The skin acts like a first line of defense towards the pathogens that may enter. It prevents pathogens from going in and causing infections in the kidneys and the bladder for example. If pathogens were to infect you might lose a kidney (and you can only live with one). The urinary system is like the skin because it gets rid of unnecessary waste. the kidneys get rid of urea and water, and the oil/ sweat glands get rid of water and salts. Both of these systems get rid of water and other unuseful materials. for more information of how the urinary system works...Urinary system link
When you excrete (pee), you are getting rid of excess water and urea. When you sweat, you get rid of water and oil. Also, when you pee you can excrete pathogens and when you sweat or shed, you can shed or sweat off pathogens. All of your body systems can act as a line of defense.
The skin acts like a first line of defense towards the pathogens that may enter. It prevents pathogens from going in and causing infections in the kidneys and the bladder for example. If pathogens were to infect you might lose a kidney (and you can only live with one). The urinary system is like the skin because it gets rid of unnecessary waste. the kidneys get rid of urea and water, and the oil/ sweat glands get rid of water and salts. Both of these systems get rid of water and other unuseful materials.
for more information of how the urinary system works...Urinary system link
When you excrete (pee), you are getting rid of excess water and urea. When you sweat, you get rid of water and oil. Also, when you pee you can excrete pathogens and when you sweat or shed, you can shed or sweat off pathogens. All of your body systems can act as a line of defense.