Digestive System
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This document provides information about the human digestive and excretory systems. It describes the major organs involved in digestion, including the mouth, esophagus, stomach, small intestine, large intestine, liver, and pancreas. It explains the physical and chemical processes of digestion that break down food into smaller molecules that can be absorbed and used by the body. These include mechanical and chemical digestion in the mouth, stomach acid and enzymes, and nutrient absorption in the small intestine. The document also covers the role of the kidneys and urinary system in filtering waste from the blood and excreting it from the body as urine.
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Digestive System
- 1. Life Science Human Body Systems Digestion & Excretion
- 2. In your lab notebook, please answer as best you can: Week 19 Review Quiz Bonus: Explain the difference between an endoskeleton and an exoskeleton. - An endoskeleton is hard parts inside for support and protection (i.e. mammalian bones); an exoskeleton is hard parts outside for protection & support (i.e. crustacean, beetle shell, sea urchin, clam) 1. What two substances in the matrix give bones strength & flexibility? ⢠Collagen (gives flexibility) and Minerals (calcium & phosphate give strength). 1. What happens in the red bone marrow of bones? ⢠New blood cells are formed. 1. Name 3 types of muscle tissue. ⢠Skeletal muscle (movement), Smooth muscle (stomach/intestines/blood vessels), and Cardiac muscle: (heart pumps blood around body) 1. Name a set of bones or body area for each type of joint: a ball-and-socket join, a hinge joint, and a gliding (planar) joint. ⢠Ball/Socket: shoulder, hip, Hinge: finger, knee, elbow, Gliding: vertebrae, wrist, ankle 1. What is an antagonistic muscle pair? Give an example or explain what it does. ⢠A set of muscles that move a joint in opposite directions, like the biceps & triceps in the upper arm, quadriceps & hamstring in the thigh, or wrist flexors & extensors
- 3. Digestive System ⢠Organs â mouth â esophagus â stomach â gall bladder & liver â pancreas â small intestine â large intestine ⢠Role â to extract nutrients and water from ingested food and beverages â to conveniently store and eliminate all leftover waste products
- 4. Digestion of Food Molecules Carbohydrate Fat Protein Monosaccharide Fatty Acid Amino Acid Leucine Glucose Starch
- 5. Where Does Digestion Begin? ⢠Sight/Smell/Taste â triggers release of saliva & stomach fluids (digestive enzymes, acid) ⢠Mouth â mechanical digestion of food with teeth and tongue â chemical digestion: saliva helps dissolve big pieces and lubricates esophagus ⢠Esophagus â peristalsis moves bolus of food along this tube into stomach â esophageal sphincter at top of stomach keeps contents down Swallowing demo
- 6. Experiment 19.1 Physical vs. Chemical Digestion
- 7. Stomach ⢠Peristalsis â wave-like churning smashes food â 3-4 hours before chyme leaves stomach ⢠Absorption â small amounts of digested carbohydrates, alcohol and water and absorbed directly into the bloodstream ďŽ Chemical digestion ďĄ acid & enzymes squirted into stomach ďĄ food liquefied into chyme ďĄ thick mucus membrane protects stomach lining from acid ďŽ ulcers: infection (& stress, caffeine, NSAIDS, smoking, spicy/acidic foods)
- 8. Small Intestine ⢠Pyloric sphincter â allows digested food out bit by bit ⢠Duodenum â first curve of the intestines ⢠Peristalsis â keeps things moving through 20 feet or so of coiled tubes ⢠Absorption (diffusion) â villi (finger-like folds) increase surface area for diffusion â nutrients (fats, carbohydrates & proteins) cross cell membranes into bloodstream â vitamins & minerals absorbed here ⢠all B's & C (water-soluble) ⢠A, D, E, & K (fat-soluble) â Blood taken to liver for processing ⢠then taken to kidneys for filtering
- 9. Lining of the Small Intestine
- 10. Large Intestine ⢠a.k.a. the colon & rectum â shorter (~ 5 ft.) & wider than small intestine â no villi - smooth â waste takes from 12 hrs. up to 2 days to travel through â remaining water diffuses back into bloodstream â undigested "leftovers" are stored until feces can be eliminated ďŽ Helpful bacteria ďĄ more than 700 different types ďĄ help digest/break down nutrients ďĄ produce some vitamins (K)
- 11. Organs that Aid in Digestion ⢠Liver â Produces bile (a chemical that breaks down fat molecules) â Filters toxins from the blood (blood's first stop after small intestine) ⢠Alcohol/drugs, bacteria, worn out blood cells â Stores macronutrients (carbohydrates/fats/proteins) ⢠Stores excess glucose as glycogen ⢠Also stores fatty acids and amino acids (can convert these to glucose if needed) Glucose
- 12. Secretions that Aid in Digestion ⢠Bile â stored in the Gall Bladder â bile released into the duodenum (first part of the small intestine) â bile salts break down fats ⢠emulsifier (like dish detergent) ⢠Pancreatic Juice â fluid contains water, enzymes (speed up chemical reactions), and sodium bicarbonate â The Pancreas also releases insulin, necessary for glucose to enter cells Pancreas & Insulin Video
- 13. Chemical Digestion Demo Stomach Acid
- 14. Excretory System ⢠Tears and sweat â Remove tiny amounts of salts ⢠Respiration â Eliminates CO2 from the body ⢠Digestive System â Liver filters out toxins â Colon removes solid waste, including dead cell parts & indigestible fiber ⢠Urinary System â Kidneys remove excess salts, water and filter out nitrogenous wastes (urea)
- 15. Urinary System ⢠Organs of the Urinary Tract â Blood flows into kidneys ⢠Nephrons clean blood ⢠Filtered blood flows back into circulatory system â Waste products (as urine) flow down thin tubes called ureters â Urine is stored in the bladder â Wastes exits body via urethra
- 17. Kidneys Filter your Blood Animation Cortex Medulla Nephron ⢠Kidneys filter waste products out of your blood: â extra salt and sugar â extra vitamins & minerals (water-soluble) â urea - left over from protein broken down in the liver ⢠They also remove extra water: â prevents edema & dehydration â regulates blood pressure ďŽ Nephrons are the filtering units of the kidney ďĄ There are 1,000,000 in each kidney!
- 18. Unfiltered blood with absorbed nutrients goes in Filtered blood w/ cells & proteins comes out Waste products exit through renal tubule Bowman's capsule collects filtrate ďŤ ďŹ ď Kidney Filtration Water, salts, sugar & urea pressed through slits in capillaries of the Glomerulus ďŞ ď Nephron
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- 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 âcracker solutionsâ 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 âspitâ) 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.
- 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
- Without the surface area of villi and microvilli, it would take weeks to absorb nutrients from food. Lacteals collect triglycerides into the lymphatic system.
- EXPERIMENT 13.2 - Stomach Acid and Antacids Supplies : white TUMSÂŽ antacid tablets and THE WORKSÂŽ Toilet bowl cleaner (with HCl, also called hydrogen chloride, colorless or clear, but NOT the âclingâ 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.
- 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 ž as high as one of the glasses.) Procedure : Boil 1 â 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 âbridgeâ between the two.) Note what you see happening. After one hour, observe the empty glass and note what you see.