Problem 7 - Campbell Biology Concepts & Connections

Question

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.

Step-by-Step Solution

Answer

Option c illustrates homeostasis by regulating blood salt concentration through kidney function.

Step 1: Understand Homeostasis

Homeostasis refers to the process by which biological systems maintain internal stability despite changing external conditions. It involves the regulation of internal variables such as temperature, pH, and the concentration of chemicals.

Step 2: Evaluate Option a

Option a states that 'Most adult humans are between 5 and 6 feet tall.' This refers to a physical characteristic but does not explain a regulatory process maintaining internal stability.

Step 3: Evaluate Option b

Option b states that 'All the cells of the body are about the same size.' This is about cell size uniformity and does not involve regulatory mechanisms maintaining internal stability.

Step 4: Evaluate Option c

Option c states that 'When the salt concentration of the blood goes up, the kidneys expel more salt.' This describes a regulatory process where the kidneys maintain stable salt concentration in the blood, embodying homeostasis.

Step 5: Evaluate Option d

Option d states that 'When oxygen in the blood decreases, you feel dizzy.' Feeling dizzy is a response to a change in oxygen levels but does not specifically describe a process actively working to stabilize internal conditions.

Step 6: Choose the Best Option

Among the given options, only option c describes a regulatory process that maintains internal stability, which is the essence of homeostasis.

Key Concepts

biological regulation

Biological regulation is the process through which living organisms control various functions and processes to maintain a stable internal environment. This involves complex interactions between different organs, tissues, and cells. Biological regulation ensures that internal conditions remain constant despite external changes. Examples include regulating body temperature, blood sugar levels, and hormone levels. Without these regulatory mechanisms, organisms would not be able to survive in changing environments.

internal stability

Internal stability, also known as homeostasis, is crucial for the proper functioning of living organisms. It refers to the ability of the body to maintain a stable internal environment. This stability is essential for cells to function optimally and for the overall health of the organism. Internal stability involves balancing factors like temperature, pH, and salt concentration. Any significant deviation from these stable conditions can lead to dysfunction or disease. The body employs various mechanisms, such as sweating to cool down or shivering to warm up, to maintain this stability.

kidney function

The kidneys are vital organs responsible for filtering blood and removing waste products. They play a key role in maintaining homeostasis by regulating fluid balance, salt concentration, and pH levels. When the salt concentration in the blood increases, the kidneys expel more salt through urine. This process helps to bring the salt concentration back to normal levels, illustrating homeostasis. The kidneys also regulate the volume of blood by adjusting the amount of water excreted. By selectively reabsorbing water, salts, and other useful substances, the kidneys help maintain internal stability.

salt concentration regulation

Salt concentration regulation is essential for maintaining fluid balance and proper cell function. The body must keep the levels of salts, such as sodium and potassium, within a narrow range. This regulation is achieved through the coordinated actions of organs like the kidneys. When the salt concentration in the blood rises, the kidneys respond by increasing the excretion of salt in the urine. This helps to lower the blood's salt concentration to safe levels. Salt concentration regulation is a part of homeostasis, ensuring that cells maintain the right conditions to function properly.

feedback mechanisms

Feedback mechanisms are processes that help maintain homeostasis by making adjustments based on changes in the internal environment. There are two main types of feedback mechanisms: negative and positive. Negative feedback mechanisms work to reverse a change and bring conditions back to their normal state. For example, if the blood's salt concentration rises, the kidneys expel more salt to lower it. In contrast, positive feedback mechanisms amplify a change. Although less common, positive feedback occurs in specific situations, such as during childbirth. Feedback mechanisms are critical for the body's ability to maintain internal stability.