GI Flashcards
1
Q
what is found in the lamina propria of GI mucosa
A
lymph nodules and capillaries
2
Q
what enzyme is sued in the liver to produce cholesterol
A
acetyl coa
3
Q
what is the clinical relevance of intrinsic factor
A
because it is necessary for B12 absorption, insufficieny will cause defects in DNA synthesis and lead to pernicious anemia (megaloblastic)
4
Q
what membrane protein allows secreteion of HCO3 into the lumen
A
Cl-HCO3 exchanger on the apical membrane
5
Q
orad stomach
caudad stomach
A
the upper part
lower part
6
Q
zollinger-ellison disease
A
a gastrin producing tumor that causes excessive production of H+
7
Q
what is the purpose of emulsification
A
to break particles into smaller pieces
8
Q
what properities of the gastic mucosa make it a good barrier to prevent peptic ullcers
A
tight junctions to prevent acid penetration
hydrophobic to prevent ionized water soluble molecules from entering
9
Q
how is Na absorbed and K secreted in the large intestine
what happens in diarrhea in relation to K secretion
A
passive channels
high flow rate of K into the lumin causes hypokalemia
10
Q
what is the driving force behind H2O absorption in the GI tract
how else is water absorbed
A
high osmolality in the intercellular spaces between enterocytes
bulk transport
11
Q
three phases of swallowing
A
oral
pharyngeal
esophageal
12
Q
what are the three phases that regulate gastric secretion
A
cephalic
gastric
intestinal
13
Q
wha three structures are found in the muscularis propria
A
circular muscle
lognitudinal muscle
myenteric plexus
14
Q
what enzyme will absorb free amino acids in the small intestine
A
Na/AA symporter
15
Q
what drug will inihibt the stimulating effect of muscarinic receptors on the proton pump
what does it do
A
atropine
it stops ACh from binding to muscarninc receptors
16
Q
what does the submandibular gland secrete
A
mixed serous and mucous secretion
17
Q
what is the parasympathetic effect on gastric emptying
sympathetic
A
PNS enhances peristalsis
SNS inhibits peristalsis
18
Q
what specific chemical is released in response to gastric emptying of lipids into the duodenum
what cells secrete it
A
cholecystokinin
I cellls
19
Q
what happens in the cephalic phase of gastric secretion
whhat percent of acid secretion is produced by this
A
conditioned response sends efferent signals to the stomach before food arives from the limbic system via the vagus nerve
40%
20
Q
two types of epithelium found in the GI mucosa and their function
A
columnar: barrier, enzyme production, absorption
goblet: secretion of mucus
21
Q
symptoms associated with a motility disorder
A
heartburn
stomach pain
cramping
nausea
vomitting
constipation
diarrhea
22
Q
what is the impact of intraabdominal pressure on defectation
A
increased pressure facilitates defeccaton, especially during forced expiration
23
Q
what is the driving for behind CHO absorption in the jejunum and ileum
A
Na/CHO symporters on the apical membrane that follow the Na gradient set up by the Na/K pump on the basolateral membrane
24
Q
what are the hormone GI peptides
where are the secreted
what is the target
A
gastrin, CCK, secretin, gastric inhibitory hormone
from the stomach into the splanchnic and systemic circulation
either GI tract cells or distant cells
25
what happens during the emptying phase of the gastric pump
the liquids in the antrum are expelled into the duodenum while the large particles are left in the bulge of the terminal antrum
26
how often does the antrum contract in a fed state
how does this change in a fasted state
3 contractions/min
the antrum will be still for 2-3 hours, then have 10-20 minutes of intense contractions with relaxed pyloric sphincter, followed by another quiet period
27
three actions of lipid metabolism in the liver
cholestrol synthesis to form bile salts
triglycerides and VLDL
fatty acid metabolism for ATP or Ketones
28
what cells secrete histamine
what does it do
ECL cells in the H+ secreting region of the stomach
stimulates H+ secretion by parietal cells
29
what deficiency is the root cause of disorders associated with CHO digestion
Lack of dissacharidases (lactose intolerance)
30
four functions of the GI system
mix and move food
digest mechanically and enyzmatically
absorb nutrients from food
excrete by products
31
what is the RMP of smoothmuscle in the GI
-50 to -60 mV
32
where do phasic contractions occur in the GI tract
esophagus, antrum of stomach, small intestine
33
