Some stomach or esophagus may expand into a pouch

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Some ____________________________: stomach or esophagus may expand into a pouch Storing food temporarily and some gastric digestion occurs here Mammalian small intestine is long & coiled Differentiated into duodenum, jejunum, ileum Large intestine is long but not as long as small intestine & ends in rectum Herbivores: cecum is at junction between large & small intestines Humans: cecum is greatly reduced & is the _______________________ Monotremes & a few marsupials: large intestine terminates in the cloaca Placental mammals: it opens directly to outside through anal sphincter Ruminants: stomach is highly specialized & ferments food in the foregut Stomach: 4-chambers: rumen, reticulum, & omasum; all derivatives of esophagus 4thcompartment true stomach: _________________________ Rumen: large; collects food after clipped by teeth & swallowed Reticulum: small accessory chamber with honeycombed texture __________________ lack a true omasum have 3-chambered stomach: rumen, reticulum, abomasum Hindgut Fermenters: Large cecum between small & large intestines; no 4-chambered stomach Hindgut fermenters: cecum and/or large intestine are major sites of fermentation Many herbivores: digestion of plant _______________________ enhanced by a cecum Cecum contains microorganisms effective in cellulose digestion; provides expanded region prolonging time available for digestion Associated Glands in Digestion: Liver Liver: second largest organ in humans Variety of functions: 1)Liver is involved in production of __________, early in fetal life Involved in destruction of old blood cells, later in life 2)Detoxifies & removes toxic substances from blood 3)______________ is manufactured in liver & released into intestine Emulsify fats or break them up into smaller droplets 4)Carbohydrates, proteins, & fats are stored & metabolized in liver All vertebrates possess a liver Bile: ___________________ product of liver; delivered to intestine where it emulsifies fats
11 Most vertebrates: bile is stored in gallbladder & released in quantities when digesta enter intestine Gallbladder is absent in _____________________, most birds, and a few mammals Otherwise present in vertebrates Associated Glands in Digestion: Pancreas Pancreas is both an Exocrine gland: produces pancreatic juice Endocrine gland: produces insulin & glucagon Embedded in pancreas = small pancreatic islets Islets of ______________________________: produce insulin & glucagon Both regulate the level of glucose in blood Pancreas is present throughout vertebrates Function & Evolution of the Digestive System Absorption of food begins in stomach Water, salts, & simple sugars cross _______________ & are absorbed in blood capillaries End products of digestion in most vertebrates are usually formed & absorbed in intestine Absorption of food depends on both __________ available Time spent in the alimentary canal Both microscopic & gross anatomical features can increase surface area Numerous villi on epithelial lining of intestine greatly increase area available for absorption Many fishes: a __________________ valve in the intestines Forces food through winding channel & increases time exposed to digestion Herbivorous intestines: long & numerous ceca Modifications prolong time food takes to traverse intestines Allows microbial fermentation to digest cellulose more completely Long intestines present a packing problem Leaf-eating ______________________ & other herbivores Abdominal space expands after a large meal & results in enlarged belly

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