The part of the skin which is excretory in function is the

Step 1: Analyze the question We need the part of the skin whose job is excretion, meaning the removal of metabolic waste products from the body.

Step 2: Key concept Excretion is the removal of waste products of metabolism, such as urea, excess salts, and water. The skin does this through sweat. Sweat is made of water, sodium chloride (salt), and a little urea.

Step 3: Go through the options

• A. Adipose tissue: This is fat tissue under the skin. It stores energy and insulates the body. It does not excrete.
• B. Erector muscle: This muscle raises the hair when it is cold, which traps a layer of warm air. It is not excretory.
• C. Hair follicle: This is where hair grows. It is not excretory.
• D. Sebaceous gland: This gland secretes sebum, an oily substance that lubricates the skin and hair and has some waterproofing and antibacterial effect. Sebum is a secretion, not an excretory waste product, so this gland is not the best answer.
• E. Sweat gland: This gland produces sweat, which carries out water, salts, and urea. This is excretion. Sweating also cools the body by evaporation.

Step 4: Answer The sweat gland is the excretory part of the skin.

Exam tip: Remember the difference between secretion and excretion. Sebaceous glands secrete oil, which is useful to the body. Sweat glands excrete waste. "Sweat = waste out" is an easy way to recall it.