Module 4: Gastrointestinal system Flashcards
1
Q
primary function of the GI system
A
bring nutrients into the internal environment (blood) so they can be used
2
Q
what four aspects are specialised for function of the GI system
A
motility, secretion, digestion and absorption
3
Q
how long is the GI system
A
approx. 9m
4
Q
sphincters are
A
thickened regions of circular smooth muscle
5
Q
epithelium that lines the mouth to esophagus is
A
stratified squamous
6
Q
epithelium that lines the stomach, large and small intestines is
A
simple columnar
7
Q
epithelium that lines the anal canal is
A
stratified squamous
8
Q
four layers fo the gut tube from inner most to outermost
A
- mucosa
- submucosa
- muscularis
- adventitia
9
Q
mucosa is a ____ membrane
A
mucus
10
Q
submucosa contains
A
blood vessels and glands.
11
Q
what type of muscle makes up muscularis
A
smooth
12
Q
adventitia is
A
connective tissue
13
Q
mucosa is divided into 3 layers
A
- epithelium
- lamina propria (FCT)
- muscularis mucosa
14
Q
secretion is regulation by ____ part of the ____
A
submucosal nerve plexus; enteric nervous system (ENS)
15
Q
two layers of the muscularis
A
- inner circular
2. outer longitudal
16
Q
myenteric plexus regulates
A
motility
17
Q
the peritoneum is
A
a serous membrane
18
Q
parietal layer
A
lines the body wall
19
Q
visceral layer
A
lines the organs
20
Q
mesentery
A
double layer of visceral peritoneum that connects organ to body wall
21
Q
omenta
A
double layer of visceral peritoneum that connects an organ to another organ
22
Q
what are the 3 types of salivary glands
A
parotid, sublingual and submandibular
23
Q
total volume of salivary secretions
A
1 litre per day
24
Q
acinus are
A
cells in clusters
25
acinar cells secrete
enzymes specifically amylase
26
duct cells secrete
bicarbonate
27
how long is the esophagus
25cm
28
epithelium of mucosa
stratified squamous
29
4 parts of the stomach
1. cardia
2. fundus
3. body
4. pylorus
30
omentum is
a double layer of peritoneum that connects one to another
31
lesser omentum
stomach to liver
32
greater omentum
stomach to transverse colon
33
rugae are
temporary folds that allow for the expansion of the stomach (1.5L)
34
rugae function is
storage
35
function of acid and enzymes
digestion
36
function of mucous
protection
37
function of hormones
regulation
38
chief cells produce
enzymes for protein digestion
39
chief cells contain
an abundance of rough ER, apical zymogen granules
40
parietal cells produce
acid
41
parietal cells have an abundance of
mitochondria
42
pyloric sphincter function
need controlled release of chyme into the small intestine
43
enzymes and bicarbonate are provided by
pancreas
44
release is controlled by
heptopancreatic sphincter
45
endocrine function
- pancreatic islet alpha cells
| - pancreatic islet beta cells
46
pancreatic islet alpha cells secrete
glucogen
47
pancreatic islet beta cells secrete
insulin
48
exocrine function
- acinar cells
| - duct cells
49
acinar cells secrete
digestive enzymes
50
duct cells secrete
bicarbonate
51
three regions of the small intestine
1. duodenum
2. jejunum
3. ileum
52
length of small intestine
approx. 6m
53
Plicae circulares are the core of
submucosa
54
Core of villi is
lamina propria
55
villi contain which vessels
lacteal and capillary network
56
lymph lacteal aids in ____ digestion
protein
57
nutrient rich, deoxygenated blood absorbed in the ____ enter into the ____then drain into the ____
small intestine; mesenteric vein; hepatic portal vein
58
___ ultimately drain into the ___, ____ and then the ____
lymph lacteals; cisterna chyli; thoracic duct; left subclavian vein
59
Mesentery contain
arteries, veins, nerves, lymphatics and some adipose tissue
60
epithelium on small intestine is
simple columnar with microvilli
61
glycoproteins are
branched filaments which tether enzymes
62
enterocytes are
absorptive cells
63
goblet cells
secrete mucous for protection
64
paneth cells
granules, antibacterial enzymes
65
endocrine cells
secrete hormones
66
