United States or Benin ? Vote for the TOP Country of the Week !
A typical sweat gland consists of a tube which, starting at the surface of the cuticle, penetrates to the under portion of the true skin and there forms a ball-shaped coil. The coiled extremity, which forms the secreting portion, is lined with secreting cells and surrounded by a network of capillaries. Outer layer of skin or cuticle. b. Dermis or true skin. d, e.
The hair and the nails are important modifications of the epidermis. *A Hair* is a slender cylinder, formed by the union of epidermal cells, which grows from a kind of pit in the dermis, called the hair follicle. The oval and somewhat enlarged part of the hair within the follicle is called the root, or bulb, and the uniform cylinder beyond the follicle is called the shaft.
Local fever, and that to a considerable extent, becomes established; it reacts on the general economy of the animal, who scarcely moves from his bed, and at length refuses all food. At other times a separation takes place between the dermis and the epidermis, which is a perfect mass of serosity.
No blood vessels are found in the epidermis, its nourishment being derived from the lymph which reaches it from the dermis. Only the part next to the dermis is made up of living cells. These are active, however, in the formation of new cells, which take the place of those that are worn off at the surface. The epidermis contains no nerves and is therefore non-sensitive.
It is able to protect the body on account of the tough connective tissue in the dermis, the non-sensitive cells of the epidermis, and also by the touch corpuscles and their connecting nerve fibers. This protection is of at least three kinds, as follows: 1. From mechanical injuries such as might result from contact with hard, rough, or sharp objects.
Deep in the substance of the true skin, or in the fatty tissue beneath it, are the sweat glands. Each gland consists of a single tube with a blind end, coiled in a sort of ball about 1/60 of an inch in diameter. From this coil the tube passes upwards through the dermis in a wavy course until it reaches the cuticle, which it penetrates with a number of spiral turns, at last opening on the surface.
Seiffert examined a case of this nature in a young man of nineteen, and, contrary to Kopp's supposition, found that in some skin from over the left second rib the elastic fibers were quite normal, but there was transformation of the connective tissue of the dermis into an unformed tissue like a myxoma, with total disappearance of the connective-tissue bundles.
Compare the dermis and the epidermis with reference to thickness, composition, and function. To what is the color of the skin due? How is the color of the skin affected by the sunlight? What modifications of the epidermis are found on our bodies? What are found on the body of a chicken? What different kinds of protection are provided by the skin? How does the perspiration cool the body?
The main quality needed for resisting mechanical injuries is toughness, and this is supplied both by the epidermis and by the connective tissue of the dermis. From chemical injuries caused by contact with various chemical agents, as acids, alkalies, and the oxygen of the air.
Sweat gland and duct. i, k. Hair and follicle. l. Oil gland. On the outer surface of the dermis are numerous elevations, called papillæ. These average about one one-hundredth of an inch in height, and one two hundred and fiftieth of an inch in diameter. They are most numerous on the palms of the hands, the soles of the feet, and the under surfaces of the fingers and toes.
Word Of The Day