describe the location, structure, and function ofsebaceous and ceruminous glands; and
describe the location, structure, and function of
sebaceous and ceruminous glands; and
The human skin is made up of epidermis, dermis and hypodermis. The epidermis forms the barrier and protects the body against pathogens and infections. The dermis is the middle layer in which there is presence of connective tissue made up of collagen and sebacious glands, nerve endings, hair follicles etc. The hypodermis is the third layer which consists of fat cells, blood vessels, nerve endings etc.
The sebaceous glands are present in the dermis layer of the skin whereas the ceruminous glands are present in the ear.
The sebaceous gland is an exocrine gland that secretes sebum which is an acidic secretion having a pH of 3.5. It opens into the hair follicles and secretes sebum there which is responsible for the lubrication of the hair and skin. These glands have a density of approximately 100/cm2 throughout the skin. In humans, they are present all over the skin except the palms. of the hands and soles of the foot. These glands are also present on the face, scalp, eyelids, area surrounding the female nipple, genitals.
Their number is elevated in the anogenital area, scalp, face, chest and neck. In other areas they are few in number.
The corners of the lip, nipple,areola, anal area, genital area the sebaceous glands open directly onto the surface of skin.
The sebaceous glands are holocrine in nature and their secretion is continuous. During the secretion mechanism, there is accumulation of sebum in the secreting cells and the volume increases as well as the size of the cells increase resulting in the bursting of the cells. So therefore they are called as exocrine glands.
The composition of the sebum-
Triglycerides, wax, free fatty acids, cholesterol and other substances. After production, the sebum is released through the orifice of the gland, hair follicles. After mixing with the lipids of the skin and with the aqueous part of sweat and perspiration, a thin superficial emulsion called as cutaneous hydrolipid is formed.
Functions of sebum-It forms hydrolipid layer with the help of sweat, this emulsion protects the skin from chemicals and microbial agents. The second function is to lubricate and make the external surface of the hair waterproof as the hair grows.
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