why do we need such a long alimentary canal?
370056
In short (ok bad choice of words), we need it to extract as much as we can from the food we eat. Long canal = large internal surface areafor absorption. There are lots of other adaptations to increase this as well.
408564
Here is a good article for you - http://en.wikipedia.org/wiki/Digestive_system.
803019
Its not as complicated as every one else made it.\n\nSo we can move.\n\nCellulose keeps the cells ridged, with ridged cells we would have a very small range of motion.\n\nOur cells need to be able to flex and squish so we can move. If we couldn't move we would need to be able to produce our own food, like plants do, or we would need to be single celled/simple organisms like bacteria.\n\nLike two of the others said: we use our bones for structural support, so cellulose is not needed for that purpose. Why have something when you don't need it, that is what evolution is all about.
748414
The conduction of food materials,water,etc is very essential for the survival of an organism.If u take the example of lower organism devoid of any specialized structures for conduction,the complexities of life processes are not as complex as that of the higher organisms.The specialized structures are more efficient,protective in their own ways and above all indispensable.If the complex life forms can carry out many processes at same time its because they get uninterrupted supply of oxygen,blood in case of higher animals,water and many materials at the same time .its all because of specialized structures.
655873
Too much can obstuct a persons intestines. Paper is not meant to be eaten. Eating non food items can sometimes be a symptom of a vitamin/mineral deficiancy. She needs to go to the doc.
1110231
i've wondered that myself..i guess it is so you can ger the food out from between your teeth so when you wake up in the morning you won't have rotting food in your mouth that your toothbrush missed
527175
to keep ourselves from taking and consuming too much.
749969
Because it provides us with water, this is a very important necessity of life.
525426
In the middle ages, people had to grow their own food. If they didn't, then they would die of starvation. The reason why they'd die of starvation is because they didn't have a lot of things that we have today like refrigerators, freezers or ice coolers. If something was bad then they would just add a lot of spice to it.\n\nAn everyday person like you and me would eat dark bread made from wheat that was mixed with rye or oatmeal, garden vegetables and meat (mostly pork).\n\nA nobel, with all of his guests, would eat cooked meat, fish, roast swan, peacocks and spicy dishes. The lord was always served first.\n\nOne of the recipes they had in the 5th century was called Pudding of Porpoise. You would take the blood and fat of a porpoise and then mix it with oatmeal, salt, pepper and ginger. Then you would put the mix into the gut of the porpoise and let it cook. And then it would be time to eat. Yummy, huh?
537489
They prevent your body from digesting the food properly and absorbing everything you need.
415926
they want to bind w/ food. it helps get them absorbed.
596708
you are probably not cutting your food small enough. big food, big mouth, big air.
729914
There is a reason why plants only grow so high in nature.  They have to be able to still pump nutrients from the roots to the farthest limb.\n\nBesides, you would be providing a home for rats.
1159894
FACTS:\n1.Our teeth should be differently shaped in order to cut the meat.\n\n2.Our gastric acids would be as strong as the ones of a carnivore, to absorb all the nutrients.\n\n3.Our intestines wouldn’t be as long, since all great carnivores have it short in order to get rid of the toxins faster. (meat do decompose faster/worse than vegetables, its just that it have lots of preservatives and colorants). In the other hand, must animals with a vegetarian diet have long intestines in order to absorb all the nutrients, since their gastric acids are not as strong… you can see that there are some that even digest their meals more than once…\n\n4.Our nails would be sharper and stronger, if we were to be having meat as our main meal.\n\n5.… what does a bull have for meals?? Are they weak?? … eating a bull doesn’t transfer their strength…. or meat!!! (as I read above)\n\n6.By eating meat you are more likely to get ostheoporosis, since there are elements in the meat that make your bones wear out, by that i mean that people literally pee their calcium.\n\n7.You should tell those people that in the long term your decision is wiser… \na.Yeah, we are ALL of F..cked up with all the transgenic and lack of control over the conditions and place in which those seeds are planted.\nb.Yeah, earth is becoming less fertile worldwide (believe me, I’m not in USA)\nc.But an animal is not hurt in order for you to eat… I’ve seen reports on genetic modifications to improve the mass production in Israel, such as lack of feather, nails and beak.\nd.and in the other hand, you are not absorbing all the chemicals they get those animals to grow fast with.\ne.and you are not absorbing all the bugs they have inside, including mad caw, etc. (by the way the mad cow disease started over twenty years ago, or at least that is as far back as we can track cases… it started with stupid eager farmers feeding their animals with dead animals)\nf.and you are not absorbing all the chemicals/antibiotics to get those animals to survive with.\ng.And finally, just as we could all, in a future... go into a world crisis because the water is not potable anymore, the trees have all become transgenic thanks to good mother nature and pollinization, same.. or I’d say worst!!! Would be to be starving as all of us with the addition of a disease that has no way of being controlled because it has been chemically fortified by the alphabet of antibiotics and hormones that are in the meat.\n\nBonus:\n1.I grew up hearing that as little as seven almonds a day could give me the amount of protein I could get from the meat.\n\nAs long as you don't base your diet on your favorite vegetables only, you'll be just fine. Amino, anti oxidants (... is that the way to spell it?) ... I'd say there are too many extremist in both currents.. just respect, and make yourself be respected... it is a choice, a philosophy of life.\n\n2.Meat eaters tend to have more cholesterol and heart problems. Vegetarians live longer.\n\n3.Meat eaters should check on their diet just as much, even though must of them, don't care much and are not selective at all\n \n4.www.themeatrix.com\n\n5. yes it's harder to get the iron in a natural source. but you should have a good balance in your meals, have the honey for the royal queen bee, something great that comes from sugar cane we call "melaza", if neither of the last two, then folic acid and finally morning sun bath\n\nnot as long, and much easier to answer in my language, hope it served for something...
309987
Depends on what you mean by efficient? Being that the purpose of the digestive system if to extract nutrients from food, how well it does that would be a measure of how efficient it was. Since the absorption of nutrients in the digestive system is dependent on the surface area of the intestines, if you were missing any of them you would be less efficient.
713104
This goes right back to a basic body plan for most animals going throughout evolution.  (A lot of this I got from Richard Dawkins, Ancestor's Tale.)\n\nThe basic body plan for most animals is a tube, with one end for feeding, and the other for excreting.  It then becomes useful to have all the senses at the feeding end, as the senses are helpful for finding food (and not needed at all for excreting).\n\nAnd then, as the nervous system gets more sophisticated, it becomes convenient to have the ganglia, and later the brain, near the main sensory organs.  This reduces the length of vital nerves from the sensory organs to the brain.  (E.g., if your brain was in the most protected part of your body, your abdomen, then think of how long the optic nerves would have to be from your eyes.  Not only does this cause a delay in signal transmission, but it increases the odds of damage to the optic nerve.) \n\nFast forward a couple of billion years, and this tube body plan hasn't changed much.  Sensory organ snear the feeding end, and brain near the sensory organs.  Humans are no different, except that they stand upright.  \n\nBut even then, it is advantageous to have our sensory organs perched as high up as possible, and again, to have the brain as close to these sense organs as possible in order to shorten the distance that sensory impulses have to travel.
463302
How is food carried on through the alimentary canal? Simple.\n\nThrough the process of peristalsis. Peristalsis is crudely defined as the waves of involuntary muscle contractions that transport food, waste matter, or other contents through a tube-shaped organ such as the intestine.\n\nMicrosoft® Encarta® Reference Library 2004. © 1993-2003 Microsoft Corporation. All rights reserved.