the large intestine consists of
cecum, colon and rectum
67
colon is divided into
ascending, transverse, descending, sigmoid
68
function of ileocecal valve
regulates the passage of material into the cecum
69
the appendix holds
a reserve of large intestine bacteria population
70
teniae coli are
bands of longitudinal smooth muscle
71
haustra are
series of pouches in the wall of the colon
72
omental appendices are
sacs of fat
73
function of mucosa in the colon
water and salt absorption
74
epithelium of anal canal
stratified columnar
75
what type of muscle is the internal anal sphincter
smooth
76
what type of muscle is the external anal sphincter
skeletal
77
function of the liver
produce bile
78
bile is stored in the
gall bladder
79
how much cardiac output does the liver receive
25%
80
liver receives ___ of the blood from the hepatic artery
1/3
81
hepatocytes produce
bile
82
portal triad is
- branch of hepatic artery
- branch of hepatic portal vein
- a bile duct
83
direction of bile is in the ____ direction to blood flow
opposite
84
bile duct joins ___ at ___
pancreatic duct; hepatopancreatic ampulla
85
receptors in the wall of the GI tract respond to
stretch, change in composition, pH, osmolarity, amino acids, sugars, fats
86
effectors are
smooth muscles and glands
87
reflexes stimulated by receptors stimulate
smooth muscle contractions and gland secretion
88
the central nervous system...
coordinates activity over long distances
89
the enteric nervous system is
totally self contained
90
parasympathetic nervous system
stimulates motility and secretion
91
sympathetic nervous system
inhibits motility and secretion
92
what is the largest endocrine organ in the body
GI tract
93
critical hormones to GI tract
- Gastrin
- Gastric inhibitory peptide
- Secretin
- Cholecystokinin (CCK)
94
functions of motility in the GI tract
movement at a controlled rate, mechanical digestion, mixing and exposure to absorptive surfaces
95
fasting invloves
migrating motor complex
96
feeding involves
storage, propulsion and mixing
97
peristalsis can be explained as
the propulsion on food along the tube ie. like toothpaste
98
segmentation can be explained as
food moving back and forth mixing with chyme
99
functions of gastric motility
storage, mechanical digestion, mixing and controlled delivery to duodenum
100
storage occurs in the
fundus and body of stomach
101
mechanical digestion occurs it the
antrum
102
mixing occurs in the
antrum
103
controlled delivery to duodenum occurs via the
pyloric sphincter
104
stomach shrinks to approx. ___ during fasting
50mL in volume
105
fasting occurs ___ after a meal
4 hours
106
there is ___ of inactivity of movement in fasting
1 hour
107
___ of uncoordinated activity in fasting
50mins
108
___ of coordinated activity in fasting
10mins
109
functions of fasting
residual secretions and undigested materials
110
nervous regulation of storage occurs via the
vagus nerve
111
peristalsis is initiated on
greater curvature and spreads to antrum
112
The rate of gastric emptying matches
digestive capacity of intestine
113
factors that affect gastric emptying are
size of meal and composition of meals
114
function of small intestine motility
mixing with secretions from pancreas, biliary system and intestine
115
segmentation occurs
after meal
116
salivary glands produce how much fluid per day
1.5L
117
function of salivary secretion
hygeine and digestion
118
lingual lipase breaks down
fats
119
alpha amylase breaks down
starch
120
regulation of salivary secretion via nervous system
thought, smell, sight and presence of food
121
regulation of salivary secretion via parasympathetic
stimulates secretion of copious amounts of fluid
122
regulations of salivary secretion via sympathetic
small volumes of viscous fluid
123
how much fluid is secreted via gastric secretion daily
2-3L
124
chief cells produce
pepsinogen
125
intrinsic factor absorbs
vitamin b12 in small intestine
126
what is the inactive form of pepsin
pepsinogen
127
how is pepsinogen converted into pepsin
