Digestive System

Editor's Notes

• #7 Supplies : saltine crackers, spoons for stirring, Iodine, clear plastic cups Demonstrates physical and chemical digestion. Procedure : Take a saltine cracker and break it in half. Crumble half of the cracker and allow the crumbs to fall into one of the two glasses. Add two tablespoons of water to the cracker crumbs and swirl the glass to mix the cracker crumbs with the water. Take the other half of the cracker and chew it up really well. DO NOT SWALLOW . Just chew the cracker well. Now spit the stuff in your mouth out into the other glass. Add two tablespoons of water to the chewed-up mess and swirl the glass. Note any differences you see in the two glasses. Add equal amounts of iodine to both glasses. It doesn't need to be a lot - just a drop or two. Swirl each glass. Note any difference you see in the two glasses. Clean everything up. The first thing you should notice is the chewed up cracker was reduced to much smaller pieces than the cracker you crumbled. That's the first part of digestion: breaking up food into small pieces. We call that physical digestion, because it does not change the chemical nature of the food. It simply breaks food into smaller pieces. The second thing that you should notice is how differently the two “cracker solutions” acted in response to iodine. The unchewed half of the cracker should have produced a dark blue color. Depending on how well you chewed the other half of the cracker, it should have produced a much lighter blue. If you chewed the cracker really well, you might have seen no blue color at all in that glass. When iodine mixes with starch, it produces a deep blue color. The deep blue color you saw when you put the iodine in the glass with the unchewed cracker, then, tells you that saltine crackers have starch in them. Remember what starch is. It is a polysaccharide. When you put the iodine with the chewed cracker, the much lighter blue or absence of blue tells you that there was less starch in the chewed up cracker. Where did the starch go? Well, the saliva (some people call it “spit”) that your mouth produces contains chemicals which break starch down. Remember, our bodies must break polysaccharides (like starch) down into monosaccharides before they can be used. The saliva in your mouth starts this process by breaking starch down into disaccharides. This is the second component of digestion: chemical digestion. It is not enough to just break the food down into tiny pieces. Your body must also change the chemical nature of the food in order to extract what it can use.
• #9 Space Mountain Disneyland ride: pyloric sphincter is like the end of the que line (only lets one or two people in, single-file) duodenum: switchbacks of the line
• #10 Without the surface area of villi and microvilli, it would take weeks to absorb nutrients from food. Lacteals collect triglycerides into the lymphatic system.
• #14 EXPERIMENT 13.2 - Stomach Acid and Antacids Supplies : white TUMS® antacid tablets and THE WORKS® Toilet bowl cleaner (with HCl, also called hydrogen chloride, colorless or clear, but NOT the “cling” type. Red/purple cabbage water, small glass (like a juice glass), cup & teaspoons (for measuring and stirring) Procedure : Add one teaspoon of toilet bowl cleaner to the small glass. BE CAREFUL WHILE HANDLING THE TOILET BOWL CLEANER . If you get it on your hands, immediately rinse them with LOTS of water. The toilet bowl cleaner will burn skin. Pour one cup of cabbage water into the small glass. Use the spoon to stir the contents, so that the teaspoon of toilet bowl cleaner mixes with the cabbage water. The color of the contents should be pink or red. If not, the color of your toilet bowl cleaner is too strong and you need to try a different kind of toilet bowl cleaner. Add a white antacid tablet to the small glass. Note what happens when the tablet hits the cabbage water/toilet bowl cleaner mixture. After you have watched the tablet for a few moments, start stirring it. You want the tablet to completely disappear. This will take a little while. You can speed the process up by using the spoon to cut up and crush the tablet. Note the color change that begins to occur. Once the tablet is gone, note the color. If you do not see purple or blue, add another tablet and continue to stir. Your goal is to get the solution to be purple or blue. Once you get to the purple or blue color, add another teaspoon of toilet bowl cleaner. What happens? Clean everything up. EXPERIMENT 13.3 - The Effect of Sodium Bicarbonate on Stomach Acid Supplies : Baking soda, Toilet bowl cleaner, cabbage water, small glass, cup & spoons for measuring and stirring. Introduction - This experiment will show you what happens when the sodium bicarbonate from your pancreas is mixed with the stomach acid in the chyme that comes from the stomach. Procedure : Add one teaspoon of toilet bowl cleaner to the small glass. BE CAREFUL WHILE HANDLING THE TOILET BOWL CLEANER . If you get it on your hands, immediately rinse them with LOTS of water. The toilet bowl cleaner will burn skin. Pour one cup of cabbage water in the small glass. Use the spoon to stir the contents, so that the teaspoon of toilet bowl cleaner mixes with the cabbage water. The color of the contents should be pink or red. If not, the color of your toilet bowl cleaner is too strong and you need to try a different kind of toilet bowl cleaner. Take the other spoon and scoop some baking soda out of the box. SLOWLY add the sodium bicarbonate to the mixture in the glass. Note what happens. Continue to slowly add baking soda to the mixture in the glass until the color of the mixture changes from red/pink to blue/purple. Clean everything up.
• #17 EXPERIMENT 15.2 - A Model of Kidney Function Supplies : tea bag, three small glasses (like juice glasses), paper towel, coffee filter, funnel, scissors, boiling water, spoon for stirring, a pile of books (at least ¾ as high as one of the glasses.) Procedure : Boil 1 – 2 cups of water. Place the contents one tea bag into a small glass. Carefully pour some hot water into the glass with tea leaves. BE CAREFUL, THE WATER IS HOT!!!!! Stir or let sit for a few minutes. Describe the resulting liquid (color, texture/thickness, particulates, etc.) Pour the tea mixture through a coffee filter (placed in funnel) into another glass. Note the appearance of the filter and the resulting (filtered) liquid. Set that glass with filtered tea on the top of a pile of books. Fold a paper towel in half lengthwise. Fold it in half again until you have a long, thin paper towel. Place one end into the filtered tea, touching the bottom of the glass. Place the other end into a clean, empty glass that is below the level of the first glass. (You should have two glasses: one with tea in it sitting on the pile of books and one empty glass sitting on the table or counter next to the pile of books. The long, thin paper towel should have an end in both glasses, forming a “bridge” between the two.) Note what you see happening. After one hour, observe the empty glass and note what you see.