Knowing the kidneys will help us better understand kidney disease

The basic function of the kidney is to produce urine to remove excess water, metabolites, certain wastes and poisons from the body, regulate water and electrolyte balance and maintain acid-base balance. At the same time, the kidney has a reabsorption function to retain water and other useful substances, such as glucose, protein, amino acids, etc. In addition, the kidney has an endocrine function and can produce erythropoietin, active vitamin D3, renin, prostaglandins, kinins, etc. Not only that, the kidney is also the degradation site of some hormones in the body and the target organ of extrarenal hormones. These functions of the kidney ensure the stability of the internal environment of the body and enable metabolism to proceed normally. Therefore, the kidney is an important organ of the human body. In order to maintain health, we need to take good care of the kidney. Let us understand the basic situation of the kidney from several aspects.

01Kidney shape

Kidneys are paired bean-shaped organs, and their sizes vary from person to person. A normal adult's kidney is 10 to 12 cm long, 5 to 6 cm wide, 3 to 4 cm thick, and weighs 120 to 150 grams. Generally, female kidneys are smaller than male kidneys, and the left kidney is slightly larger than the right kidney. The human body has two kidneys. If one kidney loses its function, the other can take on the functions of both kidneys to a certain extent. However, in this overworked situation, the kidneys are more fragile and more prone to kidney disease.

02The location of the kidneys

The kidney is a retroperitoneal organ, located on both sides of the spine behind the peritoneum, one on each side. The right kidney is 1 to 2 cm lower than the left kidney due to the liver. A normal kidney moves up and down 1 to 2 cm with breathing. The kidney is below the diaphragm. During a physical examination, the left kidney is not easy to touch, except for the lower pole of the right kidney, which can be palpated at the lower edge of the ribs. Clinically, the area between the outer edge of the psoas muscle and the 12th rib is often called the costal waist point, and the intersection of the 12th rib and the spine is called the costovertebral point. When there is a lesion in the kidney, touching or tapping this area often causes tenderness or percussion pain.

03Structure of the kidney

From the longitudinal section of the kidney, we can see that the renal parenchyma is divided into two layers: the outer layer is the cortex and the inner layer is the medulla. The renal cortex is composed of more than 1 million nephrons. Part of the cortex extends to the medullary pyramids to become renal columns. The renal medulla is composed of 10 to 20 pyramids. The nephron is the basic unit of kidney structure and function.

04 Functions of the Kidneys

Our kidneys have the following functions:

(1) Urine production: When blood flows through the kidneys, most of the plasma components, except for cells and large molecular proteins, will pass through the glomerular filtration membrane to form primary urine, which is then concentrated and diluted to form final urine that flows into the renal pelvis and is excreted from the body.

(2) Excretion of metabolic products: The body produces a variety of waste products during metabolism. Most of the metabolic waste products, represented by urea nitrogen, creatinine, uric acid, etc., enter the kidneys through the blood and are excreted from the body with urine.

(3) Maintaining body fluid, electrolyte and acid-base balance: In the process of urine production by the kidneys, the kidneys regulate the body's water, electrolyte and acid-base balance through their concentration and dilution functions, thereby maintaining the stability of the internal environment.

(4) Endocrine function: It regulates blood pressure by secreting renin, prostaglandins, and kinins through the renin-angiotensin-aldosterone system and the kinin-bradykinin-prostaglandin system. It stimulates hematopoiesis by secreting erythropoietin. It activates vitamin D3 and regulates calcium and phosphorus metabolism by secreting 1α-hydroxylase. The kidney is the degradation site of many endocrine hormones, such as insulin and certain gastrointestinal hormones. When renal function is impaired, the half-life of these hormones will be significantly prolonged, causing metabolic disorders.

This shows that the kidneys play an important role in maintaining the stability of the body's internal environment.

05Early signs of kidney disease

The kidneys do not beat like the heart, nor do they feel bloated and painful like the stomach due to overeating. They work hard and silently play the role of "scavenger" in the body, filtering and removing metabolites. Because of this, the damage they suffer is also silent; if you wait until symptoms appear before seeking medical treatment, most of the kidney function may have been lost, affecting not only the urinary system, but also various organs and systems of the body, which is very harmful to physical health. Clinical experience shows that the following signs may appear in the early stages of kidney disease: edema, high blood pressure, excessive or insufficient urine volume or increased nocturia, abnormal urine color, increased foam in the urine that is not easy to subside after standing, etc. If the above situation occurs, you need to go to the hospital for further examination as soon as possible to determine whether you are ill.

06Common kidney diseases

The most common types of kidney diseases are:

(1) Chronic glomerulonephritis; (2) Nephrotic syndrome; (3) Chronic interstitial nephritis; (4) Chronic renal failure; (5) Kidney stones; (6) Pyelonephritis; (7) Renal cysts; (8) Diabetic nephropathy; (9) Hypertensive renal damage; (10) Purpura nephritis; (11) Lupus nephritis, etc.

In short, we must pay more attention to and attach more importance to our kidneys in our daily lives and learn more about the kidneys, which will be beneficial to our health.