What type of transport mechanisms are involved in tubular secretion?

What type of transport mechanisms are involved in tubular secretion?

• A. Only passive transport
• B. Only active transport
• C. Both active and passive transport
• D. Neither active nor passive transport

Answer: (C)

In tubular secretion, both active and passive transport mechanisms are utilized to move substances from the bloodstream into the renal tubule. Active transport involves the use of energy, typically in the form of ATP, to move molecules against their concentration gradient. This is crucial for the secretion of substances such as potassium ions and hydrogen ions, which are often present at lower concentrations in the tubule than in the blood. Active transport allows the kidneys to regulate the concentration of these ions effectively. On the other hand, passive transport occurs when substances move down their concentration gradient without the expenditure of energy. This can happen through simple diffusion or facilitated diffusion, where substances pass through the cell membrane via specific transport proteins. For instance, urea can be secreted into the renal tubule through passive mechanisms when the concentration of urea in the blood is higher than in the tubular fluid. The involvement of both active and passive transport mechanisms allows for a flexible and efficient process in regulating various substances in the body, making option C the correct choice.

In tubular secretion, both active and passive transport mechanisms are utilized to move substances from the bloodstream into the renal tubule.

Active transport involves the use of energy, typically in the form of ATP, to move molecules against their concentration gradient. This is crucial for the secretion of substances such as potassium ions and hydrogen ions, which are often present at lower concentrations in the tubule than in the blood. Active transport allows the kidneys to regulate the concentration of these ions effectively.

On the other hand, passive transport occurs when substances move down their concentration gradient without the expenditure of energy. This can happen through simple diffusion or facilitated diffusion, where substances pass through the cell membrane via specific transport proteins. For instance, urea can be secreted into the renal tubule through passive mechanisms when the concentration of urea in the blood is higher than in the tubular fluid.

The involvement of both active and passive transport mechanisms allows for a flexible and efficient process in regulating various substances in the body, making option C the correct choice.