|
|
The human body produces and destroys 15 million blood cells every second.
Giardia is one of the most common intestinal parasites worldwide, and infects up to 20% of the world population, mostly in poorer countries with inadequate sanitation. Infections are most common in children, though chronic Giardia is more common in adults.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
Barbituric acid, the base material of barbiturates, was first synthesized in 1863 by Adolph von Bayer. His company later went on to synthesize aspirin for the first time, and Bayer aspirin is still a popular brand today.
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
![Modern primate study sometimes involves high-tech methods. This golden lion tamarin is having a batt](https://biology-forums.com/gallery/47/medium_269691_26_01_15_5_55_22_204311589.jpeg)
![Running time on 100-meter sprint for men and women master athletes increases with age. Source: Korho](https://biology-forums.com/gallery/47/medium_102911_16_06_15_7_18_43_220328.jpeg)
![The percentage of never-married men and women decreases with age, and by the age of 65, more than ...](https://biology-forums.com/gallery/47/medium_660365_23_12_16_3_52_08_243731791.jpeg)