Calcium levels in Mr. Gallariani's blood are dropping to dangerously low levels. The hormone PTH is released and soon blood calcium levels begin to rise. Shortly after, PTH release slows. Is this an example of a positive or negative feedback mechanism? What is the initial stimulus? What is the result?

Verified step by step guidance

1. Identify the type of feedback mechanism by analyzing the process: When calcium levels drop, PTH (parathyroid hormone) is released to increase calcium levels, and once calcium levels rise, PTH release slows down. This regulation that reverses the initial change is characteristic of a negative feedback mechanism.
2. Determine the initial stimulus: The initial stimulus is the drop in blood calcium levels, which triggers the release of PTH.
3. Explain the role of PTH: PTH acts to increase blood calcium levels by stimulating bone resorption, increasing calcium absorption in the intestines, and reducing calcium excretion by the kidneys.
4. Describe the result of the feedback loop: The blood calcium levels rise back toward normal, which then signals the parathyroid glands to reduce PTH secretion.
5. Summarize the overall process: The negative feedback mechanism maintains calcium homeostasis by detecting low calcium levels, releasing PTH to correct the imbalance, and then slowing PTH release once calcium levels are restored.

Key Concepts

Negative Feedback Mechanism

A negative feedback mechanism is a biological process where a change in a variable triggers a response that counteracts the initial change, restoring balance. In this case, low calcium levels stimulate PTH release, which raises calcium, then PTH release slows as levels normalize, maintaining homeostasis.

Parathyroid Hormone (PTH) Function

Parathyroid hormone (PTH) is secreted by the parathyroid glands in response to low blood calcium. It increases calcium levels by stimulating bone resorption, enhancing calcium absorption in the intestines, and reducing calcium excretion by the kidneys.

Initial Stimulus and Result in Hormonal Regulation

The initial stimulus is the drop in blood calcium levels, which triggers PTH release. The result is an increase in blood calcium concentration, restoring normal levels and ensuring proper physiological functions like muscle contraction and nerve signaling.