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16 Cards in this Set
- Front
- Back
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How are digestive juices secreted?
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through exocrine glands. Exocrine gland cells release digestive juice by exocytosis, after which it travels along ducts.
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What is an acinus?
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a group of secretory cells clustered around the end of a digestive duct
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What are some distinctive features of exocrine gland cells?
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prominent nucleoli (one or two), large rough ER, golgi apparatus, many large vesicles or secretory granules, mitochondria
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What controls digestive juice secretion?
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nerves and hormones
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The sight or smell of food stimulates the brain to send nerve impulses to exocrine glands in the stomach, which do what?
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secrete gastrice juice. salivary glands are also stimulated to secrete saliva w/ amylase.
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What causes "much more" gastric juice to be secreted when food enters the stomach?
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Touch receptors in chemoreceptors and stretch receptors in the stomach's wall detect the food and send messages to the brain, which tells the exocrine glands to secrete more gastric juice.
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The entrance of food into the stomach also stimulates the secretion of gastrin, which stimulates exocrine gland cells in the stomach wall to increase secretion of what?
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hydrochloric acid
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What main digestive enzymes and substances are in saliva?
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salivary amylase and mucus
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What main digestive enzymes and substances are in gastric juice?
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pepsinogen, hydrochloric acid, and mucus
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What main digestive enzymes and substances are in pancreatic juice?
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pancreatic amylase, pancreatic lipase, phospholipase, trypsinogen, carboxypeptidase, and HCO3- ions
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Lipids are harder to digest, because droplets of lipids tend to group together to form large droplets. What helps break these up so that the lipids can be digested easier?
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Bile salts in bile are natural detergents, which emulsify the lipid droplets, causing them to break up into smaller droplets.
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How is cellulose digested in humans?
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Humans don't have the enzyme cellulase, which digests cellulose, so cellulose is egested in feces.
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Pepsin and trypsin are harmful to the exocrine gland cells, so are secreted as what?
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Pepsinogen and trypsinogen
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What do endopeptidases do?
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break polypeptides into smaller ones
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What do exopeptidases do?
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complete the digestion of proteins to release single amino acids
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How do pepsinogen and trypsinogen become pepsin and trypsin?
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Hydrochloric acid secreted in the wall of the stomach converts pepsinogen to pepsin, while the enzyme enterokinase secreted by the lining of the small intestine activates trypsinogen.
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