what is the direction of bile flow in the liver compared to blood floe
blood flow goes from the portal triad and sinusiods to the central vein
bile flows from the hepatocyes into bile cannaliculi and into the bile duct
34
what is the migrating myoelectric complex
the pattern of muscle contractions during fasting
35
where are peptic ulcers most common
where else can they occur
when will this cause bleeding
the duodenum
the antrum of the stomach and lower esophagus
when the ulcer penetrates to the submucosa
36
which pancreatic fat enzyme is secreted in its active form
cholesterol ester hydrolase
37
craniosacral = \_\_\_\_
thoracolumbar = \_\_\_\_
PsNS
SNS
38
5 effects of the CCK
contraction of the gall bladder
secretion of pancreatic enzymes
secretion of HCO3 from the pancreas
growth of exocrine pancreas and gallbladder
inhibition of gastric emptying
39
what is the end produce of protein digestion in the Gi tract
dipeptides and amino acids that are absorbed in the small intestine
40
what pancreatic enyzme will break down carbohydrates
amylase
41
how is lipase-bile converted into lipase-colipase
procolipase from the pancreas is converted to lipase by tyrosine, which removes bile salts from lipase and binds with it
42
what part of the enteric nervous system is found in the submucosa
the submucosal plexus
43
what is the function of the enteric nervous system
integrate the motor and secretory functions of the GI tract
44
where are mucus cells in the stomach and what do they secrete
antrum
mucus and pepsinogen
45
what is the basic function of the large intestine
reabsorption of water and elimination of waste
46
what is the empty volume of the stomach
what volume can it hold before intramluminar pressure begins to rise
50mL
1000mL
47
why is bile important
it is needed for the digestion of lipids and fat soluble vitamins
48
four functions of GI peptides
motility of smooth muscles and sphincters
secretion of enzymes, fluid, electrolytes
growth
regulation of other peptides
49
how does food content change gastric emptying
liquid food empties faster than solid
CHO faster than protein faster than fat
50
where are ICC cells found
what is their function
how are thei regulated
muscularis externa
responsible for slow wave potentials in the GI
the action of other ICCs, SMC, and the ENS
51
what are the neurocrine GI peptides
where are they secreted
ACh, NE, VIP, gastrin releasing peptide, neuropeptide Y, and substance P
into the GI tract from neurons following an AP
52
what currents work to produce the plateau in phase 3
inward Ca and outward K
53
what is the fucntion of norepinephrine in the GI tract
relaxation in the SMC wall
contraction of sphincters
stimulation of salivary secretion
54
four basic digestive actions
motility
secretion
digestion
absorption
55
where are parietal cells found in the stomach
what do they secrete
body
HCl and intrinsic factor
56
propuslion
controlled movement of the contents of the GI tract froms stomach to large intestines
57
how is HCl secretion regulated in parietal cells
G cells
vagus nerve stimulation
ECL cells
58
5 functions of cholestrol in the body
cell membranes
Vitamin D
hormones
myelin
bile salts
59
what is the function of crypts in the large intestine
secretion of mucus
60
what determines if the pattern of action for SMCs will be peristalsis or segmentation
the orientation of the fibers (circular or longitudinal)
61
where are chief cells in teh stomach
what do they secrete
body
pepsinogen
62
what type of glands make up 90% of the pancreas
exocrine glands
63
what provides extrinsic innervation to the GI tract
autonomic nervous system
64
how often does the small intestine contract
what are the contraction patterns
12/min (constant)
primary: segmentation, secondary: peristalsis
65
how is fat absorbed into the lymph after digestion in the small intestine
lacteals
66
how do ductal cells modify the compostion of saliva
extraction of Na and Cl
addition of K and HCO3
67
how are CHO and proteins absorbed after digestion in the small intestine
capillaries
68
four pancreatic enzymes that break down proteins
trypsin, chymotripsin, carboxypeptidase, elastase
69
where are G cells in the stomach and what do they secrete
antrum
gastrin
70
four regions of the stomach
fundus
body
antrum
pyloris
71
what are the endocrine cells of the pancreas
what do they do
islets of langerhans cells
secretes insulin and glucagon
72
what are the primary functons of motility in the small intestine
