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Urinary System: Parts, Function, and 5 Fun Facts

Urinary System: Parts, Function, And 5 Fun Facts

Our body has different ways to get rid of its waste products. The lungs, intestine, skin, and urinary system work in harmony to expel any waste products that might harm you. So our urinary system is one of the main ways our body uses to wash away toxins. But our urinary system is not just a waste disposal machine. It is way more than that.

In this article, we are going to discover the four parts of the urinary system, its function, how to keep it healthy, and finally, some diseases that may affect your urinary system. And at the end, we are going to finish with five fun facts about the urinary system.

Parts of the Urinary System

Our urinary system is composed of four main structures:

  1. Two kidneys
  2. Two ureters
  3. One urinary bladder
  4. One urethra

The urine is formed in the kidneys and then travels its way down through the ureters, then to the urinary and finally to the urethra before it gets flushed in the toilette.

The components of the urinary system

1. The Kidneys

We have two kidneys, one on each side of the vertebral column just under the rib cage. The kidneys are located at the back of your abdomen. They are protected by the lower ribs from behind and are surrounded by pads of fat which also protect them from any trauma. Each kidney has the shape of a bean and measures 6cm in width, 12cm in length, and 3cm in thickness.

Your kidneys aren’t just organs that form urine and allow us to get rid of waste products. They play a bigger role in keeping your body’s internal environment stable. See the section on the function of our urinary system below to know more about it.

If we take a cross-section of a human kidney, we will find a very well-organized structure. The kidney is divided from the inside into two main areas; the outer cortex and the inner medulla. The medulla is then divided into pyramidal-shaped structures called renal pyramids. The tip of each pyramid is called papillae. In between these pyramids lie the renal columns, which are considered part of the renal cortex. An indented area in the medial aspect of each kidney is called the hilum. Through this hilum, the renal artery enters the kidney, and the renal vein also leaves it.

kidney, Anatomy of the human urinary system, Cross Section. Shown are the renal artery, renal vein, renal cortex, renal medulla, ureter, minor calyx, and major calyx.

2. The Ureters

In the last section, we stopped at the tip of the renal pyramids. Now, let’s move down the way. Just after the renal papillae, a tubular system emerges that would later form what is called the ureter. This tubular system starts with the minor calyces (the singular of which is the calyx). These minor calyces coalesce together to make the major calyces which in turn form the renal pelvis. Finally, the renal pelvis continues as the ureter.

The ureter is a thin muscular tube about 25cm long. Its function is to transport the urine formed in the kidneys to the next station, which is the urinary bladder. That is why it has muscles in its wall. These muscles contract and relax to propel the urine downward, where it gets stored in the urinary bladder. It is very dangerous if your urine stays in the ureters for a long time. For example, if you have a renal stone and your ureters can’t expel that urine down to the urinary bladder, it will cause back pressure on your kidneys and increases the risk of having a urinary tract infection.

3. The Urinary Bladder

The urinary bladder is a hollow organ that looks like a balloon. It lies in the pelvic cavity and acts as a reservoir of your urine. Like the ureter, it also has a smooth muscle layer that allows it to push urine to the next station. When these muscles relax, they allow your bladder to extend to accommodate more urine. And when they contract, they squeeze your urinary bladder and allow it to push the urine into the urethra. It holds the urine until it receives an order from your brain, telling it that it’s an appropriate time to expel that urine.

4. The Urethra

Here we are at the final station our urine travels through. The urethra is a thin tube that takes the urine that has been collected by the urinary bladder and moves it to its final destination; The toilette. Your urethra has muscle bands that encircle it tightly like a rubber band. They work as a guard. In fact, it has two guards that control the urine flow through it and prevent any potential leakage. These guards are the internal and external urethral sphincters.

The internal urethral sphincter lies at the beginning of your urethra (at the end of your urinary bladder). This sphincter contains smooth muscle fibres, which means it is not under your voluntary control. These muscle fibres encircle the urethra tightly like a rubber band.

The external urethral sphincter, on the other hand, lies below your internal urethral sphincter. It is composed of skeletal muscles, which means it is under your voluntary control. That is why you can hold your urine for a while if your brain tells you it is not the appropriate time or place to urinate.

How does urination occur?

