Module 15 - Digestive System Flashcards

1
Q

Mouth Function

A
  • Breakdown of food through chewing (mastication)
  • Chemical breakdown through saliva
  • Forms bolus
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2
Q

Saliva Composition

A
  • Majority water
  • Some ions & protein
  • Under ANS control
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3
Q

Saliva Function

A
  • Lubrication of food bolus
  • Beings digestion carbs via salivary amylase enzyme
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4
Q

Salivary Glands

A
  • Parotid
  • Submandibular
  • Sublingual
  • Produce 2L/day each
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5
Q

Esophagus Function

A
  • Connects mouth & pharynx to stomach
  • Straight muscular tube
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6
Q

Stomach Function

A
  • Stores, mixes & digests some food
  • Delivers food to small intestine
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7
Q

Liver Function

A
  • Produces & secretes bile
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8
Q

Gallbladder Function

A
  • Stores & concentrates bile
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9
Q

Pancreas Function

A
  • Secretes digestive enzymes, hormones, HCO3-
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10
Q

Small Intestine Function

A
  • Digestion & absorption of majority of food particles
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11
Q

Large Intestine Function

A
  • Stores & concentrates undigested material
  • Absorbs salt & water
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12
Q

Rectum Function

A
  • Triggering of defecation reflex
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13
Q

GI System Processes

A
  • Secretion
  • Digestion
  • Absorption
  • Motility
  • Excretion
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14
Q

Secretion

A
  • Release of digestive fluids into lumen of GI tract
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15
Q

Digestion

A
  • Breakdown of food into small molecules
  • By digestive enzymes
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16
Q

Absorption

A
  • Small molecules taken up by circulatory system
  • Distributed throughout body
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17
Q

Motility

A
  • Movement of food through system
  • Contraction of smooth muscle lining
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18
Q

Excretion

A
  • Removal of unwanted waste products
  • After wanted material is reabsorbed
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19
Q

Swallowing Process

A
  • Food bolus pushed to back of tongue
  • Triggers swallow reflex
  • Uvula of soft palate closes over nasopharynx
  • Larynx lifted by neck muscles
  • Epiglottis bends over glottis, covering larynx
  • Bolus moves down esophagus
  • Through cardiac orifice
  • Into stomach by peristalsis
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20
Q

Peristalsis

A
  • Wave of smooth muscle contractions
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21
Q

Stomach Areas

A
  • Fundus, upper
  • Body, middle (largest)
  • Antrum/pylorus, lower
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22
Q

Pyloric Sphincter

A
  • Distal portion
  • Regulates emptying of stomach into small intestine (duodenum)
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23
Q

Empty Stomach

A
  • Folds (rugae)
  • Increase surface area
  • Allow for expansion when food comes
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24
Q

Stomach Digestion

A
  • Proteins begin process by pepsin enzyme
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25
Q

Stomach Absorption

A
  • Alcohol & aspirin
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26
Q

Peristaltic Contraction

A
  • Activates mixing of chyme
  • Move chyme through pyloric sphincter into small intestine
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27
Q

Motility

A
  • Muscle activity moving substances through tract
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28
Q

Mucus

A
  • Secreted by cells in body & antrum of stomach
  • Protects smooth muscle lining from HCl
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29
Q

HCl Function

A
  • Unfolds complex protein & connective tissue
  • Kills bacteria
  • Activates conversion of pepsinogen to pepsin
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30
Q

Pesinogen (Pepsin)

A
  • Secreted by stomach body cells
  • Active enzyme pepsin breaks down large proteins
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31
Q

Intrinsic Factor

A
  • Vitamin B12 absorption
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32
Q

Pancreas Functions

A
  • Exocrine, digestion
  • Endocrine, glucose homeostasis
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33
Q

Excorine Process

A
  • Secreted into pancreatic duct
  • Merges with common bile duct
  • Enters duodenum
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34
Q

Pancreas Products

A
  • Amylase (carbohydrate-digesting enzyme)
  • Trypsin, chymotrypsin, proteases (protein digesting enzymes)
  • Lipase (fat-digesting enzyme)
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35
Q

Pancreas Secretion

A
  • Sodium bicarbonate
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36
Q

Pancreatic Amylase

A
  • Digest starch (polysaccharide) to maltose (disaccharide)
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37
Q

Small Intestine Segments

A
  • Duodenum (1st, shortest)
  • Jejunum (2nd)
  • Ileum (3rd, longest)
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38
Q

Ileocecal Sphincter

A
  • End of small intestine
  • Empty into ascending colon of large intestine
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39
Q

Inner Wall

A
  • Composed of folds
  • Contain villi (projections)
  • Large surface area for food contact
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40
Q

Villi

A
  • Contain capillary network
  • Lymphatic lacteal
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41
Q

Epithelial Cells

A
  • Secrete digestive enzymes
  • Cover villi
  • Microvilli (lumen facing) forming bush border
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42
Q

Small Intestine Function

A
  • Majority of digestion & reabsorption (duodenum & jejunum)
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43
Q

Small Intestine Absorption

A
  • Digestive material to circulatory & lymphatic systems
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44
Q

