Question

Why is oral rehydration therapy with a solution of sodium chloride and glucose an effective treatment for dehydration? a. The sodium and glucose decrease urine output. b. The sodium and glucose facilitate water absorption by the small intestine. c. The sodium and glucose help kill intestinal bacteria. d. The sodium and glucose make the person thirsty.

Short answer

The correct answer is (b) - The sodium and glucose facilitate water absorption by the small intestine. This occurs due to the co-transport of glucose and sodium, which enables water to follow their movement across the intestinal cell membrane, effectively rehydrating the body and restoring the balance of essential electrolytes.

Step-by-step solution

Understand the role of sodium in the body

Sodium is an essential electrolyte that helps regulate water balance inside and outside the cells, and is also vital for nerve and muscle function. Maintaining a proper balance of sodium and other electrolytes is crucial for the normal functioning of the body. In the state of dehydration, sodium levels can be significantly reduced, leading to an imbalance.

Understand the role of glucose in the body

Glucose is a simple sugar that serves as the primary source of energy for the body. It is readily absorbed by the cells and used to generate ATP (adenosine triphosphate), the principal molecule for storing and transferring energy in cells. Glucose can also help facilitate the absorption of sodium, which in turn enhances water absorption, as well.

Eliminate incorrect options

We can now eliminate options (a), (c), and (d). Oral rehydration therapy does not reduce urine output or make the person thirsty, nor does it kill intestinal bacteria. The main purpose of this therapy is to rehydrate the body and restore the balance of essential electrolytes.

Identify the correct option and provide the explanation

The correct answer is (b) - The sodium and glucose facilitate water absorption by the small intestine. This is due to the phenomenon known as co-transport or coupled transport. In the small intestine, special transport proteins called "sodium-glucose transport proteins" (SGLT) help with the co-transport of glucose and sodium across the intestinal cell membrane. This process causes water absorption to occur since water follows the movement of sodium and glucose across the membrane, effectively rehydrating the body and restoring the balance of essential electrolytes.

Key concepts

Sodium-Glucose Co-Transport

One of the most important concepts underlying Oral Rehydration Therapy (ORT) is the sodium-glucose co-transport mechanism. This process occurs in the small intestine where specific transport proteins, called sodium-glucose linked transporters (SGLT), are located. These proteins facilitate the simultaneous movement of sodium ions and glucose molecules into the intestinal cells.

When sodium and glucose are present in the intestinal lumen, the SGLT proteins bind to them and transport them across the cell membrane into the intestinal cells. This is an efficient process because both sodium and glucose need to be present for the transport to occur.

Once inside the cell, both sodium and glucose provide favorable osmotic conditions for water absorption. Because water naturally follows the movement of solutes like sodium and glucose, this co-transport facilitates water movement from the intestine into the bloodstream, effectively rehydrating the body.

This mechanism is particularly crucial in conditions like dehydration, where replenishing lost fluids is essential.

Electrolyte Balance

Electrolytes play a vital role in maintaining critical physiological functions in the body. They include ions such as sodium, potassium, calcium, and chloride, and are essential for various body processes.

During dehydration, there's often an electrolyte imbalance, especially a decrease in sodium levels, which can lead to dizziness, muscle weakness, and even more serious complications. Sodium is crucial for maintaining the balance of fluids between the inside and the outside of cells.

Oral Rehydration Therapy helps address this imbalance by supplying sodium directly through a carefully formulated solution. The presence of glucose in the solution is beneficial because it enhances sodium absorption, which is key to restoring electrolyte balance. This dual benefit of providing both sodium and glucose ensures that the body can regain its fluid balance efficiently.

Maintaining electrolyte balance is essential not just for rehydration but also for overall health, as it supports nerve function, muscle contraction, and other critical bodily functions.

Dehydration Treatment

Dehydration occurs when the body loses more fluids than it takes in, leading to a deficit that can significantly impact health. Common causes include diarrhea, vomiting, excessive sweating, and insufficient fluid intake.

The symptoms of dehydration can range from mild to severe and include thirst, dry skin, fatigue, dizziness, and in severe cases, shock or unconsciousness. Proper treatment is essential to prevent these symptoms from worsening.

Oral Rehydration Therapy is one of the most effective treatments for dehydration. This method uses a simple solution of water, sodium chloride (salt), and glucose to rapidly replenish lost fluids and electrolytes.

The efficiency of ORT lies in its simplicity and the scientific principle of co-transport, as discussed earlier. By absorbing water alongside sodium and glucose, the body can quickly restore its fluid balance, making ORT a lifesaving treatment, especially in areas without advanced medical care.

Moreover, ORT is accessible, easy to prepare, and can be used proactively in situations with expected fluid loss. It’s a key treatment strategy both in preventing and addressing dehydration efficiently.