Question

To lower blood acidity, a. hydrogen ions are excreted, and bicarbonate ions are reabsorbed. b. hydrogen ions are reabsorbed, and bicarbonate ions are excreted. c. hydrogen ions and bicarbonate ions are reabsorbed. d. hydrogen ions and bicarbonate ions are excreted. e. urea, uric acid, and ammonia are excreted.

Short answer

To lower blood acidity, hydrogen ions are excreted, and bicarbonate ions are reabsorbed.

Step-by-step solution

Understand the concept of pH balance and the role of ions

The pH balance in our body is maintained by the balance of hydrogen ions (H+) and bicarbonate ions (HCO3-) in our blood. In this context, the hydrogen ions represent acidity, while bicarbonate ions represent alkalinity. The balance between these two ions is essential for maintaining proper blood pH and overall body functions. Step 2: Identifying the process that lowers blood acidity

Identify the process to lower blood acidity

To lower blood acidity means to reduce the concentration of H+ in the blood. This can be achieved by either excreting hydrogen ions or increasing bicarbonate ions. Therefore, the correct process should involve one of these actions or a combination of both. Step 3: Evaluating the choices based on the process of lowering blood acidity

Evaluate the options and select the correct choice

a. If hydrogen ions are excreted and bicarbonate ions are reabsorbed, this would lead to a decrease in blood acidity, since the concentration of hydrogen ions will be reduced and the bicarbonate ions will be increased. b. If hydrogen ions are reabsorbed and bicarbonate ions are excreted, this would increase blood acidity, as the concentration of hydrogen ions would increase and the bicarbonate ions would decrease. c. If both hydrogen ions and bicarbonate ions are reabsorbed, it would not necessarily change the overall blood acidity, as both acidity and alkalinity components would be increased. d. If both hydrogen ions and bicarbonate ions are excreted, then it would also not necessarily change the overall blood acidity, as both acidity and alkalinity components would be decreased. e. Excreting urea, uric acid, and ammonia does not directly lower blood acidity, as these substances are not directly involved in the pH balance in the blood. Step 4: Choosing the correct answer

Choose the correct answer

Based on the evaluation of the options, the correct answer to this question is: a. To lower blood acidity, hydrogen ions are excreted, and bicarbonate ions are reabsorbed.

Key concepts

pH Balance

Understanding the concept of pH balance is central to comprehending how our bodies regulate acidity. The pH scale is a numerical scale used to determine the acidity or alkalinity of a solution, including blood. A pH of 7 is considered neutral, while a pH lower than 7 is acidic, and a pH higher than 7 is alkaline. The human body naturally maintains blood pH within a very narrow range, usually around 7.35 to 7.45, which is slightly alkaline.

Why is this balance important? Enzymatic reactions, oxygen delivery, and overall cellular function depend heavily on the blood maintaining this tight window. When the pH balance is disrupted, it can lead to conditions like acidosis or alkalosis, which can have serious impacts on health. To prevent this, our bodies utilize various mechanisms to tightly regulate blood pH, including the excretion of hydrogen ions and the reabsorption of bicarbonate ions in the kidneys.

Hydrogen Ion Excretion

One of the body’s critical mechanisms for maintaining pH balance is through the excretion of hydrogen ions (H+). These ions play a role as the primary determinant of blood acidity. The kidneys are the workhorses in this process and are responsible for filtering out excess hydrogen ions from the blood through urine.

To grasp this concept, think of hydrogen ions as tiny particles that can influence the acidity of a liquid. In the kidneys, specific cells called tubular cells actively transport hydrogen ions out of the blood and into the urine. This process of hydrogen ion excretion is continuously adjusted, ensuring that the blood does not become too acidic. It is a precise balance act, akin to removing just enough salt from a soup to maintain the perfect flavor.

Bicarbonate Ion Reabsorption

Concurrently with hydrogen ion excretion, the body also reabsorbs bicarbonate ions (HCO3-) to manage blood pH. Bicarbonate serves as a buffer to neutralize excess acidity in the blood. During blood filtration in the kidneys, bicarbonate ions are conserved and reclaimed to maintain the alkaline reserve of the blood.

This reabsorption is a vital counterbalance to the removal of hydrogen ions. If bicarbonate ions were not reabsorbed but lost in urine instead, the blood would become overly acidic. The kidneys selectively retain these ions, fine-tuning the blood's pH levels. Simply put, just as a sponge soaks up water, the kidneys soak up bicarbonate ions to keep the blood's pH level stable. Together, hydrogen ion excretion and bicarbonate ion reabsorption are synergistic functions that the body uses to maintain homeostasis and ensure our physiological systems operate optimally.