Question

The mother of a child diagnosed with glomerulonephritis asks about the normal function of the kidney. Which functions would be correct for the nurse to identify? a. Excretion of waste products b. Control of blood pressure c. Manufacture of electrolytes d. Regulation of red blood cell production

Short answer

The correct functions of the kidneys to identify are: Excretion of waste products, Control of blood pressure, and Regulation of red blood cell production.

Step-by-step solution

Understanding Kidney Functions

First, understand that the kidneys have multiple functions critical to maintaining homeostasis. These include filtering blood, removing waste products via urine, regulating blood pressure, balancing electrolytes, and stimulating red blood cell production.

Excretion of Waste Products

Explain that excreting waste products is indeed a primary function of the kidneys. They remove urea, creatinine, and other waste substances from the bloodstream.

Control of Blood Pressure

The kidneys play a significant role in controlling blood pressure by regulating the volume of blood (by adjusting the amount of water excreted) and by releasing the enzyme renin that helps control blood pressure.

Manufacture of Electrolytes

Clarify that although kidneys regulate electrolyte levels by filtering and reabsorbing necessary amounts, they do not manufacture them. Electrolytes enter the body through consumption of food and drink.

Regulation of Red Blood Cell Production

Explain that kidneys help regulate red blood cell production by releasing erythropoietin, a hormone that stimulates the bone marrow to produce red blood cells, especially in response to hypoxia.

Identifying Correct Functions

Based on the above steps, correctly identify the functions of the kidneys that include excretion of waste products (a), control of blood pressure (b), and regulation of red blood cell production (d). Option (c) is not a function of the kidneys.

Key concepts

Excretion of Waste Products

The kidneys are fundamental in the body's ability to detoxify the blood and eliminate waste. They perform the essential task of excreting waste products like urea, creatinine, and various toxins, which are byproducts of metabolism. Think of the kidneys as a sophisticated waste management system. They meticulously filter out unwanted substances from the bloodstream and convert them into urine.

Every day, these bean-shaped organs process around 200 quarts of blood, sifting through it to produce about 1 to 2 quarts of urine, which then travels to the bladder for excretion. This process is crucial because accumulation of waste can be toxic and harmful to the body. It’s important to note that improperly functioning kidneys, as seen in conditions like glomerulonephritis, can lead to serious health issues due to the accumulation of waste products in the blood.

Blood Pressure Regulation

In addition to their waste removal role, kidneys are also vital in maintaining blood pressure within a normal range. They regulate blood pressure through a complex mechanism involving the balance of fluid and salts, and the release of hormones. For example, when the kidneys detect a drop in blood pressure, they can retain water and salts to increase blood volume, which in turn boosts blood pressure.

To get more technical, part of this process involves the renin-angiotensin-aldosterone system (RAAS). When blood pressure drops, the kidneys release the enzyme renin. Renin then converts angiotensinogen, a plasma protein produced by the liver, into angiotensin I, which is further converted into angiotensin II. Angiotensin II is a potent vasoconstrictor, narrowing blood vessels and increasing blood pressure. Furthermore, this signal also prompts the adrenal gland to release aldosterone, a hormone that prompts the kidneys to retain sodium and water, further influencing blood pressure. Disruptions in this precise regulatory system can lead to hypertension or hypotension, highlighting the kidneys' critical role in cardiovascular health.

Regulation of Red Blood Cell Production

Lastly but importantly, the kidneys play a role in hematopoiesis—the production of red blood cells (RBCs). This function is governed by the hormone erythropoietin (EPO), which is produced by the kidneys. Erythropoietin is released in response to hypoxia, a condition where the body or a region of the body is deprived of adequate oxygen supply.

When oxygen levels are low, EPO is released into the bloodstream and travels to the bone marrow, where it stimulates the production of more red blood cells, which are essential for carrying oxygen to tissues throughout the body. Keeping red blood cell counts within a normal range is crucial for preventing anemia, a condition characterized by a deficiency in the number or quality of red blood cells, which can cause fatigue and other health issues. Therefore, the kidneys indirectly ensure that your body’s tissues receive sufficient oxygen to function properly.