Lipid-Derived Hormones (or Lipid-soluble Hormones) Most
lipid hormones are derived from cholesterol and thus are structurally similar to it, as
illustrated in Figure 151. The primary class of lipid hormones in humans is the steroid hormones.
Chemically, these hormones are usually ketones or alcohols; their chemical names will end in “-ol”
for alcohols or “-one” for ketones. Examples of steroid hormones include estrogens (such as estradiol)
and androgens (such as testosterone), both of which regulate bone and tissue development in all
humans.
Steroid and peptide hormones are both examples of gonadal hormones, which are made by
the gonads. The chemical structures of androgens and estrogens are similar and they both come from
the same molecule. While androgens are the primary drivers of sexual development in the testicular
reproductive system, estrogens are the primary drivers in the ovarian reproductive system. Estradiol
and progesterone, two steroid hormones, are produced by the ovaries. Some of the androgens
produced are later changed into estrogens. By converting testosterone to estrogen, aromatase enzymes
in the adipose, brain, skin, and bone produce trace amounts of estrogen. Both the adrenal cortex and
the testes secrete testosterone.
Aldosterone and cortisol are additional steroid hormones that are released by the adrenal
glands along with some other kinds of androgens. Insoluble in water, steroid hormones are carried by
transport proteins in the blood. They stay in the body longer than peptide hormones as a result.
Cortisol, for instance, has a half-life of 60 to 90 minutes, whereas the hormone epinephrine, which is
derived from an amino acid, has a half-life of about one minute.
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(credit a: modification of work by Uniformed Services University; credit b: modification of work by Jurjen Broeke;
scale-bar data from Matt Russell)