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Topic XIV

Emma Granger Physiology Inglés 5,0Valoración media 5,0 de 5 (1 valoración) 91 fichas

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  1. 1What does the digestive system involve?1) Digestive tract - mouth to anus
    2) Accessory organs - e.g. teeth, tongue, salivary glands, liver, gallbladder, pancreas
  2. 2What are the 4 basic processes of digestion?1) Digestion
    2) Absorption
    3) Motility
    4) Secretion
  3. 3What is digestion? What are the two types?Breakdown of large food pieces into small molecules
    a) mechanical - motility
    b) chemical - enzymes or acid
  4. 4What is the path of absorption?From lumen --> enterocytes (small intestinal cells) of villi --> blood or lymph
  5. 5What is motility? What are the methods?Smooth muscle contractions in tract
    -mix (segmentation, churning)
    -move (peristalsis)
  6. 6What is secretion?Digestive juice into lumen
  7. 7What is the purpose of saliva?It moistens (taste, speech, food manipulation) + prevents caries (contains lysozyme, antibodies)
  8. 8What does PSNS do to saliva?Stimulates secretion of thin, enzyme-rich saliva
  9. 9What does SNS do to saliva?Creates mucus rich saliva
  10. 10What are the processes in the mouth?Digestion and absorption
  11. 11What is the mechanical and chemical digestion in the mouth?Mechanical - chewing
    Chemical
    -i. carbohydrates (starch/glycogen) --salivary amylase--> disaccharides + oligosaccharides
    -ii. triglycides --lingual lipase--> fatty acids + monoglycerides
  12. 12What is the absorption in the mouth?-No food
    -Some drugs e.g. nitroglycerine for angina = vasodilator
  13. 13What is the main purpose of the pharynx + esophagus?Swallowing (deglutition)
  14. 14What are the phases of swallowing?Buccal phase, pharyngeal phase and esophageal phase
  15. 15Which phases are voluntary/involuntary?Buccal phase is voluntary, pharyngeal and esophageal are involuntary
  16. 16What happens during the buccal phase?Food is compacted by the tongue into a "bolus" - moves to pharynx by tongue pressing on hard palate
  17. 17What happens during pharyngeal phase? What happens along the different parts of esophagus?Food moves down esophagus (peristalsis)
    -Somatic motor neurons to skeletal muscle --> upper 1/3
    -PSNS (vagus) to smooth muscle --> lower ⅓
    -middle ⅓ = mix of both
  18. 18Food can't enter (or re-enter) which structures?Mouth, nasopharynx or trachea
  19. 19What doesn't let food enter/re-enter mouth?Tongue on hard palate
  20. 20What doesn't let food enter/re-enter the nasopharynx?Uvula, soft plate elevated
  21. 21What doesn't let food enter/re-enter the trachea?Glottis + epiglottis closed (breathing temporarily stops)
  22. 22What are the processes for the stomach?Digestion and absorption
  23. 23What is the mechanical part of digestion in the stomach?Churning - motility
  24. 24How does chemical digestion work for carbohydrates in the stomach?Salivary amylase until pH < 7
  25. 25How does chemical digestion work for lipids in the stomach?Lingual lipase (tongue), gastric lipase (chief cells) - until pH < 5-6
    Food = buffer - pH doesn't change right away
  26. 26How does chemical digestion work for proteins in the stomach?HCl (parietal cells) - denatures proteins + acts on pepsinogen (chief cells)
  27. 27What protects the stomach from self-digestion? What can it be penetrated by?By alkaline mucus (mucus cells)
    -Barrier can be penetrated by alcohol, aspirin, vinegar, bile
  28. 28What is the absorption in the stomach?-Food - very little (if any)
    -Some drugs - alcohol, aspirin (penetrate mucus)
  29. 29What are the processes in the small intestine?Digestion, absorption, fat digestion + absorption
  30. 30What is the mechanical part of digestion in the small intestine?Segmentation + peristalsis
