Question

A rise in the concentration of thyroid hormone in the blood slows the release of thyroid hormone. This is an example of __________. a. positive feedback b. negative feedback

Short answer

The situation described is an example of negative feedback.

Step-by-step solution

Understanding Feedback Mechanisms

Feedback mechanisms are biological processes that maintain homeostasis, the stable, balanced conditions in the body. They can either amplify a process (positive feedback) or reduce it to keep it under control (negative feedback). This distinction is crucial in analyzing the example given.

Identifying the Feedback Type

In the exercise, an increase in thyroid hormone concentration leads to a slowdown in the release of more thyroid hormones. This suggests that the process is self-regulating and aims to stabilize the hormone levels back to normal instead of intensifying them.

Analyzing Negative Feedback Characteristics

Negative feedback is characterized by a reduction or opposition of the original stimulus. In this situation, the increased hormone levels cause a reaction that decreases further production, showing an attempt to negate the initial change.

Conclusion on Feedback Type

Given the definitions and the behavior described, this scenario is best described by negative feedback. The system is regulating itself to counteract the rise in hormone levels.

Key concepts

Negative Feedback

Negative feedback is a fundamental concept in the regulation of biological systems. It's a process where the output of a system acts to reduce or dampen the processes that lead to that output. This helps maintain stability and balance within the system, a state known as homeostasis. When a system detects any change from its normal state, it triggers mechanisms to return to that state.
This is like a thermostat in a heating system. When the room gets too warm, the thermostat switches the heat off, reducing the temperature back to the desired setting. Similarly, in biology, when a certain level of substances, like hormones, rises too high, negative feedback mechanisms bring it back down.
The example from the exercise, where a rise in thyroid hormone levels slows further release, demonstrates this principle. The body detects the higher levels, and instead of producing even more hormones, it reduces production to stabilize the situation.

Thyroid Hormone

The thyroid hormone plays a significant role in regulating metabolism and energy in the body. It is produced in the thyroid gland, which is located in the neck. This hormone helps control various important functions, such as heart rate, body temperature, and energy levels.
To maintain proper function, the level of thyroid hormone in the blood must be tightly controlled. This control is achieved through a negative feedback loop involving the pituitary gland. The pituitary gland releases Thyroid Stimulating Hormone (TSH), which prompts the thyroid gland to produce thyroid hormone.
When there's enough thyroid hormone in the bloodstream, the pituitary gland reduces TSH production, reducing the stimulus for more thyroid hormone production. This feedback loop ensures that hormone levels remain balanced and that metabolic processes function smoothly.

Biological Processes

Biological processes are the routines and functions carried out by systems within living organisms. These include growth, response to the environment, energy production, and internal balance regulation, among others.
The regulation and maintenance of these processes ensure that an organism functions effectively and efficiently. Feedback loops like negative feedback are present in various biological processes to ensure homeostasis.
Without negative feedback, systems could spiral out of control. For instance, in hormone regulation, a lack of negative feedback might cause excessive hormone levels, leading to serious health issues. This demonstrates the importance of these intricate control mechanisms in our daily biological functioning.