Enhancement of Absorption

A
  • Large surface area (villi lining)
  • Large blood supply
  • Motility
45
Q

Small Intestine Digestion

A
  • Digestive enzymes, pancreas & epithelial cells
  • Bile
46
Q

Large Intestine Structure

A
  • Begins at ileocecal valve
  • Connects to small intestine via ileum
  • Ascending, longitudinal, descending limb
  • Curved sigmoid section
  • Rectum ending at anus
  • Larger diameter than small intestine
  • Lacks folds
  • Smaller villi
47
Q

Large Intestine Functions

A
  • Water & electrolyte absorption
  • Mucus secretion
  • Digestion (small amount)
  • Store & concentrate feces
48
Q

Water & Electrolyte Absorption

A
  • Na+ active transport
  • Water osmosis
49
Q

Mucus Secretion

A
  • Protects lining from chemical & mechanical damage
  • Lubricates forming feces
  • K+ & HCO3- secreted into colon
50
Q

Digestion (Large Intestine)

A
  • Undigested polysaccharides metabolized into free fatty acids (bacteria)
  • Bacteria produce gas (flatus)
  • Vitamin K for blood coagulation
51
Q

Carbohydrate Types

A
  • Monosaccharides
  • Disaccharides
  • Polysaccharides
52
Q

Monosaccharides

A
  • Single building block
  • Glucose, fructose, galactose
53
Q

Disaccharides

A
  • Two monosaccharides
  • Maltose, lactose, sucrose
54
Q

Polysaccharides

A
  • 3+ building blocks
  • Starch, glycogen
55
Q

Carb Digestion Mouth

A
  • Starting point
  • Salivary amylase
  • Break up large polysaccharides
56
Q

Carb Digestion Stomach

A
  • None
  • Acidic environment
57
Q

Carb Digestion Small Intestine

A
  • Pancreatic amylase into duodenum, digest polysaccharide to disaccharide
  • Pancreas secretes HCO3- to neutralize stomach acid
  • Disaccharides require specific enzymes to break down
58
Q

Small Intestine Enzyme Location

A
  • Bush border of microvilli
  • Intestinal epithelial cells
59
Q

Lactose Intolerance

A
  • Inability to digest lactose
  • No/little lactase enzyme
60
Q

Carb Absorption

A
  • Na+/K+ pump on basal side of intestinal epithelial cells
  • Establish Na+ gradient (high outside)
  • Powering Na+/glucose co-transporter on luminal side
  • Moves glucose into cell
  • Glucose diffuse out basal side via facilitated diffusion
61
Q

Protein Composition

A
  • Long linked amino acid chains
  • Different enzymes required for different amino acid groups
  • Must be broken into building blocks before absorption
62
Q

Protein Digestion Stomach

A
  • Beginning
  • HCl converts pepsinogen to active pepsin
  • HCl aids to uncoil proteins to give pepsin access
  • Pepsin digests protein chains into polypeptides
  • Polypeptides pass through pyloric sphincter
63
Q

Protein Digestion Small Intestine

A
  • HCO3- neutralized acidic stomach chyme
  • Pepsin becomes inactive
  • Trypsin & chymotrypsin (pancreatic enzymes) continue digestion
  • Proteases enzymes continue process
64
Q

Proteases Enzymes

A
  • Produced in pancreas
  • Secreted into small intestine
  • Brush border of intestinal epithelial cells
65
Q

Proteases Enzyme Classes

A
  • Endopeptidases, break bonds between amino acids (inner)
  • Exopeptidases, break bonds at ends of amino acid (outer)
66
Q

Protein Absorption

A
  • After proteins broken into single amino acids
  • Na+/K+ pump on basal side of intestinal epithelial cells
  • Establish Na+ gradient (high outside)
  • Powering Na+/amino acid co-transporter on luminal cell
  • Moving amino acids into cell
  • Remaining small peptides absorbed by endocytosis
67
Q

Fat/Lipids Composition

A
  • Phospholipids, cholesterol
  • Not water soluble, don’t mix with water
68
Q

Emulsification

A
  • Churning action of stomach
  • Breaks down large fat drops to aid enzymes with digestion
69
Q

Bile

A
  • Product of liver
  • Transported to gallbladder (stored & concentrated)
  • Not an enzyme
  • Composed of water, bile salt, ions, fatty acids
70
Q

Bile Function

A
  • Released into duodenum
  • Bile salts keep lipid drops emulsified
  • Preventing formation of large droplets
71
Q

Colipase

A
  • Protein
  • From pancreas
  • Allows lipase to gain access to interior of fat droplet
72
Q

Lipase Enzyme

A
  • Digestion of lipids from interior
73
Q

Fat Digestion

A
  • Pancreatic lipase attacks phospholipids & removes 2 chains
  • Monoglyceride remains
  • Lipase works from interior to shrink droplets
  • Droplets form micelles
74
Q

Micelles

A
  • Single layer of bile salts
  • Surrounding small lipid droplet
  • Ferry droplets to intestinal epithelial cells for absorption
75
Q

