Control of sebaceous glands is hormonal. Enlargement of the acini occurs at puberty.
Hairs are long, filamentous projections consisting of dead keratini—zed epidermal cells. Each hair derives from an epidermal invagination called the hair follicle, which possesses a terminal hair bulb, located in the dermis or hypo—dermis, from which the hair shaft grows. Contraction of smooth muscles raise the hairs and dimple the epidermis («goose flesh»).
Nails, like hair, are a modified stratum corneum of the epidermis. They contain hard keratin that forms in a manner similar to the formation of hair. Cells continually proliferate and keratinize from the stratum basale of the nail matrix.
New words
cutaneous – кожный
appendace – покров
tubular – трубчатый
pyramidal – пирамидальный
surface – поверхность
thermal – тепловой
innervation – иннервация
7. Matter
Matter is anything that occupies space, possesses mass and can be perceived by our sense organs. It exists in nature in three, usually inter convertible physical states: solids, liquids and gases. For instance, ice, water and steam are respectively the solid, liquid and gaseous states of water. Things in the physical world are made up of a relatively small number of basic materials combined in various ways. The physical material of which everything that we can see or touch is made is matter. Matter exists in three different states: solid, liquid and gaseous. Human senses with the help of tools allow us to determine the properties of matter. Matter can undergo a variety of changes – physical and chemical, natural and controlled.