Unit 6: Digestive System Flashcards

1
Q

2 major divisions

A
  • digestive tract
  • accessory glands and structures
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2
Q

digestie system length

A

15 ft but 30 when dissected

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3
Q

general functions

A
  • motility
  • secretion
  • digestion
  • absorption
  • immunological
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4
Q

the digestive system is ?

A

unidirectional

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5
Q

volume absorbed by the small intestine per day

A

9000 mL

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6
Q

sources of volume absorbed by the small intestine per day

A
  • ingested
  • secreted from plasma
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7
Q

volume of food eaten per day

A

1250 g

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8
Q

volume of fluid drank per day

A

1250 mL

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9
Q

sources secreted from the plasma

A
  • saliva
  • gastric juice
  • pancreatic juice
  • bile
  • intestinal juice
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10
Q

tissue types in the digestive tract wall

A
  • epithelium
  • lymphoid tissue
  • connective tissue
  • nerve plexuses
  • smooth muscle
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11
Q

digestive tract wall

A
  • mesentery
  • serosa
  • submucosa
  • muscularis externa
  • mucosa
  • myenteric plexus
  • submucosal plexus
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12
Q

digestive tract wall nerves

A
  • myenteric plexus
  • submucosal plexus
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13
Q

mesentery

A
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14
Q

serosa

A
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15
Q

submucosa

A
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16
Q

muscularis externa layers

A
  • outer longitudinal muscle
  • inner circular muscle
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17
Q

mucosa

A
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18
Q

myenteric plexus

A
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19
Q

submucosal plexus

A
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20
Q

outer longitudinal muscle

A
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21
Q

inner circular muscle

A
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22
Q

the serosa is continuous with the ?

A

mesentery

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23
Q

outer longitudinal muscle versus inner circular muscle

A
  • outer muscle shortens lengthens
  • inner circular muscle contracts
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24
Q

stomach anatomy

A
  • abdominal esophagus
  • cardia
  • cardial notch
  • fundus
  • lesser curvature
  • pyloric orifice
  • duodenum
  • pyloric constriction
  • pyloric sphincter
  • pyloric canal
  • pyloric antrum
  • body
  • greater curvature
  • fundus
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25
Q

stomach cardia

A
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26
Q

stomach fundus

A
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27
Q

stomach pyloric orifice

A
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28
Q

stomach pyloric constriction

A
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29
Q

stomach pyloric sphincter

A
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30
Q

stomach pyloric canal

A
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31
Q

stomach pyloric antrum

A
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32
Q

stomach body

A
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33
Q

stomach functions

A
  • storage
  • mixing
  • digestion
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34
Q

where are interstitial cells of cajal located

A

fundus

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35
Q

interstitial cells of cajal

A
  • pacemaker cells
  • 3 per minute
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36
Q

in which region does major mixing in the stomach happen

A

pyloric

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37
Q

mucosal linings of the stomach

A
  • oxyntic mucosa
  • pyloric gland area
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38
Q

gastric gland definition

A

cells for gastric secretion

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39
Q

how much gastric juice is produced per day

A

2 liters

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40
Q

oxyntic mucosa

A
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41
Q

pyloric gland area

A
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42
Q

gastric pit

A
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43
Q

gastric glands

A
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44
Q

types of exocrine secretory cells

A
  • exocrine cells
  • mucous cells
  • chief cells
  • parietal cells
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45
Q

types of endocrine/paracrine secretory cells

A
  • enterochromaffin-like (ECL) cells
  • G cells
  • D cells
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46
Q

mucous cell purpose

A
  • produce alkaline mucus
  • protects against enzymes
  • neutralizes acidic content
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47
Q

chief cell purpose

A
  • produce pepsinogen (enzyme precursor)
  • protein digestion
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48
Q

parietal cell purpose

A
  • hydrochloric acid
  • activates pepsinogen for protein digestion
  • produce intrinsic factor
  • absorbs vitamins (mainly B12)
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49
Q

enterochromaffin-like (ECL) cell purpose

A

produce histamines that produce HCl for parietal cells

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50
Q

G cell purpose

A
  • produce gastrin
  • stimulate chief, parietal, and ECL cells
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51
Q

