When you press on the gums, release the pressure, and then measure the time it takes for the gums to return to the starting color, you're checking

Capillary refill time

Explanation:

Capillary refill time refers to the time that it takes for color to return to an external capillary bed after pressure has been applied (which causes blanching). Usually, on healthy individuals, capillary refill time takes less than 2 seconds. If the time is much longer, this could indicate problems such as shock, dehydration or peripheral artery disease.

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.