  31. 31What does the chemical digestion in the small intestine involve?i) pancreas
    ii) gallbladder/liver
    iii) intestinal wall
  32. 32What are the steps of chemical digestion in the small intestine?Neutralize acid, pancreatic enzymes, and intestinal wall enzymes
  33. 33What is the goal of neutralizing the acid? What fluid is used?So pancreatic enzymes can work
    Alkaline fluid (HCO3-) - duct cells of pancreas and gallbladder
  34. 34How does the regulation of neutralizing the acid work?acid in duodenum --> ups secretin (hormone) --> ups HCO3- (duct cells) OR lowers gastric acid secretion (parietal cells)
  35. 35Pancreatic enzymes - where do they come from ~ where do they go (where do they come from cotton eye joe ;) )From pancreatic acinar cells, into intestinal lumen
  36. 36How do the pancreatic enzymes work for carbohydrates?polysaccharides --pancreatic amylase--> disaccharides (e.g. maltose) + oligosaccharides
  37. 37How do the pancreatic enzymes work for proteins?1) trypsinogen --enteropeptidase [on intestinal wall]--> trypsin
    2) trypsin activates proteases:
    INACTIVE ---> ACTIVE
    trypsinogen --trypsin--> trypsin (+ve feedback)
    chymotrypsinogen --trypsin--> chymotrypsin
    procarboxypeptidase --trypsin--> carboxypeptidase
    3) dietary + secreted proteins --proteases (active)--> peptides + amino acids
  38. 38How do the pancreatic enzymes work for fats?triglycerides --lipase (with bile salts)--> fatty acids + monoglycerides
  39. 39How does the regulation of pancreas enzyme secretion work?Fatty acids + aa's in duodenum --> ups cholecystokinin (CCK = hormone)
  40. 40What are the effects of CCK?i) ups pancreatic enzyme secretion
    ii) stimulation gallbladder contractions - releases bile
    iii) lowers gastric motility (slows emptying) + lowers gastric secretion
  41. 41After the pancreatic enzymes catalyze, what do we have for each macromolecule and can it be absorbed?a) di- and oligosaccharides - too big to be absorbed
    b) amino acids - can be absorbed
    peptides - most too big to be absorbed
    c) fatty acids and monoglycerides - can be absorbed
  42. 42What is the purpose of intestinal wall enzymes?Further break down on microvilli of enterocytes
  43. 43How do the intestinal wall enzymes work for carbohydrates?di- + oligosaccharides --disaccharidases + oligosaccharidases--> monosaccharides
    e.g.1: sucrose --sucrase--> glucose + fructose
    e.g.2: maltose --maltase--> glucose + glucose
    e.g.3: lactose --lactase--> glucose + galactose
  44. 44What happens if one has a lactase deficiency?= lactose intolerance - remains undigested so bacteria in large intestine ferment lactose
    -gas, diarrhea
  45. 45How do the intestinal wall enzymes work with proteins?peptides --aminopeptidases + dipeptidases--> smaller peptides + aa's
  46. 46What is celiac disease?Gluten (protein in grains) damages villi - lowers absorptive area for everything --> bacterial fermentation in large intestine --> gas, diarrhea
  47. 47How do the intestinal wall enzymes work with lipids?No digestion (no lipase on intestinal wall)
  48. 48Why is small intestine the main site for absorption?a) large surface area (folds, villi, microvilli)
    b) nutrients = small molecules
  49. 49How do monosaccharides [glucose and galactose] enter the enterocyte and leave the enterocyte (to blood or lymph)?2^o AT to enter, facilitated transport (blood) to leave
  50. 50How do monosaccharides [fructose] enter the enterocyte and leave the enterocyte (to blood or lymph)?Facilitated transport to enter, facilitated transport (blood) to leave
  51. 51How do amino acids enter the enterocyte and leave the enterocyte (to blood or lymph)?2^o transport to enter, facilitated transport (blood) to leave
  52. 52How do di + tripeptides enter the enterocyte and leave the enterocyte (to blood or lymph)?2^o AT to enter, facilitated transport (blood) to leave
