Chapter 6 - Section 6.3 - Study Guide - Assess Your Learning Outcomes - Page 199: 2

Sebaceous glands are another type of gland found in the skin, and they have distinct characteristics, produce a specific product, and differ in their mode of secretion compared to sweat glands. Here are the details: **Characteristics of Sebaceous Glands:** 1. **Distribution:** Sebaceous glands are found all over the skin, except for the palms of the hands and the soles of the feet. They are particularly abundant on the face and scalp. 2. **Development:** Sebaceous glands typically start to develop during fetal development and become more active during puberty when they enlarge and produce more sebum. 3. **Structure:** Sebaceous glands are simple, branched, and acinar (sac-like) glands. They consist of a cluster of cells that produce sebum, a waxy, oily substance. **Product of Sebaceous Glands:** The product of sebaceous glands is called "sebum." Sebum is an oily, lipid-rich substance that serves several important functions for the skin and hair: - **Moisturization:** Sebum helps to keep the skin and hair moisturized and prevents them from drying out. - **Protection:** Sebum forms a protective barrier on the skin's surface, helping to defend against harmful microorganisms and environmental factors like UV radiation. - **Hair Lubrication:** Sebum also lubricates hair follicles and prevents hair from becoming brittle. **Mode of Secretion and Difference from Sweat Glands:** The mode of secretion of sebaceous glands is holocrine, which is different from the merocrine mode of secretion in sweat glands: - **Holocrine Secretion:** In holocrine secretion, the entire secretory cell itself becomes the secretory product. In the case of sebaceous glands, the cells in the glandular acini accumulate sebum until they burst open, releasing the sebum along with the ruptured cell fragments into the ducts and onto the skin's surface. This process leads to the regeneration of new sebaceous cells. - **Difference from Sweat Glands:** Sweat glands, both apocrine and merocrine, use merocrine secretion, where the secretory cells release their products through exocytosis, without the destruction of the cells. In merocrine secretion, the cells remain intact, and sweat is released onto the skin surface through ducts without cell disintegration. In summary, sebaceous glands produce sebum, an oily substance that serves various protective and lubricating functions for the skin and hair. They use holocrine secretion, which involves the entire cell's destruction during secretion, contrasting with the merocrine secretion used by sweat glands, where the cells remain intact while releasing their products.

Sebaceous glands are another type of gland found in the skin, and they have distinct characteristics, produce a specific product, and differ in their mode of secretion compared to sweat glands. Here are the details: **Characteristics of Sebaceous Glands:** 1. **Distribution:** Sebaceous glands are found all over the skin, except for the palms of the hands and the soles of the feet. They are particularly abundant on the face and scalp. 2. **Development:** Sebaceous glands typically start to develop during fetal development and become more active during puberty when they enlarge and produce more sebum. 3. **Structure:** Sebaceous glands are simple, branched, and acinar (sac-like) glands. They consist of a cluster of cells that produce sebum, a waxy, oily substance. **Product of Sebaceous Glands:** The product of sebaceous glands is called "sebum." Sebum is an oily, lipid-rich substance that serves several important functions for the skin and hair: - **Moisturization:** Sebum helps to keep the skin and hair moisturized and prevents them from drying out. - **Protection:** Sebum forms a protective barrier on the skin's surface, helping to defend against harmful microorganisms and environmental factors like UV radiation. - **Hair Lubrication:** Sebum also lubricates hair follicles and prevents hair from becoming brittle. **Mode of Secretion and Difference from Sweat Glands:** The mode of secretion of sebaceous glands is holocrine, which is different from the merocrine mode of secretion in sweat glands: - **Holocrine Secretion:** In holocrine secretion, the entire secretory cell itself becomes the secretory product. In the case of sebaceous glands, the cells in the glandular acini accumulate sebum until they burst open, releasing the sebum along with the ruptured cell fragments into the ducts and onto the skin's surface. This process leads to the regeneration of new sebaceous cells. - **Difference from Sweat Glands:** Sweat glands, both apocrine and merocrine, use merocrine secretion, where the secretory cells release their products through exocytosis, without the destruction of the cells. In merocrine secretion, the cells remain intact, and sweat is released onto the skin surface through ducts without cell disintegration. In summary, sebaceous glands produce sebum, an oily substance that serves various protective and lubricating functions for the skin and hair. They use holocrine secretion, which involves the entire cell's destruction during secretion, contrasting with the merocrine secretion used by sweat glands, where the cells remain intact while releasing their products.