Chemical substances having a specific regulatory effect on the activity of a certain organ or organs. The term was originally applied to substances secreted by various ENDOCRINE GLANDS and transported in the bloodstream to the target organs. It is sometimes extended to include those substances that are not produced by the endocrine glands but that have similar effects.
Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000368
Aged
A person 65 years of age or older. For a person older than 79 years, AGED, 80 AND OVER is available.
Elderly
D000375
Aging
The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.
Senescence,Aging, Biological,Biological Aging
D013256
Steroids
A group of polycyclic compounds closely related biochemically to TERPENES. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (STEROLS), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. (From Hawley's Condensed Chemical Dictionary, 11th ed)