D cell purpose

A
  • produce somatostatin
  • inhibits parietal, ECL, and G cells
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52
Q

G cell location

A

pyloric gland area

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53
Q

D cell location

A

pyloric gland area

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54
Q

parietal cell location

A

oxyntic mucosa

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55
Q

chief cell location

A

oxyntic mucosa

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56
Q

mucous cell location

A

oxyntic mucosa

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57
Q

mucosal barrier function

A

protection of gastric mucosa

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58
Q

mucosal barrier

A

secretion of mucous and HCO3 by epithelial cells to form a barrier that protects stomach from low pH and digestion by pepsin

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59
Q

gastric mucosal barrier lines of defense to protect from self-injury

A
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60
Q

3 parts of the small intestine

A
  • duodenum
  • jejenum
  • ileum
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61
Q

primary site of absorption

A

small intestine

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62
Q

villi definition and function

A
  • tiny hair-like projections that line the inside of the small intestine
  • increase surface area 10x to increase absorption
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63
Q

microvilli increase surface area by __x

A

20

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64
Q

duodenum

A
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65
Q

jejenum

A
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66
Q

ileum

A
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67
Q

types and function of membrane bound enzymes in villi

A

types:
- enteropeptidase
- disaccharidases
- aminopeptidases

function:
- carbohydrate and protein digestion

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68
Q

villi epithelial cell

A
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69
Q

villi central lacteal location and function

A
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70
Q

villi capillaries

A
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71
Q

large intestine parts

A
  • appendix
  • cecum
  • ascending colon
  • transverse colon
  • descending colon
  • sigmoid colon
  • rectum
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72
Q

(large intestine) appendix

A
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73
Q

(large intestine) cecum

A
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74
Q

(large intestine) ascending colon

A
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75
Q

(large intestine) transverse colon

A
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76
Q

(large intestine) descending colon

A
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77
Q

(large intestine) sigmoid colon

A
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78
Q

(large intestine) rectum

A
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79
Q

gastrointestinal accessory glands

A
  • salivary glands
  • submandibular glands
  • sublingual glands
  • pancreatic secretions
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80
Q

salivary glands

A
  • parotid gland
  • parotid duct pierces buccinator and secretes a serous secretion
  • produce amylase
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81
Q

where does the parotid duct drain

A

into cheek opposite maxillary 2nd molar (parotid papilla)

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82
Q

amylase

A

digestive enzyme

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83
Q

submandibular glands

A
  • hook shaped with superficial and deep arms
  • submandibular duct
  • merges from deep part to open on sublingual papilla
  • runs over lingual nerve
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84
Q

lingual frenum

A
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85
Q

sublingual fold

A
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86
Q

sublingual papilla

A
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87
Q

submandibular duct

A
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88
Q

submandibular gland

A
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89
Q

sublingual glands

A
  • almond-shaped glands lateral to the submandibular duct
  • sublingual duct drains into oral cavity via several minor ducts
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90
Q

sublingual gland

A
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91
Q

small ducts of sublingual gland

A
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92
Q

type of secretion produced by submandibular glands

A

mixed mucous and serous secretion

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93
Q

type of secretion produced by sublingual glands

A

mixed mucous and serous secretion (predominantly mucous)

