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What is the structure of the kidneys An important organ in our body that has many essential functions.

structure of the kidneys

Introduction to kidney

Before we learn about the complex structure of kidneys, let us first understand their importance. The kidneys are two bean-shaped organs located in the lower back, just above the waist.

These remarkable organs play a vital role in maintaining our overall health.

External structure

The kidney consists of two main regions – the outer cortex and the inner medulla. The cortex is the outermost layer, which is made up of millions of tiny tubules known as renal corpuscles.

These corpuscles filter our blood by removing waste products and excess water, as well as retaining important substances such as glucose and amino acids.


Explore nephrons – the complex units responsible for kidney function. Nephrons are the structural and functional units of the kidney.

Each kidney contains about one million nephrons, which act like tiny filters that perform important functions such as filtering the blood, maintaining fluid balance, and controlling blood pressure.

Blood supply

A strong blood supply is essential for the kidneys to function optimally. The renal artery carries oxygenated blood to the kidney for filtration.

Upon reaching the nephron, the blood enters a network of capillaries called the glomerulus. The glomerulus serves as the site of initial filtration, where excess waste and fluid are removed before the filtered blood passes through.

Filtration process

As blood passes through the glomerulus, pressure forces water, essential nutrients, and waste products into a cup-shaped structure called Bowman’s capsule.

This filtered fluid, known as the glomerular filtrate, then enters the renal tubules, where further processing takes place.

Renal tubules

The renal tubules are a convoluted network of tubules responsible for reabsorbing essential substances from the glomerular filtrate back into the bloodstream.

These tubules are divided into different sections, including the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule. Each section plays a specific role in maintaining fluid balance and electrolyte levels.

Collecting ducts

After its journey through the renal tubules, the filtered fluid, now called urine, collects in larger tubes called collecting ducts.

The collecting ducts further refine the urine and regulate its amount by reabsorbing water back into the bloodstream as needed. This process ensures that our body maintains a delicate balance of fluids and electrolytes.


Once urine is filtered by the collecting ducts, it is carried to the renal pelvis, a basin-like structure in the kidney.

From there, urine flows into the ureters, long muscular tubes that carry urine from the kidneys to the bladder. Ultimately, the bladder releases urine through the urethra during the process of urination.


The fascinating structure of the kidney, a masterpiece of design and engineering within our bodies. Through complex filtration processes from the outer cortex to the nephron and beyond, we have explored the complex functioning of this vital organ.

structure of the kidneys
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