Digestion Study Guide – Flashcards
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What two processes are involved in digestion?
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- Breaking down food, followed by absorption and elimination
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What results from digestion?
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Small molecules that the body is able to use.
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What type of reaction is involved with the chemical breakdown of food?
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An acidic reaction.
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Where is most of the absorption of nutrient carried out?
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Small intestine
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What structures are especially designed for absorption?
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Ileum
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Name four materials that our bodies are able to absorb.
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Sugar, Amino Acids, Glycerol, and Fatty Acids
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What is another name for elimination?
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Waste removal (Using the bathroom)
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What is another name for the mouth in digestion?
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Salivary Glands
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What process are the teeth responsible for?
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Mechanical Digestion (breaking down using physical force)
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What two things does the saliva do to your food?
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1) liquifies food 2) Lubricates and softens the BOLUS of food.
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How does your tongue participate in the digestion?
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- protects us against poisons - Moves food around - Helps swallow food
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Prior to swallowing, the food is pushed to this part of the throat called the ?
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swallow reflex center
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What structure keeps food from entering the trachea ?
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epiglottis
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From the pharynx, the food enters the...
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Esophagus
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What is the function of the cardiac sphincter at the end of the esophagus?
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ensures that no food re-enters the esophagus
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Describe the stomach
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A large organ that helps in the digestive process (J shaped).
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Explain how the stomach is involved in physical digestion
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Churns food and liquifies it
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Explain how the stomach is involved in chemical digestion?
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-Columnar epithelium produces an inactive enzyme called PEPSINOGEN. -These cells contain many mitochondria for active transport. - Chief Cells produce 3M Hydrochloric Acid (HCl). - HCL is a strong acid and therefore very effective at breaking down materials
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What is the band of muscles that closes off the far end of the stomach?
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pyloric sphincter
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How does the pyloric sphincter regulate the activities of digestion?
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Move the chyme (an acidic liquid) into the duodenum at a slow, controlled rate.
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The duodenum is actually part of what structure?
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The Small Intestine
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Which organs secrete their digestive enzymes in the duodenum?
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Liver, Pancreas
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What does the liver produce for the digestive process?
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Bilirubin : A waste product from Haemoglobin
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What happens to bile after it is produced by the liver?
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1) The bilirubin is exported in bile to the gall bladder 2) It is also put into the blood stream where it is removed by the kidneys
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What types of diet do the pancreatic enzymes digest?
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Proteins, Lipids, and Carbohydrates
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Where does the remaining food go after it leaves the duodenum?
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The large intestine
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What is the main function of the small intestine?
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To complete digestion and begin absorption of nutrients.
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What is found at the junction of the small intestine and the large intestine?
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The Ileum
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What is the function of the ileum?
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to absorb all of the nutrients into the circulatory and lymphatic systems.
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Another name for the colon is the what?
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The large intestine
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What happens in the colon?
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Water is absorbed and undigested food is eliminated
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What structure is found at the end of the colon?
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The rectum
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What is the function of the rectum?
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Compress waste materials into a solid form before being eliminated
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The band of muscle that releases wastes is called the what?
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The anus
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What foods start breaking down in the mouth?
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Starch
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What enzyme is responsible for the breakdown of food in the mouth?
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Amylase
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The stomach is used primarily for the breakdown of which type of foods?
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Proteins
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What is the function of Hydrochloric acid in the stomach?
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Digest proteins into peptides and polypeptides
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The enzyme responsible for the breakdown in the stomach is called what?
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Pepsin
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What is formed form the initial breakdown of proteins?
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Peptides + Polypeptides
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What is a protease?
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an enzyme that breaks down proteins and peptides.
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Name two proteases.
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chymotrypsin, chymotrypsin
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What three enzymes are produced by the pancreas?
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Trypsin, Lipase, Amylase
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Where do pancreatic enzymes do their work?
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the exocrine gland
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Which enzyme is used to break down carbohydrates?
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Amylase
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What does the enzyme trypsin produce?
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peptides, di-peptides, and tri-peptides.
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What are peptidases?
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intestinal enzyme that completes digestion of partially digested proteins to amino acids
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Before lipase can begin work, what must happen?
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Fats must be broken down into smaller pieces using bile produced by blood in the liver.
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What products are formed after peptidases do their work?
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Amino Acids
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What organ produces peptidases?
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The small intestine
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What enzyme is produced by the small intestine besides peptidases?
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maltase
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Swallowing is a reflex action. What does this mean?
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Involuntary due to a give stimulus (food entering the back of the mouth)
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Where in the digestive system does swallowing originate?
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The Pharynx
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What keeps food from going up onto the nasal cavity?
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A soft palate covers the opening to the nose
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What directs food into the esophagus?
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The pharynx closes off the nose and trachea, and guides food with the help of the tongue
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Once in the esophagus, how is food moved towards the stomach?