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94
Q

pancreatic gland types

A
  • exocrine
  • endocrine
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95
Q

exocrine pancreatic secretions

A
  • enzymes (proteolytic enzymes, pancreatic amylase, pancreatic lipase)
  • bicarbonate
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96
Q

endocrine pancreatic secretions

A
  • insulin
  • glucagon
  • hormones
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97
Q

exocrine pancreatic cells

A
  • duct cells
  • acinar cells
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98
Q

pancreas duct cell purpose

A

neutralize acid

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99
Q

pancreas acinar cell purpose

A

enzymes assist in digestion

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100
Q

liver is the …

A

destination of absorbed materials

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101
Q

absorbed nutrient path

A

nutrients absorbed into blood –> hepatic portal vein –> liver

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102
Q

peristalsis definition

A

wave of contraction

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103
Q

basic electrical rhythm (peristalsis) definition

A

sets up a wave of contraction in the muscularis externa

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104
Q

segmentation

A

muscular activity that divides and mixes the chyme by alternating between backward and forward movement of the gastrointestinal tract (GI) contents

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105
Q

pacemaker cells of the stomach

A

interstitial cells of cajal

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106
Q

teniae coli

A
  • 3 longitudinal bands of muscle
  • scrunch to form haustra
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107
Q

haustra

A

pouches or sacs

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108
Q

what is mainly responsible for colonic motility

A

haustral contractions

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109
Q

haustral contraction characteristics

A
  • slow
  • nonpropulsive
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110
Q

what initiates haustral contractions

A

basic electrical rhythym

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111
Q

defecation reflex

A
  1. feces move into and distend rectum, stimulating stretch receptors. receptors transmit signals along afferent fibers to spinal cord neurons
  2. spinal reflex initiated (parasympathetic motor fibers stimulate contraction of the rectum and sigmoid colon and relaxation of the internal anal sphincter)
  3. voluntary motor neurons inhibited when it is convenient to defecate allowing external anal sphincter to relax for feces to pass

*voluntary raising intra-abdominal pressure and relaxing external sphincter permits defecation

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112
Q

continence

A

defecation delayed by contraction of external sphincter

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113
Q

water movement across intestinal epithelium is ? to ions and solutes

A

secondary

114
Q

transcellular

A

transportation of solutes by a cell through a cell

115
Q

paracellular

A

transport of solutes that occurs in an intercellular pathway

116
Q

transcellular and paracellular pathway function

A

transport mechanism for carbohydrates and protein across luminal and basolateral membranes

117
Q

basolateral membrane

A
  • the cell membrane at the basolateral (cell base) side of the cell
  • faces adjacent cells and the underlying connective tissue
118
Q

luminal membrane

A

the cell membrane which is oriented towards the lumen

119
Q

apical membrane

A

the plasma membrane located at the apex of the epithelial cell

120
Q

epithelial tight junctions

A

intercellular space that forms the continuous intercellular barrier between epithelial cells (separates tissue spaces and regulates selective movement of solutes across the epithelium)

121
Q

where does the most absorption occur

A

duodenum and jejunum

122
Q

for what material is absorption adjusted and why

A
  • iron and calcium
  • body only takes in what it needs
123
Q

carbohydrate digestion goal

A

break down all disaccharides and complex carbohydrates into monosaccharides for absorption

124
Q

carbohydrate polysaccharide composition

A
125
Q

how are carbohydrate polysaccharides digested

A
  • initially digested by amylase
  • secondary digested at the brush border/microvilli on intestinal epithelial cells
126
Q

amylase function

A

break carbohydrate polysaccharides into disaccharides

127
Q

polysaccharide examples

A
  • starch
  • glycogen
128
Q

disaccharide examples

A
  • lactose
  • maltose
  • sucrose
129
Q

monosaccharides examples

A
  • galactose
  • glucose
  • fructose
130
Q

from where is amylase secreted

A
  • salivary glands
  • pancreas
131
Q

dietary carbohydrate examples

A
  • lactose
  • starch
  • glycogen
  • sucrose
132
Q

how is lactose digested

A
  • lactose is a disaccharide
  • no amylase used, only brush border
  • not digested in mouth or digestive tract lumen, only small intestine
133
Q

how is sucrose digested

A
  • sucrose is a disaccharide
  • no amylase used, only brush border
  • not digested in mouth or digestive tract lumen, only small intestine
134
Q

how is starch digested

A
  • starch is a polysaccharide
  • with amylase and brush border
  • digested in mouth, digestive tract lumen, and small intestine
135
Q

how is glycogen digested

A
  • glycogen is a polysaccharide
  • with amylase and brush border
  • digested in mouth, digestive tract lumen, and small intestine
136
Q

