Those mall trips are infrequent—about once a month. More often, Athena and her friends spend time together on their phones, unchaperoned. Unlike the teens of my generation, who might have spent an evening tying up the family landline with gossip, they talk on Snapchat, the smartphone app that allows users to send pictures and videos that quickly disappear. They make sure to keep up their Snapstreaks, which show how many days in a row they have Snapchatted with each other. Sometimes they save screenshots of particularly ridiculous pictures of friends. “It’s good blackmail,” Athena said. (Because she’s a minor, I’m not using her real name.) She told me she’d spent most of the summer hanging out alone in her room with her phone. That’s just the way her generation is, she said. “We didn’t have a choice to know any life without iPads or iPhones. I think we like our phones more than we like actual people.”
steroids, class of lipids having a particular molecular ring structure called the cyclopentanoperhydro-phenanthrene ring system. Steroids differ from one another in the structure of various side chains and additional rings. Steroids are common in both plants and animals. In humans, steroids are secreted by the ovaries and testes, the adrenal cortex (see adrenal gland ), and the placenta.
The range of steroids is diverse, including several forms of vitamin D, digitalis, sterols (., cholesterol ), and the bile acids. Many steroids are biologically active hormones that control a number of the body's metabolic processes. This group includes the male sex hormone testosterone and the female sex hormones estrogen and progesterone . The steroid hormones of the adrenal cortex include glucocorticoids such as cortisone and cortisol (see also corticosteroid drug ) and mineralocorticoids such as aldosterone .
Natural or synthetic steroids are used in oral contraceptives and in the treatment of arthritis , Addison's disease , and certain skin ailments. Side effects, related to dosage and length of treatment, can be serious and include high blood pressure, edema, unwanted hair growth, and menstrual cycle disruption. Anabolic steroids , male hormones given to build up strength in seriously ill patients, have been abused by bodybuilders and athletes in an attempt to increase muscle mass and strength.