|
|
People who have myopia, or nearsightedness, are not able to see objects at a distance but only up close. It occurs when the cornea is either curved too steeply, the eye is too long, or both. This condition is progressive and worsens with time. More than 100 million people in the United States are nearsighted, but only 20% of those are born with the condition. Diet, eye exercise, drug therapy, and corrective lenses can all help manage nearsightedness.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
Throughout history, plants containing cardiac steroids have been used as heart drugs and as poisons (e.g., in arrows used in combat), emetics, and diuretics.
Calcitonin is a naturally occurring hormone. In women who are at least 5 years beyond menopause, it slows bone loss and increases spinal bone density.
![A mother dies, a father loses his leg—such calamities shattered poor urban families. Orphaned street](https://biology-forums.com/gallery/47/medium_6_24_08_15_12_36_55_224282222.jpeg)
![Everyday situations sometimes present opportunities for children to build information processing ...](https://biology-forums.com/gallery/47/medium_667187_21_02_17_7_13_13_256711128.png)