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Animal Nutrition and Digestion

Animal Nutrition and Digestion

Common Mistakes


Have no fear! Shmoop is looking out for you, and we've come up with a helpful way to remember the essential amino acids. You'll never know when it will come in handy: a test perhaps, or while you are trying to impress a potential mate, or when you are watching Jeopardy! with your weird cousin Chuckie. Just remember:

Angry Hippopotami Interest Lazy Lemurs Munching Peaches Tossed Via Trampoline.

Of course, that is: arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, valine, and tryptophan.

You'll thank us later.

From Start to Finish

The pH of the alimentary canal is really important, but it gets confusing because it changes depending on whether you are considering the stomach or the colon or the small intestine. It might help just to think that as you move along the alimentary canal, the pH goes up. If you are in the stomach, the pH is going to be lower (pH = 2-3) than if you are in the small intestine (pH = 7). Just remember: as food moves down the body, the pH gets higher.


All this hypo- and hyperosmolarity stuff can get a person down in the dumps. It gets confusing trying to keep the two in order, and remember which has the higher solute concentration, and where water likes to go.

But the next time you see hyperosmolarity, just think about a hyperactive kid who devoured 3 large Pixy Stix of sugar. He's bouncing off the walls and generally driving his parents insane. There's lots of sugar hanging around in his blood, and he'd have hyperosmotic blood if we would check.

Hypo sort of sounds like hippo, and hippos are slow, lethargic animals without much going on. They hang out in the artificial lake built by the zoo workers, every so often opening their mouths much to the excitement of 4 year old girls. Hypoosmolarity describes a solution that doesn't have much going on, and it's not being bothered by all the extra things (solutes) in life. 

Water Balance and the Kidney

Proper Peeing

There's a lot to keep straight when it comes to proper peeing, and it can get pretty confusing about what is permeable where and when. But in general, things will flow according to their concentration gradient and osmolarity—the place with too much of one thing will lose it to the place with less. The Loop of Henle is the exception, where the body gets a bit picker.

At the descending Loop of Henle, water is the only thing that can get through the membrane. No salts, ions, proteins, nothing. Just water.

Life as we know it would change if water was permeable in the ascending Loop, since there's no way water will flow up a water slide. That's just silly. That way, salt is the only thing that's permeable in the ascending Loop.

The battle of all battles: Excretion versus Elimination

Don't worry if you get confused on whether peeing is scientifically described by the term excretion or elimination. Despite what your science teacher tells you, getting these terms mixed up won't prevent you from getting into or graduating from college. It will haunt you for the rest of your life, though. And we wouldn't want that.

Here's a handy mental exercise to help you keep it all straight. Pretend that you are a world class singing talent and you're pursuing your dreams of superstardom on American Idol. After belting your heart out to a rousing rendition of Billy Joel's Piano Man, you find yourself standing on a stage next to your competitor, desperately waiting to hear who got more votes and can stick around a bit longer.

The envelope opens to reveal who will be eliminated, and your heart jumps to your throat.

You are eliminated. Roll credits.

How do you feel after being eliminated? Like poop, of course.

There you have it, elimination describes poop and excretion describes pee. 


Trying to remember all these hormones and what stimulates their release and what they do can put a person down in the dumps. Shmoop is here to save the day and teach you ways to keep these hormones straight.

RAAS used to stand for Renin Angiotensin Aldosterone System. Imagine you are babysitting a loud, obnoxious kid named Allan. Finally, he gets sleepy and falls asleep. Now, RAAS stands for Rest Assured, Allan's Sleeping. Ahh, hear that quiet (as in low volume)? You are now worry free, and can focus on your late-night comedy shows (low pressure). Think RAAS, think low blood volume and low blood pressure.

ADH used to stand for AntiDiuretic Hormone, but we are changing the name of the game here at Shmoop, HQ. All you need to know is: Always Depend on High! High osmolarity triggers ADH release.

ANP? Not Atrial Natriuretic Peptide anymore, but Awesome! Nickleback's Playing! All that rock 'n' roll, pump up the volume!

Just keep those little phrases in mind, and you'll never forget that RAAS is stimulated by low blood volume or pressure. It'll become second nature to say that ADH responds to high osmolarity. Every time you hear Nickleback on the radio, you'll remember that ANP is released by high blood volume.

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