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Digestive System


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Digestion & excretion

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Digestive System

  1. 1. Life Science Human Body Systems Digestion & Excretion
  2. 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. 3. Digestive System • Organs – mouth – esophagus – stomach – gall bladder & liver – pancreas – small intestine – large intestine • Role – to extract nutrients and water from ingested food and beverages – to conveniently store and eliminate all leftover waste products
  4. 4. Digestion of Food Molecules Carbohydrate Fat Protein Monosaccharide Fatty Acid Amino Acid Leucine Glucose Starch
  5. 5. Where Does Digestion Begin? • Sight/Smell/Taste – triggers release of saliva & stomach fluids (digestive enzymes, acid) • Mouth – mechanical digestion of food with teeth and tongue – chemical digestion: saliva helps dissolve big pieces and lubricates esophagus • Esophagus – peristalsis moves bolus of food along this tube into stomach – esophageal sphincter at top of stomach keeps contents down Swallowing demo
  6. 6. Experiment 19.1 Physical vs. Chemical Digestion
  7. 7. Stomach • Peristalsis – wave-like churning smashes food – 3-4 hours before chyme leaves stomach • Absorption – small amounts of digested carbohydrates, alcohol and water and absorbed directly into the bloodstream  Chemical digestion  acid & enzymes squirted into stomach  food liquefied into chyme  thick mucus membrane protects stomach lining from acid  ulcers: infection (& stress, caffeine, NSAIDS, smoking, spicy/acidic foods)
  8. 8. Small Intestine • Pyloric sphincter – allows digested food out bit by bit • Duodenum – first curve of the intestines • Peristalsis – keeps things moving through 20 feet or so of coiled tubes • Absorption (diffusion) – villi (finger-like folds) increase surface area for diffusion – nutrients (fats, carbohydrates & proteins) cross cell membranes into bloodstream – vitamins & minerals absorbed here • all B's & C (water-soluble) • A, D, E, & K (fat-soluble) – Blood taken to liver for processing • then taken to kidneys for filtering
  9. 9. Lining of the Small Intestine
  10. 10. Large Intestine • a.k.a. the colon & rectum – shorter (~ 5 ft.) & wider than small intestine – no villi - smooth – waste takes from 12 hrs. up to 2 days to travel through – remaining water diffuses back into bloodstream – undigested "leftovers" are stored until feces can be eliminated  Helpful bacteria  more than 700 different types  help digest/break down nutrients  produce some vitamins (K)
  11. 11. Organs that Aid in Digestion • Liver – Produces bile (a chemical that breaks down fat molecules) – Filters toxins from the blood (blood's first stop after small intestine) • Alcohol/drugs, bacteria, worn out blood cells – 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. 12. Secretions that Aid in Digestion • Bile – stored in the Gall Bladder – bile released into the duodenum (first part of the small intestine) – bile salts break down fats • emulsifier (like dish detergent) • Pancreatic Juice – fluid contains water, enzymes (speed up chemical reactions), and sodium bicarbonate – The Pancreas also releases insulin, necessary for glucose to enter cells Pancreas & Insulin Video
  13. 13. Chemical Digestion Demo Stomach Acid
  14. 14. Excretory System • Tears and sweat – Remove tiny amounts of salts • Respiration – Eliminates CO2 from the body • Digestive System – Liver filters out toxins – Colon removes solid waste, including dead cell parts & indigestible fiber • Urinary System – Kidneys remove excess salts, water and filter out nitrogenous wastes (urea)
  15. 15. Urinary System • Organs of the Urinary Tract – Blood flows into kidneys • Nephrons clean blood • Filtered blood flows back into circulatory system – Waste products (as urine) flow down thin tubes called ureters – Urine is stored in the bladder – Wastes exits body via urethra
  16. 16. Experiment 19.2 Kidney Function
  17. 17. Kidneys Filter your Blood Animation Cortex Medulla Nephron • Kidneys filter waste products out of your blood: – extra salt and sugar – extra vitamins & minerals (water-soluble) – urea - left over from protein broken down in the liver • They also remove extra water: – prevents edema & dehydration – regulates blood pressure  Nephrons are the filtering units of the kidney  There are 1,000,000 in each kidney!
  18. 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    Kidney Filtration Water, salts, sugar & urea pressed through slits in capillaries of the Glomerulus   Nephron