MICROANATOMY

Detailed explanation-1: -In negative feedback systems, a stimulus elicits the release of a substance; once the substance reaches a certain level, it sends a signal that stops further release of the substance. In this way, the concentration of hormones in blood is maintained within a narrow range.

Detailed explanation-2: -Another example of negative feedback is the regulation of the blood calcium level. The parathyroid glands secrete parathyroid hormone, which regulates the level of calcium in the blood. If calcium decreases, the parathyroid glands sense the decrease and secrete more parathyroid hormone.

Detailed explanation-3: -ACTH activates the adrenal glands to release cortisol, which induces metabolic effects. Cortisol also acts back on the hypothalamus and pituitary gland by negative feedback.

Detailed explanation-4: -The thyroid gland is regulated by a negative feedback loop. The loop includes the hypothalamus and pituitary gland in addition to the thyroid.