Chapter 26: Digestive System Flashcards

1
Q

six main functions of the digestive system

A

1- ingestion
2- motility
3- secretion
4- digestion
5- absorption
6- elimination

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2
Q

ingestion

A

solid and liquid nutrients into oral cavity

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3
Q

motility

A
  • voluntary and involuntary muscular contractions
  • mixing and moving materials through the GI tract
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4
Q

secretion

A

producing and releasing fluid products to aid in digestion

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5
Q

digestion

A

breakdown of ingested food into smaller structures

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6
Q

2 kinds of digestion

A

1- mechanical digestion
2- chemical digestion

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7
Q

mechanical digestion

A

material physically broken down by chewing and mixing

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8
Q

chemical digestion

A

large complex molecules to smaller molecules - enzymes break chemical bonds

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9
Q

absorption

A

digested molecules, electrolytes, vitamins, water from GI tract INTO BLOOD AND LYMPH

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10
Q

elimination

A

expulsion of indigestible components that are not absorbed

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11
Q

enzymes are

A

catalysts

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12
Q

catalysts are

A
  • proteins that speed up a chemical reaction
  • not changed or used up in the reaction
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13
Q

4 layers/tunics of the GI tract

A

1- mucosa
2- submucosa
3- muscularis
4- serosa

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14
Q

serosa

A

is the outermost layer of the GI tract; superficial serous membrane

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15
Q

mucosa

A

the innermost layer; deep mucous membrane

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16
Q

muscularis

A

consists of smooth muscle

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17
Q

submucosa

A

consists of blood vessels, lymph, and nerves

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18
Q

functions of the muscularis to mix and propel contents within GI tract

A
  • peristalsis
  • mixing
  • mass movements
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19
Q

peristalsis

A

propels ingested materials through tract

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20
Q

mixing

A

blends ingested materials with secretions

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21
Q

mass movements

A

forces fecal matter from the transverse colon through the rest of the large intestine

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22
Q

submucosal nerve plexus

A

innervates smooth muscle and glands

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23
Q

MALT

A

mucosa-associated lymphatic tissue

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24
Q

Peyer patches

A

larger aggregates of lymphatic nodules in distal small intestine

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25
Q

muscularis (externa) inner circular layer

A

smooth muscle; contraction constricts tube lumen

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26
Q

muscularis outer longitudinal layer

A

contraction shortens tube

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27
Q

muscularis myenteric nerve plexus

A

between layers, control contractions

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28
Q

sphincter

A

closes off the lumen, controls movements

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29
Q

propulsion

A

forward movement down the tract

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30
Q

2 nervous systems that communicate with the digestion system

A

1- enteric nervous system (ENS)
2- autonomic nervous system (ANS)

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31
Q

enteric nervous system (ENS)

A
  • includes submucosal plexus and myenteric plexus
  • innervates smooth muscle and glands of GI tract
  • coordinates mixing and propulsion reflexes
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32
Q

autonomic nervous system (ANS)

A
  • parasympathetic innervation promotes GI tract activity
  • sympathetic innervation opposes GI tract activity
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33
Q

nerve receptors in the digestive system

A
  • baroreceptors
  • chemoreceptors
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33
Q

short reflex

A

LOCAL reflex only involves ENS; coordinates small segments of the GI tract

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34
Q

long reflex

A

involves sensory input to CNS and ANS motor output; coordinate GI tract motility, secretions, and accessory digestive organs

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35
Q

hormonal control

A

three primary hormones in the regulation of digestion:
1- gastrin, from stomach
2- secretin, from SI
3- cholecystokinin (CCK), from SI

