Chapter 26: Digestive System Flashcards
(155 cards)
1
Q
six main functions of the digestive system
A
1- ingestion
2- motility
3- secretion
4- digestion
5- absorption
6- elimination
2
Q
ingestion
A
solid and liquid nutrients into oral cavity
3
Q
motility
A
- voluntary and involuntary muscular contractions
- mixing and moving materials through the GI tract
4
Q
secretion
A
producing and releasing fluid products to aid in digestion
5
Q
digestion
A
breakdown of ingested food into smaller structures
6
Q
2 kinds of digestion
A
1- mechanical digestion
2- chemical digestion
7
Q
mechanical digestion
A
material physically broken down by chewing and mixing
8
Q
chemical digestion
A
large complex molecules to smaller molecules - enzymes break chemical bonds
9
Q
absorption
A
digested molecules, electrolytes, vitamins, water from GI tract INTO BLOOD AND LYMPH
10
Q
elimination
A
expulsion of indigestible components that are not absorbed
11
Q
enzymes are
A
catalysts
12
Q
catalysts are
A
- proteins that speed up a chemical reaction
- not changed or used up in the reaction
13
Q
4 layers/tunics of the GI tract
A
1- mucosa
2- submucosa
3- muscularis
4- serosa
14
Q
serosa
A
is the outermost layer of the GI tract; superficial serous membrane
15
Q
mucosa
A
the innermost layer; deep mucous membrane
16
Q
muscularis
A
consists of smooth muscle
17
Q
submucosa
A
consists of blood vessels, lymph, and nerves
18
Q
functions of the muscularis to mix and propel contents within GI tract
A
- peristalsis
- mixing
- mass movements
19
Q
peristalsis
A
propels ingested materials through tract
20
Q
mixing
A
blends ingested materials with secretions
21
Q
mass movements
A
forces fecal matter from the transverse colon through the rest of the large intestine
22
Q
submucosal nerve plexus
A
innervates smooth muscle and glands
23
Q
MALT
A
mucosa-associated lymphatic tissue
24
Q
Peyer patches
A
larger aggregates of lymphatic nodules in distal small intestine
25
muscularis (externa) inner circular layer
smooth muscle; contraction constricts tube lumen
26
muscularis outer longitudinal layer
contraction shortens tube
27
muscularis myenteric nerve plexus
between layers, control contractions
28
sphincter
closes off the lumen, controls movements
29
propulsion
forward movement down the tract
30
2 nervous systems that communicate with the digestion system
1- enteric nervous system (ENS)
2- autonomic nervous system (ANS)
31
enteric nervous system (ENS)
- includes submucosal plexus and myenteric plexus
- innervates smooth muscle and glands of GI tract
- coordinates mixing and propulsion reflexes
32
autonomic nervous system (ANS)
- parasympathetic innervation promotes GI tract activity
- sympathetic innervation opposes GI tract activity
33
nerve receptors in the digestive system
- baroreceptors
- chemoreceptors
33
short reflex
LOCAL reflex only involves ENS; coordinates small segments of the GI tract
34
long reflex
involves sensory input to CNS and ANS motor output; coordinate GI tract motility, secretions, and accessory digestive organs
35
hormonal control
three primary hormones in the regulation of digestion:
1- gastrin, from stomach
2- secretin, from SI
3- cholecystokinin (CCK), from SI
36
upper GI tract organs and accessory structues
- oral cavity and salivary glands
- pharynx
- esophagus
- stomach
- duodenum
37
oral cavity and salivary glands
- mechanical digestion
- saliva secreted in response to food
- mixed with ingested materials form bolus
38
saliva enzymes secreted in response to food
- salivary amylase
- lingual lipase
39
pharynx
bolus moved to the pharynx during swallowing
40
bolus
a ball of food that you are ready to swallow
41
esophagus
- bolus transported from pharynx into stomach
- lubricated by mucus secretions
42
stomach
- bolus mixed with gastric secretions by smooth muscle contractions
- secretions produced by epithelial cells of stomach
- chyme formed from mixing
43
chyme
the contents in the stomach;
food and stomach secretions
44
tongue within the oral cavity
on interior surface of cavity
- manipulates and mixes materials during chewing
- important functions in swallowing and speech
45
2 kinds of salivary glands
- intrinsic
- extrinsic
46
intrinsic salivary glands
- located within the oral cavity
- unicellular
- continuously release secretions independent of food
47
extrinsic salivary glands
- located outside the oral cavity
- larger
