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What are the primary mechanisms of the digestive system?
What is the condition of digestive activity called?
What are the three steps or stages of deglutition?
- oral stage (mouth to oropharynx), voluntary movement
- pharyngeal stage (oropharynx to esophagus)
- esophageal stage (esophagus to stomach)
What is progressive kind of motility that is a type of motion that produces forward movement of ingested material along the GI tract; it is a wavelike ripple of muscle layer?
What can be described as mixing movement, when digestive reflexes cause a forward-and-backward movement withinn a single region, or segment, of the GI tract?
The process of emptying the stomach takes about how mnay hours?
2 to 6 hours
What is known as when food is churned with gastric juices to form a thick, milky material?
Chime is ejected about every how many seconds into what?
every 20 seconds into the duodenum
What hormone is released when fats and other nutrients in the duodenum stimulate in the intestinal mucosa?
gastric inhibitory peptide (GIP)
The chemical process in which a compound unites with water and then splits into simpler compounds is called.
What enzymes are proteases (protein-digesting enzymes)?
pepsin and trypsin
Why are digestive enzymes classified as extracellular?
they operate in the lumen of the digestive tract, outside any cells of the body
What is the main enzyme in saliva?
Most digestive enzymes are synthesized and secreted as what?
What are substances that convert proenzymes to active enzymes?
What are polysaccharides?
starches and glycogen
What are disaccharides?
sucrose, lactose, and maltose
What are monosaccharides?
glucose, fructose, and galactose
What hydrolyzes polysaccharides into disaccharides?
amylase in saliva and pancreatic juice
What enzymes hydrolyze proteins to proteoses and peptides?
gastric juice protease (pepsin) and pancreatic juic protease (trypsin and chymotrypsin)
When is protein digestion completed?
pancreatic proteases (trypsin and chymotrypsin), which hydrolyze proteoses to amino acids,, and by intestinal peptidases, which hydrolyze peptides to amino acids
What enzymes are catalyzing at the final steps in carbohydrate digestion?
sucrose, lactase, and maltase
What are two substances found in bile?
lecithin and bile salts
Lecithin mixes with lipids and water forming tiny spheres called?
What is the mechanical process of emulsification?
facilitates chemical digestion of fats by breaking large fat drops into small droplets
What are the main fat-digesting enzymes called?
What binds to hydrogen ions, thus taking the hydrogen ions out of solution and causing a decrease in acidity (increase in pH)?
sodium bicarbonate (small amount found in saliva)
What type of juice is secreted by exocrine gastric glands, which have ducts that lead to the gastric lumen by way of the gastric pts?
What is secreted as the exocrine acinar cells?
What is secreted as tthe inactive proenzyme pepsinogen?
pepsin (pepsinogen is converted to pepsin by hydrochloric acid)
What is an interesting mixture of many different substances that is secreted by the liver, stored, and concentrated by the gallbladder?
What is referred to the sum of interstinal secretions rather than to a premixed combination of substances, that enters the GI lumen by way of a duct?
What the 3 types of phases in the control of gastric secretion?
- a) cephalic phase-"psyhic phase," psychic factors activate the mechanism
- b) gastric phase-gastrin is released by the stimulation of the mucosa
- c) intestinal phase-endocrine reflexes involving gastric inhibitory peptide, secretin and CCK inhibit gastric secretions
What hormones are secreted by endocrine cells in the mucosa of the duodenum?
gastric inhibitory peptide (GIP), secretin, CCK
What hormone evokes the producitn of pancreatic fluid flow in enzyme content buy high in bicarbonate (HCO3)?
What intestinal hormone stimulates contraction of the gallbladder so that bile can passs into the duodenum?
What is the passage of substances through the intestinal mucosa into the blood or lymph?
absorption (most absorption occurs in the small intestine)
What is the final step in lipid transport by the intestine?
formation of chylomicrons
Where is chylomicrons formed by?
the golgi apparatus
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