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36
Q

upper GI tract organs and accessory structues

A
  • oral cavity and salivary glands
  • pharynx
  • esophagus
  • stomach
  • duodenum
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37
Q

oral cavity and salivary glands

A
  • mechanical digestion
  • saliva secreted in response to food
  • mixed with ingested materials form bolus
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38
Q

saliva enzymes secreted in response to food

A
  • salivary amylase
  • lingual lipase
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39
Q

pharynx

A

bolus moved to the pharynx during swallowing

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40
Q

bolus

A

a ball of food that you are ready to swallow

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41
Q

esophagus

A
  • bolus transported from pharynx into stomach
  • lubricated by mucus secretions
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42
Q

stomach

A
  • bolus mixed with gastric secretions by smooth muscle contractions
  • secretions produced by epithelial cells of stomach
  • chyme formed from mixing
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43
Q

chyme

A

the contents in the stomach;
food and stomach secretions

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44
Q

tongue within the oral cavity

A

on interior surface of cavity
- manipulates and mixes materials during chewing
- important functions in swallowing and speech

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45
Q

2 kinds of salivary glands

A
  • intrinsic
  • extrinsic
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46
Q

intrinsic salivary glands

A
  • located within the oral cavity
  • unicellular
  • continuously release secretions independent of food
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47
Q

extrinsic salivary glands

A
  • located outside the oral cavity
  • larger
  • stimulated to release by food
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48
Q

3 pairs of salivary glands

A

1- parotid salivary glands
2- submandibular salivary glands
3- sublingual salivary gland

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49
Q

parotid salivary glands

A
  • largest salivary glands
  • 25-30% of saliva
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50
Q

submandibular salivary glands

A

60-70% of saliva

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51
Q

sublingual salivary gland

A

3-5% of saliva

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52
Q

saliva

A

1.0 - 1.5 L secreted daily, most produced during mealtime

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53
Q

functions of saliva

A
  • moistens ingested food to help become bolus
  • dissolves chemicals that stimulate taste buds
  • cleanses oral cavity
  • antibacterial substances inhibit bacterial growth
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54
Q

antibacterial substances that inhibit bacterial growth

A
  • lysozyme
  • IgA antibodies
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55
Q

regulation of salivary secretions are regulated by

A

salivary nuclei within brainstem

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56
Q

another name for swallowing

A

deglutition

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57
Q

3 phases of swallowing

A

1- voluntary phase
2- pharyngeal phase
3- esophageal phase

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58
Q

voluntary phase

A

bolus of food is pushed by tongue against hard palate and then moves toward oropharynx

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59
Q

pharyngeal phase

A
  • soft palate and uvula close off the nasopharynx
  • larynx elevates so the epiglottis closes over laryngeal opening
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60
Q

esophageal phase

A
  • bolus passes through esophagus
  • propels bolus toward stomach
  • esophageal sphincters closed at rest
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61
Q

salivary amylase

A

enzyme for carbohydrate digestion

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62
Q

mucin

A

mucus

63
Q

lysozyme

A

antibacterial enzyme

64
Q

gastric glands extend

A

deep into mucosa from base of each gastric pit

65
Q

gastric secretions produced by 5 types of secretory cells

A

1- surface mucous cells
2- mucous neck cells
3- parietal cells
4- chief cells
5- G-cells

66
Q

parietal cells

A

produce intrinsic factors and hydrochloric acid

67
Q

chief cells

A
  • most numerous secretory cells within gastric glands
  • secretes pepsinogen and gastric lipase
68
Q

hydrochloric acid activates

A

pepsinogen to transform into pepsin

69
Q

pepsinogen is a

A

proteolytic enzyme

70
Q

intrinsic factor

A
  • required for the absorption of vitamin B12 in the ileum
  • B12 is necessary for the production of normal erythrocytes
71
Q

hydrochloric acid functions

A
  • helps break down plant cell walls and animal CT
  • denatures proteins, facilitating chemical digestion
  • converts inactive enzyme pepsinogen into active pepsin
  • kills most microorganisms entering stomach
72
Q

lipase

A

cutting fats

73
Q

G-cell

A
  • enteroendocrine cells that are widely distributed in gastric glands
  • secrete gastrin hormone
74
Q

gastrin

A

stimulates stomach secretions and motility

75
Q

stomach

A

holding bag for partially digested food until the food is moved into the small intestine where digestion is completed

76
Q

pacemaker cells in stomach

A
  • spontaneously depolarize
  • establish a basic rhythm of muscular contraction
  • signals spreading through smooth muscle cells in the muscular layer
77
Q

force of contraction and gastric gland secretion are regulated by what and what are the three phases it’s organized into?