- stimulated to release by food
48
3 pairs of salivary glands
1- parotid salivary glands
2- submandibular salivary glands
3- sublingual salivary gland
49
parotid salivary glands
- largest salivary glands
- 25-30% of saliva
50
submandibular salivary glands
60-70% of saliva
51
sublingual salivary gland
3-5% of saliva
52
saliva
1.0 - 1.5 L secreted daily, most produced during mealtime
53
functions of saliva
- moistens ingested food to help become bolus
- dissolves chemicals that stimulate taste buds
- cleanses oral cavity
- antibacterial substances inhibit bacterial growth
54
antibacterial substances that inhibit bacterial growth
- lysozyme
- IgA antibodies
55
regulation of salivary secretions are regulated by
salivary nuclei within brainstem
56
another name for swallowing
deglutition
57
3 phases of swallowing
1- voluntary phase
2- pharyngeal phase
3- esophageal phase
58
voluntary phase
bolus of food is pushed by tongue against hard palate and then moves toward oropharynx
59
pharyngeal phase
- soft palate and uvula close off the nasopharynx
- larynx elevates so the epiglottis closes over laryngeal opening
60
esophageal phase
- bolus passes through esophagus
- propels bolus toward stomach
- esophageal sphincters closed at rest
61
salivary amylase
enzyme for carbohydrate digestion
62
mucin
mucus
63
lysozyme
antibacterial enzyme
64
gastric glands extend
deep into mucosa from base of each gastric pit
65
gastric secretions produced by 5 types of secretory cells
1- surface mucous cells
2- mucous neck cells
3- parietal cells
4- chief cells
5- G-cells
66
parietal cells
produce intrinsic factors and hydrochloric acid
67
chief cells
- most numerous secretory cells within gastric glands
- secretes pepsinogen and gastric lipase
68
hydrochloric acid activates
pepsinogen to transform into pepsin
69
pepsinogen is a
proteolytic enzyme
70
intrinsic factor
- required for the absorption of vitamin B12 in the ileum
- B12 is necessary for the production of normal erythrocytes
71
hydrochloric acid functions
- 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
lipase
cutting fats
73
G-cell
- enteroendocrine cells that are widely distributed in gastric glands
- secrete gastrin hormone
74
gastrin
stimulates stomach secretions and motility
75
stomach
holding bag for partially digested food until the food is moved into the small intestine where digestion is completed
76
pacemaker cells in stomach
- spontaneously depolarize
- establish a basic rhythm of muscular contraction
- signals spreading through smooth muscle cells in the muscular layer
77
force of contraction and gastric gland secretion are regulated by what and what are the three phases it's organized into?
nervous reflexes and hormones
- organized in three phases;
1- cephalic
2- gastric
3- intestinal
78
vagus nerve=
"rest and digest"; PNS
79
cephalic phase
- initiated by thought, smell, sight, or taste of food (or even sounds of food preparation)
80
gastric phase
initiated by presence of food in stomach
81
intestinal phase
initiated by presence of acidic chyme in duodenum
82
the small intestine is how long
20 ft
83
accessory digestive organs
- liver
- gallbladder
- pancreas
84
the large intestine is how long
5 ft
85
small intestine
- 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
organic compounds/nutrients
- carbs
- lipids
- proteins
- nucleic acids
87
carbs break down into
simple sugars
88
duodenum
receives accessory gland secretions from the liver, gallbladder, and pancreas
89
intestinal glands
- invaginations of mucosa between intestinal villi
- secrete intestinal juice
90
SI surface area from largest to smallest
- 20 ft long
- circ. folds
- villi
- microvilli
91
simple columnar epithelial cells with microvilli in intestinal villi
absorbs nutrients
92
lacteals
fats (large)
93
intestinal capillaries
mainly absorb amino acids + carbs
94
goblet cells
produces mucin
95
3 secretions made by the intestinal glands
1- enteropeptidase
2- CCK
3- secretin
96
brush border enzyme
enteropeptidase
97
brush border
referring to the villi
98
gastroileal reflex
moves contents from ileum to cecum in response to food arrival in stomach
- ileocecal sphincter and cecum reflexes
99
liver
accessory digestive organ and the largest internal organ
- production of bile
100
bile is secreted by
liver
101
gallbladder _________ and _____________ bile
stores and concentrates
102
bile contains
- water
