If a normal individual receives an insulin injection that lowers plasma glucose to 30 mg/dl, which of the following hormones will NOT be released?
**Core Concept**
The body maintains blood glucose homeostasis through a complex interplay of hormones, including insulin, glucagon, epinephrine, and growth hormone, among others. When plasma glucose levels drop, the body responds by releasing hormones that mobilize energy stores and promote glucose production.
**Why the Correct Answer is Right**
Aldosterone is a mineralocorticoid hormone produced by the adrenal cortex, primarily involved in regulating electrolyte balance and blood pressure through its effects on the kidneys. It does not play a direct role in glucose homeostasis or the response to hypoglycemia. In contrast, when plasma glucose levels drop, the body releases hormones such as epinephrine, growth hormone, and ACTH (adrenocorticotropic hormone) to mobilize glucose stores, promote gluconeogenesis, and increase blood glucose levels.
**Why Each Wrong Option is Incorrect**
**Option A:** ACTH is released in response to low blood glucose, triggering the adrenal cortex to produce cortisol, which promotes gluconeogenesis and increases blood glucose levels.
**Option B:** Epinephrine is released in response to hypoglycemia, stimulating glycogen breakdown in the liver and muscles, promoting glucose release into the bloodstream.
**Option C:** Growth hormone is released in response to low blood glucose, promoting gluconeogenesis, lipolysis, and glycogen breakdown to increase blood glucose levels.
**Clinical Pearl / High-Yield Fact**
In the setting of hypoglycemia, the body's primary response is to mobilize glucose stores and promote glucose production through the release of hormones such as epinephrine, growth hormone, and ACTH. Mineralocorticoids like aldosterone are not directly involved in this response, highlighting the importance of understanding the distinct roles of different hormone classes in glucose homeostasis.
✓ Correct Answer: D. Aldosterone