SGLT1

A
  • sodium-glucose cotransporter (SGLT)
  • secondary active transport (against the concentration gradient but no ATP used since glucose/galactose cotransports with Na+)
  • apical sodium and glucose/galactose move across cell membranes
137
Q

how does glucose enter the luminal membrane

A

secondary active transport via SGLT1

138
Q

how does galactose enter the luminal membrane

A

secondary active transport via SGLT1

139
Q

how does fructose enter the luminal membrane

A

simple diffusion via GLUT-5

140
Q

how does Na+ enter the luminal membrane

A

simple diffusion via SGLT1

141
Q

GLUT-2

A
  • facilitative diffusion
  • transports dietary sugars, glucose, fructose and galactose across the basolateral membrane
142
Q

how does glucose exit the basolateral membrane

A

facilitative diffusion via GLUT-2

143
Q

how does galactose exit the basolateral membrane

A

facilitative diffusion via GLUT-2

144
Q

how does fructose exit the basolateral membrane

A

facilitative diffusion via GLUT-2

145
Q

diarrhea definition

A

passage of a highly fluid fecal matter

146
Q

what does diarrhea cause

A
  • dehydration
  • loss of nutrient material (small intestine unable to absorb fluid extensively)
  • metabolic acidosis
147
Q

metabolic acidosis

A

buildup of acid in the body due to kidney disease or kidney failure

148
Q

causes of diarrhea

A
  • excessive small-intestinal mobility
  • toxins of the bacterium vibrio cholera
  • excess osmotically active particles
    (eg lactase deficiency)
  • anxiety
  • illness
149
Q

where does protein digestion begin

A

pyloric antrum

150
Q

in which environment does pepsin work most effectively

A

an acidic one

151
Q

HCl importance

A

converts pepsinogen into pepsin

152
Q

what secretes pepsinogen

A

chief cells

153
Q

what secretes HCl

A

parietal cells

154
Q

pepsin function

A

breaks down dietary protein into large peptides and free amino acids

155
Q

types of protein

A
  • exogenous
  • endogenous
156
Q

exogenous protein

A

dietary protein

157
Q

endogenous protein

A
  • digestive enzymes
  • sloughed epithelial cells
  • leaked plasma proteins
158
Q

how/where is protein digested

A
  • digestive tract lumen (exogenous and endogenous proteins broken into small peptides and amino acids by pepsin and pancreatic proteolytic enzymes)
  • brush border of small intestine epithelial cells and cytosol of epithelial cells (small peptides broken into amino acids by aminopeptidases and intracellular peptidases)
159
Q

how do amino acids enter the luminal membrane

A

secondary active transport with Na+

160
Q

how does Na+ enter the luminal membrane

A

facilitative diffusion

161
Q

how does H+ exit the luminal membrane

A

secondary active transport with Na+ (H+ exits cell white Na+ enters cell)

162
Q

how does H+ enter the luminal membrane

A

facilitated diffusion

163
Q

how do small peptides enter the luminal membrane

A

tertiary active transport with H+

164
Q

how do small peptides leave the basolateral membrane

A
  • they don’t
  • small peptides are broken down into amino acids via intracellular peptidases
165
Q

how do amino acids exit the basolateral membrane

A

facilitated diffusion

166
Q

3 inactive proteolytic enzymes in the duodenum for protein digestion

A
  • trypsinogen
  • chymotrypsinogen
  • procarboxypeptidase
167
Q

how do inactive proteolytic enzymes for protein digestion enter the small intestine lumen