- bicarbonate ions
- bile salts and pigments
- cholesterol, lecithin, and mucin
103
main pancreatic duct carries
pancreatic secretions
104
bile salts and lecithin help
mechanically digest lipids
105
RBC recycling of "Heme" turns into
bile
106
pancreas endocrine function
produces and secretes insulin and glucagon
107
pancreas exocrine function
produces pancreatic juice to assist with digestive activities
108
pancreatic juice
formed by acinar cells
- composed of alkaline fluid and digestive enzymes
109
pancreatic juice contains
- pancreatic amylase
- pancreatic lipase
- inactive proteases
- nucleases
110
pancreatic amylase
to digest starch (amylose- carbohydrate)
111
pancreatic lipase
digest triglycerides (lipids)
112
inactive proteases
digest proteins when activated (ex: trypsinogen- proteins)
113
nucleases
digestion of nucleic acids
114
trypsinogen is activated by
enteropeptidase
115
cholecystokinin (CCK)
hormone released from enteroendocrine cells of SI in response to fatty chyme
116
secretin
released from SI in response to increased chyme acidity
117
large intestine functions
- absorbs water, electrolytes and vitamins from remaining digested material
- stores feces until eliminated through defecation
118
4 big nutrient groups
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
normal bacteria flora in large intestine
indigenous microbiota
120
haustral churning in the colon
mixing; increases churning and moves material to distal haustra
121
mass movement in the colon
propels the fecal material toward the rectum
122
peristalsis
weak and sluggish
123
gastrocolic reflex
- initiated by stomach distension
- causes a mass movement
124
defecation reflex
- increases parasympathetic output to the sigmoid colon and rectum
- relaxes (involuntary) internal anal sphincter
125
voluntary defecation
- learned about age 3
- called Valsalva maneuver
- relaxes external (voluntary) anal sphincter
126
carbohydrates
- monosaccharides
- disaccharides
- polysaccharides
127
________ and _______________ broken down into individual monosaccharides (glucose)
starch and disaccharides
128
main digestion sites
oral cavity- salivary amylase and small intestine- pancreatic amylase
129
monosaccharide ex
glucose and fructose
130
disaccharide ex
sucrose- table sugar
131
polysaccharide ex
starch and cellulose- leafy plants
132
proteins
- polymers composed of amino acid linked by peptide bonds
- broken down by enzymes (pepsinogen, trypsinogen)
133
pepsinogen is made by the
stomach
134
trypsinogen is made by the
pancreas
135
what activates pepsinogen
hydrochloric acid (HCL)
136
what activates trypsinogen
enteropeptidase
137
proteins in the body
- albumin
- fibrinogen
- hemoglobin
- immunoglobin
- myoglobin
- collagen fibers
- elastic fibers
- reticular fibers
- myosin
- actin
- troponin
- tropomyosin
- hormones
- enzymes
138
amino acids are called the monomers of
proteins
139
saccharides are
carbs
140
lipids
- not water-soluble, highly variable structures
- triglycerides
- cholesterol
141
triglycerides
- made of glycerol and three fatty acids
- several enzymes required to break bonds
142
cholesterol
does not need to be broken down for reabsorption
143
lipid breakdown in the stomach
these start triglyceride digestion
- lingual lipase
- gastric lipase
- pancreatic lipase
144
lingual lipase
- component of saliva in the mouth
- activated when reaches the stomach
145
gastric lipase
produced by chief cells
146
pancreatic lipase
- requires separation of large lipid droplets into smaller droplets called EMULSIFICATION
- digests triglycerides into monoglycerides and two fatty acids
147
lipid absorption
lipids transported to the simple columnar epithelial lining by micelles
148
triglycerides and cholesterols are wrapped with protein to form
chylomicrons
149
water absorption
- small intestine absorbs almost all ingested water
- large intestine absorbs some
- rest passed in feces
150
vitamin absorption
- fat-soluble vitamins absorbed in small intestine along with lipids within micelles
- water-soluble vitamins absorbed through diffusion and active transport
151
fat-soluble vitamins
A, D, E, and K
152
water-soluble vitamins
B and C
153
B12 absorption requires
intrinsic factor (formed by parietal cells in stomach)
154
micelles
tiny, spherical structures formed by bile salts that encapsulate digested fat molecules (like fatty acids and monoglycerides)
