Many steels add to the iron-steel mix other metals that give the entire substance desirable properties such as strength, heat resistance, or flexibility. Steel is considered a mixture rather than a compound because the iron does not chemically bond with the carbon and other components.
Some of estrogen's effects include: 1  Increasing serotonin, and the number of serotonin receptors in the brain. 2  Modifying the production and the effects of endorphins, the feel-good chemicals in the brain. 3  Protecting nerves from damage, and possibly stimulating nerve growth.
During puberty, it's normal for levels of estrogen to rise. Thatâs because this hormone fuels changes in a young girl's body. For example, it plays a role in the development of breasts, a more mature curved figure, fuller hips, and pubic and underarm hair.