steroid

Examples of steroid in the following topics:

• Steroids

  • Unlike phospholipids and fats, steroids have a fused ring structure.
  • Many steroids also have the –OH functional group, and these steroids are classified as alcohols called sterols.
  • Therefore, steroids play very important roles in the body's reproductive system.
  • Thus, steroids also play an important role in the structure and function of membranes.
  • Steroids, such as cholesterol and cortisol, are composed of four fused hydrocarbon rings.

• Anabolic Steroids and Muscles

  • Anabolic steroids , known technically as anabolic-androgen steroids (AAS) or colloquially as "steroids" (or even "roids"), are drugs that mimic the effects of testosterone and dihydrotestosterone in the body.
  • The pharmacodynamics of anabolic steroids are unlike peptide hormones.
  • Some hypothesize that this reduction in muscle breakdown may occur by way of anabolic steroids inhibiting the action of other steroid hormones called glucocorticoids, which promote the breakdown of muscles.
  • This makes steroids attractive to those wishing to alter their appearance, particularly for body building.
  • In addition, because steroids are often injected, users risk contracting or transmitting HIV or hepatitis.

• Steroids

  • Sterols are special forms of steroids, with a hydroxyl group at position-3 and a skeleton derived from cholestane.
  • Hundreds of distinct steroids are found in plants, animals, and fungi.
  • All steroids are made in cells either from the cycloartenol (plants) or sterols lanosterol (animals and fungi) .
  • Steroid biosynthesis is an anabolic metabolic pathway that produces steroids from simple precursors.
  • This is the stick model of the steroid lanosterol.

• Steroids

  • Examples of some important steroids are shown in the following diagram.
  • Different kinds of steroids will be displayed by in the diagrams below.
  • Norethindrone is a synthetic steroid, all the other examples occur naturally.
  • With the exception of C-5, natural steroids generally have a single common configuration.
  • Consequently, the steroid molecule is locked in the all chair conformation shown here.

• Signaling Molecules

  • Important members of this class of ligands are the steroid hormones.
  • Steroids are lipids that have a hydrocarbon skeleton with four fused rings; different steroids have different functional groups attached to the carbon skeleton.
  • Steroid hormones include the female sex hormone, estradiol, which is a type of estrogen; the male sex hormone, testosterone; and cholesterol, which is an important structural component of biological membranes and a precursor of steriod hormones .
  • Steroid hormones have similar chemical structures to their precursor, cholesterol.

• Lipid-Derived, Amino Acid-Derived, and Peptide Hormones

  • The primary class of lipid hormones in humans is the steroid hormones.
  • Examples of steroid hormones include estradiol, which is an estrogen, or female sex hormone, and testosterone, which is an androgen, or male sex hormone.
  • Other steroid hormones include aldosterone and cortisol, which are released by the adrenal glands along with some other types of androgens.
  • Steroid hormones are insoluble in water; they are carried by transport proteins in blood.
  • The structures shown here represent (a) cholesterol, plus the steroid hormones (b) testosterone and (c) estradiol.

• Intracellular Hormone Receptors

  • Lipid-derived (soluble) hormones such as steroid hormones diffuse across the lipid bilayer membranes of the endocrine cell.
  • The cell signaling pathways induced by the steroid hormones regulate specific genes within the cell's DNA.
  • In this way, the steroid hormone regulates specific cell processes .
  • Other lipid-soluble hormones that are not steroid hormones, such as vitamin D and thyroxine, have receptors located in the nucleus.
  • The hormone-receptor complex stimulates transcription of specific genes in the same way that steroid hormones do.

• The Endocrine System and Stress

  • The hypothalamic-pituitary-adrenal (HPA or HTPA) axis is a complex set of direct influences and steroid-producing feedback interactions among the hypothalamus, the pituitary gland, and the adrenal glands.
  • All vertebrates have an HPA, but the steroid-producing stress response is so important that even invertebrates and monocellular organisms have analogous systems.
  • The ACTH acts on the adrenal cortex, which produces steroids—in humans, primarily the steroid cortisol.
  • This causes a negative feedback cycle in which the steroids inhibit the hypothalamus and the pituitary gland, and it also causes the adrenal gland to produce the hormones epinephrine (also known as adrenaline) and norepinephrine.

• Transport of Hormones

  • There are two types of hormones secreted in the endocrine system: Steroidal (or lipid based) and non-steroidal, (or protein based) hormones.The endocrine system regulates its hormones through negative feedback, except in very specific cases like childbirth.
  • Hormones can diffuse through the plasma membrane of the cell if they are lipid soluble (as in the case of steroid hormones and hormones of the thyroid gland).

• Tenosynovitis

  • Mild tenosynovitis causing small scale swelling can be treated with non-steroidal anti-inflammatory drugs (NSAID) such as Naproxen, ibuprofen, or diclofenac (marketed as Voltaren and other trade names), taken to reduce inflammation and as an analgesic.
  • More acute cases are treated with cortisone (steroid) injections, then a course of paracetamol and ibuprofen for pain.