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Chapter 49: Digestive and Excretory Systems

Chapter 49: Digestive and Excretory Systems. 49-1 Nutrients. 49-2 Digestive System. 49-3 Urinary System. 49-1 Nutrients. I. Six Basic Food Ingredients. MOST foods contain a bulk of just ONE or TWO nutrient types. (1) Nutrients (2 CLASSES: (1) Organic (CPLV) (2) inorganic (MW).

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Chapter 49: Digestive and Excretory Systems

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  1. Chapter 49: Digestive and Excretory Systems 49-1 Nutrients 49-2 Digestive System 49-3 Urinary System

  2. 49-1 Nutrients I. Six Basic Food Ingredients • MOST foods contain a bulk of just ONE or TWO nutrient types.

  3. (1) Nutrients (2 CLASSES: (1) Organic (CPLV) (2) inorganic (MW) • Chemicals NEEDED for growth, maintenance, and metabolic activity.

  4. Critical Thinking (1)In some countries, many children suffer from a type of malnutrition called “kwashiorkor.” Symptoms include swollen stomachs and a tendency to become increasingly thinner until they die. Even when provided with RICE and WATER, these children still cannot survive. What TYPE of nutritional deficiency might these children possess?

  5. (A) Carbohydrates (e.g., mono-, di-, and polysaccharides) • Broken down (hydrolysis) to monosaccharides (glucose) to be used by cells during AEROBIC RESPIRATION to make ATP.

  6. (B) Proteins (e.g., keratin, polymerase, collagen, hemoglobin, lactase) • Help with growth, reproduction, repair, and ALSO serve as ENZYMES (chemical reactions) [NOTE: essential and non-essential AA].

  7. (C) Lipids (e.g., oils, waxes, saturated and unsaturated fats) • Cell MEMBRANE repair, insulation, protective padding, and serve as an NRG reserve (adipose tissue).

  8. (D) Vitamins (e.g., Vitamin D is the only one self-synthesized) • Large, ORGANIC compounds work as COENZYMES  activate true enzymes during our METABOLISM.

  9. (E) Minerals (e.g., calcium, iron, potassium, phosphorous, salts, iodine, zinc) • INORGANIC substances needed for HEALTHY cellular functioning.

  10. Critical Thinking (2)Which of the SIX basic nutrients might a person need to RESTRICT after an operation to REMOVE the gall bladder? Explain your choice.

  11. (F) Water • MEDIUM for cellular RXNS, PLASMA (blood pressure), and used to REGULATE body temperature (heating/cooling).

  12. (1) Dehydration (NOTE: A 12% loss = fatal) • If water is LOST (and NOT replenished), then water will be DRAWN from ECM to blood (via osmosis)—eventually cells lose water AND die.

  13. 49-2 The Digestive System I. The Gastrointestinal Tract (a.k.a., alimentary canal) • G.I. TUBE  mouth TO anus (excludes ACCESSORY organs  liver and pancreas).

  14. (A) Mouth • Mechanical (mastication) AND chemical digestion (salivary amylases).

  15. (1) Incisors and Molars • EXPOSE larger SURFACE AREA for enzymes to ACT UPON.

  16. (2) Hard Palate and Soft Palate (UPPER MOUTH) • Bony region (FRONT), grinds food AGAINST; SOFT tissue (BACK) separates mouth from NASAL cavity.

  17. (3) Saliva (i.e., water, mucus, and amylase—breaks down STARCHES) • SOFTENS food for swallowing AND assists with digestion.

  18. (B) Esophagus (i.e., food pipe; circular AND longitudinal smooth muscle) • Delivers BOLIS (via peristalsis) from oral cavity TO stomach.

  19. (1) Bolis (i.e., food BALL) • Once chewed and moistened, food is ROLLED into a swallow-able ball.

  20. (2) Epiglottis (separates esophagus-trachea) • Flap of cartilage PREVENTS material from entering TRACHEA.

  21. (3) Peristalsis (carried out by TWO smooth muscle types) • Involuntary, muscular CONTRACTIONS squeeze bolis through a VALVE into stomach. (NOTE: defies gravity)

  22. (C) Stomach (made of circular, longitudinal, AND diagonal smooth muscles) • Elastic, muscular sac  MAXIMIZING mechanical (churning) and chemical (digestive acids) digestion [3-4 hours per meal].

  23. (1) Gastric Pits (open ends of GASTRIC GLANDS lining the stomach) • Secrete MUCUS, digestive ENZYMES, and HCl  mix to produce an ACIDIC fluid (pH < 2).

  24. II. Chemical Digestion • Amylase (saliva), HCl (stomach), pepsin (stomach), other enzymes (intestines)—liberate nutrients, allow for ABSORPTION into bloodstream.

  25. Critical Thinking (3) Some people CANNOT drink milk because they are unable to digest LACTOSE, the sugar in milk. Doctors believe this inability involves SPECIFIC areas of the digestive system. What do you suppose these areas are?

  26. (1) Gastric Fluid (i.e., product of gastric pits) • Responsible for CHEMICAL digestion in stomach (enzymes and acid).

  27. (2) Pepsin (NOTE: Converted from inactive pepsinogen (needs LOW pH) • Enzyme SPLITS large PROTEINS into SMALLER chains of amino acids (peptides).

  28. (3) Ulcer (lesions recently attributed to some H. pylori bacteria species) • Mucous coating BREAKS down, allowing gastric fluid to DIGEST part of stomach epithelial lining.

  29. (A) Formation of Chyme • Mouth Esophagus  Cardiac Sphincter  Stomach  Pyloric Sphincter  CHYME enters INTESTINES.

  30. (1) Cardiac Sphincter (circular muscle BETWEEN esophagus and stomach) • Regulates what ENTERS or LEAVES stomach from esophagus.

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