H U M A N     B O D Y


Excretory System


The excretory system is in charge of getting rid of bodily wastes and excess water.


Jobs of the excretory system:

Maintain volume of extracellular (outside the cells) fluid
Maintain ionic balance in extracellular fluid
Maintain pH and osmotic concentration of the extracellular fluid.
Excrete toxic by-products such as urea, ammonia, and uric acid.


Parts of the excretory system:


Within each kidney are an estimated one million microscopic nephrons. Filtering of the blood takes place within these areas. Each nephron contains a cluster of capillaries called a glomerulus. A cup-shaped sac called a Bowman's capsule surrounds each glomerolus. The blood that flows through the glomerulus is under great pressure. This causes glomerulus, water, glucose and urea to enter the Bowman's capsule. White blood cells, red blood cells and proteins remains in the blood. As the blood continues through the blood vessels, it winds around the renal tubule. During this time, reabsorption occurs. Glucose and chemicals, such as potassium, sodium, hydrogen magnesium and calcium are reabsorbed into the blood. Almost all the water removed during filtration returns to the blood during the reabsorption phase. The kidneys control the amount of liquid in our bodies. Now only wastes are in the nephron. These wastes are called urine and include urea, water and inorganic salts. The cleansed blood goes into veins that carry the blood from the kidneys and back to the heart.


Ureters are muscular ducts that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually 25–30 cm (10–12 in) long.


A tube that carries urine from the bladder to the outside of the body.


The urinary bladder is the organ that collects urine excreted by the kidneys prior to disposal by urination. It is a hollow muscular, and elastic organ, and sits on the pelvic floor. Urine enters the bladder via the ureters and exits via the urethra.


Gives off bodily sweat or perspiration. Skin is the largest organ of the human body. It also protects the inner organs and tissues of the body.


Lungs give off carbon dioxide, a bodily waste, during respiration.


Urinary System Diagram

Urinary System




Skin Diagram

Excretory System Quiz


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