A

via the pancreatic duct

168
Q

what does trypsinogen convert to

A

trypsin

169
Q

what does chymptrypsinogen convert to

A

chymotrypsin

170
Q

what does preocarboxypeptidase convert to

A

carboxypeptidase

171
Q

what converts trypsinogen into trypsin

A

enterokinase

172
Q

what secretes inactive proteolytic enzymes for protein digestion

A

acinar cells

173
Q

what converts chymotrypsinogen into chymotrypsin

A

trypsin

174
Q

what converts procarboxypeptidase into carboxypeptidase

A

chymotrypsin

175
Q

trypsinogen must remain inactive within the ?

A

pancreas

176
Q

mucus secretion function

A

protection

177
Q

trypsin, chymotrypsin, carbozypeptidase function

A

attack active peptide and break them down into amino acids

178
Q

what are triglycerides broken down into

A
  • monoglyceride
  • free fatty acids
179
Q

what is a triglyceride

A

a type of fat

180
Q

what breaks triglycerides down

A

lingual, gastric, and pancreatic lipases

181
Q

lipase definition

A

a type of digestive enzyme that helps your body digest fats

182
Q

how is fat absorption different from carbohydrate and protein absorption

A

fat is insoluble in water

183
Q

micelle definition

A
  • water-soluble particles
    that can carry the end products of fat digestion within their lipid-soluble
    interiors
  • vehicle for carrying water-insoluble stances through watery luminal contents
184
Q

fat digestion process (triglyceride droplet to central lacteal)

A
  1. triglyceride droplet emulsified by bile salts
  2. pancreatic lipase breaks droplet into monoglyceride and free fatty acids (insoluble in water)
  3. bile salts envelop the fatty acids and monoglycerides to form micelles
  4. micelles enter the luminal membrane
  5. monoglycerides and fatty acids resynthesize in the cell to form triglycerides
  6. triglycerides aggregate and are coated with lipoprotein to form chylomicrons (water soluble)
  7. chylomicrons exit the basolateral membrane and enter the central lacteal via exocytosis
185
Q

exocytosis

A

-the fusion of secretory vesicles with the plasma membrane
- results in the discharge of vesicle content into the extracellular space and the incorporation of new proteins and lipids into the plasma membrane

186
Q

why do chylomicrons enter the central lacteal instead of capillaries

A

chylomicrons too big

187
Q

central lacteal

A
  • blood capillaries and special lymph capillaries, called lacteals, in the center of each villus
  • fats and fat-soluble vitamins are absorbed by the lacteals
  • filled with chyle
188
Q

chyle

A
  • a milky fluid consisting of fat droplets and lymph
  • drains from the lacteals of the small intestine into the lymphatic system during digestion
189
Q

how does the fat go from the central lacteal into the bloodstream

A

lacteal –> lymph vessel –> duct –> subclavian veins

190
Q

how do micelles enter the luminal membrane

A

passive absorption

191
Q

how are micelles water soluble

A
  • have hydrophilic shells
  • can dissolve water-insoluble (lipid-soluble) substances in their lipid-soluble cores
192
Q

do micelles have a hydrophillic/phoblic core and shell?

A
193
Q

cholecystokinin (CCK) function

A

stimulates contraction of gallbladder and relaxation of the sphincter of oddi

194
Q

feedback loop of cholecystokinin (CCK) in digestion

A
195
Q

?% of bile salts are reabsorbed by the terminal ileum

A

95

196
Q

?% of bile salts are lost in feces

A

5

197
Q

how are reabsorbed bile salts recycled

A

via enterohepatic circulation

198
Q

enterohepatic circulation

A

movement of bile acid molecules from the liver to the small intestine and back to the liver

