Under the hair accessories or peripheral organs we mean hair sebaceous gland and muscle, which erects the hair:
1 - epidermis (cuticle); 2 - dermis (skin); 3 - hipodermis (subcutaneous tissue); 4 - subcataneous fat; 5 - arrector pili muscle; 6 - hair follicle; 7 - vien; 8 - sweat gland; 9 - sweat pore; 10 - sebaceous gland; 11 - hair shaft

 

The sebaceous glands - in humans, sebaceous glands are primarily found in association with hair follicles but also occur in hairless areas of the skin, except for the palms of the hand and soles of the feet. Sebaceous glands together with hair follicle is called pilosebaceous unit. These units are found everywhere on the body except on the palms, soles, top of the feet, and the lower lip. The number of pilosebaceous units is greatest on the face, upper neck, and chest. Sebaceous glands produce a substance called sebum, which is responsible for keeping the skin and hair moisturized. The sebaceous gland secretes sebum - a semi-fluid secretion consisting chiefly of fat, keratin, and cellular material. The cells at the periphery of the gland are small, nucleated, and devoid of lipid (fat). These cells divide and are displaced into the center of the gland where they produce and accumulate lipid. They then lose their sub-cellular organelles, disintegrate and release their contents into the sebaceous duct. The cells are often divided into several lobes of the sebaceous gland connected together by a sebaceous duct. The duct has a single opening into the tube where the hair fiber sits. The sebaceous duct empties into the hair canal at the border of the isthmus and infundibulum. In addition to its role in producing sebum, the sebaceous gland may also be important in normal hair shaft outgrowth. Generally the sebum is deposited on the hairs inside the follicles and is brought up to the surface of the skin along the hair shaft. In hairless areas, the sebum surfaces through ducts. Sebum lubricates and protects the hair and skin and prevents drying and irritation of membranes. During adolescence, sebaceous glands enlarge and produce more sebum under the influence of hormones called androgens. After about age 20, sebum production begins to decrease. In the pilosebaceous unit, sebum produced by the sebaceous gland combines with cells being sloughed off within the hair follicle and "fills up" the hair follicle. When the follicle is "full," the sebum spreads over the skin surface giving the skin an oily appearance. When this process works correctly, the skin is moisturized and remains healthy. If the sebaceous gland does not produce enough sebum, the skin is dry. Sebum may collect excessively as a result of poor hygiene, a diet rich in fats, or accelerated glandular activity, especially during adolescence. Excessive secretions of sebum may be related certain forms of baldness and other skin disorders, skin condition called seborrhea. If sebum gets trapped in the pore, acne can develop.

The arrector pili muscle is connected to the epidermis at the other end. The contraction of the muscle pulls on both the hair to make it erect and pulls on the skin making a bumpy surface.