Which of the following best illustrates homeostasis? (Explain your answer.)
a. Most adult humans are between 5 and 6 feet tall.
b. All the cells of the body are about the same size.
c. When the salt concentration of the blood goes up, the kidneys expel more salt.
d. When oxygen in the blood decreases, you feel dizzy.

Verified step by step guidance

1. Step 1: Begin by understanding the concept of maintaining a stable internal environment despite changes in the external environment. This is a fundamental biological process known as homeostasis.
2. Step 2: Evaluate the options provided in the question. Thermoregulation refers specifically to the regulation of body temperature, which is a subset of homeostasis. Homeostasis, on the other hand, encompasses a broader range of processes, including temperature regulation, pH balance, and more.
3. Step 3: Consider the other options: Defecation is the process of eliminating waste from the digestive system, and Evaporation is a physical process where liquid turns into vapor. Neither of these directly relates to maintaining internal stability.
4. Step 4: Recognize that the term describing the protection of the internal environment against external changes is 'Homeostasis,' as it is the overarching concept that includes various regulatory mechanisms.
5. Step 5: Conclude that the correct answer is 'Homeostasis,' as it best fits the description provided in the question.

Key Concepts

Homeostasis

Homeostasis is the biological process through which living organisms maintain a stable internal environment despite external changes. This involves regulating factors such as temperature, pH, and ion concentrations to ensure optimal functioning of cells and systems. For example, humans maintain a body temperature around 37°C, adjusting through mechanisms like sweating or shivering.

Thermoregulation

Thermoregulation is a specific aspect of homeostasis that focuses on maintaining an organism's body temperature within a certain range. This process can involve physiological responses such as altering blood flow, sweating, or shivering to either dissipate or conserve heat. It is crucial for the survival of endothermic (warm-blooded) animals, which rely on internal mechanisms to regulate their temperature.

External Environment

The external environment refers to all the external factors that can influence an organism's internal conditions, including temperature, humidity, and availability of resources. Changes in the external environment can pose challenges to homeostasis, prompting organisms to adapt through behavioral or physiological changes. Understanding these interactions is essential for studying how organisms survive and thrive in varying conditions.