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Involuntary constriction and relaxation of the muscles. (peristalsis of the esophagus)
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What type of muscle is responsible peristalsis
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cardiac sphincter
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What is meant by gastric juice?
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a digestive fluid secreted by the stomach.
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What two substances make up the gastric juices?
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HCl and Pepsinogen
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Why is it important for the stomach contents to be acidic?
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Breaks down molecules (acids are very corrosive)
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What substances make up pancreatic juice?
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Sodium Bicarbonate, trypsin, lipase, amylase
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. What is the function of sodium bicarbonate (NaHCO3)?
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digest food and neutralize chyme
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What happens if the pancreatic juice contains an insufficient amount of sodium bicarbonate?
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acidic chyme will not be neutralized
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What two enzymes make up the intestinal juice?
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nuclease, maltase, peptidases
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Gastric secretions are under the control of what hormone?
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Gastrin
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Where is gastrin produced?
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the submucosa of the lower stomach (Stomach)
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What causes production of this hormone?
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Presence of BOLUS in stomach
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What happens to gastrin after it has been produced?
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Gastric juice is released, killing bacteria and digesting protein
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What effect does it have on the stomach?
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The stomach becomes more acidic, and also gains the ability to Pepsinogen to Pepsin, and Pepsin to Peptides + Polypeptides
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Explain how the production of gastrin is an example of negative feedback.
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If HCl formed from Gastrin enters the duodenum, NaHCO3 from the pancreatic juices (high pH) lowers the acidity of the solution.
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What two important hormones are produced by the duodenum?
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Secretin, and CCK
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What causes the production of secretin?
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Presence of CHYME in duodenum
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What causes the production of CCK?
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Presence of fatty acids in duodenum
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Which hormone causes the gall bladder to release its bile?
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CCK
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Both hormones causes what to release its enzymes?
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The pancreas
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What organ is responsible for the production of insulin?
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The pancreas
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What hormone besides insulin is produced by the pancreas?
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glucagon
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What is an endocrine gland?
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A gland in the pancreas that produces hormones
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Explain how insulin controls the blood sugar level in a negative feed back cycle?
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If there is excess blood glucose in the liver, insulin converts it to glycogen
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What happens to excess glucose in the blood?
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Converted to glycogen.
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Why does insulin promote protein and fat synthesis?
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1. Inhibition of glycogen synthesis (liver glycogen 5-6%) 2. Activation of acetyl-CoA carboxylase, leading to an excess of citrate & isocitrate ions and conversion of acetyl-CoA to Malonyl-CoA 3. Activation of lipoprotein lipase which splits triglycerides into fatty acids, which are transported into adipose cells and stored.
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What hormone raises the blood sugar level?
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Glucagon
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What does glucagons cause the liver to do?
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produce glucose in the bloodstream
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Describe the function of bile.
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aids in the emulsification, digestion, and absorption of fats
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Where is it produced?
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the liver
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Where does it function?
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the gall bladder
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The liver maintains this vital concentration in the blood.
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sugar
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The liver produces what from the breakdown of amino acids?
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converted into glucose to maintain glucose concentration of plasma (this is called gluconeogenesis).
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The liver metabolizes poisonous substance. What does this mean?
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The liver detoxifies any poisons or harmful substances that were absorbed by the digestive tract (ie: alcohol is metabolised into fatty acids).
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The liver breaks down old red blood cells and recycles hemoglobin by turning it into what?
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bilirubin and biliverdin (the components of bile)
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The liver produces blood proteins such as what? Give two examples
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fibrinogen and prothrombin
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The small intestine has at least three features that increase the surface area. What are those features?
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convoluted (folded) walls, VILLI (folds in mucose layer), and MICROVILLI (smaller folds)
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Why is increased surface area vital for absorption?
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Increases amount of food absorbed (more time to go through the organ)
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What are the special projections on the wall of the intestine called?
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villi
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Within villi are special cells called what?
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collumnar cells
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Within each villus are blood vessels and an extension of the lymphatic system called a what?
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microvilli
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What are the two functions of the blood vessels?
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- Carry blood (containing oxygen and nutrients) through the body. - Carry hormones, and enzymes to stimulate specific functions of organs
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What is the function of the lacteals?
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Absorb dietary lipids into the lymphatic system
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What process is used to transport materials from the gut into the blood stream?
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The hepatic portal vein (drains blood from the gastrointestinal tract and spleen to capillary beds in the liver)
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Where do the products of fat digestion go after they are absorbed into the lacteal?
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It travels through the lymphatic system until it is dumped into the circulatory system.
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Where do the sugars go after they are absorbed into the bloodstream?
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They are carried to all of the body's tissues and are used to supply energy
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What are anaerobic bacteria?
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Bacteria that does not require oxygen
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Where are anaerobic bacteria found?
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In the intestinal tracks
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Why are anaerobic bacteria important for us?
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Breakdown bio-organic materials (help with digestion)
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What is one socially embarrassing problem related to anaerobic bacteria living within our intestines?
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Farts
