BeginBegin

© Craig Weston, 2008

The Urinary System/Excretory SystemThe Urinary System/Excretory System Dang…

gotta go!

#1 Review Me!#1 Review Me!

A structure is a part or organ in the body.

Each structure has a function or functions (jobs) that itcarries out.

Homeostasis is the idea that your body adjusts itself to stay inequilibrium (balance).

A stimulus:response situation involves something thatyour body reacts to and the reaction itself.

#3 Urinary System Overview#3 Urinary System Overview

So why do we have to “pee” anyway?

Well, this guy might not know, but yousure will. Yes, you’re going to learn waymore about urine than you ever thoughtyou would.

Yep, if you’reat all nervousabout learningabout your urinary system, well, partner,urine trouble!

(sorry)

#4 Urinary Sys. Overview, Cont.(why we have to urinate)

#4 Urinary Sys. Overview, Cont.(why we have to urinate)

It hasn’t been long since you learned about the different kinds of nutrients you need to stay healthy. Let’s focus on two:

Water does SO much for you…keeps yourblood and nerves working properly, your digestive system healthy, and about a thousand other things.You need protein to build your solid stuff—skin, muscle, hair, nails…all that. Very important, too.

#5 Urinary Sys. Overview, Cont. (why we have to urinate)

#5 Urinary Sys. Overview, Cont. (why we have to urinate)

You should drink plenty of water every day. Most of us don’t getenough. However, once it’s in your body, you tend to accumulate toomuch at a time, so your body wants to get rid of some of the excess tomaintain homeostasis.

After you eat protein, your liver, in one ofits many, many jobs, breaks the protein down into its building blocks—amino acids.

This chemical breakdownof protein is not withoutbyproducts, however…

#6 Urinary Sys. Overview, Cont.(why we have to urinate)

#6 Urinary Sys. Overview, Cont.(why we have to urinate)

The liver’s breaking down of protein releases a waste from the chemicalreactions called urea. Urea is mostly nitrogen and is pretty harsh stuff.

This waste, urea, is very similarto ammonia, a foul-smellingchemical used in cleaners.

Your body has too muchwater and is making thisurea waste, so it combines them togetherand flushes it out thebody. Ta daa! You’vemade urine!

#7 Urinary Sys. Overview, Cont.#7 Urinary Sys. Overview, Cont.

If you’ve ever let the cat’s litter box go too long without cleaning, youmay have smelled that really strong chemical odor…that’s the cat’surine clumps decomposing from urea back into ammonia. Nasty!

Clean myBox,

Please!

The white part of birddroppings is their formof pasty urine. The dark stuff in the droppings is,well, you know…feces.

#8 Urinary Sys. Overview, Cont.#8 Urinary Sys. Overview, Cont.

The Urinary System is the collection of organs that clean wastes from blood and get rid of extra water. Remember, these wastes in the bloodwere made in the liver as a by-product of protein breakdown.As you see here, theurinary system doesn’t takeup much room in your body.

It sure is important, however,and features one of the morefamous pairs of organs youhave—the kidneys.

#9 FUNCTIONS of the Urinary System#9 FUNCTIONS of the Urinary System

1. Filters blood of urea (toxic waste made in liver)

2. Gets rid of extra water (water + urea = urine)

3. Maintains balance of salts(most people eat more than theyneed)

#10 STRUCTURES of the Urinary System#10 STRUCTURES of the Urinary System

Like the respiratory and digestive systems, the urinary system is a tract.It is a series of organs arranged one after another that a substancepasses through (in this case, urine).Be sure to label the structures on the back of your notes page as you go.

1. kidneys – 2 organs in abdomen that filter blood of wastes.• nephron – microscopic filtering tube in a kidney (~1 million

nephrons per kidney)

#11 Structures, contd.#11 Structures, contd.2. ureter – tube that carries urine from kidney to bladder

3. urinary bladder – muscular bag that collects urine

4. urethra – tube that passes urine out when bladder relaxes

Like many other places inyour body, the urethra ispinched off by a ring ofsmooth muscle known asa sphincter. It’s invol-untarily held shut so thatyou don’t have to thinkabout it all day (and night! )

#12 DISORDERS of the Urinary System#12 DISORDERS of the Urinary SystemHey, look…it’s Joe with one of his favorite drinks.

Coffee, besides being a diuretic (makes you produce a lot of urine), is one of several foods that has been linked by some studies to the formation of kidney stones. However, not drinking enough water is the most common cause. Heredity can also be a factor -- if mom/dad have had kidney stones, chances are you might too.

1. kidney stones – mineral rocks that build up and cause pain somewhere in urinary tract

SomebodyJust shoot me!AAAAAARRRRGGGHH

#13 DISORDERS, contd.#13 DISORDERS, contd.This might surprise you…your urine is actually a pretty clean liquid, interms of being germ-free. Bacteria normally isn’t found in fresh urine.

But Joe has been noticing that he’s having to go more often and his urine is cloudy, not clear-yellow. He also has a burning sensation when he urinates. There’s a good chance that bacteria have entered through his urethra and given him a U.T.I.

Hmm…

2. urinary tract infection – bacteria build-up causing pain (usually in bladder)

Women tend to get U.T.I.s more often than men. This is because their urethras are shorter, which allow the bacteria to get up into their bladder easier.

#14 DISORDERS, contd.#14 DISORDERS, contd.Your kidneys have a hard, hard job. They work constantly to clean yourblood so that YOU DON’T DIE of poisoning. Kidneys can wear out,though, due to infections, a blood disorder like diabetes, alcoholism, orjust general poor health.

In this case, you might needdialysis – machine-done filtering after kidneys fail.

Most people on dialysis haveto sit at the clinic for 3-5 hours, at least three times aweek. What a pain.LOVE YOUR KIDNEYS!

#15 Review…could you live without this system?#15 Review…could you live without this system?

Function 1: Filters blood of urea (waste made in liver)Joe would feel ill after several hours…he would lose energy and eventually fall unconscious as his organs became poisoned by his liver.He’d likely die within a week or two.

Function 2: Gets rid of extra waterThis might surprise you, but too much water will cause your brain toperform poorly. Everybody reacts differently to this, but there have beendocumented cases of people DYING from having too much water in theirblood, causing your electrolytes to be too dilute.

Function 3: Maintains salt balanceJust like in function 2, your water and salt balance go hand in hand. You can’t have too much/little water or too much/little electrolyte.

#16 Review#16 ReviewUrinary System…how does it maintain homeostasis?

This system is all about homeostasis!•Keeps your waste level at a minimum•Balances your water•Balances your salts/electrolytes

Stimulus : Response

Drinking lots of water in a day : Making extra urine to get rid of excess

#17 And That’s…#17 And That’s…