Digestion

  • What do animals need to live   * Animals make energy using food and oxygen   * Animals build bodies using food for raw materials and ATP energy for synthesis
  • Different diets; different lives   * All animals eat other organisms   * Herbivores     * Eat mainly plants     * Ex: gorillas, cows, rabbits, snails   * Carnivores     * Eat other animals     * Ex: sharks, hawks, spiders, snakes   * Omnivores     * Eat animals and plants     * Ex: cockroaches, bears, raccoons, humans       * Humans evolves as hunters, scavengers, and gatherers
  • Getting and Using Food   * Ingest     * Taking in food   * Digest     * Mechanical digestion       * Breaking up food into smaller pieces     * Chemical digestion       * Breaking down food into molecules small enough to be absorbed into cells       * Enzymes     * Absorb       * Absorb nutrients across cell membranes         * Diffusion         * Active transport     * Eliminate       * Undigested material passes out of the body
  • Mouth   * Functions     * Mechanical digestion       * Teeth         * Break up food     * Chemical digestion       * Saliva       * Amylase enzyme         * Digests starch       * Mucus         * Protects soft lining of digestive system         * Lubricates foods for easier swallowing       * Buffers         * Neutralizes acid to prevent tooth decay       * Antibacterial chemicals         * Kill bacteria that enter mouth with food
  • Swallowing   * Epiglottis     * Flap of cartilage     * Closes trachea (windpipe) when swallowing     * Food travels down the esophagus   * Peristalsis     * Involuntary muscle contractions to move food along
  • Stomach   * Functions     * Disinfect food       * Hydrochloric acid         * pH 2         * Kill bacteria     * Food storage       * Can stretch to fit about 2 liters of food     * Digests protein       * Pepsin enzyme
  • Ulcers   * Used to think that ulcers were caused by stress     * Tried to control with antacids   * Now know that ulcers are caused by a bacterial infection of the stomach     * Now cure with antibiotics
  • Small intestine   * Functions     * Digestion       * Digests carbohydrates         * Amylase from pancreas       * Digests proteins         * Trypsin and chymotrypsin from pancreas       * Digest lipids         * Bile from liver and lipase from pancreas     * Absorption       * Nutrients move into body cells by diffusion and active transport       * Absorption through villi and microvilli         * Finger-like projectors         * Increases surface area for absorption
  • Pancreas   * Produces digestive enzymes     * Digests proteins       * Trypsin, chymotrypsin     * Digests starch       * Amylase     * Digests lipids       * Lipase   * Buffers     * Neutralize acid from stomach
  • Liver and Gall Bladder   * Produces bile     * Breaks up fats     * Gallbladder only stores bile       * That’s why it can be removed
  • Large intestines (colon)   * Function     * Reabsorbs water       * Uses about 9 liters of water every day in digestive juices         * If you don’t reabsorb water, would die of dehydration       * \         > 90% of water is reabsorbed         * Not enough water reabsorbed

Diarrhea

Can be fatal

  • Too much water reabsorbed

Constipation

  • Reabsorb by diffusion   * Company     * Escherichia coli       * E. coli         * Digest cellulose

Digests fruits and vegetables

  • Produce vitamins

Vitamin K and B vitamins

  • Generate gases

By product of bacterial metabolism

Methane and hydrogen sulfide

  • Rectum   * Last section of large intestines     * Eliminate feces     * Left over       * Undigested materials         * Mainly cellulose from plants         * Called roughage or fiber         * Keeps everything moving and cleans out intestines       * Masses of bacteria
  • Different diets; different bodies   * Adaptations of herbivores vs. carnivores     * Teeth     * Length of digestive system     * Number and size of stomachs
  • Teeth   * Carnivore     * Sharp ripping teeth     * Canines   * Herbivore     * Wide grinding teeth     * Molars   * Omnivore     * Both kinds of teeth
  • Length of digestive system   * Herbivores and omnivores     * Long digestive systems     * Harder to digest cellulose       * Bacteria in intestines help   * Carnivores     * Short digestive systems     * Protein easier to digest than cellulose
  • Deficiency diseases   * Scurvy - vitamin C     * Collagen productions   * Rickets - vitamin D     * Calcium absorption   * Blindness - vitamin A     * Retinol production   * Anemia - vitamin B12     * Energy production   * Kwashiorkor - protein
  • Vegetarian diets   * Need to make sure you get enough protein     * 20 amino acids make protein       * 12 amino acids humans can produce       * 8 we have to eat         * “Essential amino acids”     * Grains like corn have 6 amino acids     * Beans have 6 amino acids       * Mix beans and grains for complete group of amino acids

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