Digestion and absorption of nutrients
73
two types of motility in the large intestine
haustral movement
mass movement
74
where does intrinsic regulation of the GI tract come from
ENS
75
three functions of bacteria in the GI
protection against pathogens
metabolic functions
vitamin production
76
what digestive processes happen in the large intestine
none, water and Na are reclaimed, K is secreted, undigestable wastes are broken down by bacteria
77
function of secretion in the GI tract
producting liquid to lubricate the canal and aid in the process of digestion
78
what is the function of gastrin releasing peptide in the GI tract
releasing gastrin
79
what are the functions of HCl in the stomach
kills microorganisms
activates pepsin
reduces gastric emptying rate
80
what is controled by the enteric nervous system
intrinsic innervation of the GI
81
pharmacomechanical coupling
release of CA from the SR through G protein coupled receptors with no change in membrane potential
82
how do ECL cells regulate HCl production in parietal cells
producing histamine which stimulates H2 receptors to produce G protein and cAMP, increasing proton pump activity
83
what causes duodenal ulcers
rapid gastric emptying will cause too low of a pH to be effectively buffered by the duodenum, leading to ulcer
84
T/F there are no vili in the large intestine
true
85
two parts of the glandular structures in the mucosa of the stomach
gastric pits
gastric glands
86
gastrocolic reflex
the intiation of peristalsis in the GI tract caused by eating that can lead to defecation
87
three functions of bile salts
emulsification of fat
micelle formation to make fats soluble
removal of waste products (bilirubin)
88
what happens during phase 4 that allows for repolarization of SMCs in the Gi tract
voltage gated Ca channes close, activation of Ca gates K channels
89
describe the process of dysfunction in lactose intolerance
ingested lactose is not broken down in the small intestine
lactose in the large intestine feeds bacteria
bacteria ferment lactose to produce CO2, H2, and carbon metabolites
H2O is taken out of the body into the colon
90
patterns of GI motility
propulsion
trituration
mixing
reservoir functions
phasic contractions
91
three types of ducts found in salivons
intercalated ducts
striated
excretory
92
what triggers esophageal peristalsis
stimulation of stretch receptors in the wall that trigger local and CNS distension reflexes
93
what extracts bile slats from portal blood
hepatocytes
94
what is the relationship between flow rate and salivary composition
the higher the flow rate the less ionic modification can take place
95
two conditions that can cause osmotic diarrhea
ingestion of a poorly absorbed substrate such as epsom slats
malabsorption (lactose intolerance)
96
T/F the ENS can regulate all of the GI functions indepenently
true
97
what are the common manifestations of sjogrens syndrome
dry mouth
difficulty chewing and swallowing
candida
rotten teeth
98
what are the three main ways teh GI breaks down proteins
Pepsin in gastric juice
pancreatice enzymes
amino peptidases in the small intestine
99
what must accompany esophageal peristalsis
relaxation of the esophageal sphincter
100
why are micelles important to lipid digestion
because they are water soluble and will difuse across the apical membrane
101
portal triad
the trio of portal vein, hepatic artery, and bile duct that runs through every level of organization of the liver
102
what is the function of villi and microvilli in the small intestin
increase surface area of absorption
103
what is secreted by acinar mucous cells in the salivon
mucin
104
what causes gastric ulcers
regurgitation of duodenal contents can, because they are basic and gastric mucosa is resistant to acid, not base
105
where is B12 absorbed
the small intestine
106
what cells secrete Gastric inhibitory peptide
what is the secretion stimulus
K cells in the small intestine
fat, carbs, amino acids
107
T/F muscle contraction is always present in the GI tract
true, but the magnitude of contraction depends on the presence of an AP
108
describe primary perstalsis
what part of the brainr regulates this
perstalsis that follows the distention reflex in the esophagus
the brain stemm
109
what is the purpose of CCK inhibition of gastric emptying
ensures adequate time for digestion and absorption
110
describe the "alkaline tide"
HCO3 from the parietal cells is absorbed into venous blood in the portal system and released into the duodenum via the pancreas