acid
128
pepsin breaks down
proteins
129
functions of gastric acid
dilutes food, denatures proteins, activates pepsinogen, protection
130
source of acid in parietal cells
formation of H2CO3 by carbonic anhydrase, then the dissociation of H2CO3 to give H+ and HCO3-
131
secretion of acid in parietal cells
H+-K+ ATPase pumps H+ into lumen in exchange for K+ which returns to lumen via membrane channel
132
source of chloride in parietal cells
Cl- diffuse across cell then enters lumen via Cl- channel in apical membrane
133
regulation of gastric secretion
coordinated with eating and arrival of food
134
three phases of gastric secretion
1. cephalic phase
2. gastric phase
3. intestinal phase
135
what controls secretion in the cephalic phase
head
136
what controls secretion in the gastric phase
stomach
137
what controls secretion in the intestinal phase
intestine
138
how much of secretion is associated with cephalic phase
20%
139
how much of secretion is associated with gastric phase
70%
140
how much secretion is associated with intestinal phase
10%
141
function of cephalic phase
preparation for arrival of food
142
function of gastric phase
ensures sufficient secretion to handle ingested food
143
function of intestinal phase
controls delivery to small intestine
144
is the pancreas and endocrine or exocrine organ
both
145
what are the two components to pancreatic secretion
1. enzymes
| 2. alkaline fluid
146
how much fluid is secreted via pancreatic secretion
1-1.5L per day
147
the stimulation of pancreatic enzymes being secreted is done by
acinar cells stimulated by hormone CCK
148
in the small intestine activation of enzymes involves
enterokinase/ enteropeptidase
149
alkaline is secreted by
duct cells
150
purpose of alkaline fluid
neutralise stomach acid
151
volume of biliary secretion
0.5L per day
152
a product of biliary secretion is
bile salts
153
excretory products of biliary secretion are
- bile pigments
| - cholesterol
154
function of bile salts
fat digestion
155
function of HCO3- rich fluid
neutralises acid
156
function of bile pigments
excretion
157
bile is secreted by
the liver
158
bile is stored in
the gall bladder
159
bile stimulates its own secretion via
enterohepatic circulation
160
__ of bile is reabsorbed into the ileum
95%
161
bile is reabsorbed into the
ileum
162
volume of intestinal secretion per day
1.5L
163
intestines secrete
isosmotic fluid
164
function of isosmotic fluid
helps neutralise acid and dilutes food to aid digestion
165
digestive enzymes...
shed cells
166
large intestines secrete
mucus
167
function of mucus
lubricaiton
168
main nutrients that undergo chemical digestion
carbohydrates, proteins, lipids
169
composition of ingested carbohydrates
starch and glycogen--> long chains of glucose joined by alpha 1-4 glycosidic bonds
170
example of monosaccharide
glucose
171
examples of disaccharide
sucrose, lactose and maltose
172
composition of ingested proteins
long chains of amino acids linked by peptide bones
173
composition of lipids
mainly triglycerides, glycerol backbone and 3 fatty acids
174
short chain fatty acids contain
less than 6 carbons
175
medium chain fatty acids contain
6-12 carbons
176
long chain fatty acids contain
12-24 carbons
177
why do we need chemical digestion
ingest nutrients in form of large complex molecules
178
digestive enzymes
enzyme + substrate enzyme substrate complex enzyme and product
179
salivary enzymes pH
alkaline
180
gastic enzymes pH
Acidic
181
small intestinal pH
alkaline
182
stage one of digestive enzyme process
luminal digestion
183
what is stage one of the digestive enzyme process
initial digestion involving enzymes secreted in lumen
184
stage two of digestive enzyme process
contact digestion
185
what is stage two of the digestive enzyme process
completing digestion before absorption in small intestine
186
luminal digestion involves
salivary and pancreatic amylase, polysaccharides converted to oligosaccharides and disaccharides and proteins converting to polypeptides.
