Gastrointestinal Tract Flashcards
(171 cards)
1
Q
Digestion
A
form absorbable molecules from food through
- GIT motility
- pH changes
- biologic detergents
- enzymes from pancreas
2
Q
Absorption
A
movement of digestive food from intestine to blood or lymphatic system
3
Q
excretion
A
non absorbable components of food, bacteria, intestinal cells, hydrophobic molecules (drugs), cholesterol, steroids are excreted
4
Q
host defense
A
inactivate harmful bacteria and micro-organisms by forming a barrier, lumen is considered to are exterior to the body
5
Q
mouth
A
chopper
6
Q
stomach
A
blender, acid reservoir
7
Q
duodenum
A
reaction vessel
8
Q
jejunum and ileum
A
catalytic and absorptive surfaces
9
Q
large intestine
A
residue combuster, dessicator, pelleter
10
Q
pancreas
A
enzymes supplier, neutralizer
11
Q
liver
A
detergent supplier, exocrine gland, forms secretes bile, metabolize and store fats, circulating proteins
12
Q
anus
A
emission control device
13
Q
top third of esophagus is made of _______ muscle and rest of GIT is composed of _______ muscle
A
skeletal, smooth
14
Q
where are the villi
A
circular folds of the lumen
15
Q
epithelial layer of the mucosa
A
single layer of cells, polarized, selective uptake of nutrients, electrolytes and water
16
Q
how is surface area of the mucosal epithelial layer increased
A
villi contain single layer of epithelial cells that have microvilli, crypt invaginate into lamina propria
17
Q
apical surface
A
inserts inside tube or lumen of tube
18
Q
basolateral surface
A
closest to blood surface, facing away from tube, basal and lateral surface
19
Q
polarized epithelial cells has different/same transport proteins at apical and basolateral surface
A
different
20
Q
transport proteins are confined to different cell surfaces due to presence of __________ __________
A
tight junctions
20
Q
transport proteins are confined to different cell surfaces due to presence of __________ __________
A
tight junctions
21
Q
where are stem cells located
A
within crypts
22
Q
stem cell flow chart
A
crypt to daughter cells migrating up the villus, reach the end of their life at the top of the villus and slough off
23
Q
in the small intestine, epithelial cell layer is replace every _____
A
5 days
24
paracellular pathway
chemicals move between cell junctions, limited by tight junctions so only small ions and water can diffuse (in a healthy intestine not much else can get through)
25
Transcellular pathway
2 step process which requires transport proteins on apical and basolateral surface of cell
26
Lamina propria
includes everything above muscle layer (connective tissue, blood vessels, nerve fibres, lymphatic cells and immune cells)
27
muscularis mucosa
thin layer of smooth muscle, may function in moving the vili but not involved in GI contraction
28
Submucosa
contains submucosal nerve plexus, nerves that relay info to and away from mucosa
29
muscularis external
circular muscle: fibers in circular pattern that contract and relax to open and close tube
myenteric nerve plexus: regulate muscle function of GIT
longtitudinal muscle: lengthens and shortens control length of tube
30
Serosa
connective tissue layer encasing intestine and connects to intestinal wall
31
lacteals are important for ...
