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digestion I - d salivary glands parotids(in front of ears...

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Digestion I A. Introduction 1. Heterotrophic- can’t make own food 2. Holotrophs- injestive a. herbivores b. carnivores c. omnivores 3. Digestion- need food to be small enough to diffuse into cells, animals are made of different macromolecules a. hydrolytic- enzymatic b. intracellular- Amoebas, Sponges, (Cnidarians, flatworms have gastrovascular cavities and start extracellular and finish intracellular) c. extracellular- have tube within a tube body plan (higher organisms only intracellular is in white blood cells)
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B. Mammalian Digestive system 1. Oral cavity a. hard and soft palates b. tongue- skeletal muscle - mastication- chewing, helps form bolus (a food sphere) - deglutition- swallowing, pushes bolus against hard palate which pushes bolus back toward pharynx - taste buds- helps taste food c. teeth- heterodant dentition - 8 incisors- chisel-shaped, used for cutting - 4 canine (cuspids)- pointed, used for holding and tearing - 8 bicuspids (premolars)- two points, used for grinding and holding - 12 molars- flat, used for grinding
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Unformatted text preview: d. salivary glands- parotids (in front of ears), submandibular (under mandible), sublingual (below tongue) - salivary amylase- enzyme that breaks down carbohydrates i. works in pH in mouth (6.5-6.8)- moisten bolus- lubrication- forms a glycoprotein- prevents dry mouth- prevents dirt from entering respiratory system- prevents dent caries- cavities 2. Pharynx- “throat,” the point where the respiratory and digestive tracts cross a. deglutition- the passage of food down pharynx- form bolus- tongue presses bolus against hard palate - soft palate moves up to close off nasal passage- larynx moves up, epiglottis covers glottis (opening of larynx) (involuntary) 3. Esophagus- tube that connects pharynx to stomach, smooth muscle a. upper esophageal sphincter- relaxes to let bolus down- peristaltic movement- in front of bolus muscles relax, behind bolus muscles contract b. lower esophageal sphincter- closed until food bolus enters stomach. (if always open → acid reflux → cancer...
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