111
what parts of the stomach serve as a reservior
what allows them to do this
the fundus and upper body
relaxation of tonic contractions in the SM to distend the cavity
112
where is 92-97% of the diet absorbed
the small intestine
113
how is the prophospholipase converted to phospholipase
trypsin in the small intestine
114
gastric punp
the contraction that periodically propels a portion of chyme through the pylorus int the duodenum
115
what is the serosa/adventitia
a layer of simple squamous epthelium furthest from the lumen in the GI tract that has little conective tissue
116
during fasted contractions of the antrum, what will happen to indigestable objects in the stomach
they will be pushed into the duodenum
117
why is pancreatic venous blood acidic
because H+ is secreted through the basolateral membrane into the blood
118
what digestive processes happen in the mouth
chewing and break down of CHO by salivary amylase
119
how do slow waves from the ICC induce peristalsis
they release a slow action potential that acts a pacemaker current and depolarizes SMCs when threshold is reacted
120
three CHO metabolic functions of the liver
gluconeogenesis
glycogenolysis
glycogenesis
121
what stimulates the gastrocolic reflex
what are the chemical/neurological mediators
what happens in response
stretch in the stomach and byproduct in the small intestine
gastrin and ANS
forceful peristaliss in the colon which increases rectum pressure and encourages the defecation
122
two conditions that will cause a deficiency in proteases
chronic pancreatitis and cystic fibrosis
123
what is the function of trypsin
to activate other proteases
124
what is the only site for the secretion of intrinsic factor
what does IF do
parietal cells of teh stomach
absorps vitamin b
125
what is the preganglionic parasympathetic neurotransmitter
postganglionic
acetylcholine for both
126
what vitamin stored in the liver is important for Ca absorption
Vitamin D
127
what is the role of the stomach in lipid digestion
it breaks fat into smaller parts and empties at a controlled rate into the small intestine to allow for proper absorption
128
what is the function of substance P in the GI tract
contraction of smooth muscle
stimulation of salivary secretion
129
what digestive processes happen in the esophagus
none, food bolus is sent to the stomach via peristalsis
130
what is the function of segmentation
how does it work
to mix chyme and expose to enzymes and secretions
circular muscle contracts and splits the chyme, then the two halves merge during relaxation
131
when would secondary peristalsis occur
when primary peristalsis is not enough to move food through the esophagus
132
disaccharidases
enzymes located at the brush border of teh small intestine used to break dissacharides into glucose
133
causes of maldigestion GI tract
pancreatin insufficiency
zollinger ellison
cholestasis/bile deficiency
lack of brush border enzymes
nutrient digestion by bacteria overgrowth
134
what is the function of ducts in the salivon
modification of fluid compositon
135
is saliva typically basic or acidic
basic (7-8)
136
what are the AP phases of a GI SMC
Phase 0: resting MP (-50 to -60) with an outward K
Phase 1: Upstroke
Phase 2: transient repolarization
Phase 3: plateau
Phase 4: repolarization
137
what happens to bile salts after lipids are absorbed
they are recirculated into the enterohepatic circulation
138
two GI disorders related to abnormal motility
Duodenal and Gastric ulcers
139
what are the two types of electrically coupled cells in the GI tract
smooth muscle cells
interstitial cells of cajal
140
three proteins found in saliva with their function
amylase (breaks down starch into maltose)
lysozyme and IgA (antimicrobial)
lactoferrin (binds Fe to suppress bacteria
141
T/F acinar cells in the salivon secrete mostly isotonic lfuid
what bout the ducts
true
the secrete a hypotonic fluid
142
stellate cells
cells that store lipid droplets that contain vitamin A
143
what is the functon of mixing movement
mixxes food and enzymes to facilitate digestion
144
what are the exocrine cells of the pancreas
what do they do
acinar cells and ductal cells
secretes digestive enzymes into the dudodenum
145
what is the action of acetylcholine in the GI tract
contraction of the SMC in the wall
relaxation of sphincters
stimulation of secretions
146
what two reflex mechanisms increase or decrease saliva production
