Question

Which of the following is not a homeostatic response? a. In a contest, a student eats an entire chocolate cake in 10 minutes, and his blood glucose level does not change dramatically. b. A jogger is sweating after a two-mile jog. c. The pupils in humans' eyes constrict when looking at a light. d. Physical activity increases carbon dioxide blood levels, which lowers blood \(\mathrm{pH}\) and increases breathing. e. Oxytocin is released by the hypothalamus during human childbirth.

Short answer

Option e (Oxytocin is released by the hypothalamus during human childbirth) is not a homeostatic response.

Step-by-step solution

Understanding Homeostasis

Before identifying which option is not a homeostatic response, it's important to understand what homeostasis is. Homeostasis refers to the ability of an organism or environment to maintain stability in spite of changes. A homeostatic response is a reaction by a system to help maintain its normal state.

Analyzing Each Option

Review each option and consider whether it describes a process that helps an organism maintain physiological balance or not.

Elimination of Homeostatic Responses

Options a, b, c, and d all describe processes that help the body maintain its physiological balance. In option a, the regulation of blood glucose after eating a lot of sugar is an example of homeostasis. In option b, sweating is a thermoregulatory response to cool the body, which is homeostatic. In option c, the constriction of pupils protects the eyes from bright light, which is a homeostatic reflex. In option d, increased breathing in response to high carbon dioxide levels is the body's way of maintaining a stable pH, which is homeostatic.

Identifying the Non-Homeostatic Response

Review option e and evaluate whether it describes a homeostatic process. Oxytocin release during childbirth is part of a positive feedback mechanism, which is different from homeostasis. This process intensifies the conditions rather than stabilizing them, which is opposite to a homeostatic mechanism.

Key concepts

Homeostasis in Biology

Homeostasis is the state of steady internal, physical, and chemical conditions maintained by living systems. It is the concept that refers to the self-regulating process by which biological systems tend to maintain stability while adjusting to conditions that are optimal for survival. This dynamic equilibrium is essential for the functioning of organisms and includes various physiological processes to regulate factors such as temperature, pH level, and glucose concentration.

For example, consider body temperature in humans. The normal range is around 98.6 degrees Fahrenheit, and when you exercise, your body temperature begins to rise. Homeostatic mechanisms, such as sweating, kick in to cool your skin with evaporative cooling, thereby preventing your body from overheating. Similarly, the kidneys maintain a balance of electrolytes and water, and the liver regulates blood glucose levels. If these processes didn't occur, your body wouldn't be able to function properly. It is through homeostasis that organisms can manage external changes and internal variability to ensure survival.

Positive Feedback Mechanism

Unlike homeostasis, which works to maintain physiological balance, a positive feedback mechanism is a process that moves a system further from its starting state, often resulting in a greater change in the same direction. This kind of feedback is less common but can have significant effects when it occurs. It is like pushing a snowball down a hill - once it starts rolling, it gathers more snow, becoming bigger and faster.

An easily understandable example of positive feedback is the release of oxytocin during childbirth. Oxytocin causes contractions to become stronger and more frequent, which intensifies labor and advances the process until birth occurs. The key distinction between positive feedback mechanisms and homeostasis is that positive feedback amplifies changes and moves the system away from equilibrium, rather than stabilizing it. Despite the differences, both processes are fundamental for the functioning and survival of organisms, but they serve different purposes within biological systems.

Physiological Balance

Physiological balance, or equilibrium, is the state in which the internal physical and chemical conditions of an organism are stable and efficiently regulated. This concept is closely related to homeostasis and involves a myriad of tightly controlled processes that respond to fluctuations within the body and the external environment.

Main factors include temperature regulation, pH balance, glucose regulation, and osmoregulation, among others. For example, when you consume food, your digestive system works to convert it into glucose, which your cells use for energy. Yet, if your glucose levels rise too high or drop too low, you could end up with hyperglycemia or hypoglycemia, respectively. Through mechanisms like insulin secretion, your body maintains glucose at a steady level.

• Temperature regulation helps to ensure that your enzymes work optimally.
• pH balance is crucial because even small deviations can be harmful or fatal.
• Osmotic balance is maintained to ensure proper hydration and cell function.

Together, these aspects of physiological balance are essential for health and survival, as they embody the stability that is necessary for all living organisms to thrive.