199
Q

sphincter of oddi

A
  • the muscular valve surrounding the exit of the bile duct and pancreatic duct into the duodenum
  • sphincter is normally closed, opening only in response to a meal so that digestive juices can enter the duodenum and mix with food for digestion
200
Q

gallbladder

A

stores and concentrates bile from the liver

201
Q

where does bile go if the gallbladder is removed

A

common bile duct stores and expands to compensate

202
Q

digestive system malabsorption and deficiencies

A
  • gallstones
  • IBD (UC and Crohns)
203
Q

gallstones

A
  • hard, pebble-like pieces of material, usually made of cholesterol or bilirubin, that develop in the gallbladder
  • bile in gallbladder can precipitate out to form gallstones
  • when gallstones block bile ducts, they can cause sudden pain
204
Q

ulcerative collitis (UC)

A
  • a chronic inflammatory bowel disease (IBD)
  • abnormal reactions of the immune system cause inflammation and ulcers on the inner lining of your large intestine
205
Q

inflammatory bowel disease (IBD)

A
  • chronic digestive system inflammation
  • ideopathic but suspected that immune system dysfunction is the cause
206
Q

crohns

A
  • a chronic disease that causes inflammation in your digestive tract
  • usually affects your small intestine and the beginning of your large intestine
  • an inflammatory bowel disease (IBD)
207
Q

IBD treatment

A
  • anti-inflammatories
  • suppress abnormal immune system function
208
Q

ileus definition

A
  • a temporary lack of the normal muscle contractions of the intestines
  • lack of peristalsis, not caused by a physical block
209
Q

ileus causes

A
  • injury
  • inactivity
  • infection
  • cancer
  • medication (morphine)
  • volvulus
  • surgery
210
Q

volvulus definition

A

when a loop of intestine twists around itself and the mesentery that supports it, causing bowel obstruction

211
Q

ileus symptoms

A
  • abdominal discomfort
  • bloating
  • diarrhea
  • nausea
  • vomiting
  • constipation
212
Q

ileus treatment

A
  • electrolytes
  • laxatives
  • physical activity
213
Q

4 important factors of motility and secretion control

A
  • autonomous smooth muscle function
  • intrinsic nerves
  • extrinsic nerves
  • gastrointestinal hormones
214
Q

how is autonomous smooth muscle function important in motility and secretion

A

responsible for basic electrical rhythm (BER) that creates peristalsis

215
Q

how are intrinsic nerves important in motility and secretion

A
  • controls local (intrinsic) submucosal and myenteric nerve plexuses
  • respond locally to chemical gut changes, mechanical distention
  • regulate secretory elements and contractility
216
Q

how are extrinsic nerves important in motility and secretion

A

control glandular secretion via extrinsic visceral (autonomic) efferents (sight, smell, hearing input) via CNX or vagus

217
Q

how are gastrointestinal hormones important in motility and secretion

A

controls GI hormones like CCK

218
Q

types of reflexes

A
  • short
  • long
219
Q

short reflex triggers

A

local chemical or mechanical changes

220
Q

long reflex triggers

A
  • external input (5 special senses)
  • nerve impulse to digest
221
Q

which pathway does intrinsic nerve plexus use

A

short reflex

222
Q

which pathway does extrinsic autonomic nerve use

A

long reflex

223
Q

which pathway do gastrointestinal hormones use

A

hormonal pathway

224
Q

what kind of pathways are triggered by external influences

A

long reflex

225
Q

what kind of pathways are triggered by local changes in digestive tract

A

short reflex, long reflex, hormonal pathway

226
Q

what detects local changes in digestive tract

A

receptors in digestive tract

227
Q

smooth muscle function

A
  • contraction for motility
  • self-excitable
228
Q

exocrine gland function

A

secrete digestive juices

229
Q

endocrine gland function

A

secrete gastrointestinal and pancreatic hormones

230
Q

CNS

A
  • brain
  • spinal cord
231
Q

PNS

A

nerve fibers carry info between CNS and body

232
Q

PNS divisions

A
  • afferent
  • efferent
233
Q

afferent PNS division

A

sensory and visceral stimuli input

234
Q

efferent PNS division

A
  • voluntary somatic nervous system (motor neurons and skeletal muscle)
  • involuntary autonomic nervous system
235
Q

autonomic nervous system (PNS)