Absorption Fatty Acids & Monoglycerides

A
  • Lipid soluble
  • Diffuse through cell membrane
  • Smooth endoplasmic reticulum
  • Combine with cholesterol & proteins to form chylomicrons
76
Q

Chylomicrons

A
  • Packaged into secretory vessels by Golgi apparatus
  • Enter lacteals of lymphatic system
77
Q

Absorption of Cholesterol

A
  • Specific active transport system
78
Q

Absorption of Bile Salts

A
  • Left behind after lipid absorption
  • Reabsorbed by transport system in ileum cells
  • Returned to liver to be reused
79
Q

Lipid Soluble Vitamins

A
  • Diffuse through cell membrane
  • Absorbed like fats
  • Vitamins A, D, E, K
80
Q

Water Soluble Vitamins

A
  • Absorbed by carrier-mediated mechanisms
  • Require Na+ concentration gradient & co-transporter
  • Vitamins B, C, folic acid, niacin
81
Q

Water Production

A
  • 80% water in saliva & digestive enzymes
  • 20% water & food
82
Q

Water Absorption

A
  • Small Intestine, high
  • Large intestine, low
83
Q

Water Absorption Process

A
  • Osmotic gradient forms as other solutes are absorbed
  • Epithelial cells develop higher solute concentration
  • Water flows into cells via osmosis
  • As solutes move out of cell, water follows
84
Q

Absorption of Na+

A
  • Na+/K+ pump on basal lateral surface
  • Establish Na+ gradient (high outside)
  • Na+ move into cell from lumen
  • Na+ absorbed with carbs & amino acids
85
Q

Absorption K+

A
  • Passively absorbed
  • Concentration gradient forms as solutes are absorbed
  • High concentration in lumen
  • Passive diffusion into cells
86
Q

Unregulated Processes

A
  • Digestion
  • Absorption
87
Q

Regulated Processes

A
  • Motility
  • Enzyme secretion
88
Q

Hormonal Regulation

A
  • Release of chemicals from intestinal cells
  • Response mechanical stimulation/neural activation
89
Q

Neural Regulation

A
  • Enteric NS, division of ANS
90
Q

Enteric NS

A
  • Sympathetic & parasympathetic divisions can influence digestive activity
  • Altering activity of enteric nerves
91
Q

ENS Nerve Effects

A
  • Smooth muscle walls
  • Enzyme-secreting cells
  • Endocrine cells
  • Blood vessels
92
Q

PSYN Alteration

A
  • Increase gastric motility & secretions
  • Production of watery saliva
93
Q

SYN Alteration

A
  • Decreases gastric motility
  • Secretes thick saliva (dry mouth)
94
Q

ENS Short Loop

A
  • Begins with mechanical distension/chemical changes
  • Changes detected by sensors of ENS creating reflex
  • Activating effector organs
  • Causing release of enzymes/altering motility
95
Q

ENS Long Loop

A
  • Stimulated by sight/smell of food
  • Detected by sensors (eyes/nose)
  • Send signals through PSYN to ENS
  • Alter enzyme release/motility
96
Q

Interstitial Cells

A
  • Smooth muscle cells
  • Surrounding tract
  • Alter own membrane potentials
  • Producing BERS
97
Q

BER Membrane Potential

A
  • Does not meet threshold
  • Need additional stimulus
98
Q

BER Frequencies

A
  • Stomach 3/min
  • Duodenum 12/min
99
Q

Secretin Hormone

A
  • Presence of acid
  • Inhibits stomach emptying
  • Causes release of HCO3- & bile
  • Neutralizing acid for optimal enzyme function
100
Q

Cholecystokinin (CCK)

A
  • Presence of fats
  • Slows emptying of stomach
  • Releasing enzymes & bile
101
Q

Glucose-Dependent Insulinotropic Peptide

A
  • Response to glucose & amino acids
  • Stimulates insulin release
  • May inhibit stomach emptying
102
Q

Gastrin Hormone

A
  • Secreted by G cells in stomach antrum
  • Response to proteins, mechanical distention & PSYN
  • Secrete HCl to convert pepsinogen to pepsin
103
Q

Gastric Acid Phases

A
  • Cephalic, brain
  • Gastric, stomach
  • Intestinal, intestine
104
Q

Cephalic Phase

A
  • Increase gastric acid secretion
  • Response to sight, smell, taste, chewing
  • Anticipatory response
  • Activating ENS, long loop
105
Q

Cephalic Phase Effects

A
  • Parietal cells release HCl
  • G cells release gastrin
  • Increased stomach motility
106
Q

Gastric Phase

A
  • Presence of food/amino acids in stomach
  • Triggering ENS
  • Short loop
107
Q

Gastric Phase Effects

A
  • Release of HCl
  • Release of gastrin
  • Release of pepsinogen
  • Increased gastric motility
108
Q

Intestinal Phase

A
  • Presence of glucose, fat, acidic chyme
  • Activating ENS
  • CCK, secretin, glucose-dependent insulinotropic peptide
109
Q

Intestinal Phase Effects

A
  • Decreased motility
  • Inhibit secretions in stomach