products and help guard against infection Mucous lubricating properties to help

Products and help guard against infection mucous

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products and help guard against infection Mucous: lubricating properties to help in swallowing and dissolving food molecules and carrying them to taste buds on the tongue Mechanical/Chemical Digestion
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o As teeth begin breaking food down, first phase of digestion: depends on 3 salivary glands that secrete saliva in a response to smell, feel, taste and even the thought of food when you’re hungry o Salivary glands: produce/secrete saliva into oral cavity Parotid (beneath the cheeks) Submandibular gland (below the jaw bone) Sublingual (Below the tongue) saliva moistens the food and contains enzymes (ptyalin or salivary amylase) that begins digestion of starch into smaller polysaccharides o Salivary glands produce approximately 1-1.5 liters of saliva daily. Mechanism of Swallowing: o Coordinated activity of tongue, soft palate, pharynx, esophagus o Phases Food pushed into pharynx by tongue, (voluntary) Where digestive/respiratory come together Soft palate closes off nasopharynx, allowing food to enter the oropharynx Larynx (adam’s apple) rises so the epiglottis can close the opening of the trachea (glottis) Esophagus o Straight muscular tube that is about 10 inches (25 cm) long which connects the mouth with the stomach o Food takes about 4-8 seconds to pass through the stomach o Walls contain smooth muscle that contracts in wavy motion (peristalsis) Rhythmical contractions move contents in tubular organs o Peristalsis propels food and liquid slowly down esophagus into stomach o Cardiac sphincter: ring like valve: relaxes to allow food to pass into stomach
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Stomach: o J shaped muscular sac o Has inner folds (rugae) that increases surface area of stomach o Churns and grinds together the bolus into smaller pieces o Food is mixed with gastric juices (hydrochloric acid and enzymes) secreted by stomach walls o HCL breaks down food and kills bacteria that came along with food o Normal capacity: 1 liter in adult o Food enters the stomach by first passing circular ring called cardiac sphincter Keeps food and stomach acids from moving up into esophagus o Stomach walls have deep folds o Folds disappear as the stomach fills to an approximate volume of one liter o Stomach has epithelial lining: millions of gastric pits that drain gastric glands Pepsin: hydrolytic enzyme that acts on proteins to produce peptides o Stomach secretions Parietal cells: located in body of the stomach Secrete gastric acid and intrinsic factor Gastric acid: (HCl) digests proteins by activating various digestive enzymes that uncoil proteins and denature them into amino acids Intrinsic factors: helps in absorption of vitamin B.
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