187
contact digestion involves
disaccharides converted to monosaccharides and converting polypeptides converting to amino acids
188
stages of chemical digestion in order
emulsification, stabilisation, hydrolysis/ digestion and formation of micelles
189
emulsification is where
motility breaks up lipid droplets into small droplets
190
emulsification occurs in
stomach (retropulsion) and small intestine (segmentation)
191
stabilisation involves
bile salts which stabilise the emulsion in small intestines
192
stabilisation occurs in
small intestines
193
hydrolysis involves
lipase and cofactor colipase which are secreted by the pancreas. Colipase anchors lipase to surface of droplet
194
function of lipase
converts triglycerides into monoglycerides and fatty acids
195
hydrolysis occurs
in small intestine at surface of emulsion droplets
196
formation of micelles invloves
keeping products of fat digestion in solution within micelles
197
formation of micelles occur because
fats are hydrophilic/ insoluble so need a way to stay in solution
198
absorption is
the net passage of substances from GI lumen across the lining of the intestine into the interstitial fluid and then into the blood or lymph
199
sites of absorption include
mouth, esophagus, stomach, small intestine, large intestine
200
what is the main site of absorption
small intestine (90%)
201
factors affecting absorption
motility, surface area availability, transport across epithelium and removal from interstitial fluid
202
the paracellular pathway is
gap between cells
203
the cellular pathway is
across the cell membrane and through the cytoplasm
204
how much water do we drink each day
approx 1.5L
205
how much water do we secrete into the GI tract daily
9-10L
206
osmosis is
the passive movement of water from lumen into blood that requires an osmotic gradient set up by absorption of salts and nutrients
207
sodium absorption is through
passive movement via paracellular pathway or active transport via cells
208
active transport of sodium requires
transporters to cross the cell membranes ie. Na+ alone, Na+ coupled with monosaccharides or Na+ coupled with amino acids
209
Absorption of Na+ alone into the cell requires
transport proteins such as Na+ channel and Na+/H+ exchange
210
Absorption of Na+ alone out of the cell requires
energy and a Na+/K+ ATPase
211
carbohydrate absorption requires two mechanisms
passive absorption and active absorption
212
passive absorption of carbohydrates involves
monosaccharides moving down a concentration gradient via paracellular pathway
213
active absorption of carbohydrates involves
co-transport with Na+ via cellular pathway.
214
the apical membrane requires what transporters
Na+ glucose cotransporter and Na+ amino acid cotransporter
215
the basolateral membrane requires what transporter
glucose carrier and amino acid carrier
216
protein absorption requires two mechanisms
passive absorption and active absorption
217
passive absorption of protein absorption involves
amino acids diffusing down a concentration gradient via paracellular pathway
218
active absorption of proteins involve
co-transport with Na+ via cellular pathway which is similar to glucose absorption
219
absorption of products of fat digestion are
lipid soluble so can diffuse across the cell membrane without transporters
220
are whole micelles absorber
no
221
what are triglycerides packaged into within the cell
chylomicrons
222
how do chylomicrons exit the cell
exocytosis
223
where are bile salts absorbed
ileum- active transport and colon- passive transport
224
fat soluble vitamins are
A, D, E and K
225
water soluble vitamins are
C
226
special case vitamins are
B12
227
Pernicious anaemia is
the lower ability of RBCs to carry oxygen due to a deficiency of the intrinsic factor that carries B12
228
Things that are eliminated rather than absorbed are
residues of digestion which are formed into faeces
229
how are faeces transferred out the body
via the rectum through peristaltic waves
