Overview
This lecture reviews the three main types of skin glands—holocrine, apocrine, and merocrine—focusing on their structure, secretion methods, locations, and functions.
Types of Skin Glands
- There are three types of glands in the skin: holocrine, apocrine, and merocrine glands.
- All glands are located in the reticular dermis and have ducts that lead to the skin surface.
Holocrine (Sebaceous) Glands
- Holocrine glands release their secretion by disintegrating the whole cell.
- Their secretion is called sebum, an oily, lipid-rich substance.
- Holocrine (sebaceous) glands are found on the face, chest, and back.
- Sebum lubricates the skin and slows bacterial growth.
Apocrine Glands
- Apocrine glands release a mix of proteins, lipids, and steroids by shedding the cell apex.
- Mainly located in the armpits, groin, and around the nipples.
- Apocrine glands release contents into hair follicles, unlike the other types.
- They become active after puberty and are involved in emotional sweating (anxiety, stress, fear, pain).
Merocrine (Eccrine) Glands
- Merocrine glands secrete watery, salty sweat via exocytosis.
- Found throughout the body, especially on palms and soles.
- Functions include evaporative cooling, waste elimination, and microbial defense.
- Merocrine sweat contains lysozymes (break down bacteria) and antibodies (tag pathogens).
Key Terms & Definitions
- Holocrine gland — gland that releases its secretion by destroying the whole cell.
- Sebum — oily secretion of holocrine (sebaceous) glands.
- Apocrine gland — gland that releases secretions by breaking off part of the cell apex.
- Merocrine (eccrine) gland — gland that secretes sweat by exocytosis.
- Lysozyme — enzyme in sweat that destroys bacteria.
- Antibody — immune protein in sweat that identifies foreign invaders.
Action Items / Next Steps
- Review differences in secretion methods and locations of each gland type.
- Prepare for questions on gland functions and significance in skin physiology.