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The adrenal glands (also known as suprarenal glands) are endocrine glands that sit atop the kidneys; in humans, the right suprarenal gland is triangular shaped, while the left suprarenal gland is semilunar shaped.

It is pyramidal in structure and weights about four grams.

These hormones control many important functions in the body, such as:

1. Maintaining metabolic processes, such as managing blood sugar levels and regulating inflammation

2. Regulating the balance of salt and water

3. Controlling the "fight or flight" response to stress

4. Maintaining pregnancy

5. Initiating and controlling sexual maturation during childhood and puberty

Each adrenal gland has two distinct structures, the adrenal cortex and the medulla, both of which produce hormones.

The cortex mainly produces cortisol, aldosterone and androgens, while the medulla chiefly produces epinephrine and norepinephrine.

Parts Of Adrenal Gland

The adrenal cortex is devoted to the synthesis of corticosteroid hormones.

Specific cortical cells produce particular hormones including cortisol, corticosterone, androgens such as testosterone, and aldosterone.

The cortex is regulated by neuroendocrine hormones secreted by the pituitary gland and hypothalamus, as well as by the renin-angiotensin system.

It is divided into 3 zones in the adult gland:

1. Zona Glomerulosa,2. Zona Fasciculata, 3. Zona Rericularis.

Is divided onto 4 zones in the fetal gland.

The three zones of the permanent cortex constitutes only 20% of the fetal gland’s size. The remaining zone (fetal cortex) comprises up to 80% of gland’s size during fetal life.

The outermost layer, the zona glomerulosa is the main site for production of mineralocorticoids, mainly aldosterone,

Aldosterone is largely responsible for the long-term regulation of blood pressure.

Complete failure to secrete aldosterone leads to death (dehydration, low blood volume).

Hyperalsdosterone states: Contribute to hypertension associated with increased blood volume.

Glomerulosa,

Situated between the glomerulosa and reticularis, the zona fasciculata is responsible for producing glucocorticoids, chiefly cortisol in humans.

The zona fasciculata secretes a basal level of cortisol but can also produce bursts of the hormone in response to adrenocorticotropic hormone (ACTH) from the anterior pituitary.

Fasciculata

The inner most cortical layer, the zona reticularis produces androgens, mainly dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S) in humans.

Reticularis

1. Permissive effect on glucagon2. Memory, learning & mood 3. Gluconeogenesis4. Skeletal muscle breakdown5. Lipolysis, calcium balance6. Immune depression7. Circadian rhythms

Use as immunosuppressantHyperimmune reactions (bee stings)Serious side effects

Hypercortisolism (Cushing's syndrome)Tumors (pituitary or adrenal)Iatrogenic (physician caused)

Hypocortisolism (Addison's disease)

The adrenal medulla is the core of the adrenal gland, and is surrounded by the adrenal cortex.

The chromaffin cells of the medulla, named for their characteristic brown staining with chromic acid salts, are the body's main source of the circulating catecholamines adrenaline (epinephrine) and noradrenaline (norepinephrine).

Adrenal Medulla

Derived from the amino acid tyrosine, these water-soluble hormones are major hormones underlying the fight-or-flight response.

adrenal medulla receives input from the sympathetic nervous system through preganglionic fibers originating in the thoracic spinal cord

Adrenal Medulla

the adrenal medulla lacks distinct synapses and releases its secretions directly into the blood.

Cortisol also promotes epinephrine synthesis in the medulla. Produced in the cortex, cortisol reaches the adrenal medulla and at high levels, the hormone can promote the upregulation of phenylethanolamine N-methyltransferase (PNMT), thereby increasing epinephrine synthesis and secretion.

Adrenal Medulla

Although variations of the blood supply to the adrenal glands (and indeed the kidneys themselves) are common, there are usually three arteries that supply each adrenal gland:

1. The superior suprarenal artery is provided by the inferior phrenic artery

2. The middle suprarenal artery is provided by the abdominal aorta

3. The inferior suprarenal artery is provided by the renal artery

Blood Supply

Venous drainage of the adrenal glands is achieved via the suprarenal veins:

1. The right suprarenal vein drains into the inferior vena cava

2. The left suprarenal vein drains into the left renal vein or the left inferior phrenic vein.

Blood Supply

Adrenal Gland Disorders

Adrenal gland disorders occur when the adrenal glands don’t work properly.

Sometimes, the cause is a problem in another gland that helps to regulate the adrenal gland.

In other cases, the adrenal gland itself may have the problem.

Adrenal Gland Disorders

Some examples include:

1. Cushing's Syndrome

2. Congenital Adrenal Hyperplasia

3. Pituitary Tumors

Adrenal Gland Disorders

Some examples include:

1. Cushing's Syndrome

2. Congenital Adrenal Hyperplasia

3. Pituitary Tumors

Treatment

Cushing’s syndrome The treatment for Cushing’s syndrome

depends on the cause. If the excess cortisol is caused by medication, your health care provider can change dosages or try a different medication to correct the problem.

If the Cushing’s syndrome is caused by the body making too much cortisol, treatments may include oral medication, surgery, radiation, or a combination of these treatments.

Treatment

Congenital adrenal hyperplasia Congenital adrenal hyperplasia can’t

be cured, but it can be treated and controlled.  People with congenital adrenal hyperplasia can take medication to help replace the hormones their bodies are not making.

Some people with congenital adrenal hyperplasia only need these medications when they are sick, but others may need to take them every day.

Treatment

Doctors can successfully treat most pituitary tumors with microsurgery, radiation therapy, surgery, drugs, or a combination of these treatments.

Surgery is currently the treatment of choice for tumors that grow rapidly, especially if they threaten or affect vision.The treatment plan for other pituitary tumors differs according to the type and size of the tumor.