The Function of Our Urinary System

When we talk about the function of our urinary system, we are mainly talking about the kidneys, as they are the primary organ of your urinary system. The other components of the urinary system play a minor role: that is, to transport the urine that the kidneys have formed until it is out of your system.

  1. Form the urine, which is a waste product.
  2. Maintain your body’s internal environment in balance; by keeping water, electrolytes (sodium, potassium, calcium, phosphate, etc.), acids, bases and other substances at the correct and optimal amount for your body’s function.
  3. Help in the production of your RBCs (red blood cells) by secreting a very important hormone called erythropoietin. This hormone is also produced in your liver.
  4. Share in the activation of vitamin D together with the liver. So it plays a very pivotal role in your bone health.
  5. It is the main organ concerned with regulating your blood pressure. The kidney plays a very complex role in keeping your blood pressure normal and adjusting it to your body condition.

How is Urine Formed

The urine is formed mainly of a waste product called urea and water. Urea is formed from protein breakdown in the liver to be excreted by the kidneys. To know how urine is formed, we need to take a close look at the microscopic structure of our kidneys.

We have already talked about the macroscopic picture of the kidney, but the microscopic picture is way more complex and deserves some time to be well understood. Under the microscope, each kidney is formed of over a million functional units called nephrons.

Illustration of the nephron and glomerulus, a part of the kidney.

What controls the amount or colour of your urine?

The amount of urine your body produces each day varies depending on several factors.

Things that cause diuresis (increase your urine output):

  • Some beverages, such as coffee and alcohol.
  • Drugs as diuretics.

Things that decrease your urine output (antidiuretic):

  • Hot weather. As it leads to water loss in other ways, such as sweating.

The process of urine formation occurs involuntarily. You can’t control how much urine your kidneys form a day. However, you can voluntarily control the process of urination. You can hold your urine in certain situations where you think it is not suitable to empty your bladder or decide to go to the bathroom whenever you want.

It is a very complex process, but before you give up, here’s a 3D video that would make it easier for you to get it.

Disorders of the Urinary System

Different disorders can affect your urinary system, starting from your kidney down to the bladder. In this section, we are going to talk about some common diseases of this system.

1. Urinary Tract Infection (UTI)

2. Kidney Stones

3. Urinary Bladder Cancer

How to Keep Your Urinary System Healthy

Given the countless functions your urinary system does, you have to know how to keep it healthy. You can do so in many ways.

  1. Drink an adequate amount of water.
  2. Eat healthy food.
  3. For girls, Wipe yourself after urination the right way.
  4. Do not neglect or delay your body’s desire to get rid of its waste.


We will finish with five fun facts about the urinary system.

  1. Urine volume filtered each day
  2. Urinary tract infections are more common in women than in men. That is mainly because women have shorter urethrae, making it easier for them to get infected.
  3. The right kidney lies slightly lower than the left kidney. That is because the right kidney lies behind the liver, which displaces it downward.
  4. The size of your kidney is almost the same as the size of your hand fist.

Now it is time to test yourself out. Ready!

Q1. Which one of these parts of your urinary system forms the urine?

  1. The ureters.
  2. The kidneys.
  3. The urethra.
  4. The urinary bladder.

Q2. What is the name of the structure pointed at by the black arrow?

  1. The kidney.
  2. The ureter.
  3. The urinary bladder.
  4. The urethra.

Q3. All the following are things done by your kidneys except:

  1. Form the urine.
  2. Keep water balance.
  3. Secrete some hormones.
  4. Digest food.

Q4. The outer layer of the kidney in a vertical cross-section is known as:

  1. Renal pyramid.
  2. Renal papillae.
  3. Renal medulla.
  4. Renal cortex.

Q5. The main organ responsible for regulating your blood pressure is:

  1. Your heart.
  2. Your kidney.
  3. Your liver.
  4. Your pancreas.

The correct answers

Q1 – 2

Q2 – 3

Q3 – 4

Q4 – 4

Q5 – 2

Want to know more about your cardiovascular system and how your heart works? Check out this article.

The post Urinary System: Parts, Function, and 5 Fun Facts first appeared on Learning Mole.

This post first appeared on Online Learning And Educational Resources For Kids, please read the originial post: here

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Urinary System: Parts, Function, and 5 Fun Facts