|
|
Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
This year, an estimated 1.4 million Americans will have a new or recurrent heart attack.
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.
Eating food that has been cooked with poppy seeds may cause you to fail a drug screening test, because the seeds contain enough opiate alkaloids to register as a positive.
![A typical variable cam timing control valve. The solenoid is controlled by the engine computer and ...](https://biology-forums.com/gallery/29/medium_548020_30_05_17_3_43_29_29648118.png)
![In a multiair engine design, the exhaust valves are opened by the exhaust camshaft lobes. Intake ...](https://biology-forums.com/gallery/30/medium_548020_31_05_17_2_37_19_300551001.png)