simple reflex
conditioned reflex
147
How do g cells regulate HCl secretion by parietal cells
gastrin produced CCK, producing G protein and IP3Ca to stimulate the proton pump
148
what is the function of the acini in the salivon
what are the two cells that make up this structure
secretion
serous cells and mucous cells
149
mass movement leads to distention of the rectum, which does what
when will this lead to defecation
provides the urge to crap
reflexive relaxtion of the the internal anal sphincter and contraction of the rectum and sigmoid colon
if the external anal sphincter is relaxed
150
what are the two main enyzmes that absorb Na in the GI tract
how is the gradient established
Na/glucose and Na/AA symporter
Na/K pumps on the basolateral membrane
151
two enzymes secreted in gastric juices
protease, gastric lipase
152
how does the vagus nerve regulate HCl secretion by parietal cells
acetylcholine stimulates muscarinic receptors, producing g protein to produce IP3Ca2, which stimulates the H/K proton pump
153
in what part of the GI are slow waves always present
small intestine
154
what is found in the submucosal layer of the GI tract
connetive tissue
blood
glands
submucosal plexus
155
how is the constant movement produced by smooth muscle and ICC cells in the GI regulated
nerves, hormones, paracrine substances which can increase or decrease activity
156
three major salivary glands
parotid gland
submandibular gland
sublingual
157
T/F submucosa is present in the small and large intestines but not into the esophagus
true, it is also sparse in the stomach
158
what are two inbitory pathways for the proton pump
somatostatin and prostaglandins will both produce g proteins that inhibit cAMP production and decrease pump activity
159
what are five proteases of the Gi tract
trypsin, chymotrypsin, elastase, carbpxypeptidase A and B
160
three layers of GI mucosa
epithelium
lamina propria
muscularis mucosa
161
what is the function of somatostatin in the GI ttract
inhibition of GI hormones
inhibition of H+ secretion
162
what are the receptors that feed into the ENS
autonomic nerve receptors in the CNS
mechano and chemoreceptors in the the mucosa
163
what is the function of the migrating myoelectric complex
to empty the stomach of any residue from the last meal
164
what cells secrete CCK
what is the secretion stimulus
I cells of the small intestine
ingested fatty acids or small peptides
165
why is the size of micelles important
they are smalle enough to be absorbed past the apical membrane
166
what is the purpose of carbonic anhydrase in ductal cells
what will happen to the components
it breaks carbonic acid into HCO3 and H+
H+ is exchanged with Na on the basolateral membrane
HCO3 is exchanged with Cl on the apical membrane
167
why is there a high osmolality in the intercellular spaces between enterocytes
because a lot of sodium is secreted into this space
168
which of the three regulatory pathways of gastric secretion is inbitory
the intestinal phase
acid and fat in the duodenum stimulate cells in the small intestine that will inhibit gastrin secretion and decrease empyting rate
169
what is the function of the ENS
controls contractile, secretory, and endocrine functions of the GI
170
how does pH effect gastric emptying rate
activation of H+ receptors in the duodenum reduce gastric emptying to allow for buffering by pancreatic HCO3
171
cholera causes what type of diarrhea
secretiry diarrhea from cholera toxin
172
what cells secrete somatostatin
what is the stimulus
D cells in the gastric antrum
decreased luminal pH
173
three pancreatic enzymes that break down lipids
lipase/colipase, phospholipase, cholesterol esteras
174
what is the state of the colon with no stimulus
what happens after feeding
what happens during mass movement
a quiet colon or haustral shuttling with no net movement of chyme
increased contractions shuttle chyme from one haustra to the next
there is multihaustral propulsion
175
E-C coupling
the activation of Ca channels via action potentials
176
what cells secrete secretin
what is the secretion stimulus
S cells in the duodenum
H+ and fatty acids
177
cystinuria
a genetic disorder with the lack of a transporter for di-basic AAs
178
what are the fat soluble vitamins
how are they absorbed
A, D, E, K
the same as lipids
179
what converts stellate cells into myofibroblasts
what will myofibroblasts do
inflammation
secrete collagen and extracellular matrix into the perisinusoidal space
