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 all exocrine glands (secretions via ducts)  Sebaceous glands  Sweat glands  Hair/hair follicles  Nails © 2015 Pearson Education, Inc.

Dermal papillae Hair shaft Pore Appendages of skin Eccrine sweat gland Arrector pili muscle Sebaceous (oil) gland Hair follicle Hair root Cutaneous vascular plexus Adipose tissue Epidermis Dermis Papillary layer Reticular layer Hypodermis (subcutaneous tissue) Nervous structures Sensory nerve fiber Lamellar corpuscle Hair follicle receptor (root hair plexus)

 Produce sebum (oil) which:  Lubricates skin/ slows water loss  Prevents brittle hair  Kills bacteria  Highly active at puberty © 2015 Pearson Education, Inc.

Eccrine gland Sebaceous gland Sweat pore Sebaceous gland duct Dermal connective tissue Hair in hair follicle Secretory cells (a) Photomicrograph of a sectioned sebaceous gland (100 × )

 Two types:  Eccrine glands  Produce sweat through pores all over skin surface  Sweat has salts, Vit. C, excretory wastes (uric acid)  Apocrine glands  Ducts empty into hair follicles  Activated at puberty; found in armpit and genital areas  Sweat that also contains fatty acids and proteins (milky or yellowish color)  Bacteria like this stuff – they create body odor when they use it © 2015 Pearson Education, Inc.

Eccrine gland Sebaceous gland Sweat pore Dermal connective tissue Eccrine gland duct Secretory cells (b) Photomicrograph of a sectioned eccrine gland (205 × )

 Produced by hair follicle  Outer tissue= connective  Inner= epithelial  Root is enclosed in the follicle  Shaft (dead part) projects from surface of scalp or skin  Consists of hard keratinized epithelial cells  Melanocytes provide pigment for hair color  Hair grows from hair bulb in stratum basale © 2015 Pearson Education, Inc.

Hair follicle (c) Fibrous sheath Epithelial sheath Hair matrix (growth zone) in hair bulb Melanocyte Subcutaneous adipose tissue Hair papilla containing blood vessels

 Arrector pili muscle  Smooth muscle tissue  Pulls hairs upright when person is cold or frightened (gives us goosebumps)  You could consider this a vestigial structure- it has lost all of its function/use for humans © 2015 Pearson Education, Inc.

 Heavily keratinized = very hard  Stratum basale is responsible for growth  Lack of pigment makes them colorless  Growth is similar to that of hair  Functions:  Protection  Tools  Scratch an itch! © 2015 Pearson Education, Inc.