Kidneys are more than just filters! Discover their seven amazing functions!

In our body, the kidney is like a super "little guard" that works silently, always guarding our health. Most people may only know that the kidney is the body's "filter" that can filter waste from the blood to form urine for excretion. However, the function of the kidney is far more than that. It also has many magical functions and plays an indispensable role in maintaining the normal operation of our body. Now, let us unveil the mystery of the seven magical functions of the kidney.

1. Excretion of metabolic waste

This is the most well-known kidney function. Our bodies produce a variety of waste products during metabolism, such as urea, creatinine, uric acid, etc. If these waste products accumulate in the body, they will cause damage to the body. The kidneys filter out these metabolic waste products in the blood through the filtration of the glomeruli, and then through the reabsorption and secretion of the renal tubules, they are finally excreted as urine. Every day, the kidneys filter about 180 liters of blood and separate about 1-2 liters of urine from it to ensure the timely removal of metabolic waste products in the body and maintain the cleanliness of the internal environment.

2. Regulate water and electrolyte balance

The kidney is like a precise "regulator" that can adjust the body's water and electrolyte balance according to the body's needs. When we drink too much water, the kidneys will increase urine production to excrete excess water from the body; when our body is dehydrated, the kidneys will reduce urine production and retain water. At the same time, the kidneys can also regulate the concentration of electrolytes such as sodium, potassium, calcium, and magnesium. For example, when there are too many sodium ions in the body, the kidneys will increase the excretion of sodium ions to restore the body's sodium ion concentration to normal; when the body's potassium ion concentration is abnormal, the kidneys will also maintain the balance of potassium ions by regulating the excretion or reabsorption of potassium ions. This fine regulatory function ensures the stability of the internal and external environment of our body's cells, allowing cells to function normally.

3. Maintaining acid-base balance

The normal physiological functions of the human body need to be carried out in a relatively stable acid-base environment, and the kidneys play a key role in maintaining acid-base balance. In our daily diet and metabolic process, various acidic and alkaline substances are produced. The kidneys regulate the acid-base balance in the body by secreting hydrogen ions and reabsorbing bicarbonate ions. When the acidic substances in the body increase, the kidneys will increase the secretion of hydrogen ions and reabsorb more bicarbonate ions to neutralize the acidic substances; when the alkaline substances in the body increase, the kidneys will reduce the secretion of hydrogen ions and increase the excretion of bicarbonate ions. In this way, the kidneys maintain the pH value of the blood within the normal range of 7.35-7.45 to ensure the normal functioning of various physiological functions of the body.

4. Endocrine Function

The kidney is also an important endocrine organ that can secrete a variety of hormones to regulate the body's physiological functions. Among them, the renin-angiotensin-aldosterone system (RAAS) is an important endocrine system that regulates blood pressure and water-sodium balance. When the kidney senses a drop in blood pressure or a decrease in blood volume, it will secrete renin. Renin acts on angiotensinogen to convert it into angiotensin I, which is further converted into angiotensin II under the action of angiotensin converting enzyme. Angiotensin II has a strong vasoconstriction effect, which can increase blood pressure and stimulate the secretion of aldosterone. Aldosterone promotes the reabsorption of sodium ions and the excretion of potassium ions by the kidneys, thereby increasing blood volume and raising blood pressure. In addition, the kidneys can also secrete erythropoietin, which can stimulate bone marrow hematopoietic stem cells to produce red blood cells, maintain a normal number of red blood cells, and prevent and treat anemia.

5. Promote the activation of vitamin D

Vitamin D is essential for maintaining bone health and calcium-phosphorus metabolism. However, the vitamin D we take from food or synthesized by the skin through ultraviolet radiation needs to be activated by the kidneys to play its physiological role. The 1-α hydroxylase in the kidneys can convert vitamin D precursors into active 1,25-dihydroxyvitamin D. Active vitamin D not only promotes intestinal absorption of calcium, but also regulates bone metabolism and maintains normal bone structure and function. If kidney function is impaired, the activation of vitamin D will be affected, leading to calcium-phosphorus metabolism disorders and bone diseases such as osteoporosis and osteomalacia.

6. Participate in blood pressure regulation

In addition to regulating blood pressure through the renin-angiotensin-aldosterone system, the kidneys can also participate in the regulation of blood pressure in other ways. The kidneys affect blood volume and blood pressure by regulating water and sodium balance. When blood volume increases, blood pressure rises, and the kidneys will reduce blood volume by increasing urine production; conversely, when blood volume decreases, the kidneys will reduce urine production, increase blood volume, and increase blood pressure. In addition, the kidneys can also secrete some vasoactive substances, such as prostaglandins and kinins, which have the effect of dilating blood vessels and can lower blood pressure. They coordinate with the renin-angiotensin-aldosterone system to maintain blood pressure stability.

7. Remove foreign matter and drugs

In our daily lives, we may come into contact with various foreign bodies and drugs. After these substances enter the body, most of them need to be excreted through the kidneys. The kidneys can identify and remove these foreign bodies and drugs to protect the body from their harm. For example, when we take antibiotics, antipyretics and other drugs, the kidneys will filter out the drugs and their metabolites and excrete them through urine. However, if kidney function is impaired, the excretion of drugs will be affected, causing the drugs to accumulate in the body and increasing the risk of adverse drug reactions.

The functions of the kidney are multifaceted and complex. It is not just a simple "filter", but also a key organ to maintain our health. Understanding these amazing functions of the kidney makes us more deeply aware of the importance of protecting kidney health. In daily life, we should develop good living habits, such as a reasonable diet, moderate exercise, and avoid drug abuse, so as to protect our kidneys and enable them to continue to play these important functions and safeguard our health.