An Introduction to the Excretory System

 

       Ever wonder why our armpits – and various other body parts – get  B.O. (body odor) when we don’t bathe?  What’s the problem?  Here’s how it works.

Except for your lips and a couple of the reproductive parts, your body is covered with little sweat glands.  Sweat glands ooze lots of sweat out of the little openings, or pores, in your skin.  On an average day, you’ll sweat away four cups of liquid.  Smelly sweat comes from glands located mostly in the armpits but also in the crotch, anus and a little on the scalp.  Until a person gets to be about twelve years old, these glands don’t do anything.  After age twelve or so, they start oozing, and they never stop.  That’s why adults are so stinky and kids aren’t.  Sweat doesn’t smell until bacteria munch on it.  Fuzzy, round armpit bacteria change sweat to make it stinky.  They love the oil and salt mix (think french fries without the potatoes) of sweat and end up inviting all their friends to a party at the “Underarm Mall.”  To get rid of the smell, deodorants contain chemicals that poison the stink-making bacteria.

Did you know that the sweat that squirts from millions of other pores on your body is actually very weak urine (yes, urine!) with some other stuff thrown in.  Let’s learn a little about pee.

Actually, pee isn’t as disgusting as it seems.  About 96 percent of urine is extra water that your body doesn’t need.  The rest is salts, urea (yur EE a), vitamins your body didn’t use, pigments, and other stuff that your body didn’t need.  Fresh urine is cleaner than poop, spit, or the skin on your face because healthy pee is not home to bacteria.

Pee is produced by the kidneys.  It travels directly to the bladder, then exits through the urethra (you REE thra), a tube that connects your bladder to your pee hole.  Every day you make and deliver four to eight cups of urine.  The amount depends on how hot it is, what you eat, and how much you drink.  The reason you pea more than once a day is that the  bladder can’t hold all eight cups.  It can hold about two cups comfortably.  An empty bladder looks like a shriveled up balloon.  Controlling your bladder muscles is learned.  That’s why babies get potty trained.

Now let’s discover more about the…

 

Excretory System

 

1. What is the function of the excretory system?

 

2. What are some wastes that are removed by the excretory system?

 

3. What are the four main organs of the excretory system? 

 

1. Which organ of the excretory system filters urea, toxins, and wastes from the blood?

 

2. Your body releases carbon dioxide from which organ of excretion?

 

3. Which organ uses sweat to excrete water, salts, and a small amount of urea?

 

4. What role does the liver play in excretion?

 

5. List three ways the kidneys maintain homeostasis in the body.

 

4. Using the diagram provided by your teacher, identify the four main structures of the excretory system.  Give the function of each part.

 

5. Sketch a diagram of the urinary system.

 

 

6. What is the functional unit of the kidney?
7. What is urine?

 

8. What is urea?

 

9. What is sweat?

 

10. How does sweat control your body temperature?

 

11. What structure(s) are primarily involved in getting rid of wastes in plants?

 

12. Explain the following diseases that can result when homeostasis isn’t maintained in the excretory system.  Be sure to include definition of each disease, the possible cause(s), possible symptom(s) and possible treatment(s).

 

1. Jaundice
2. Cirrhosis
3. Hepatitis
4. End Stage Renal Disease
5. Kidney Stones
6. Bladder Cancer

 

 

13. What is dialysis?

 

14. Excretion Factoids:

 

1. Why is urine yellow?

 

2. Why does asparagus make your pee smell?