fat absorption
32
pathway of food entering stomach
food enter, digested in stomach, absorption and secretion occurs in the small intestine, processing happens in the colon, elimination of faces containing material that is not absorbed or digested
33
blood flow in the GIT
oxygenated blood enters GIT and loses oxygen as it travels through the intestine, blood from intestine goes to lower before it travels back to heart via portal vein
34
Portal circulation
blood from IT to liver, removes harmful substances as liver is a filter, processes nutrients in blood
35
Hepatic Artery and Vein in Liver
hepatic artery contain oxygen rich blood, nutrient poor
vein carries blood from GIT that is low in oxygen but high in nutrients
36
Liver has _______ circulation while most other organs have _____
series, parallel
37
Reflexes regulating GI processes are initiated by:
a. distention of GIT wall
b. osmolarity of pH
c. concentration of digestion content
37
Reflexes regulating GI processes are initiated by:
a. distention of GIT wall
b. osmolarity of pH
c. concentration of digestion content
38
enteric nervous system has ________
intrinsic nerve regualtion
39
what is the enteric nervous system important for
functions independently of CNS, controls involuntary functions such as digestion
40
myenteric plexus
influencing and regulating smooth muscle
41
submucosal plexus
influences secretion
42
Extrinsic regualtion
occurs through ANS, hunger, smell of food, emotional state
43
parasympathetic in GIT
stimulates peristalsis, secretion, bile release
44
sympathetic in GIT
inhibits peristalsis and secretion
45
regulations: endocrine, neurocrine, paracrine, autocrine
hormones target distant cells
neuron or effector cells in close proximity
local release of paracrine substance
autocrine locally releases substances that acts on itself
46
CCK
released into blood upon stimulation by fatty acids and amino acids in SI
stimulates pancreas to increase digestive enzyme secretion, gall bladder to contract, release bile and acids for breakdown
negative feedback- absorption of fatty acid and amino acids stops release of CCK
47
function of segmentation
allows mixing of digestive system enzymes with GIT content
slows transit time for nutrients to be absorbed
48
pacemaker cells in GIT
spontaneous polarization and depolarization, when stimulus is there only then contraction occur (AP happens)
49
frequency of contraction is determined by _______, force of contraction mediated by
basal electrical rhythm, neuronal and hormonal input
50
cephalic phase
parasympathetic, emotional, sight, smell food
51
gastric
distension, acidity, amino acids, peptides
short and long neural reflexes (gastrin, Ach)
52
intestinal
distention, acidity, osmolarity, digestive products
short long neural reflexes, hormones CCK, GIP
53
activation of the lateral region of the hypothalamus does what to GIT
increases hunger, lesions can cause anorexia in animals
54
activation of what region makes you feel full
satiety center in the ventromedial region, lesions will cause obesity
55
neuropeptide Y (NPY)
stimulates hunger and or apetite
56
ghrelin
endocrine cells release when fasting and start to starve, released in blood goes to hypothalamus to increase release of NPY
57
orexigenic factors
increase intake
58
anorexigenic factors examples
decrease intake
leptin, insulin, peptide YY, melanocortin
59
leptin pathway
eat more than burned, fat deposit, increased leptin secretion in adipose cells, leptin concentration increases, goes to hypothalamus and inhibits NPY, decrease in appetite, reduced eating increased metabolism
60
water intake is stimulated by
increased plasma osmolarity, decreased plasma volume, dry mouth and throat, prevention of over hydration
61
what hormone is released to conserve water
vasopressin or anti-diuretic conserves water in kidneys
62
WATER INTAKE SUMMARY
lec 2 slide 24
63
3 types of salivary glands
parotid, submandibular, sublingual
64
composition of saliva
mostly water (hypotonic), electrolytes (more K and HCO3, less Na and Cl), digestive enzymes (amylase, lipase), glycoprotein (mucin), anti microbial factors (lysozyme, lactoferrin)
65
salivary gland muscles
acinar- secrete initial saliva
ductal - create alkaline and hypotonic
myoepithelial- both smooth and epithelial characteristics, can contract
66
saliva pathway
acinus to striated duct by contraction of myoepthilial cells
67
which salivary duct allows water through
acinar have leaky tight junctions, so do ductal but they do not allow water
68
what makes saliva alkaline or basic
