Adrenal Gland (Adrenal Cortex) Anatomy, Physiology, Disorders, and Hormones

Summary

In this MedCram video, the focus is on the adrenal cortex, a key component of the adrenal gland situated above the kidneys. The video explains the anatomy of the adrenal cortex, which consists of three layers: the zona glomerulosa, zona fasciculata, and zona reticularis, each responsible for secreting different hormones. These hormones include aldosterone (a mineralocorticoid), cortisol (a glucocorticoid), and androgens. The video also discusses the impact of these hormones on the body and common disorders such as Addison's disease and Cushing's syndrome, outlining how imbalances can affect potassium levels, glucose, sodium, and blood pressure.

Takeaways

• 😀 The adrenal cortex is located on top of the kidneys and is divided into three layers: zona glomerulosa, zona fasciculata, and zona reticularis.
• 😀 The adrenal cortex secretes steroid hormones, which are lipid-soluble and affect protein transcription in the cell nucleus.
• 😀 The outermost layer of the adrenal cortex, zona glomerulosa, produces aldosterone, a mineralocorticoid.
• 😀 Zona fasciculata, the middle layer, produces cortisol, a glucocorticoid, which helps regulate glucose levels in the body.
• 😀 The innermost layer, zona reticularis, primarily produces androgens like testosterone, contributing to male secondary sexual characteristics.
• 😀 Aldosterone acts on the distal convoluted tubules of the kidneys, reabsorbing sodium and excreting potassium and protons.
• 😀 Cortisol helps the body increase glucose through gluconeogenesis and glycogenolysis, especially in stressful situations.
• 😀 Androgens from the adrenal cortex are crucial for sex drive in women and male secondary sexual characteristics.
• 😀 The adrenal cortex's hormone secretion is regulated by ACTH (Adrenocorticotropic Hormone) and potassium levels.
• 😀 Addison's disease occurs when adrenal glands don't function properly, leading to symptoms like hyperkalemia, metabolic acidosis, and hyponatremia.
• 😀 Cushing's syndrome results from excessive cortisol or steroids, causing symptoms like hyperglycemia, high blood pressure, and increased testosterone.

Q & A

What is the adrenal cortex and where is it located?

The adrenal cortex is the outer portion of the adrenal gland, which sits atop the kidneys. The adrenal gland consists of two main parts: the medulla (inner part) and the cortex (outer part).

How is the adrenal cortex structured?

The adrenal cortex is divided into three layers: the outer zona glomerulosa, the middle zona fasciculata, and the inner zona reticularis. These layers are abbreviated as GFR, from outermost to innermost.

What are the main hormones secreted by the adrenal cortex?

The adrenal cortex secretes three main types of hormones: aldosterone (a mineralocorticoid), cortisol (a glucocorticoid), and androgens (such as testosterone).

What is the role of aldosterone?

Aldosterone, produced in the zona glomerulosa, primarily acts at the distal convoluted tubules of the kidneys, promoting the reabsorption of sodium and the excretion of potassium and protons. This helps maintain electrolyte balance and blood pressure.

How does cortisol function in the body?

Cortisol, produced in the zona fasciculata, helps regulate glucose levels in the body. It promotes gluconeogenesis (the creation of glucose from non-carbohydrate sources) and glycogenolysis (the breakdown of glycogen), ensuring the body has enough energy, especially during stress.

What is the function of androgens produced by the adrenal cortex?

Androgens, such as testosterone, are produced in the zona reticularis and are responsible for male secondary sexual characteristics. In women, they also play a role in maintaining sex drive.

What causes aldosterone secretion?

Aldosterone secretion is primarily stimulated by high levels of potassium in the blood. Potassium signals the zona glomerulosa to release aldosterone to help regulate potassium balance.

How does ACTH influence the adrenal cortex?

ACTH (adrenocorticotropic hormone) stimulates the zona fasciculata to produce cortisol and the zona reticularis to produce androgens. ACTH is secreted by the pituitary gland and plays a key role in regulating adrenal gland function.

What would happen in Addison's disease?

In Addison's disease, where the adrenal glands fail to produce hormones, individuals experience symptoms like hyperkalemia (high potassium), metabolic acidosis, hyponatremia (low sodium), hypoglycemia, and low blood pressure due to insufficient aldosterone, cortisol, and androgens.

What are the symptoms of Cushing's syndrome and Cushing's disease?

In Cushing's syndrome, excess cortisol (often from external sources) leads to symptoms like low potassium, high sodium, metabolic alkalosis, hyperglycemia, and increased testosterone. In Cushing's disease, excessive ACTH secretion from the pituitary causes similar symptoms but with a different underlying cause.