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Answer:
It is normal for there to be veins visible underneath the tongue, partly because the mucous membrane is so thin and translucent in this region, but where these vessels become dilated and tortuous, they may appear round and black like caviar.
What property makes the normal pacemaker region of the heart function as a pacemaker?
The property of the normal pacemaker region is able to provide a normal setting for the heart to beat. It allows the heart to beat at a regular rate.
