Kidney: anatomy and fucntions

2021-02-13 12:00 AM

The kidneys are two pea-shaped organs in the urinary system that help the body get rid of waste products like urine, and it also helps to filter the blood before sending it back to the heart.


The kidneys perform many important functions:

Maintain overall fluid balance.

Regulates and filters minerals from the blood.

Filter waste from food, drugs, and toxic substances.

Creates hormones that help build red blood cells, promote bone health and regulate blood pressure.

Kidney anatomy 



The nephron is the most important part of each kidney. They draw blood, metabolize nutrients, and help remove waste products from the filtered blood. Each kidney has about 1 million nephrons. Each has its own set of internal structures.

Renal corpuscle

After blood enters a nephron, it enters the renal corpuscle, also known as the Malpighian body. The renal corpuscle contains two additional structures:

Kidney glomerulus. This is a group of capillaries that absorb protein from the blood passing through the renal corpuscle.

Bowman's cyst. The remaining fluid, called cyst urine, passes through the Bowman's cyst into the renal tubule.

Renal tubules

The renal tubules are a series of tubes that begin after the Bowman's cyst and end at the collection of the ducts.

Each tube has several sections:

Proximal tubule. This part absorbs water, sodium, and glucose back into the bloodstream.

Henle. This part continues to absorb potassium, chloride, and sodium into the bloodstream.

Distal tubule. This part absorbs more sodium into the blood and absorbs potassium and acid.

When the fluid reaches the end of the tube, it is diluted and filled with urea. Urea is a by-product of protein metabolism that is released in the urine.

Renal cortex

The renal cortex is the outer part of the kidney. It contains glomeruli and renal tubules.

The renal cortex is surrounded at its outer edge by the renal capsule, a layer of fatty tissue. Together, the renal cortex and cyst and protect the internal structures of the kidney.

Renal medulla

The renal medulla is the smooth, inner tissue of the kidney. It contains the loop of Henle as well as the renal pyramids.

Renal pyramid

The renal pyramid is a small structure containing chains of nephrons and tubules. These tubes transport fluid into the kidneys. This fluid then moves from the nephrons toward the internal structures that collect and transport urine out of the kidney.

Renal collecting duct

There is a collection duct at the end of each nephron in the renal medulla. This is where the filtered fluid exits the nephron.

Once in the collecting duct, the fluid moves to its final stop in the renal pelvis.

Renal pelvis

The renal pelvis is a funnel-shaped space in the innermost part of the kidney. It acts as a pathway for fluid on its way to the bladder.

Renal navel

The umbilicus is a small opening located at the inner edge of the kidney, where it curves inward to give its distinct bean-like shape. The renal pelvis passes through it, as well as:

Renal artery. Carry oxygenated blood from the heart to the kidneys for filtration.

Renal veins. Brings filtered blood from the kidneys back to the heart.


The ureter is a tube that pushes urine into the bladder, where it collects and exits the body.

Kidney problems

Due to all the important functions the kidneys perform and the toxins they encounter, the kidneys are susceptible to various problems.

Some issues include:


Chronic kidney disease (CKD).

Kidney stones.


Acute nephritis.

Polycystic kidney disease.

Urinary tract infections.




The kidneys retain water.


Kidney cyst.

Nephrotic syndrome.


Symptoms of a kidney problem

Kidney problems can cause a wide range of symptoms. Some popular ones include:

Difficulty sleeping.


Inability to concentrate.

Dry itchy skin.

Increased or decreased urination.


Foamy urine.

Eye oedema.

Swelling of the legs or ankles.


Muscle cramps.

If you notice any of these symptoms, contact your doctor. Depending on symptoms, some kidney function tests may be done to diagnose.

Kidneys are healthy

The kidneys are an important organ that affects many other body organs, including the heart. Follow these tips to keep them working properly:

Avoid adding salt

Eating plenty of salty foods can disrupt the balance of minerals in the blood. This can make it harder for the kidneys to function. Try swapping processed foods - often high in salt - for whole foods, such as:

Fresh fruits and vegetables.



Do exercise

High blood pressure is a known risk factor for chronic kidney disease. Regular exercise, even just 20 minutes a day, can help lower blood pressure.

Drink enough water

Drinking plenty of water helps the kidneys perform one of their most important functions: getting rid of toxins.

Use the drug with caution

Frequently taking certain over-the-counter medications, such as nonsteroidal anti-inflammatory drugs, can cause kidney damage over time. Taking them from time to time is fine, but work with your doctor to find alternatives if there is a condition that requires pain control, such as arthritis.

Know your risk factors

Several things can increase your risk of developing kidney problems. Be sure to regularly check for kidney function if:

Have diabetes.


Have high blood pressure.

Have a family history of kidney disease.