bicarbonate
69
SUMMARY SLIDE
lec 2 pg 34
70
know sympathetic vs parasympathetic nature of salivary glands
ok u got this keep going
71
Amylase (ptyalin)
enzyme that breaks down starches in saliva, stomach pH inhibits it, pancreatic amylase breaks down 95% carbs in small intestine
72
SLIDE WITH POLYMERS
Amy, -lose,-lopectin,-lase, lec 3 slide 3
73
lingual lipase
in saliva, but can survive stomach acid stable
73
lingual lipase
in saliva, but can survive stomach acid stable
74
in what conditions are amylase and lingual lipase useful
reduced pancreatic activity, pancreatic insufficiency, neonates (immature digestive system)
75
xerostomia
dry mouth
76
conditions where salivary secretion is impaired
congenital, sjogrens syndrome (immune system destroys salivary glands), drug side effects, radiation treatment
77
consequences of xerostomia and treatment
dry mouth, decreased oral pH, tooth decay, esophageal erosions, poor nutrition cuz you can't swallow properly - drink water
78
swallowing
receptors stimulated with entrance of food that signals muscles in pharynx, esophagus, respiratory muscles
79
Esophagus
no absorption, mucus lined, stratified cell layer
80
where are the lower and upper esophageal rings (sphincter)
below pharynx and above stomach
81
when are the esophageal rings open
swallowing, vomiting, burping
82
esophagus pathway
upper ring opens bolus enters (then is closes and glottis opens to breathe and sphincter closes), peristalsis moves the bolus down then lower ring opens so bolus can go into stomach
83
heart burn cause
lower sphincter usually closes to not allow any acidic components from stomach to pass up into esophagus but some does because it doesn't close properly
84
how does the body treat heartburn
peristalsis to much acid back, neutralization, increased salivary secretion
85
Stomach
food storage, mechanical and chemical breakdown, control the rate food enters intestine, secrete intrinsic factor to absorb B12
86
how does the stomach do chemical breakdown
secrete pepsinogen and HCl
87
chyme
reduced fragments of food in stomach
88
chyme
reduced fragments of food in stomach
89
fundus
top part of stomach, secretes HCL
90
antrum
lower part of stomach secretes gastrin
91
exocrine
chemical messengers secreted into epithelial surface without passing into blood
92
mucus
helps avoid self digestion
93
HCl
breakdown protein, hydrolysis, digest macromolecules, sterilize food
94
pepsinogen
digestion of proteins
95
gastrin
endocrine, stimulate HCl production and increase stomach motility
96
histamine
paracrine, increase HCl production, secreted by ECL cells
97
somatostatin
paracrine, inhibit HCl production, secreted by D-cells
98
mucous cell
luminal end of gland, produces mucus
99
parietal cell
produces HCl and intrinsic factor, found in fundus
100
parietal cell
produces HCl and intrinsic factor, found in fundus
101
chief cell
gastric glands, secreters pepsinogen
102
canaliculi
increase SA of cells and maximize secretion of parietal cells
103
enterendocrine cells, G cells
gastric glands in antrum, G cell, secrete gastrin, stimulate HCl production and stomach motility
104
enterochromaffin cells
secrete histamine, increase HCl release
105
D-cells
secrete somatostatin
106
ACIDIFICATION SLIDES
lec 3 slides 28/29
107
s cells
acid entering duodenum stimulates secretin release
108
secretin
goes to pancreatic duct cells stimulates HCO3 release
109
I cells
digested fats and protein stimulate release of CCK
110
CCK
acts on acinar cells in pancreatic duct to stimulate zymogen granules to release digestive enzymes, stimulates release of bile acid and sphincter of oddi relaxes, negative feeback
111
cephalic phase
stimulation in brain, smell and sight of food trigger vagus nerve that causes parasympathetic system to release Act
112
gastric phase
food enters stomach, acid regulation, G cells release gastrin interacting with partial cells to release HCl
113
intestinal phase
food has been broken down partially, inhibitory, secretin and CCK released, negative influence on gastrin production
114
LEC 4 SLIDE 4
hormone review chart
115
vomiting center
medulla oblongata
116
during vomitting what relaxes and contracts
lower esophageal sphincter and esophagus relax, diaphragm and abdominal muscles contract
117
metabolic alkalosis
pH of tissue elevated beyond normal range
118
ulcer
imbalance of acid and protective functions, bacteria or NSAIDs can occur in esophagus, stomach or duodenum
119
gastric bypass surgery
stomach bypassed, low B12 have to receive injection to prevent anemia
120