180
why is motility of the GI tract important
grinding, mixing, and fragmenting digested food to prepare it for digestion and absorption, then movement throough the GI
181
digestions
breaking down proteins, fats, and carbs in the GI traft
182
the reservior function of the stomach is mediated by what reflex
afferent and efferent fibers of this reflex are carried by what nerve
vagovagal stretch reflex
the vagus nerve
183
what two structures make up the myenteric plexus
submucosal and myenteric plexus
184
what happens if the external anal sphincter doesn't relax in response to the urge to defecate
the urge subsides
185
what is the final product of lactose intolerance
osmotid diarrhea caused by CO2, H2, and carbon metabolites
186
what will inhibit the secretion of gastrin
low pH in the stomach
187
what is secreted by serous cells in the acini
watery fluid
digestive enzymes (amylase)
188
what digestive processes happen in the small intestine
chemical digestion of macronutrients is completed and the products absorbed
189
how much fluid is absorbed in the small intestine vs the colon
80% vs 20%
190
what are the extrinsic factors that regulate the ENS
ANS
neuotransmitters
hormones
inflammatory mediators or stress factors
191
three types of GI peptides
hormones, neurocrines, paracrines
192
why are parietal cells considered polar
they have different membrane proteins on the apical and basolateral membranes
193
four things that happen in the large intestine
absorption of H2O, Na, Cl
digestion and metabolism of remaining CHO
synthesis of vitamin K and B vitamins by flora
bacteral fermentation that produce gases and organic acids
194
causes of malabsorption in the GI tract
celiac sprue
gastronenteritis
crohns
lymph obstriction
195
two hormones found in gastric juices
gastrin and intrinsic factor
196
what controls gastric emptying rate
pH and food contents
197
what regulates the enzymatic secretion from acinar cells
CCK and Ach
198
what channels open during Phase 1 to create upstroke
voltage gated Ca and K channels
199
what is the function of secretin
promotes the secretion of pancreatic HCO3 to neutralize acid and inhibits the effect of gastrin on parietal cells
200
four Gi hormones
Secretin, GIP, Gastrin, CCK
201
what fat soluble vitamins are stored by the liver
A, D, K
202
what is the paradox of lipid absorption
the body goes through a lot of troube breaking fat into micelles and chol/TF/PL, then builds them into large molecules before absorbing them
203
describe the series of contractions that produces peristalsis
circular muscle behind the bolus pushes forward
contraction of longitudinal muscle and relaxation of the circular muscle ahead of the bolus makes space
204
what is the first step of protein digestion
activation of trysinogen into trypsin by the brush border enzyme enterokinase
205
where does the phasic contraction of the gastic (antral) pump start
why is the pump necessary
in the middle stomach
mixiing and trituration of food
206
where are minerals absorbed in the GI tract
the small intestine
207
what system plays a roll in regulation of all ENS functions
parasympathetic nervous system
208
name four substances found in saliva
water
mucin
proteins
salts
209
what is the function of striated and excretory cells in the salivon
they modify the ionic compositon of saliva
210
what drives the conditioned reflex in regards to salivation
thinking about, seeing, or smelling food
211
what happens in the gastric phase of regulation of gastric secretion
what percent of acid is secreted this way
distention in the stomach activates long and local reflexes in the stomach, increasing production of ACh, histamine, and gastrin to increase HCl production
212
what is the functon of zymogen granuales in acinar serous cells
production and storage of amylase
213
what is the process of breakdown of lipids after absorption into enterocytes
micelles are broken down into cholesterol, monoglycerides, phospholipids, and free fatty acids
fats are then formed into cholestrol, triglycerides, and phospholipids
cholestrol, triglycerides, and phospholipids are used to form chylomicrons
214
# define a tonic contraction
what happens during this time
when the contraction produced membrane potential of a slow wave is not enough to breach threshold
no AP is generated and the muscle undergoes small contractions with incomplete relaxations
215
what regulates motility of the small intestine