A
  • sympathetic and parasympathetic nervous system trigger smooth/cardiac muscle, exocrine/endocrine glands
  • enteric submucosal and myenteric plexus nervous system trigger digestive organs
236
Q

stimuli in digestive tract triggers ?

A

enteric nervous system (digestive organs)

237
Q

sympathetic nervous system

A
  • inhibit GI tract contraction and secretion
  • main function: inhibitory
238
Q

parasympathetic nervous system

A
  • increase GI motility and secretion of digestive enzymes and hormones via vagus nerve
  • main function: stimulatory
239
Q

salivary secretion process

A
  • inputs stimulate cerebral cortex
  • cerebral cortex and pressure/chemoreceptors stimulate salivary center in medulla
  • medulla stimulates autonomic nerves
  • nerves stimulate salivary glands which increase secretion
240
Q

types of salivary secretion reflexes

A
  • conditioned
  • simple
241
Q

salivary reflexes function

A

increase salivary secretion

242
Q

oral chemoreceptors

A

taste buds

243
Q

normal amount of saliva produced per day

A

1-2 liters

244
Q

simple salivary reflex triggers

A
  • pressure receptors
  • chemoreceptors
245
Q

conditioned salivary reflex triggers

A
  • cerebral cortex
  • sight, smell, etc.
246
Q

gastric secretion phases

A
  1. cephalic phase
  2. gastric phase
  3. intestinal phase
247
Q

gastric secretion - cephalic phase (when, why, how it is intensified)

A
  • occurs before food enters the stomach, especially while it is being eaten
  • results from sight, smell, thought, or taste of food
  • greater the appetite, the more intense is the stimulation
248
Q

end goal of cephalic phase

A

parietal and chief cells secrete pepsinogen and increase acid

249
Q

excitatory mechanism of cephalic phase

A
  • stimuli: sight, smell, taste, chewing, swallowing
  • stimuli excites vagus nerve which stimulates intrinsic nerves and G cells
  • intrinsic nerves increase Ach which stimulates chief and parietal cells that secrete gastric secretions
  • G cells secrete gastrin which stimulate chief, parietal, and ECL cells which secrete histamine (and further stimulate chief and parietal cells)
250
Q

where does vagus nerve arise

A

medulla

251
Q

from where does the vagus nerve exit

A

jugular foramen

252
Q

grp function

A

release of gastrointestinal hormones to trigger G-cells

253
Q

what is gastrin released into

A

blood

254
Q

what is histamine released into

A

lamina propia

255
Q

what is pepsinogen released into

A

lumen

256
Q

what is Hcl released into

A

lumen

257
Q

gastric secretion - gastric phase (when, how much of gastric secretion occurs here, and what does it stimulate)

A
  • swallowed food and semi-digested protein (peptides and amino acids) activate gastric activity
  • two-thirds of gastric secretion occurs during this phase
  • stimulates gastric activity in two ways: by stretching the stomach and by raising the pH of its contents
258
Q

end goal of gastric phase

A

parietal and chief cells stimulate pepsinogen secretion and increase acid

259
Q

excitatory mechanism of gastric phase

A
  • stimuli: protein (peptide fragments), distension, caffeine, alcohol
  • stimuli excites vagus nerve, intrinsic nerves, and G cells
  • vagus nerve stimulates intrinsic nerves and G cells
  • intrinsic nerves stimulate Ach and G cells increase gastrin secretion
  • Ach stimulates chief and parietal cells
  • gastrin stimulates chief, parietal, and ECL cells
  • chief and parietal cells increase gastric secretion
  • ECL cells secrete histamine which stimulates chief and parietal cells
260
Q

