Your hearts stops, your blood goes cold and your limbs stiffen. Yet amidst the signs that you are no more, your fingernails continue to lengthen and your hair grows – or so we’re told.
Different cages die with a different speed. So, after cardiac arrest oxygen stops to arrive in a brain, and nervous cages, without possessing a glucose inventory, die within three-seven minutes.
Lengthening of nails is a process of formation of new cages which is impossible without glucose. Average growth rate of a nail - 0,1 mm a day; with age this process is slowed down. An overwhelming part of new cells of a nail is made by a so-called matrix - a fabric layer which is under the basis of a nail plate. New cages force out old, and the nail is displaced forward because of what it seems that his edge grows. After death intake of glucose stops, so, also growth of nails stops.
Similar happens also to hair. Each hair grows from a hair bulb, or a follicle. In the basis of each follicle there is a hair matrix - group of cages from which by division the new cages adding to length hair turn out. These cages share very quickly, but they need energy. Energy arises at combustion of glucose, and oxygen is for this purpose necessary. Once the heart stops pumping oxygen round the body in the blood, the energy supply dries up, and so does the cell division that drives hair growth.
So why do myths persist about stubble growing on dead men’s chins and fingernails lengthening? While such observations are false, they do have a biological basis. It is not that the fingernails are growing, but that the skin around them retracts as it becomes dehydrated, making them appear longer. When preparing a body, funeral directors will sometimes moisturise the fingertips to counteract this.
Skin on a chin of the dead person also loses moisture and shrinks, baring earlier invisible part of hair. The emergence of so-called goose-pimples caused by reduction of the muscles straightening hair strengthens this effect.
Therefore if you are frightened by an image of the cemetery and dead persons whose hair and the long, fancifully twirled nails raise covers of coffins, you can sleep peacefully. It happens in books and horror films - but not actually.
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