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Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
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.
Studies show that systolic blood pressure can be significantly lowered by taking statins. In fact, the higher the patient's baseline blood pressure, the greater the effect of statins on his or her blood pressure.
Not getting enough sleep can greatly weaken the immune system. Lack of sleep makes you more likely to catch a cold, or more difficult to fight off an infection.
Amoebae are the simplest type of protozoans, and are characterized by a feeding and dividing trophozoite stage that moves by temporary extensions called pseudopodia or false feet.