Which of the following is true regarding endocrine organ histology?
a The thyroid gland contains calcitonin-secreting follicle cells.
b The pancreas has an exocrine portion consisting of pancreatic acinar cells and an endocrine portion consisting of pancreatic islets.
c The adrenal medulla has three zones of cells that secrete steroid hormones.
d The adrenal cortex is modified nervous tissue of the parasympathetic nervous system.
The correct answer and explanation is :
The correct answer is b: The pancreas has an exocrine portion consisting of pancreatic acinar cells and an endocrine portion consisting of pancreatic islets.
Explanation:
a. The thyroid gland contains calcitonin-secreting follicle cells.
- This statement is incorrect. The thyroid gland contains follicle cells, but they primarily secrete thyroid hormones (T3 and T4). Calcitonin is actually secreted by parafollicular cells (or C cells), not the follicle cells. Calcitonin helps regulate calcium levels in the blood, lowering it when necessary.
b. The pancreas has an exocrine portion consisting of pancreatic acinar cells and an endocrine portion consisting of pancreatic islets.
- This statement is correct. The pancreas is a mixed gland with both exocrine and endocrine functions. The exocrine portion consists of pancreatic acinar cells that produce digestive enzymes, which are secreted into the small intestine to aid in digestion. The endocrine portion consists of pancreatic islets (also known as islets of Langerhans), which contain different types of cells that secrete hormones like insulin, glucagon, and somatostatin into the bloodstream, regulating blood glucose levels and other metabolic processes.
c. The adrenal medulla has three zones of cells that secrete steroid hormones.
- This statement is incorrect. The adrenal medulla is the inner part of the adrenal glands and primarily secretes catecholamines (adrenaline and noradrenaline), not steroid hormones. The adrenal cortex, on the other hand, is responsible for producing steroid hormones like cortisol, aldosterone, and androgens. The adrenal cortex does have three zones: the zona glomerulosa, zona fasciculata, and zona reticularis.
d. The adrenal cortex is modified nervous tissue of the parasympathetic nervous system.
- This statement is incorrect. The adrenal cortex is not part of the parasympathetic nervous system. It is a part of the adrenal glands and produces steroid hormones. The adrenal medulla, however, is influenced by the sympathetic nervous system and produces adrenaline and noradrenaline in response to stress.
Thus, option b is the accurate description of the pancreas’ histology.