Excretory System By Olivia swenson

The Importance of Excretion

Excretion, in simple terms, is the elimination of products created by the body. The primary function of the excretory system is to get rid of metabolic wastes, or substances in the body that the body is not able to use, such as carbon dioxide and nitrogenous compounds such ammonia. The body needs to get rid of waste products to avoid build up. If there was no excretion of such products, the build up would continue to grow, and cause major blockage problems for the body. So in order to maintain a healthy environment within the body, waste products are eliminated through urine.



The skin is utilized in many ways. Firstly, it traps moisture in every part of your body. Secondly, it regulates your body temperature. The salt found in the skin helps during evaporation to cool of those who are hot. Sweat is also a part of this, and come from sweat glands in the skin. Sweating allows people to remain cool during warm temperatures.


Any waste that is found in the bodies are transferred quickly to the kidneys. The kidneys remove any waste from the blood transferred to it. Then, the kidneys proceed to send wastes in the blood, including urea, salts, and excess water, out to be excreted in the form of urine.


The first thing the liver does is tell the gallbladder to release bile into the intestines so that any fatty foods can be broken down and waste can be sent to the intestines. The intestine absorbs most of the fat into the bloodstream, and that blood is delivered to the liver. The liver proceeds to remove any remaining waste from the blood, along with any iron.


Your lungs play an important role in removing the carbon dioxide from your body. Special cells remove this from your blood, and allow you to breathe it out. If your lungs did not enable you to do this, the carbon dioxide would build up and cause all kinds of issues in your body.

Urine Excretion

Kidney Structure

The kidneys are bean shaped organs that help to filter out any waste, water, and salt from within the body. The kidneys are connected to the aorta, which is the main artery of the body, and above each of them are an adrenal gland. The kidneys contain two distinct regions, namely the renal cortex, which is the outer portion, and the renal medulla, which is the inner area. Each part of the kidney contains many microscopic blood vessels and tubes. In the center region of every kidney is a place called the renal pelvis, which is primarily when urine collection happens. The other main areas are the renal artery and renal vein. The renal artery works to bring oxygenated blood to the kidney, and the renal vein brings deoxygenated blood from veins within the kidney and return it to the circulatory system.

Kidney Structure Examples

Associated Structures (Ureters, Bladder, urethra)

Waste product that has been gathered it put together and leaves through ducts that are called ureters. Once it passes through these ducts, it's stored in the bladder, and then exits the body through the urethra.


The kidney contains around one million filtering units within it by the name of nephrons. Blood enters a nephron through a long tube. This tube is also surrounded by a ball of capillaries called the glomerulus. Then, the glomerulus is surrounded by a structure called the Bowman's capsule.

The renal artery delivers nutrients and wastes to the kidney. This branches into blood vessels that get smaller and smaller, and finally reach the little glomerulus. Due to the great pressure in the glomerulus, waster products are dissolved and head into Bowman's capsules. Larger molecules, like red blood cells, remain in their place in the blood stream. This is called filtration. All the filtrate that has been collected in the Bowman's capsule. The process of reabsorption then happens. A lot of the remaining water, and substances like glucose and minerals, are reabsorbed into the capillaries that surround the renal tubule. This makes the nutrients free to use throughout the body to benefit us.

Nephron Structure Example

Working Together

The excretory system and the circulatory system are connected through both their involvement in blood. Blood that circulates through the body eventually end up cycling through one of the two kidneys, primarily through the aorta, which is connected to the kidneys. Any waste is filtered or removed from the blood by the kidneys, and is then given back to be circulated throughout the body once again.


Dialysis is a type of treatment in which an artificial kidney machine is utilized to filter out any wastes or toxins in your blood for you. There are two types of this treatment. The first is a machine in which the patient's blood passes through it and is cleansed. After this, it returns to the patient's body in good condition. The second type of dialysis is using the membrane lining the abdomen as an artificial kidney. The abdomen is injected with a fluid, and any this allows any fluid that contains waste to be drained. This procedure is performed on the daily, and takes 30-40 minutes.

Dialysis Treatment One


Additional Credits:

http://www.biology4kids.com/files/systems_excretory.html, http://www.ivyroses.com/HumanBody/Urinary/Urinary_System_Kidney_Diagram.php, http://www.livestrong.com/article/139350-adrenal-glands-kidneys/, http://science.jrank.org/pages/2623/Excretory-System-Nitrogenous-wastes.html, https://www.youtube.com/watch?v=-EpyICbTkSc, http://www.kidneychat.com/nephrons.html


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