9. What integumentary gland secretes an oil-like substance?

The **sebaceous glands** are the integumentary glands that secrete an oil-like substance known as **sebum**. Sebum plays a crucial role in: - **Lubricating and Waterproofing**: It helps keep the skin and hair moisturized, preventing them from becoming dry and brittle. - **Protecting Against Bacteria**: Sebum has antimicrobial properties that help protect the skin from harmful bacteria and fungi. - **Maintaining Skin Barrier**: It contributes to the skin's barrier function, aiding in the retention of moisture and protection against environmental aggressors. Sebaceous glands are typically found all over the body except for the palms of the hands and soles of the feet. They are most abundant on the face and scalp, which is why these areas are more prone to acne when sebum production is excessive. **Key Point:** Sebaceous glands produce sebum, the oil-like substance that helps keep skin and hair moisturized and protected. **Reference:** _Anatomy and Physiology textbooks and standard dermatology resources._ **Answer:** They are the sebaceous glands, which produce an oily substance called sebum.