Related Concept Videos

Accessory Structures of the Skin: Hair Growth and Types01:20

Accessory Structures of the Skin: Hair Growth and Types

Hair growth begins with the production of keratinocytes by the basal cells of the hair bulb. As new cells are deposited at the hair bulb, the hair shaft is pushed through the follicle toward the surface. Keratinization is completed as the cells are pushed to the skin surface to form the shaft of hair that is externally visible. The external hair is completely dead and composed entirely of keratin. Hair can be cut or shaven without damaging the hair structure because the cut is superficial. Most...
Drying Shrinkage01:21

Drying Shrinkage

When hardened concrete is exposed to air with a relative humidity of less than 100 percent, it begins to lose the free water within its capillaries. As this water evaporates, the water initially adsorbed onto the calcium silicate hydrates migrates towards these now empty spaces and eventually evaporates as well. Over time, as more water leaves, the volume of the concrete decreases, a phenomenon known as drying shrinkage.
A portion of this drying shrinkage can be reversed; if the concrete is...
PPE Use in Healthcare Settings II: Doffing01:10

PPE Use in Healthcare Settings II: Doffing

The sequence of removing or doffing PPE starts with the gloves, as they are the most contaminated. Next is removal of the face shield or goggles, as they would interfere with removing other PPE. Then remove the gown, followed by the mask or respirator. Perform hand hygiene between steps if hands become contaminated and immediately after removing all PPE. Generally, the outside front and sleeves of the isolation gown, the goggles or the mask, the respirator, and the face shield are contaminated.