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Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
During pregnancy, a woman is more likely to experience bleeding gums and nosebleeds caused by hormonal changes that increase blood flow to the mouth and nose.
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.
Addicts to opiates often avoid treatment because they are afraid of withdrawal. Though unpleasant, with proper management, withdrawal is rarely fatal and passes relatively quickly.
When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.
![The toxin muscarine comes from the mushroom Amanita muscaria, more commonly known as fly agaric or m](https://biology-forums.com/gallery/47/medium_28062_06_01_13_9_23_24.jpeg)
![The paired-image subtraction technique, which is commonly employed in cognitive neuroscience. Here ...](https://biology-forums.com/gallery/30/medium_548020_05_06_17_10_54_05_302841809.png)