Question

Kidneys adjust the blood acidity by increasing or decreasing the ________ of hydrogen ions \(\left(\mathrm{H}^{+}\right)\). a. filtration b. reabsorption c. secretion d. production

Short answer

The answer is c. secretion.

Step-by-step solution

Understand the Role of Kidneys

Kidneys maintain homeostasis, which includes regulating blood pH by managing the concentration of hydrogen ions (\(\mathrm{H}^{+}\)). They can either increase or decrease the hydrogen ions to adjust the blood acidity levels.

Analyze Each Option

Understand what each term means in the context of kidney function: - Filtration: Process by which kidneys filter out waste from the blood. - Reabsorption: Process by which necessary substances are reabsorbed back into the blood. - Secretion: Process by which additional substances are added to the filtrate from blood, especially for excretion. - Production: Usually refers to the generation of new substances, not relevant here.

Eliminate Irrelevant Options

'Production' is not a relevant kidney function regarding blood acidity and adjusting ion concentration so it can be eliminated. 'Filtration' traditionally means removing things from the blood, not adjusting blood acidity directly.

Focus on Relevant Options

Reabsorption and secretion directly affect the composition of blood. Reabsorption decreases the concentration of ions like \(\mathrm{H}^{+}\) in urine while secretion increases their removal from the blood. Kidneys adjust \(\mathrm{H}^{+}\) concentration through secretion to change blood pH.

Choose the Best Option

Given the requirement to increase or decrease the hydrogen ion concentration to adjust blood acidity, the term 'secretion' involves the targeted removal of \(\mathrm{H}^{+}\) ions to influence blood acidity. Hence, the best choice is 'secretion.'

Key concepts

Blood Acidity

The acidity level of blood is crucial for proper bodily functions. Blood acidity is often discussed in terms of pH, a scale that measures how acidic or basic a fluid is. A pH less than 7 indicates acidity, while a pH greater than 7 indicates basicity, or alkalinity.
To stay healthy, the human body maintains a slightly basic blood pH, around 7.35 to 7.45. This delicate balance is vital because even small changes in the blood's pH can disrupt cellular function and lead to serious health issues.
Kidneys, along with the respiratory system, play an essential role in this regulation. They help manage the blood pH by either conserving or excreting hydrogen ions (\(\mathrm{H}^{+}\)). This process ensures that blood maintains its optimal pH range, supporting homeostasis—our body's way of keeping everything in a stable state.

Hydrogen Ions

Hydrogen ions (\(\mathrm{H}^{+}\)) are a key component in determining the acidity of the blood. They are essentially protons, and their concentration in the blood can vastly affect its pH level. The more hydrogen ions present, the more acidic the solution becomes, thus lowering the pH.
Our bodies continuously produce hydrogen ions through various metabolic processes. However, an excess of these ions can make the blood too acidic, which is dangerous. Therefore, the body must carefully regulate the concentration of hydrogen ions to keep the acid-base balance intact.
Kidneys help in this regulation by controlling the levels of \(\mathrm{H}^{+}\) in the blood. A primary way they achieve this balance is through a process known as secretion, which allows unwanted hydrogen ions to be expelled from the body, thereby maintaining the correct pH level.

Secretion

Secretion is a crucial kidney function related to maintaining blood acidity. It involves the selective movement of substances from the blood into the kidney tubules, where they become part of urine. This process is distinct from filtration and reabsorption.
In terms of acid-base balance, secretion is particularly important for removing excess hydrogen ions (\(\mathrm{H}^{+}\)). By transporting these ions into the urine, the kidneys can reduce the acidity of the blood.
Here's how it works:

• When blood is too acidic, the kidneys increase the secretion of hydrogen ions, enhancing their elimination through urine.
• This effectively lowers the concentration of \(\mathrm{H}^{+}\) in the blood, making the blood less acidic.

This process ensures that blood pH remains in a narrow, healthy range, safeguarding overall bodily function.

Homeostasis

Homeostasis is the body's way of maintaining a stable internal environment, which includes regulating blood pH, temperature, and other critical functions. The kidneys are key players in this system, especially in managing blood acidity and maintaining acid-base balance.
Through processes like filtration, reabsorption, and secretion, kidneys ensure that waste products and excess ions such as \(\mathrm{H}^{+}\) are efficiently managed. This balance keeps conditions ideal for cellular processes and overall health.
In summary:

• Homeostasis ensures that the body remains in equilibrium concerning its internal environment.
• The kidneys play a vital role in achieving this balance by regulating the composition of blood, thus impacting blood acidity.
• By adjusting the concentration of hydrogen ions, the kidneys help maintain the necessary pH levels for efficient system functioning.

This intricate orchestration underscores the significance of homeostasis in optimizing health.