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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.
Vital signs (blood pressure, temperature, pulse rate, respiration rate) should be taken before any drug administration. Patients should be informed not to use tobacco or caffeine at least 30 minutes before their appointment.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
In 1835 it was discovered that a disease of silkworms known as muscardine could be transferred from one silkworm to another, and was caused by a fungus.
As the western states of America were settled, pioneers often had to drink rancid water from ponds and other sources. This often resulted in chronic diarrhea, causing many cases of dehydration and death that could have been avoided if clean water had been available.