A

nervous reflexes and hormones
- organized in three phases;
1- cephalic
2- gastric
3- intestinal

78
Q

vagus nerve=

A

“rest and digest”; PNS

79
Q

cephalic phase

A
  • initiated by thought, smell, sight, or taste of food (or even sounds of food preparation)
80
Q

gastric phase

A

initiated by presence of food in stomach

81
Q

intestinal phase

A

initiated by presence of acidic chyme in duodenum

82
Q

the small intestine is how long

A

20 ft

83
Q

accessory digestive organs

A
  • liver
  • gallbladder
  • pancreas
84
Q

the large intestine is how long

A

5 ft

85
Q

small intestine

A
  • small bowel, long tube inferior to stomach
  • ingested nutrients reside in small intestine at least 12 hours
  • absorbs most nutrients and large percentage of water, electrolytes, and vitamins
86
Q

organic compounds/nutrients

A
  • carbs
  • lipids
  • proteins
  • nucleic acids
87
Q

carbs break down into

A

simple sugars

88
Q

duodenum

A

receives accessory gland secretions from the liver, gallbladder, and pancreas

89
Q

intestinal glands

A
  • invaginations of mucosa between intestinal villi
  • secrete intestinal juice
90
Q

SI surface area from largest to smallest

A
  • 20 ft long
  • circ. folds
  • villi
  • microvilli
91
Q

simple columnar epithelial cells with microvilli in intestinal villi

A

absorbs nutrients

92
Q

lacteals

A

fats (large)

93
Q

intestinal capillaries

A

mainly absorb amino acids + carbs

94
Q

goblet cells

A

produces mucin

95
Q

3 secretions made by the intestinal glands

A

1- enteropeptidase
2- CCK
3- secretin

96
Q

brush border enzyme

A

enteropeptidase

97
Q

brush border

A

referring to the villi

98
Q

gastroileal reflex

A

moves contents from ileum to cecum in response to food arrival in stomach
- ileocecal sphincter and cecum reflexes

99
Q

liver

A

accessory digestive organ and the largest internal organ
- production of bile

100
Q

bile is secreted by

A

liver

101
Q

gallbladder _________ and _____________ bile

A

stores and concentrates

102
Q

bile contains

A
  • water
  • bicarbonate ions
  • bile salts and pigments
  • cholesterol, lecithin, and mucin
103
Q

main pancreatic duct carries

A

pancreatic secretions

104
Q

bile salts and lecithin help

A

mechanically digest lipids

105
Q

RBC recycling of “Heme” turns into

A

bile

106
Q

pancreas endocrine function

A

produces and secretes insulin and glucagon

107
Q

pancreas exocrine function

A

produces pancreatic juice to assist with digestive activities

108
Q

pancreatic juice

A

formed by acinar cells
- composed of alkaline fluid and digestive enzymes

109
Q

pancreatic juice contains

A
  • pancreatic amylase
  • pancreatic lipase
  • inactive proteases
  • nucleases
110
Q

pancreatic amylase

A

to digest starch (amylose- carbohydrate)

111
Q

pancreatic lipase

A

digest triglycerides (lipids)

112
Q

inactive proteases

A

digest proteins when activated (ex: trypsinogen- proteins)

113
Q

nucleases

A

digestion of nucleic acids

114
Q

trypsinogen is activated by

A

enteropeptidase

115
Q

cholecystokinin (CCK)

A

hormone released from enteroendocrine cells of SI in response to fatty chyme

116
Q

secretin

A

released from SI in response to increased chyme acidity

117
Q

large intestine functions

A
  • absorbs water, electrolytes and vitamins from remaining digested material
  • stores feces until eliminated through defecation
118
Q