inhibitory and excitatory impulses from the SNS or PNS transmitted through the enteric nervous system
216
describe the process of B12 absorption
dietary B12 is released from food by pepsin
free B12 binds to R protein in salivary juice
pancreatic proteases degrade R protien, allowing B12 to be picked up by intrinsic factor
intrinstic factor-B12 is absorbed in the iluem
217
interstitial cells of cajal
pacemaker like cells in the GI tract that contract spontaneously
218
absorption in the GI tract
the process by which the products of digestion are absorbed into mucosa and enters the lymph or blood
219
how much fluid is secreted by the stomach each day
what is the pH
2-2.5L
1-4
220
three different names for heartburn
GERD
Pyrosis
Esophagitis
221
what is secreted by the intercalated ducts of the salivon
epidermal growth factor
ribonuclease
amylase
proteinases
222
what the preganglionic sympathetic neurotransmitter
what is the post ganglionic
acetylcholine
norepinephrine
223
what is the break down of cholestrol in terms of where it is produced in the body
85% is produced by our own cells
15% is taken from food
224
where is bile ejected into
the small intestine
225
two sources of blood flow to the liver
portal vein from the GI tract
hepatic artery from the celiac artery
226
what happens during the retropulsion phase of the gastric pump
large partiles are pushed back into the body and the antrum is cleared
227
what digestive processes happen in the stomach
mechanical digestion of food via churning
chemical breakdown via pepsin and HCl
228
6 functions of the liver
detoxification of drugs
CHO metabolism
Protein metabolism
lipid metabolism
bile formation
removal of RBC's and ammonium
229
what does the sublingual gland predominately secrete
mucous (70%)
230
T/F the ENS can function with or without autonmic regulation
true
231
three unique features of the GI tract
large population of bacteria
well developed local immune system
enteric nervous system for regulation
232
what is secreted by gastric glands
what is the compositon
gastric juices
Acid, enzymes, mucus, horomes
233
what is sjogrens syndrome
what is the result of this
a chronic autoimmune disorder where T and B cells attack salivary, lacrimal, or other exocrine glands
ductal lumen narrowing and atrophy of the gland
234
what simtulates secretion from ductal cells
what is the major stimulant
CCK, Ach, and secretin
secretin
235
what is the function of Vitamin A
important for vision (forms photoreceptors)
236
what is the sympathetic response that increases saliva production
NE stimiulates beta adrenergic receptors in acinor or ductal cells by producing cAMP
237
what type of contraction allows for reserrvior functions in teh GI
where is this function found (4)
tonic contrations
the lower esophagus, upper stomach, ileocecal valve, and internal anal sphincter
238
what is the chemical reponsible for most of the fat digestion in the small intestine
pancreatic lipase
239
what is the simple reflex
what will produce the strongest response via this reflex
salivation based on whats in the mouth
citric acid
240
what is the primary enzyme responsible for absorbing digested protein
H+/di - tripeptide symporter
241
what are the effectors of the GI tract
smooth muscle
exocrine galdns
endocrine galnds
242
what is the function of Vitamin K
synthesis of clotting factors II, IIV, IX, and X
243
4 plasma proteins formed by the liver
fibrinogen
albumin
prothrombin
trasnferrin
244
are ducts high or low in flow rate
low 1mL/min
245
T/F the SMCs of the GI function independent of each other
fallse, they function as a syncytium
246
two GI paracrines
Somatostatin, Histamine
247
two functions of chewing
reduce size of food particles
mix food with amalyse and saliva
248
two types of esophageal peristalsis
primary
secondary
249
what are the two types of GI contractions
tonic and phasic
250
two mechanisms that drive GI tract motility
E-C coupling
pharmacomechanical coupling
251
describe the muscular actions needed for defecation
relaxation of the puborectalis and the internal anal sphincter
contraction of the rectum and the anal canal
relaxation of the external anal sphincter
252
what four events must happen for lipid digestion
secretion of bile and lipases
emulsification by bile salts
enzymatic hydrolysis by lipases
micelle formation with bile salts
253
what are the five major secretory areas of the GI tract
mouth
stomach
pancreas
liver/gallbladder
small intestine
254