  53. 53How do MGs, FA >= 12C (long chain), cholesterol, fat soluble vitamins enter the enterocyte and leave the enterocyte (to blood or lymph)?Diffusion to enter, exocytosis from enterocyte, diffusion into lymph lacteal
  54. 54How do FA <12C (short chain) enter the enterocyte and leave the enterocyte (to blood or lymph)?Diffusion to enter, diffusion to leave (blood)
  55. 55How does H2O enter the enterocyte and leave the enterocyte (to blood or lymph)?Osmosis to enter, osmosis to leave (blood, lymph)
  56. 56How much H2O is absorbed at small intestine per day and what are the portions?~8500 mL/day absorbed at small intestine, assuming
    a) H2O ingested in food/drink = ~2000 mL/day
    b) H2O from secretions = ~7000 mL/day
    so... ~9000 mL/day enters small intestine, ~500 mL/day lost to large intestine
  57. 57Where do absorbed nutrients go?a) to liver via hepatic portal vein (blood)
    b) into lacteals (lymph) --> thoracic duct --> left subclavian vein
  58. 58Where does fat digestion, absorption require bile from?a) liver (synthesizes)
    b) gallbladder (stores)
  59. 59What does bile consist of?-H2O
    -bile salts (derived from cholesterol)
    -cholesterol (only excretory route)
    -bile pigments (bilirubin from rbc breakdown)
    -ions (e.g. HCO3-)
    -detoxified/inactivated drugs, toxins, hormones etc.
  60. 60What are the functions of bile salts?a) emulsification: breaks up larger globules of fat into many small droplets
    b) micelle formation - keeps fat digestive products in solution
    -micelle = bile salts + phospholipids
    -interior = hydrophobic
    -exterior = hydrophillic
  61. 61What happens with fat digestion, absorption in the lumen?Lipid globule --emulsification, lipase--> fatty acids + monoglycerides --diffuses into enterocyte--> FA, MG diffuse from micelle into enterocytes
  62. 62What happens with fat digestion, absorption in the enterocyte?[In SER]: MGS + FAs --enzyme--> diglycerides + FA
    --enzyme--> triglycerides --cholesterol, proteins, phospholipids added in golgi--> chylomicron (fat + protein package = water soluble) --exocytosis--> ISF --diffusion--> lymph (lacteal)
  63. 63What are the 3 regulatory phases of gastric motility/secretion?Cephalic phase, gastric phase, and intestinal phase
  64. 64What is the cephalic phase? What are the triggers?Prepares stomach for food
    -Triggers = thought, sight, smell, taste of food
  65. 65What does the NS (PSNS + enteric) affect for the cephalic phase?Ups enzymes (pepsinogen and lipase), ups gastrin secretion (hormone), ups acid and ups smooth muscle motility
  66. 66What happens if no food enters stomach?Low pH inhibits secretion
  67. 67What happens during the gastric phase?Food in stomach - distension
    Activates stretch receptors
  68. 68What happens with the NS (enteric + PSNS) for the gastric phase?Ups enzymes (pepsinogen and lipase), ups gastrin secretion (hormone), ups acid and ups smooth muscle motility
  69. 69What is food and how does it affect pH? What happens when pH < 3?= buffer - pH reduces slowly, reaches 3 when stomach nearly empty
    -shuts down NS (enteric) --> lowers acid, enzymes
    -lowers gastrin so lower acid, enzymes
  70. 70What does the intestinal phase do?Controls rate of chyme (= food + gastric juice) entry into duodenum
  71. 71Why is gastric emptying regulated?So that:
    a) acid can be neutralized in small intestine (or enzymes won't work)
    b) tonicity does not overwhelm small intestine
    c) there is time for digestion/absorption in small intestine
  72. 72What happens during intestinal phase?a) Initially (for a short time) - get higher gastric secretion - duodenal gastrin release (due to duodenal stretch)
    b) Then inhibitory signals cause:
    -i) downs gastric motility (slows emptying) due to:
    -> 1) CCK --> released due to presence of fa, aa
    -> 2) enterogastric reflex (enteric NS) - triggered by aa/peptides, acid, duodenal stretch, hypertonicity - lower motility
