|
|
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.
The liver is the only organ that has the ability to regenerate itself after certain types of damage. As much as 25% of the liver can be removed, and it will still regenerate back to its original shape and size. However, the liver cannot regenerate after severe damage caused by alcohol.
Disorders that may affect pharmacodynamics include genetic mutations, malnutrition, thyrotoxicosis, myasthenia gravis, Parkinson's disease, and certain forms of insulin-resistant diabetes mellitus.
After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.
All adults should have their cholesterol levels checked once every 5 years. During 2009–2010, 69.4% of Americans age 20 and older reported having their cholesterol checked within the last five years.
![The sexual cycle of flowering plants involves alternation of sporophyte and gametophyte generations.](https://biology-forums.com/gallery/47/medium_33_24_07_11_10_29_04.jpeg)
![The proportion of men and women with elevated blood pressure or taking hypertension medication incre](https://biology-forums.com/gallery/47/medium_102911_16_06_15_7_18_43_220301505.jpeg)