Correct Option
The parathyroid glands primarily regulate calcium and phosphate homeostasis in the blood. Their main hormone, Parathyroid Hormone (PTH), is secreted directly in response to low blood calcium levels. This regulatory mechanism operates independently of direct control by tropic hormones from the pituitary gland.
Incorrect Options
- Thyroid: The thyroid gland's secretory activity, particularly the release of thyroid hormones (T3 and T4), is primarily controlled by Thyroid Stimulating Hormone (TSH), which is secreted by the anterior pituitary gland.
- Gonads: The secretory functions of the gonads (testes and ovaries), including the production of sex hormones and gamete maturation, are regulated by Gonadotropins-Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)-both secreted by the anterior pituitary gland.
- Adrenals: The adrenal cortex's production of steroid hormones (glucocorticoids, mineralocorticoids, and adrenal androgens) is largely controlled by Adrenocorticotropic Hormone (ACTH), which is secreted by the anterior pituitary gland. While the adrenal medulla is under neural control, the overall endocrine function of the adrenal gland includes significant pituitary regulation of the cortex.