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Digestive System

Digestive System. Macronutrients (macromolecules): 1. ·Carbohydrates: provide sources of glucose needed for cellular respiration (energy) sources : breads, cereal, pasta, potatoes ... glucose stored as glycogen in liver cellulose (plant cell wall) not a human nutrient

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Digestive System

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  1. Digestive System

  2. Macronutrients (macromolecules): • 1. ·Carbohydrates:provide sources of glucose needed for cellular respiration (energy) • sources: breads, cereal, pasta, potatoes... • glucose stored as glycogen in liver • cellulose (plant cell wall) not a human nutrient • broken down into simple sugars

  3. Macronutrients (macromolecules): • 2. ·Fats:important in cell membrane structure, surrounds organ and joints, long term energy, hormones • sources: butter, oils, animal fat • saturated fats (bad)...solid at room temp • unsaturated fats (good) ...liquid at room temp • broken down into fatty acids

  4. Macronutrients (macromolecules): • 3. ·Proteins: provide structural support; transport proteins move molecules around body (haemoglobin); enzymes speed up chemical reactions • sources: meat, fish, eggs, milk, beans, nuts... • broken down into amino acids • 8 essential AAs...ingest

  5. Micronutrients: • Vitamins: organic compounds (CHO elements) ...A,B1,C,D,E • Minerals: inorganic compounds...Calcium, iron, potassium, sodium • Water:70% of the body...blood (plasma)=90% • - water transports soluble compounds • - cooling (sweating) • pg406#3,4,5 • Pg 410#1,5,11

  6. Enzymes break down macromolecules by hydrolysis (adding a water molecule breaks bonds between subunits

  7. 4 stages of food processing:

  8. 4 stages of food processing: • 1. Ingestion: the taking in of nutrients • 2. Digestion: the breakdown of complex organic molecules into smaller components: • Mechanical=physically breaking molecules up...teeth • Chemical=changing the chemical structure...enzymes • 3. Absorption: the taking up of digested molecules from digestive to circulatory system • 4. Egestion: the removal of waste from the body

  9. Alimentary canal: • a tube where food is processed: head --->anus • function is the same but the length varies depending on feeding habits. Why rabbit longer? • page 410#13-16

  10. 1. The Mouth • Mechanical digestion begins with the teeth physically breaking the food down (smaller to pass) • allow for a greater surface area for chemical digestion • Chemical digestion • ·Salivary glands secrete enzyme: salivary amylase • ·breaks down starch molecules (carbs-simple sugars) • ·This enzyme works best at a neutral pH. • ·Mucus and water added…moisten

  11. 2. Esophagus • muscular tube from mouth – stomach • epiglottiscloses over the trachea when you swallow • muscle contractions of the walls of the esophagus (called peristalsis) move the food (bolus) along

  12. 3. esophageal (cardiac) sphincter • provides some involuntary control of food entering or leaving the stomach

  13. 4. Stomach mechanical digestion • through the contraction of the muscles around it • folding called rugae.

  14. 4. Stomach: Chemical Digestion • Pepsin, an enzyme that breaks down proteins to AAs is added (inactive = needs low pH) • Food is “paste like” called chyme • Hydrochloric acid is added • breaks down fibrous tissue • kills bacteria • lowers the pH…activates pepsin • Is amylase still functioning?? • Mucus is also added to protect the stomach lining

  15. 5. Pyloric sphincter • Controls movement of chyme into the duodenum (small intestine)

  16. 6 Small Intestine • chyme into the duodenum through pyloric sphincter • release of secretin, a hormone to the pancreas • releases sodium bicarbonate (Na2HCO3)... increases pH of the chyme to 8 • activates most intestinal enzymes • pancreas (releases its enzymes: lipases, proteases, and carbohydrases) • gall bladder (stores/releases bile produced in liver) • Bile emulsifies fat (physical breakdown-breaks big blobs into little blobbies

  17. jejunum and ileum (SI) are primarily for absorption • finger-like projections: villiincrease the surface area for absorption of the digested nutrients • inside each villus is a capillary network for absorbing simple sugars and amino acids • central lacteal for absorbing fat particles

  18. 7. Large Intestine • water and dissolved minerals are absorbed from the undigested food • produce vitamins B and K as waste products (absorbed) • undigersted material=feces

  19. Accessory Organs: • Salivary Glands: amylase and mucus • Liver produces bile (fat breakdown...are not lipases)…detoxification (alcohol) • Gall Bladder stores bile • Pancreas produces and releases sodium bicarbonate and enzymes

  20. Digestive System Disorders Peptic ulcer Crohn's disease constipation hepatitis cirrhosis page 422#19-24 endoscopes diabetes and insulin page 427#2,3,4,6,13,15

  21. Digestive Review • Macronutrients (Carbohydrates, Proteins, fats); • Micronutrients (vitamins and minerals) • Enzymes, pH and control of enzyme activation • Ingestion, digestion, absorption, egestion • Mechanical and chemical digestion • Anatomy (mouth, pharynx, epiglottis, esophagus, cardiac sphincter, stomach, pyloric sphincter, duodenum, jejunum, ileum, caecum, colon, rectum, anus) • Accessory organs: pancreas, salivary glands, liver, gall bladder • Disorders: Peptic Ulcer, Cirrhosis, Hepatitis, Diabetes • Page 521#1-7,10,12,14,17-22,44,45,47,51,53,57,58, • Page 526#1-3,6-10

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