4 big nutrient groups

A

1- carbs -> sugars and starches
2- lipid -> oils, butter, nuts, dairy, and animal fat
3- proteins -> meat, nuts, veggies, and dairy
4- nucleic acids

119
Q

normal bacteria flora in large intestine

A

indigenous microbiota

120
Q

haustral churning in the colon

A

mixing; increases churning and moves material to distal haustra

121
Q

mass movement in the colon

A

propels the fecal material toward the rectum

122
Q

peristalsis

A

weak and sluggish

123
Q

gastrocolic reflex

A
  • initiated by stomach distension
  • causes a mass movement
124
Q

defecation reflex

A
  • increases parasympathetic output to the sigmoid colon and rectum
  • relaxes (involuntary) internal anal sphincter
125
Q

voluntary defecation

A
  • learned about age 3
  • called Valsalva maneuver
  • relaxes external (voluntary) anal sphincter
126
Q

carbohydrates

A
  • monosaccharides
  • disaccharides
  • polysaccharides
127
Q

________ and _______________ broken down into individual monosaccharides (glucose)

A

starch and disaccharides

128
Q

main digestion sites

A

oral cavity- salivary amylase and small intestine- pancreatic amylase

129
Q

monosaccharide ex

A

glucose and fructose

130
Q

disaccharide ex

A

sucrose- table sugar

131
Q

polysaccharide ex

A

starch and cellulose- leafy plants

132
Q

proteins

A
  • polymers composed of amino acid linked by peptide bonds
  • broken down by enzymes (pepsinogen, trypsinogen)
133
Q

pepsinogen is made by the

A

stomach

134
Q

trypsinogen is made by the

A

pancreas

135
Q

what activates pepsinogen

A

hydrochloric acid (HCL)

136
Q

what activates trypsinogen

A

enteropeptidase

137
Q

proteins in the body

A
  • albumin
  • fibrinogen
  • hemoglobin
  • immunoglobin
  • myoglobin
  • collagen fibers
  • elastic fibers
  • reticular fibers
  • myosin
  • actin
  • troponin
  • tropomyosin
  • hormones
  • enzymes
138
Q

amino acids are called the monomers of

A

proteins

139
Q

saccharides are

A

carbs

140
Q

lipids

A
  • not water-soluble, highly variable structures
  • triglycerides
  • cholesterol
141
Q

triglycerides

A
  • made of glycerol and three fatty acids
  • several enzymes required to break bonds
142
Q

cholesterol

A

does not need to be broken down for reabsorption

143
Q

lipid breakdown in the stomach

A

these start triglyceride digestion
- lingual lipase
- gastric lipase
- pancreatic lipase

144
Q

lingual lipase

A
  • component of saliva in the mouth
  • activated when reaches the stomach
145
Q

gastric lipase

A

produced by chief cells

146
Q

pancreatic lipase

A
  • requires separation of large lipid droplets into smaller droplets called EMULSIFICATION
  • digests triglycerides into monoglycerides and two fatty acids
147
Q

lipid absorption

A

lipids transported to the simple columnar epithelial lining by micelles

148
Q

triglycerides and cholesterols are wrapped with protein to form

A

chylomicrons

149
Q

water absorption

A
  • small intestine absorbs almost all ingested water
  • large intestine absorbs some
  • rest passed in feces
150
Q

vitamin absorption

A
  • fat-soluble vitamins absorbed in small intestine along with lipids within micelles
  • water-soluble vitamins absorbed through diffusion and active transport
151
Q

fat-soluble vitamins

A

A, D, E, and K

152
Q

water-soluble vitamins

A

B and C

153
Q

B12 absorption requires

A

intrinsic factor (formed by parietal cells in stomach)

154
Q

micelles

A

tiny, spherical structures formed by bile salts that encapsulate digested fat molecules (like fatty acids and monoglycerides)