Steroid fused ring system

External irritants can sometimes cause a previously retractable prepuce to become non-retractable due to swelling of the tissues. If a child whose prepuce was retractable becomes non-retractable, environmental factors should be investigated. One known culprit is bubble bath. If a child is taking bubble baths and the prepuce becomes non-retractable, the bubble bath should be discontinued. See Penile Hygiene in the Intact Non-circumcised Male for comprehensive information on foreskin care.

Because steroids are lipophilic, they diffuse easily through the cell membranes, and therefore have a very large distribution volume. In their target tissues, steroids are concentrated by an uptake mechanism which relies on their binding to intracellular proteins (or " receptors ", see below). High concentration of steroids are also found in adipose tissue, although this is not a target for hormone action. In the human male, adipose tissue contains aromatase activity, and seems to be the main source of androgen-derived estrogens found in the circulation. But most of the peripheral metabolism occurs in the liver and to some extent in the kidneys, which are the major sites of hormone inactivation and elimination, or catabolism (see below).

The chair conformation is the favored configuration, because in this conformation, the steric strain , eclipsing strain , and angle strain that are otherwise possible are minimized. [4] Which of the possible chair conformations predominate in cyclohexanes bearing one or more substituents depends on the substiuents, and where they are located on the ring; generally, "bulky" substituents—those groups with large volumes , or groups that are otherwise repulsive in their interactions [ citation needed ] —prefer to occupy an equatorial location. [4] An example of interactions within a molecule that would lead to steric strain , leading to a shift in equilibrium from boat to chair, is the interaction between the two methyl groups in cis -1,4-dimethylcyclohexane. In this molecule, the two methyl groups are in opposing positions of the ring (1,4-), and their cis stereochemistry projects both of these groups toward the same side of the ring. Hence, if forced into the higher energy boat form, these methyl groups are in steric contact, repel one another, and drive the equilibrium toward the chair conformation. [ citation needed ]

Steroid fused ring system

steroid fused ring system

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