"Steroidal Hormones"

Cholesterol:

Cholesterol is a structural component of cell membranes and serves as a building block for synthesizing various steroidal hormones, vitamin D, and bile acids.

Steroidal hormones

Steroidal hormones, also known as steroids, are a group of lipid-based hormones derived from cholesterol. These hormones include glucocorticoids, mineralocorticoids, and sexual hormones (such as testosterone and estrogen). They are produced and released by various endocrine glands, including the adrenal cortex, gonads, and placenta (during pregnancy).

Major Classes of Steroid Hormones

There are three major classes of steroid hormone

1. Glucocorticoids

2. Mineralocorticoids

3. Sex steroids. 

Glucocorticoids

Glucocorticoids are steroid hormones produced from the cortex of the adrenal glands.

Function

· Regulate glucose in the blood and also convert lipids to glucose.

· Glucocorticoids have a pivotal role in the glucose, protein, and fat metabolism of the body.

· These are the steroid hormones that affect energy metabolism (among a large variety of other actions). The primary glucocorticoids in humans are cortisol.

Types

Glucocorticoids can be natural or synthetic. 

2. Mineral corticoids

 The primary human mineralocorticoids are aldosterone. Aldosterone increases sodium reabsorption and potassium secretion by the kidneys. It exerts its main effects on sodium and potassium balance by binding to the mineralocorticoid receptor (MCR) located in the distal convoluted tubule, connecting the segment and cortical collecting duct in the kidney.

Source and Control of Secretion

Like glucocorticoids, mineralocorticoids are a mixture of steroid hormones from the adrenal cortex. In humans, aldosterone is essentially the only mineralocorticoids that affect body functions. Aldosterone secretion is controlled by four negative feedback mechanisms that operate through the kidneys. These mechanisms help maintain homeostasis by regulating blood pressure, osmotic pressure, and blood levels of sodium and potassium.

Effects

Aldosterone and other mineralocorticoids cause these adaptive responses by stimulating the kidney tubules to reabsorb sodium and water and secrete potassium and/or acids.