Question

Adapting to changes in the external environment and maintaining internal variables within physiological ranges is a. equilibrium. b. a conditioned response. c. positive feedback. d. homeostasis. e. both c and d.

Short answer

The correct response is option 'd. homeostasis'.

Step-by-step solution

Understand the Definitions

Equilibrium is a state where opposite forces are balanced. A conditioned response is a response that becomes associated with a previously unrelated stimulus as a result of conditioning. Positive feedback amplifies changes and moves the system away from its initial state. Homeostasis, on the other hand, is the ability of a system to regulate its internal environment and maintain a stable, constant condition, despite changes in the external environment.

Match the Definitions with the Choices

The question describes the process of adapting to changes in the external environment and maintaining internal variables within physiological ranges. This is not a definition of equilibrium. It is not a conditioned response as it does not involve any stimulus. The process does not amplify changes and move the system away from its initial states, so this is not the definition of positive feedback. The question's description fits the definition of homeostasis.

Choose the Correct Option

Based on the definitions and the matching process, the description given in the question is closest to the definition of homeostasis. Hence, the correct option would be option 'd. homeostasis.'

Key concepts

Physiological Regulation

Physiological regulation is at the heart of the body's ability to maintain stable internal conditions, something we commonly refer to as homeostasis. Imagine your body as a well-coordinated orchestra, where temperature, pH levels, hydration, and nutrient concentrations must all be synchronized to create perfect harmony. Whenever external conditions threaten to throw off the balance, your body's regulatory mechanisms, like a skilled conductor, step in to adjust and realign the players.

Several key systems participate in this regulation. The nervous and endocrine systems, for instance, act as information highways, communicating signals swiftly to tell organs how to respond. For instance, when you're cold, muscles receive signals to shiver, producing heat. This continuous monitoring and internal tweaking ensure you stay within the optimal range for survival and health.

Positive Feedback

Positive feedback, in contrast to the balancing act of homeostasis, is like a snowball rolling down a hill–it amplifies and accelerates change. A classic example of this is childbirth. Once labor begins, contractions lead to the release of oxytocin, which causes more intense contractions. The process escalates until the baby is born, showcasing a biological situation where more of the same accelerates the outcome.

Another example can be found in our nervous system when an exciting stimulus could cause a neuron to fire more rapidly, creating a 'buzz' of activity. While positive feedback is less common in maintaining daily physiological equilibrium, it's essential for completing certain processes that require a definitive endpoint or a rapid change.

Conditioned Response

A conditioned response might remind you of Pavlov's dogs, which drooled at the sound of a bell after being trained to associate this sound with food. It's the cornerstone of classical conditioning, where a neutral stimulus becomes associated with a reflexive response. While not directly related to maintaining internal balance, conditioned responses are fascinating examples of how we learn and adapt behaviorally.

In human context, this could be the anxiety you feel upon entering a dentist's office due to past experiences, or the sense of relaxation when smelling a scent associated with a peaceful memory. These responses highlight an intimate interplay between our environment and our learned experiences, coloring our daily reactions and decisions.

Equilibrium

Equilibrium relates to a state of balance or stability, where opposing forces or influences are equal. In the physical sciences, we might talk about objects at rest when all the forces acting upon them are even. However, biological equilibrium is dynamic—a tightrope walker in constant motion, adjusting to small disturbances to maintain a straight line.

In the human body, equilibrium applies to our balance and posture, managed by a complex system involving the inner ear, vision, and muscle coordination. This state of dynamic balance keeps us upright and allows us to perform smooth, controlled movements. It's critical not just to physical motion but to numerous other body systems that work to neutralize any form of disruption and promote steady, ongoing function amid the ceaseless changes that life throws our way.