what are the functions of gastric motility
reservior
mixing, dividing, emptying in the lower stomach
contractions in the antrum open the pylorus
255
what structure helps enhance the local immune system in the GI
where is it found
peyers patches
ileum
256
how often is mucus secreted
how much is secreted each dayq
it is continuous in varying amounts
1-2 L day
257
what does the parotid gland secrete
serous secretion and amylase
258
describe the vagovasal flex in the stomach
postganglionic peptidergic vagal efferent fibers release vasoactive intestinal peptide (VIP) which relaxes the cardiac sphincter and smooth msucle in the orad stomach
259
describe the mechanism of HCl secretion by parietal cells
CO2 and H2O are formed into carbonic acid with carbonic anhydrase, which dissociates into H and HCO3
H is pumped into the lumen of the stomach via H/K exchanger on the apical surface
HCO3 is sent into the blood via HCO3/Cl exchanger
Cl passivly diffuses through channels into the lumen to form HCl
260
what cells secrete gastrin
what is the trigger stimulus
what are the effects
G cells
protein, dstomach distention, vagal stimulaton
promotes H secretion by parietal cells, stimulates growth of gastric mucosa
261
common cuases of peptic ulcers
H pylori, smoking, alcohol, NSAIDs, stress, ischemia
262
what happens during the propulsion phase of the gastric pump
thre is a rapid flow of chyme with delayed flow of large particles towards the pylorus
263
what are the three phases of the gastric (antral) pump
propulsion
emptying
retropulsion
264
# define a phasic contraction
what will cause stronger contractions
a contraction started when the slow wave is enough to depolarize the SMCs and produce an AP
more APs on top of the slow wave produce stronger contractions
265
what is the storage capacity of the stomach
around 4 cups or 1L
266
is defecation reflexive or voluntary
both, both sphincters have to be relaxed in order to defecate
267
trituration
the crushing and grinding of ingested food
268
what element is most important for the absorption of monosaccharides in the small intestine
why
sodium
because Na/glucose and galactose symporters are important cell proteins in the process
269
what is the function of mucus in gastric juices
protecting the stomach from dehydration and helping form chyme
270
what are the paracrine GI peptides
where are they secreted
what is their target
somatostatin and histamine
in the endocrine cells of the GI tract
other cells with in the same tissue that secretes them
271
define peristalsis
a progressive wave of contractions along the wall of the GI tract from esophagus to large intestine
272
what are the four layers of te GI tract
mucosa, submucosa, mucularis propria, serosa/adventitia
273
what is the basic unit of the salivary gland
what are the two parts of this structure
salvion
acini and ducts
274
what happens to micelles as they are absorbed
the lose their bile salts
they are broken into triglycerides and protein, then formed into chylomicrons
chylomicrons are secreted into blood
275
motility
the movement of the GI system that transmits contents from mouth to rectum
276
three compnonents of bile
bile salts, bilrubin, cholestrol
277
kupffer cells
liver macrophages that line the hepatic sinusoid and ingest bacteria
278
where is the integration center for defecation found
does it take input from high CNS structures
the sacral spinal cord
yes
279
four types of diarrhea
decreased surface area (celiac sprue)
osmotic diarrhea
secretory diarrhea
intestinal infections
280
what is the PsNS response to the conditioned salivary reflex
what is the neurotransmitter
parasympathetic will increase saliva secretion in response to food, nausea, smells
decrease production due to dehydration, fear, sleep
ACh, which stimulates muscarinic receptors with atropine
281
how does bile function to digest fat
it emulsifies liquid to prepare them for digestion, then packages them into micelles for transport
282
what current provides transient repolarization during phase 2
`transient outward K rectifiers
283
what is mucin
a glycoprotein found in saliva that helps thicken saliva
284
how is SMC contraction started in the GI tract
how is the AP conducted
two orientations of SMC in the GI
response to membrane potentials created by teh ICC
gap junctions
circular and longitudinal
285
what do the acinar and ductal pancreatic cells do
acinar cells secrete pancreatic enzymes
ductal cells secrete HCO3 soloution
