Which one of the following endocrine organs is known as a mixed gland because it has both endocrine and exocrine functions in the human body?

Introduction / Context:
Glands in the human body can be classified as endocrine, exocrine, or mixed depending on how they release their secretions. Endocrine glands release hormones directly into the blood, exocrine glands release substances through ducts, and mixed glands perform both functions. This question asks you to identify which gland among the options is classically described as a mixed gland in human physiology.

Given Data / Assumptions:

• The options include pituitary, adrenal, pancreas, ovary, and thyroid glands.
• Endocrine glands are ductless and secrete hormones into the blood.
• Exocrine glands release their products through ducts onto surfaces or into body cavities.
• Only one of the listed organs has both a ductless endocrine portion and a ducted exocrine portion.

Concept / Approach:
The pancreas is considered a classic mixed gland. Its endocrine part (islets of Langerhans) secretes hormones like insulin and glucagon directly into the bloodstream. Its exocrine part produces digestive enzymes that are released through the pancreatic duct into the small intestine. In contrast, pituitary, adrenal, thyroid, and ovaries are primarily described as endocrine glands because their main recognised role is hormone secretion into blood. While ovaries have gamete producing functions, at school level the standard mixed gland example is the pancreas.

Step-by-Step Solution:
Step 1: Recall the definition of a mixed gland: it must have both endocrine and exocrine components.Step 2: Examine the pancreas: it secretes digestive juices (exocrine) into the duodenum and hormones like insulin (endocrine) into the blood.Step 3: Pituitary and adrenal glands are purely endocrine, releasing hormones directly into the bloodstream without any ducts.Step 4: The thyroid gland also functions purely as an endocrine organ, secreting thyroid hormones and calcitonin into the blood.Step 5: Although ovaries produce both eggs and hormones, the classical exam answer for a mixed gland in the context of exocrine and endocrine roles is the pancreas, so we select Pancreas.

Verification / Alternative check:
Standard biology textbooks when discussing gland types specifically highlight the pancreas as the example of a mixed gland because it has clearly separable exocrine acini and endocrine islets. Other glands listed are repeatedly categorised as endocrine glands without exocrine ducts. This repeated emphasis in academic sources confirms that pancreas is the correct answer for this question.

Why Other Options Are Wrong:
Pituitary gland is a master endocrine gland with no exocrine duct system.Adrenal glands are endocrine organs that secrete hormones like adrenaline and cortisol directly into the blood.Ovaries are mainly regarded as female reproductive organs and endocrine glands, not as mixed in the strict exocrine endocrine sense used in school texts.Thyroid gland secretes thyroid hormones into the blood and has no major exocrine role.

Common Pitfalls:
Some students wrongly pick pituitary or thyroid because they hear the terms master gland or important endocrine gland and confuse importance with mixed function. Others may think ovaries qualify because they produce eggs and hormones, but traditional exam questions on mixed glands almost always refer to the pancreas. To avoid errors, always link the phrase mixed gland to the combination of digestive exocrine secretion and hormone endocrine secretion seen in the pancreas.

Final Answer:
The correct answer is Pancreas.