Position of Kidney in the Body

What Are Kidneys?

The kidneys are paired, bean-shaped organs present on either side of the spine. They are a part of the urinary system. Each kidney is about four to five inches long and almost the size of a fist. The kidneys filter blood, remove waste and maintain the body's fluid balance and electrolytes balance. Blood supply to the kidney is via the renal artery, gets filtered to form urine, and then the urine exits the kidney through ureters. The urine is then carried by the ureters and temporarily stored in the bladder which empties whenever required. The urine flows from the urethra to the urethral office and exits from the body.

What Are the Functions of Kidneys?

Each kidney contains millions of filtering units called nephrons. The nephron is made up of a glomerulus and a tubule. The glomerulus filters the blood, whereas the tubule returns the required substances back to the blood and removes waste. The glomerulus is a bunch of tiny blood vessels made up of thin walls that allow smaller molecules, fluid, waste products, and ions to pass into the tubule. As the filtered fluid moves along the tubule, the blood vessels reabsorb the required amount of water, minerals, and nutrients back into the body.

Why Are Kidneys Important?

Kidneys remove waste products and extra fluid from the body. And they also remove acid produced by the metabolism of cells in the body and maintain a balance of water, salts, and minerals such as calcium, sodium, potassium, and phosphorus in the blood. Without this balance, nerves, muscles, and other tissues in the body may not function normally. Other hormones produced by the kidneys control blood pressure, produce RBCs (red blood cells),·and keep bones strong and healthy.

Besides blood pressure and blood volume regulation, kidneys also participate in the production of calcitriol (the active form of vitamin D). In cases with high blood loss, kidneys release a hormone called erythropoietin, which stimulates the bone marrow to initiate blood cell production. The body constantly produces hydrogen ions. A number of increased hydrogen ions can acidify the blood and cause acidosis. Kidneys excrete these hydrogen ions, and in that way consistently maintain the pH of the blood at 7.4. If the kidneys excrete too many hydrogen ions, the pH of the blood becomes too alkaline which leads to alkalosis.

The basic function of the kidneys is to remove waste products and excess fluid from the body. These waste products and excess fluid are excreted through the urine. Urine production involves excretion and reabsorption. This cycle is necessary to maintain a normal balance of body chemicals. The kidneys also produce hormones that impact the function of other organs. The regulation of the body's salt, potassium, and acid content is conducted by the kidneys. A hormone produced by the kidneys enables red blood cell production. Other hormones produced by the kidneys help regulate calcium metabolism and control blood pressure. Various functions of the kidney include the following:

• Removing drugs from the body.

• Removal of waste products from the body.

• Maintaining body fluid balance.

• Forms an active form of vitamin D that maintains healthy bones.

• Releases hormones that regulate blood pressure.

• Controls the production of red blood cells.

What Is the Position of the Kidney in the Body?

• Kidneys are positioned retroperitoneally in the right and left upper abdominal quadrants.

• The kidneys are placed on either side of the abdomen in the retroperitoneal space between the parietal peritoneum and the posterior abdominal wall.

• They are located below the ribcage between the transverse processes of T-12 (thoracic) to L-3 (lumbar) vertebrae. The left kidney is superior to the right kidney.

• The left kidney is located at the T-12 (thoracic) to L - 3 (lumbar) vertebrae. The upper portions of the kidneys are covered by the 11th and 12th ribs.

• The average weight of a kidney in males is 125 to 175 grams, whereas in females they weigh about 115 to 155 grams.

• The dimensions of the kidneys are about 11 to 14 cm in length, 6 cm wide, and 4 cm thick. They are covered by dense, fibrous, irregular connective tissue capsules that help maintain their shape and hold them in position.

• The fibrous capsule is made up of adipose connective tissue called the renal fat pad, which is again composed of a tough renal fascia. This fibrous capsule acts as a shock absorber.

• The overlying peritoneum or the renal fascia adheres to the posterior abdominal wall in a retroperitoneal position.

• The superior aspect of each kidney is covered by the adrenal gland. The adrenal gland consists of the adrenal cortex, which influences renal function through the production of the hormone aldosterone, which stimulates sodium reabsorption.

• Internal Structure- Internally, the kidney is divided into the outer part, called the renal cortex, and the inner part called the renal medulla. The renal cortex consists of renal pyramids which are six to eight in number. The renal hilum is that part of the kidney from which the renal vessels enter and exit from the kidney. The renal artery after entering the kidney divides into segmental renal arteries and interlobar arteries. The interlobar arteries then further branch to form afferent arteries. Each kidney is made up of 1.3 million afferent arterioles, which in turn, are a part of the nephron.

Conclusion

Kidneys are a part of the urinary system. They are present in pairs and are retroperitoneal in origin. Each kidney comprises 1.3 million neurons that filter the blood and remove waste products and water from the body to produce urine. The kidneys are placed below the ribcage, from the T12 to L3 vertebrae. Each kidney is covered by a gland called the adrenal gland. The adrenal gland secretes aldosterone for sodium absorption. The kidneys are enclosed in a fibrous capsule that acts as a shock absorber and maintains the position of the kidney in the body. The kidneys receive a large amount of blood flow, and there are several blood vessels that supply and drain the kidney, including the renal artery, renal vein, and a network of capillaries that surround the nephrons.