    --> i) directly
    --> ii) signals CNS --> SNS
    -ii) downs gastric secretion (acid, enzymes) due to:
    -> 1) secretin --> released due to acid
    -> 2) CCK --> released due to aa, fa
  73. 73What is the hormone from the stomach (and duodenum) and what does it do?Gastrin: ups acid, gastric enzyme secretion (lipase + pepsinogen)
  74. 74What are the hormones from duodenum and what do they do?Secretin
    a) ups alkaline fluid secretion - duct cells of pancreas, gallbladder
    b) lowers gastric secretion
    CCK
    -ups pancreatic enzyme secretion, ups contraction of gallbladder, lowers gastric motility, secretion
  75. 75What is one of the main purposes of the large intestine?Motility
  76. 76What are the two methods of motility?Haustral contractions and mass movements
  77. 77What are Haustral contractions?Slow, weak - allow mixing, absorption of salts, H2O
  78. 78What are the mass movements?Due to food in stomach, via gastrocolic reflex = powerful waves of contractions from transverse colon to rectum
    -move fecal mass into rectum - initiates urge to defecate
  79. 79What is the stimuli for the rectal (defecation) reflex?Feces in rectum (stretch receptors in rectal wall)
  80. 80What is the CNS for the rectal (defecation) reflex?Sacral segment of spinal cord (PSNS)
  81. 81What is the effector for the rectal (defecation) reflex?Smooth muscle of
    -rectum; contract
    -internal anal sphincter; relaxes
  82. 82What part does the external anal sphincter (skeletal muscle)?Under voluntary control i.e. not part of reflex
  83. 83What is the digestion in the large intestine?None, but get bacterial fermentation of undigested nutrients
    -Bacteria synthesize some vitamins (B6, B5, folate, biotin)
  84. 84What is the absorption in the large intestine?-H2O ~ 400 mL/day via osmosis (so ~ 100 mL/day lost in feces)
    -Na+ - active transport
    -some fermentation products - gases, vitamins
    -drugs (rectally) - e.g. anaesthetics
  85. 85What is the secretion from the large intestine?K+, HCO3-
  86. 86What is the fate of glucose being absorbed?-From blood into body cells (facilitated transport) --> insulin ups uptake into skeletal muscle, fat
    -In cell, used for
    a) catabolism by cells --> ATP
    b) anabolism --> glycogen (75% in skeletal muscle, 25% in liver) - 1% of body's stores
  87. 87What is the fate of lipids being absorbed?a) Cholesterol --> used to make steroid hormones, bile salts, cell membranes
    b) Triglyceride in blood
    --lipase on endothelial cells of organs--> 3 fatty acids + glycerol -->
    into tissue cells, then fa
    i) oxidized --> ATP (except neurons)
    ii) stored as TG in adipose tissue (99% of body's energy stores)
    iii) used to synthesize e.g. membranes, myelin
  88. 88What is the fate of amino acids for absorption?-They enter cells by 2^o or facilitated transport
    -GH raises entry into most cells
    -Insulin up entry into skeletal muscle
    -In cells, aa used mainly for protein synthesis
    -Not stored - excess converted to fat
    -Can be used for energy when glucose low e.g. starvation
  89. 89What is the metabolic rate?Body's rate of energy use - sum of all chemical reactions + mechanical work
  90. 90What are the factors affecting MR?1) SNS ups MR
    2) Hormones e.g. epi, TH ups MR
    3) Body temp - 1degree C rise --> 10% rise in MR
    4) Exercise ups MR
    5) Food ingestion - ups MR
    6) Sleep lowers MR
  91. 91What is the basic metabolic rate (BMR)?Energy body needs for essential activities e.g. HR, kidney function, breathing etc

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Physiology Fichas sobre Topic XIV, creado por Emma Granger el 13/04/2017.
Creado por
Emma Granger
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Valoración media 5,0 de 5 (1 valoración)

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