Compare and contrast the different types of exocrine glands found in the skin and their contributions to body homeostasis

Exocrine glands vs endocrine glands?

Exocrine glands discharge their secretion onto the surface of the epithelium, typically via a duct that empties onto the epithelial surface. Endocrine glands (ductless glands) lack excretory ducts; their secretory cells release products into the extracellular space, from where the hormones may enter the bloodstream to reach their target organs.

Sebaceous glands — structure, chemical composition, primary function?

Structure: oil glands that lubricate the hair strand; discharge sebum into hair follicles via holocrine secretion; sebum enters the gland lumen and contacts the hair follicle, and contraction of the arrector pili squeezes it into the follicle and onto the skin surface. Chemical composition: triglycerides, cholesterol, proteins and electrolytes. Primary function: inhibits bacterial growth and lubricates/protects the hair shaft and surrounding skin.

Apocrine glands — structure, chemical composition, primary function?

Structure: found in the armpits, nipples and pubic region; secrete their products into hair follicles. (Called 'apocrine' due to early classification — they actually secrete via merocrine secretion.) Chemical composition: a sticky, cloudy and sometimes odorous secretion. Primary function: creates scent and pheromones; the sweat is a nutrient source for bacteria which cause odour.

Eccrine glands — structure, chemical composition, primary function?

Structure: far more numerous than apocrine glands; secrete sweat directly onto the surface of the skin via merocrine secretion. Chemical composition: water and electrolytes. Primary function: cool the surface of the skin in thermoregulation, excrete water and electrolytes, and provide protection from environmental hazards (chemicals and microorganisms).

Merocrine vs holocrine secretion?

Merocrine: the product is released from secretory vesicles at the apical surface of the gland cell by exocytosis. Holocrine: occurs as superficial gland cells burst; continued secretion involves replacement of these cells through mitotic divisions of underlying cells.

Eccrine glands — integration with dermal capillaries, thermoregulation?

Thermoregulation: eccrine glands secrete sweat that cools the surface of the skin.

Apocrine glands — why more susceptible to bacteria and odour?

They produce a sticky, cloudy and sometimes odorous secretion. This sweat is a nutrient source for bacteria, which cause the odour.