gastric secretion - intestinal phase regions

A
  • body and atrum
  • antrum and duodenum
  • duodenum
261
Q

intestinal phase body and antrum stimuli

A

removal of protein and distension as the stomach empties

262
Q

intestinal phase antrum and duodenum stimuli

A
  • triggered by an accumulation of acid
  • acid secretions mopped up by food and fluid
  • when food is gone, acid builds up
263
Q

intestinal phase duodenum stimuli

A
  • fat
  • acid
  • hypertonicity
  • distension
264
Q

inhibitory mechanism of intestinal phase body and antrum

A
  • stimuli: removal of protein and distension as the stomach empties
  • stimuli inhibits intrinsic nerves, vagus nerve, and G cells
  • G cells decrease gastrin which decreases histamine
  • intrinsic nerves, vagus nerve, and decreased histamine inhibit gastric secretion
265
Q

inhibitory mechanism of intestinal phase antrum and duodenum

A
  • stimuli: accumulation of acid
  • stimuli excites D cells
  • D cells increase somatostatin secretion
  • somatostatin inhibits parietal, G, and ECL cells
  • these cells being inhibited decreases gastric secretion
266
Q

in gastric secretion, in which phase are the D cells used

A

intestinal phase

267
Q

inhibitory mechanism of intestinal phase duodenum

A
  • stimuli: fat, acid, hypertonicity, and distension
  • stimuli exhibits enterogastric reflex and increases enterogastrones (cholecystokinin and secretin)
  • these inhibit parietal, chief, and smooth muscle cells
  • these cells inhibit gastric secretion and motility
268
Q

intestinal phase goal

A

reduce the strength of antral peristalsis

269
Q

enterogastric reflex

A
  • nervous reflex
  • duodenum wall stretching decreases gastric motility
  • feedback mechanism that regulates how fast we digest food into the small intestine
  • enterogastrones hormones released on mucosa
270
Q

stimulation of HCl secretion

A
  • acetylcholine, gastrin, and histamine stimulate HCl secretion by parietal cells
  • gastrin-releasing peptide (GRP) increases gastrin release
  • gastrin released from G cells increases histamine release from ECL cells
  • Ach released by neurons increase histamine release
271
Q

negative feedback control of gastric secretion

A
  • decrease in pH stimulates somatostating secretion by D cells
  • somatostatin inhibits secretion by G, ECL, parietal, and chief cells
272
Q

pancreas location

A

under stomach

273
Q

acinar cells

A

secretory vesicles released by exocytosis

274
Q

pancreatic secretion occurs ?

A

at intestinal phase when chyme is in the small intestine

275
Q

control of pancreatic aqueous NaHCO3 secretion

A
  • acid duodenal lumen
  • acid stimulates an increase in secretin release from duodenal mucosa
  • secretin carried via blood and excites pancreatic duct cells
  • increases secretion of aqueous NaHCO3 solution into duodenal lumen
  • solution neutralizes acid in duodenal lumen
276
Q

control of pancreatic digestive enzyme secretion

A
  • fat and protein products in duodenal lumen
  • increase cholecystokinin (CCK) release from duodenal mucosa
  • CCK carried via blood and excites pancreatic acinar cells
  • increases secretion of pancreatic digestive enzymes (proteolytic enzymes, pancreatic amylase, pancreatic lipase) from duodenal lumen
  • enzymes digest fat and protein products in duodenal lumen
277
Q

secretin purpose

A

neutralize acid

278
Q

cholecystokinin purpose

A

digests acid

279
Q

bile salts purpose

A
  • absorb fat produced in liver
  • pancreatic duct into duodenum
280
Q

gallbladder fundus

A
281
Q

gallbladder body

A
282
Q

gallbladder neck

A