Human Excretory System

BiologyHuman biology


We've all heard the story about how your body excretes waste in the form of urine and feces, but how exactly does this process work? Whenever we talk about things we put inside our bodies, it's easy to forget that these substances are all eventually going to be re-processed and discharged, but this excretory system is an important part of our bodies that deserves a little more attention

This system is made up of organs and other structures that carry out the processes of digestion (turning what you eat into energy and nutrients), absorption (pulling those nutrients through the bloodstream), and elimination (taking out the waste byproducts). Let's take a tour of these systems.

Excretory System Organs

The excretory system organs are the kidneys, the ureters, the bladder, and the urethra. These organs work together to filter waste and extra water out of your blood and move it through your body.


Kidneys function as the body's waste processing center, filtering out unnecessary substances and removing them from the blood. They also regulate the body's balance of electrolytes, a group of elements that are crucial for keeping us alive. Kidneys have some other cool ways to help us out, too−they produce hormones like erythropoietin that stimulate the production of red blood cells in the bone marrow, and they store minerals like phosphorous and keep them readily available for other organs when they're needed.

But kidneys aren't just neat little organs with a job to do. What exactly is kidney disease? It's when the kidneys are damaged or malfunctioning, which can lead to serious problems if it's not treated. It causes kidney failure in about 1% of those affected by any disease or condition involving the organ (and it can be caused by anything from blood pressure issues to diabetes). Kidney failure is a serious condition that can lead to malnutrition, dehydration, coma, and even death.

Structure of Kidney

The kidney's functional units are the nephrons (Latin for "kidney"). The human body has about one million nephrons, and each one filters about 180 litres of blood daily. The nephrons, in turn, are made up of a glomerulus (the filtering unit) and a tubule (the reabsorption and excretion unit).

The filtering process begins when blood travels first into the renal artery, then through the renal capsule, and finally into a structure known as a "nephrion," where most of the filtering occurs. The nephrons are organized in groups known as "Bowman's Capsules." In each capsule, a long tube called a "tubule" connects a ball-like structure called a "Bowman's Space" to urine collecting tubes.

The glomerulus is a ball of capillaries that form a tiny filter within the kidney, allowing water and small molecules to pass into the surrounding tubule. After filtration, most of the water and small molecules will be reabsorbed into the blood vessels within the tubule, leaving only waste products to be excreted from the body as urine.

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Henle’s loop

Henle’s loop is a common anatomical structure of the human intestine that helps to transport water from the intestines back into the body. It’s made up of two limbs, each one running from the ileum down towards the rectum and then curving around before climbing back up to rejoin the other limb.

In medical examiners and pathologists, it can also be useful in determining whether or not a victim’s last meal was eaten before death−if there are undigested food particles still left in the stomach, they will pass through Henle’s loop during its natural peristalsis and come out of the anus with feces. In some cases, this can allow them to determine if a person had been poisoned before death.

A ureter is one of two slender tubes that carry urine from the kidney to the urinary bladder. Urine is a liquid containing waste products, salts, and water that has passed through the kidneys. The urine goes into the bladder through a channel called the ureter. The ureters are about 10 inches long and are located on either side of your backbone, from below your rib cage to your groin.

A urinary bladder stores urine until it can be passed out of your body as waste. Urine leaves the body through a tube called the urethra. The urethra is about 8 inches long in men and about 1 inch long in women.

Excretion in Humans

Humans excrete the waste out of the body in different ways. Excretion can be done through sweat, urine, feces, and breath.

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Sweat is a form of excretion that is used to cool the human body. When the body gets hot, it gets rid of heat by sweating. The sweat evaporates off the skin and cools the body.

Urine is a liquid waste that is stored in the kidneys until it is released from the body. Urine leaves the body through urination or defecation.

Feces is another form of waste that comes from the digestive tract. Feces leaves the body in one of two ways− urination or defecation. Defecation causes food to be expelled from the rectum, while urination causes urine to be expelled from the urinary tract.

Breath can also leave a smell after coming into contact with something else. Breath can leave an odor due to bacteria in the mouth or on teeth which can cause bad breath if not properly taken care of. Breaths can also leave an odor due to chemicals produced by bacteria in food items such as garlic or onions.

Mechanism of Excretion in Humans

Urine formation is a complex process that begins with blood filtration by the kidneys' nephrons. After the filtration, materials left in the bloodstream are collected and carried away. The first part of urine formation is reabsorption. It occurs in the proximal convoluted tubule and is an active transport mechanism.

It returns glucose, amino acids, and water to the bloodstream. At this stage, water will also be added back into the blood. The second stage is secretion. This occurs in Henle's loop and the distal convoluted tubule (DCT). This stage involves a passive transport system that allows for the concentration of sodium chloride, potassium, hydrogen ions, and other substances from the tubular fluid into urine. Potassium and hydrogen ions are then carried through to the collecting duct, where sodium chloride will be reabsorbed into the bloodstream when it enters the distal part of the ureter.


The human excretory system is a vital part of the body that helps to remove waste products and maintain homeostasis. The kidneys, liver, and lungs are the major organs of the excretory system, and they work together to rid the body of waste. The excretory system is important for maintaining the health of the body and preventing disease.


1. What is the function of the excretory system?

The excretory system is a collection of organs and tissues that help remove waste products from the body. This process is called excretion.

2. What are the functions of kidneys?

Kidneys have several important functions, including filtration, secretion, and reabsorption of substances in the blood. They also produce hormones that regulate blood pressure, pH balance, red blood cell production, and other processes. The kidneys are responsible for removing waste from the bloodstream through urine production.

3. What are some diseases related to the human excretory system?

Diseases affecting the human excretory system include kidney stones (nephrolithiasis), cystitis (inflammation of the bladder), incontinence (inability to control urination), nephritis (inflammation in the kidney), and urolithiasis (a stone disease).

4. What does the urinary bladder do?

The urinary bladder stores urine until it is passed out of the body through the urethra (the tube that carries urine from the bladder to the outside).

5. How many kidneys does a human have?

This depends on whether you count the two tiny kidneys in each human fetus as two or one kidneys. If you count them as two kidneys, then an adult human has two kidneys with a total of about 1 million nephrons each. If you count them as one kidney, then an adult human has one kidney with about 2 million nephrons in it.

Updated on 13-Oct-2022 11:19:47