Kidneys: Structure, Functions and Diseases

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Kidneys are two bean-shaped organs on either side of your spine just below the rib cage, each about the size of an adult fist. These tiny organs perform the very vital and complex function of filtering waste from your body and maintaining balance in the rest of the body. The kidneys are part of the urinary system.  

Parts of Kidney 

Renal Cortex 

It is the outer layer of your kidney. It is granular due to the presence of nephrons. The nephrons are the operational unit of the kidney. The renal cortex also produces the hormone erythropoietin that helps make red blood cells (RBCs) in your bone marrow. 

Renal Medulla 

It is the inner part of your kidney. They appear striated because they contain straight tubular structures and blood vessels. The nephrons, with their glomeruli and tubules, are present here. Renal tubes carry to the renal pelvis. 

Renal papilla 

These pyramid-shaped structures move urine to the ureters.  

Renal pelvis 

This funnel-shaped structure piles up urine and passes it down two ureters. Urine moves from the ureters to the bladder, where it gets stored. 

Renal vein 

Each of your kidneys contains one renal vein. This vein carries newly cleaned blood from your kidneys and back to your heart.  

Why Kidney is Important ?

The kidney filters two hundred litres of blood every day, and it is about half a cup of blood every minute. The critical function of the kidneys is to clean toxins and waste out of the blood, which is done through nephrons. 

Nephrons are filtering units present in millions in your kidney. The nephrons work in a two-step process: the glomerulus purifies your blood, and the tubule returns required substances to your blood, eliminating waste. The other essential functions of the kidney include the following. 

  • Regulate the production of RBCs (Red Blood Cells)  
  • Regulate the acid-base balance of your blood 
  • Regulate the amount of nutrients such as calcium and potassium.  

How Blood Flows Through My Kidneys ?

The blood enters from the heart to the kidney through a blood vessel named the renal artery. The millions of tiny blood vessels called nephrons clean and filter blood. These nephrons consist of Glomeruli and Renal tubules. 

The glomeruli perform the first filtration stage; they allow waste, molecules, and water to proceed to renal tubules but block large molecules like proteins and blood cells.  

The filtered fluid passes through the tubules, the blood vessels almost reabsorb most of the water, and minerals essential for the body also eliminate excess acid from the blood.  

The waste material travels through tubes of muscle called ureters to your bladder, eventually excreted as urine. The newly cleaned blood returns to your bloodstream via a large blood vessel called the renal vein.  

Types of kidney diseases 

Chronic kidney disease 

Chronic kidney disease is a prevalent form of kidney disease. In this condition, your kidneys are damaged and filter the blood properly. 

The leading causes for developing kidney diseases are high blood pressure, diabetes, heart disease, and a family history of kidney failure. Dialysis may help treat kidney disease but cannot cure it completely.  

Kidney Stones 

Kidney stones develop when minerals such as calcium, oxalate, uric acid and other substances in the blood solidify in the kidneys, forming solid masses. Usually, kidney stones come out of the body during urination, but it can be excruciating.  

The common symptoms of kidney stones are blood in your urine, nausea, severe pain in your lower back, vomiting and fever. It can be treated with lithotripsy, shockwave, ureteroscopy, and nephrolithotomy.  


Glomerulonephritis is an inflammation of the glomeruli, which acts as a kidney filter. In this condition, the kidneys slowly lose their capacity to eliminate waste products and excess fluid from the blood.  

Glomerulonephritis can be congenital or acquired by drugs, infections or disorders. High blood pressure, fatigue, decreased urine output, and swelling of the face, feet, hands and belly are the symptoms of glomerulonephritis. 

Polycystic kidney disease 

Polycystic kidney disease creates cysts, which are different from individual kidney cysts and are usually non-dangerous. But PKD is a severe chronic disease which can obstruct kidney function and eventually lead to kidney failure. Genetic mutations can cause PKD. 

Urinary tract infections 

Urinary tract infections are prevalent bacterial infections in any part of the urinary system. Infections in the urethra and bladder are most common. They are treatable and hardly lead to further health problems. But, if left untreated. These infections can eventually lead to kidney failure.  

Tests to check the health of kidneys  

Kidney biopsy 

Kidney biopsy is when your healthcare provider removes a small piece of kidney tissue and examines it under a microscope. This process is done by inserting a thin needle through the skin. 

Imaging tests 

Imaging tests such as CT scans, X-rays, MRI, and ultrasound can provide pictures of the kidneys. These pictures help the doctor to check whether there is any abnormality in your kidneys.  

Blood tests 

It is a measure of how well your glomeruli filter your blood. 

Urine test 

A urine test is when a doctor analyses a small amount of your urine to examine for indications of kidney disease and other health complications. 

Effective ways to keep kidney healthy  

Daily Exercise 

Activities like walking, cycling, running and dancing can keep you healthy. Regular exercise may lower your risk of chronic disease. 

Drinking Water 

Consistent water intake keeps your kidneys healthy. People previously affected by Kidney stones should drink more water to avoid stone deposits in future.  

Quit Smoking  

Smoking leads to lower blood flow to your kidneys and body because it damages your body’s blood vessels.  

Blood Sugar Level 

High blood sugar level forces kidneys to work extra time to filter blood. 

Blood Pressure Level 

High blood pressure can accelerate kidney damage. You may have high blood pressure if your blood pressure is regularly above 140/90. 


Kidneys are essential for the healthy functioning of your body, and any harm to vital organs may impact the body’s ability to clean your blood, filter excess water out of your body and help regulate your blood pressure. 

Health Insurance for Kidney Stones

Treating kidney stones can be challenging if you don’t have health insurance. As medical bills rise, you will require health insurance for kidney stone removal surgery to oversee the cost of care and reduce the adverse risks.


1. What is the primary function of the kidney? 

The kidney’s primary function is to purify the blood of toxins and transform the waste into urine. 

2. Explain the kidney structure and function.

– The kidneys are two bean-shaped organs around the size of an adult fist. A tough, fibrous renal capsule covers each kidney and supports the soft tissue. After that, two layers of fat serve for more protection. The adrenal glands are present on top of the kidneys. 
– The inner part of the kidneys has many number of pyramid-shaped lobes. – Each contains an outer renal cortex and an inner renal medulla. Nephrons travel between these sections.  
– Each nephron has a filter, termed the glomerulus, and a tubule. The glomerulus first filters blood, which enters the kidneys via the renal arteries and leaves through the renal veins.  
– The tubule returns essential substances to the blood, eliminating waste that becomes urine. The kidneys excrete urine along the ureter, a tube that leads to the bladder. 

3. Where is the kidney located?

The kidney is just underneath the rib cage, one on each side of your spine. 

4. What are common kidney problems? 

Common kidney problems are acute kidney injury, kidney stones, cysts, and infections.

5. How to improve kidney function? 

Quit smoking 
Exercise regularly 
Maintain a healthy weight 
Follow a balanced diet 
Drink only in moderation


The Information including but not limited to text, graphics, images and other material contained on this blog are intended for education and awareness only. No material on this blog is intended to be a substitute for professional medical help including diagnosis or treatment. It is always advisable to consult medical professional before relying on the content. Neither the Author nor Star Health and Allied Insurance Co. Ltd accepts any responsibility for any potential risk to any visitor/reader.

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