterone, which is primarily produced in the testes. However, adrenal androgens can be converted to testosterone in peripheral tissues.

The adrenal cortex produces cortisol, which plays a crucial role in glucose metabolism. Cortisol increases blood glucose levels by promoting gluconeogenesis in the liver, breaking down protein for energy, and reducing glucose uptake in peripheral tissues.

Glucocorticoids like cortisol have immunosuppressive effects. They reduce inflammation by inhibiting the production of inflammatory mediators and suppressing the activity of immune cells. This is why synthetic glucocorticoids are used to treat various inflammatory and autoimmune conditions.

The hypothalamic-pituitary-adrenal (HPA) axis regulates adrenal cortex function. The hypothalamus releases corticotropin-releasing hormone (CRH), which stimulates the pituitary to release adrenocorticotropic hormone (ACTH). ACTH then stimulates the adrenal cortex to produce cortisol.

When cortisol levels in the blood rise, they inhibit the release of CRH from the hypothalamus and ACTH from the pituitary. This negative feedback loop helps maintain appropriate cortisol levels in the body.

Aldosterone increases blood pressure by promoting sodium retention and potassium excretion in the kidneys. This leads to increased water retention, which increases blood volume and, consequently, blood pressure.

Cortisol is called the "stress hormone" because its production increases in response to physical or emotional stress. It helps the body cope with stress by mobilizing energy resources, suppressing non-essential functions, and modulating the immune system.

While the adrenal medulla is primarily responsible for the immediate "fight or flight" response, the adrenal cortex supports this by increasing cortisol production. Cortisol helps maintain this response by increasing blood glucose levels and enhancing the effects of adrenaline.

Cholesterol is the precursor for all steroid hormones produced in the adrenal cortex. The adrenal glands can synthesize cholesterol, take it up from the bloodstream, or use stored cholesterol to produce hormones as needed.

During fetal development, the adrenal cortex is relatively large and produces androgens that are important for proper development. After birth, the fetal adrenal cortex regresses, and the adult cortex takes over hormone production.

The blood-adrenal barrier, formed by endothelial cells in adrenal capillaries, regulates the passage of molecules between blood and adrenal tissue. It helps control the delivery of hormones and their precursors to and from the adrenal cortex.

An adrenal incidentaloma is a mass found incidentally on the adrenal gland during imaging for unrelated reasons. While often benign and non-functional, some can produce excess hormones, affecting normal adrenal cortex function.

The RAAS is a hormone system that regulates blood pressure and fluid balance. Angiotensin II, produced in this system, stimulates the adrenal cortex to release aldosterone, which in turn increases sodium and water retention, helping to maintain blood pressure.

Cortisol, produced by the adrenal cortex, promotes protein catabolism (breakdown) in most body tissues except the liver. This provides amino acids for gluconeogenesis, helping to maintain blood glucose levels during stress or fasting.

Aldosterone, produced by the adrenal cortex, can increase salt appetite. This is part of the body's mechanism to maintain sodium balance and blood pressure, especially when sodium levels are low.

Aldosterone, produced by the adrenal cortex, plays a role in acid-base balance by promoting potassium excretion and hydrogen ion secretion in the kidneys. This helps maintain proper pH levels in the body.

StAR is crucial for steroid hormone production in the adrenal cortex. It facilitates the transport of cholesterol from the outer to the inner mitochondrial membrane, which is the rate-limiting step in steroidogenesis.

Adrenal cortex hormones have various effects on the cardiovascular system. Aldosterone increases blood volume and pressure, while cortisol increases cardiac output and blood pressure by enhancing the sensitivity of blood vessels to catecholamines.

Cortisol plays a complex role in wound healing. In normal amounts, it supports the inflammatory phase of healing. However, excessive cortisol can impair wound healing by suppressing inflammation and collagen synthesis.

21-hydroxylase is a crucial enzyme in the synthesis of both mineralocorticoids and glucocorticoids. Deficiency of this enzyme is the most common cause of congenital adrenal hyperplasia, leading to imbalances in adrenal hormone production.

In hemorrhagic shock, the adrenal cortex increases cortisol production to help maintain blood pressure, enhance the effects of catecholamines on blood vessels, and mobilize energy resources to cope with the stress of blood loss.

During fasting, cortisol from the adrenal cortex helps maintain blood glucose levels by promoting gluconeogenesis in the liver, breaking down protein for energy, and reducing glucose uptake by peripheral tissues.

Cortisol affects mood and cognitive function through its actions on the brain. Normal cortisol rhythms are important for cognitive performance and mood regulation. However, both excessive and deficient cortisol levels can negatively impact mood and cognition.

There's a complex interplay between adrenal and thyroid function. Cortisol can inhibit the conversion of T4 to active T3 thyroid hormone. Conversely, thyroid hormones can affect the metabolism of cortisol. This interaction is important in maintaining overall metabolic balance.

During infection, the adrenal cortex increases cortisol production. Cortisol helps regulate the immune response, reducing inflammation while also maintaining blood pressure and glucose levels to support the body's fight against infection.

The adrenal cortex, through its production of aldosterone, helps maintain blood pressure during postural changes. Aldosterone promotes sodium and water retention, which helps maintain blood volume and pressure when standing up.

Cortisol levels follow a circadian rhythm, with highest levels in the early morning, helping to wake us up. Disruptions in this rhythm can affect sleep patterns. Conversely, sleep disturbances can also disrupt normal cortisol rhythms.

3β-hydroxysteroid dehydrogenase is a crucial enzyme in the synthesis of all classes of steroid hormones in the adrenal cortex. Deficiency of this enzyme can lead to various forms of congenital adrenal hyperplasia, affecting multiple hormone pathways.

In severe illness or trauma, the adrenal cortex dramatically increases cortisol production. This helps maintain blood pressure, mobilize energy resources, and modulate the immune response to cope with the physiological stress of illness or injury.

During prolonged exercise, the adrenal cortex increases aldosterone production to help maintain electrolyte balance. Aldosterone promotes sodium retention and potassium excretion, which is crucial for maintaining proper hydration and electrolyte levels during extended physical activity.

Cortisol can influence appetite and food intake in several ways. It can increase appetite, particularly for high-calorie foods. It also interacts with other hormones like insulin and leptin, which regulate hunger and satiety. Chronic high cortisol levels can lead to increased abdominal fat deposition.