Which of the following structures is an exocrine gland?
A.
Pineal gland
B.
Parathyroid gland
C.
Parotid gland
D.
Pituitary gland
The Correct answer and Explanation is:
The correct answer is C. Parotid gland.
Explanation:
An exocrine gland is a type of gland that secretes its products through ducts to the external environment or into body cavities. Exocrine glands include sweat glands, salivary glands, and glands of the digestive system. In contrast, endocrine glands secrete hormones directly into the bloodstream without the use of ducts.
Let’s examine each option:
- Pineal gland: This is an endocrine gland located in the brain. It produces melatonin, which regulates sleep-wake cycles. The pineal gland releases melatonin directly into the bloodstream, making it an endocrine gland.
- Parathyroid gland: These are small endocrine glands located on the back of the thyroid gland. They release parathyroid hormone (PTH), which regulates calcium levels in the blood. Like the pineal gland, it secretes hormones directly into the bloodstream, so it is also an endocrine gland.
- Parotid gland: This is an exocrine gland, specifically a salivary gland, located near the jaw. The parotid gland produces and secretes saliva, which helps with digestion and lubrication of food. It uses ducts to transport saliva into the mouth, making it an exocrine gland. The key feature of exocrine glands is the use of ducts to deliver their secretions to a specific location, as the parotid gland does.
- Pituitary gland: Often called the “master gland,” the pituitary is an endocrine gland located at the base of the brain. It secretes a variety of hormones that regulate growth, metabolism, and reproduction. The pituitary gland releases these hormones directly into the bloodstream, functioning as an endocrine gland.
The parotid gland, as a salivary exocrine gland, secretes saliva into the oral cavity via ducts, distinguishing it from the endocrine glands in this list, which secrete hormones directly into the blood. This characteristic makes the parotid gland the correct answer.