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Monday, May 30, 2011

Types Of Glands - Lesson 246

In this post we  would learn about glands of different types.
1. Sebaceous Glands: These glands are located in the corium layer of the skin over the entire body, ;with the exception of the palms (hands) and soles (feet). The oily substance which they secrete is called sebum. Sebum, which contains lipids, lubricates the skin and minimizes water loss. The sebaceous glands which are closely associated with hair follicles, and their ducts open into the hair follicle through which the sebum is released. These sebaceous are influenced by sex hormones, which cause them to hypertrophy at puberty and atrophy in old age. Overproduction of sebum during puberty contributes to blackhead (comedo) formation and acne in some individuals.

2. Sweat Glands: These glands are tiny, coiled glands found on almost all body surfaces (about two million in the body). In the palm of the hand they are very large in number (3000 glands per sq in) and on the sole of the foot. The coiled sweat gland originates deep in the corium and straightens out to extend up through the epidermis. The tiny opening on the surface is called a pore. 

The form of sweat, or perspiration is almost pure water, with dissolved materials such as salt making up less than 1 per cent of the total composition. It is colorless and odorless. The odor produced when sweat accumulates on the skin is due to the action of bacteria on the sweat. Sweat which cools the body as it evaporates into the air. The sympathetic nervous system controls the perspiration, whose nerve fibres are activated by the heart regulatory center in the hypothalamic region of the brain, which stimulates sweating.

The sweat gland which is a kind of special variety is active only from puberty onward and larger than the ordinary kind is concentrated in a few areas of the body which is adjacent the reproductive organs and the armpits. These glands, would secrete an odorless sweat, but it contains certain substances that are easily broken down by bacteria on the skin. The breakdown products are responsible for the characteristic human body odor. The milk-producing mammary gland is another type of modified sweat gland: it secretes milk only after the birth of a child.

In the next post we would go through vocabulary.

Tags: sebaceous sweat glands, sebaceous gland carcinoma, sebaceous glands hair follicles, overactive sweat glands, infected sweat glands, swollen sweat glands, blocked sweat gland, sweat glands in armpit, what are sweat glands, removal of sweat glands

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