exocrine pancreas
exocrine: secretions, enzymes (inactive under acidic pH), problems not noticed unless functions fall below 10%
secrete substances into ducts that go to apical surface and converge into pancreatic duct
121
endocrine pancreas
not used for digestion but produces insulin and hormones
secretion occurs across basolateral surface for diffusion, endocrine cells surround capillaries
122
sphincter of oddi
common to bile duct and pancreatic duct
123
pancreatic acinar cells
end portion of duct, produce and secrete digestive enzymes, exocytosis of vesicles with acinar cells
124
pancreatic ductal cells
secrete bicarbonate for neutralization of acid
125
PANCREATIC JUICES SLIDE
lec 4 slide 22
126
DUCTULAR CELL SECRETION
LEC 4 SLIDE 25
127
alkaline tide
large amount of bicarbonate pumped across basolateral surface pumped into the bloodstream after big meal and lots of acid is produced in stomach
128
acid tide
after large meal lots of bicarbonate produced in pancreas, large amount of H+ pumped across basolateral into bloodstream
129
alkaline and acid tide
both will meet up in portal vein and compensate each other
130
amylolase
digest starch into sugars
131
lipase
digest triglycerides into free fatty acids and monoglyceride
132
zymogens
proenzymes or inactive precursor enzymes
133
enterokinase
cleaves trypsinogen into trypsin, can degrade itself if activated, inhibited in pancreas
134
what does trypsin activate
chymotripsinogen and pro-elastase end
pro-carboxypepidase A and B exo
135
phospholipase A2
hydrolyzes phospholipids into lysophospholipids and free fatty acids
136
cholesterolesterase
hydrolyzes cholesterol esters into free fatty acids and cholesterol
137
secretin regulation
pancreas duct cells and liver duct cells increase bicarbonate to neutralize acid entering form duodenum (stimulating secretin release), negative feedback
138
cystic fibrosis
defective chloride channel, produce all digestive enzymes but bicarbonate secretion is minimal and enzymes are not removed from duct and do not reach intestine, constant autodigestions and inflmmation
139
portal triad
hepatic artery, hepatic portal vein, bile duct
140
hepatocytes
liver epithelial cells, canalicular join to make bile ducts
141
hepatic sinusoids
where hepatic blood mixes and flows toward central vein
142
what is in bile
bile acids, cholesterol, salts, phospholipids, bile pigments, trace metals BCSPT
143
emulsification
make lipid droplets smaller
144
re-aggregation agents
amphipathic bile acids and phospholipids
145
micelles
keep monglycerides and fatty acids in small aggregates, free forms diffuse into SI when micelle breaks
146
gallbladder
storing and concentrating bile between meals and releasing when chyme enters duodenum
147
gallstones
cholesterol stones high conc starts to precipitate and pigment stones excess red blood cell breakdown causing bile salts to precipitate with calcium, treat by removing , stones, or drugs
148
folds of kercking
circular folds in lumen of SI
149
crypt regions
vili like things but in opposite direction
150
absorptive cells
microvilli at apical surface, brush border membrane
151
goblet cells
secrete mucus
152
enterendocrine cells
produce I and S cells
153
panted cells
secrete antimicrobial peptides
154
brush border and enzyme
small microvilli projections, enzymes has catalytic activity in the lumen
155
APSORPTION SLIDES
LEC 6 SLIDES 25 TO 28
156
SUMMARY SLIDE
lec 6 slide 33
157
Why are free fatty and mono made tri
maintain diffusion gradient from lumen to SI, further tri chylomicrons packaged in Golgi secreted across basolateral
158
iron
body iron is high, ferritin (produced by enterocytes) is increased, reducing amount in blood, when iron depletes less ferritin produced excreted in feces
159
fluid absorbed by SI higher or LI
SI
160
Gradient direction for secretion
inward for absorption, outward for secretion
161
WATER APSROPTION
LEC 7 SLIDE 13
162
purpose of MMC
push undigested material from SI into LI prevent bacteria from staying in LI
163
vibrio cholerae
increased cAMP stimulate cl channel to open, water follows
164
Ilececal valve
sphincter between cecum and ileum, open when ileum contracts, retain LI content even bacteria
165
appendix
no apparent function, reservoir for waste
166
anus sphincters
internal: smooth involuntary
external: skeletal voluntary control
167
poop mechanism
rectum contracts, internal anal sphincter relaxes asshole initially contracts, increased perstalstic activity causes pressure resulting in reflex relaxation in asshole
168
WATER
lec 7 slide 29/30
