Digestive System Study Questions – Flashcards
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Helps to breakdown food both mechanically and in the chemical digestion of starch (minor function: chemical digestion of lipids)
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Function of saliva
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Breaking large food particles into smaller ones
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Mechanical digestion
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Breaking the chemical bonds of polymers to make smaller molecules (monomers or dimmers)
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Chemical digestion
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Movement of molecules/ions from the lumen of the GI tract to the bloodstream
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Absorption
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Movement of molecules/ions from the blood to the lumen of the GI tract
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Secretion
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The act of eating/swallowing
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Ingestion
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What is the function of the esophagus?
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Move food from the mouth to the stomach
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How does the anatomy of the esophagus help its function?
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Has a thick lining of stratifies squamous to prevent damage due to friction
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How does peristalsis begin the the esophagus and stomach
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The circular muscle layer will start contracting at the top of the stomach/esophagus
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What happens during peristalsis after the circular muscle layer starts contracting?
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The muscle contractions systematically work its way down to push food through the tract
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What is happening during peristalsis when the muscle contractions are working their way down the tract?
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The longitudinal layer contracts ahead of the food to shorten its path
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What is peristalsis?
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Rapid consecutive muscle contractions that cause fast movement of food through GI tract
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What may occur if the gastroesophageal sphincter is malfunctioning?
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Leakage of stomach acid into the esophagus causing burning of the esophageal lining
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What is the function of the stomach? mechanically?
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Continues mechanical digestion through rough peristaltic contractions and use of acidic gastric juices
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What is the function of the stomach? chemically?
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Begins chemical breakdown of proteins using the enzyme pepsin
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How does the anatomy of the stomach help its mechanical function?
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Three layers of muscle help mix and churn gastric juices
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How does the anatomy of the stomach help its chemical function?
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Gastric glands secrete HCl and pepsinogen for breakdown of protein
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Which hormones stimulate the secretion of HCl?
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Gastrin and Ach
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What happens when the stomach wall stretches and the presence of food on the stomach?
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gastrin is secreted
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What happens in response to the taste, smell, and chewing of food?
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ACh is secreted
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What inhibits HCl?
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Hormones from the duodenum: secretin and CCK
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How are secretin and CCK released?
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When stomach contents enter the duodenum
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What cells does HCl come from?
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parietal cells
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What cells does pepsinogen come from?
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chief cells
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Stimulates the pancreas to release bicarbonate and inhibits the production of acid in the stomach
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Secretin
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Stimulates the production and release on pancreatic enzymes and bile salts and inhibits the production of stomach acid
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CCK
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What digestive enzymes are made by the pancreas?
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enzymes for every food type (protein, lipids, carbs and nucleic acids); lipase and amylase
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What does lipase digest?
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lipids
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What does amylase digest?
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carbohydrates
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What is found in bile?
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Bile salts and waste products (gathered by the liver)
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Work to surround small droplets of fat to keep them from precipitating out of solution in large globules. Makes it easier for lipase to breakdown the fats.
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Function of bile salts
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How is the small intestine maximized for absorption?
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Has greatly enlarged surface area through the anatomical folding of the wall and epithelial cells
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What type of muscle contractions occur in the small intestine?
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Segmental movement
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How does segmental movement work in the small intestine?
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The circular layer contracts in a seemingly random fashion
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How does segmental movement aid in absorption in the small intestine?
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Ensures that all nutrients contact the lining for absorption
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What is fat broken down into, so that it can be absorbed?
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Fatty acids and glycerol
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What is protein broken down into in the lumen, before it can be absorbed?
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small polymers
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What are carbohydrates broken down into in the lumen, before it can be absorbed?
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small polymers or dimers
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How are proteins broken down into small polymers that can be absorbed?
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By enzymes in the lumen
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How are carbohydrates broken down into small polymers or dimers that can be absorbed?
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By enzymes in the lumen
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What are carbohydrate small polymers or dimmers broken down into at the brush border?
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monomers
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What are protein small polymers broken down into at the brush border?
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amino acids
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How are substance broken down at the brush border?
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By brush border enzymes
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How are fatty acids and glycerol absorbed?
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By diffusion
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How are amino acids absorbed?
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By facilitated diffusion or cotransport
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How are monomers absorbed?
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By facilitated diffusion or cotransport
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What happens to fatty acids and glycerol once it diffuses across the plasma membrane?
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Transformed to triglycerides and packaged with protein; travels to liver via lacteals (lymph vessels)
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What happens to amino acids once they are across the cell membrane?
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Brought across basolateral membrane into interstitial fluid and diffuses into capillaries
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How are amino acids brought across the basolateral membrane?
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By facilitated diffusion or cotransport
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What happens to monomers once they are across the cell membrane?
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Brought across basolateral membrane into interstitial fluid and diffuses into capillaries
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How are monomers brought across the basolateral membrane?
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By facilitated diffusion or cotransport
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What are the functions of the colon?
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Water and sodium absorption; Production of vitamin K; Compaction of leftover materials
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What type of muscle contractions occur in the colon?
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Segmental and peristalsis
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When do segmental contractions occur in the colon?
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Most of the day
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When does peristalsis occur in the colon?
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For compaction and removal of waste
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What happens to carbohydrates once they are absorbed?
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Stimulates the release of insulin; Stored in liver and muscle tissue as glycogen
