Ward Small and Large intestine (1) Flashcards
1
Q
duodenal (blank) increases surface area for absorption
A
folds
2
Q
Pancreatic exocrine cells are arranged in (blank)
A
acini
3
Q
Pancreatic secretions flow into larger (blank).
A
intralobular ducts
4
Q
Pancreatic secretions flow into larger intralobular ducts, and into the (blank) which drains directly into the duodenum
A
pancreatic duct
5
Q
Embedded within the exocrine tissues are islets of langerhans which secrete what?
A
insulin, glucagon etc.
6
Q
What are the four types of pancreatic secretions?
A
proteolytic enzymes
Pancreatic Amylase
pancreatic lipase
cholesterol esterase
7
Q
What are the proteolytic enzymes of the pancreas?
A
trypsin, chymotrypsin, and carboxypeptidase
8
Q
What does pancreatic amylase of the pancreas do?
A
hydrolyzes starches, glycogen, and other carbs (not cellulose) to di and tri saccharides
9
Q
What does pancreatic lipase do?
A
hydrolyzes fat to fatty acids and monoglycerides
10
Q
What does cholesterol esterase of the pancreas do?
A
hydrolyzes cholesterol esterases and phospholipase which splits fatty acids from phospholipids
11
Q
What are the inactive forms of the protolytic enzymes of the pancreas?
A
trypsinogen, chymotrypsinogen, procarboxypolypeptidase
12
Q
(blank) is activated by enterokinase (secreted by mucosa when chyme comes into contact with it) and by trypsin
A
trypsinogen
13
Q
How is chymotrypsinogen activated into chymotrypsin?
A
activated by trypsin
14
Q
(blank) stops the pancreatic enzymes from degrading the pancreas.
A
trypsin inhibitor
15
Q
(blank) it is released from glandular cells and inhibits the activation of trypsin inside secretory cells, in the acini and in the pancreatic duct
A
trypsin inhibitor
16
Q
Where is trypsin inhibitor released from?
A
glandular cells
17
Q
Where will you find trypsininhibitor be inhibiting stuff?
A
in secretory cells, acini and pancreatic duct
18
Q
Explain the release of zymogen granules
A
protein synthesis via RER-> proteins enter cisternal cavity-> enzymes are condensed into vacuoles-> concentrated enzymes become zymogen granules-> zymogen granule fuses with apical membrane and ruptures to release contents
19
Q
Enzymes of the pancreas are secreted by (blank)
A
acini
20
Q
What 2 things are secreted by the epithelial cells of the ducts from the acini?
A
bicarb and water
21
Q
When the pancreas is stimulated to secrete pancreatic juices it also releases (blank)
A
bicarbonate ions (X5 that of the plasma)
22
Q
The (blank) and (Blank) concentrations in pancreatic secretion are approx. similiar to that of plasma but (blank) concentration is lower.
A
Na+ and K+
Cl-
23
Q
The (blank) ion secretion increase with secretion rate yielding a solution of pH 8.2 in the pancreas.
A
HCO3-
24
Q
What is the first proposed mechanisms for secretion of bicarb ions?
A
Acinar cells secrete Na and Cl
duct cells secrete Bicarb
Differing rates of secretion from these cells results in diff concentration of ions in secretion
25
What is the second proposed mechanism for secretion of bicarb ions?
Primary secretion; rich in HCO3-. As secretion moves down ducts, primary secretion is modified, HCO3- ions are exchanged for Cl- ions. When flow is fast little exchange takes place.
26
There are 2 proposed mechanisms for Bicab ion secretion, do they work together or are they independent of one another?
work together
27
Explain the mechanism of secretion of bicarb
Co2 diffuses from the blood into the cell, this combines with water via carbonic anhydrase= carbonic acid->this dissociates into bicarb and H, H+ is pushed into the blood via Na/H exchanger, and HCO3 is pushed into lumen via HCO3/Cl exchanger. Na diffuses into lumen and water follows.
28
As secretion rate increases there is a marked increase in (blank) secretion and a decrease in (blank) secretion and (blank) stays steady throughout.
HCO3-
Cl-
Na+
29
HCO3 secretion is dependent upon availability of luminal (blank) ions which is dependent upon the opening of (blank) channels on the apical membrane.
Cl-
| Cl-
30
What are the four basic stimuli that are important for the stimulus of pancreatic secretion?
ACh, Gastrin, CCK, Secretin
31
(blank) is released from parasympathetic vagus nerve terminals and nerves in ENS
ACh
32
(blank) is released during the gastric phase of the stomach.
Gastrin
33
(blank) is secreted by the duodenal mucosa when food enters the small intestine.
CCK
34
(blank) is secreted when low pH products enter the small intestine.
secretin
35
ACh, Gastrin and CCK all stimulate the (blank) of the pancreas to produce large quantities of digestive enzymes, without much fluid, resulting in the build up of enzymes in the acani and ducts.
acinar cells
36
(blank) stimulates the secretion of large quantities of sodium bicarbonate solution by ductal epithelium, but little enzyme secretion.
Secretin,
37
ACh released at neural endings in the pancreas cause moderate amounts of enzymes to be secreted into the acini, however only a little flows into the intestine, Why is this?
because of the lack of water in the secretion.
38
(blank) via the gastric phase also causes relatively little pancreatic secretions.
Gastrin
39
Pancreatic secretion is increased considerably when chyme enters the duodenum in response to the hormones (Blank and blank)
secretin and CCK
40
(blank) is released from S cells in the mucosa of the upper small intestine in an inactive form.
secretin
41
What is the stimulus for release of secretin?
gastric acid and long chain fatty acids
42
(blank) is the most potent stimulant of secretin, with a threshold for secretin release being 4.5 .After secretin is released from small intestine, it is absorbed into the blood, stimulating the (blank) to release large quantities of fluid and bicarbonate ions.
HCL
| pancreas
43
Does secretin stimulate the acinar cells?
no
44
Explain how HCl reacts in the intestinal phase?
HCl reacts with NaHCO3 to make NaCl and carbonic acid (H2Co3) which dissociates into H20 and CO2
45
What happens to the CO2 produced in the reaction of HCl during the intestinal phase?
The CO2 is absorbed into the blood expired in the lungs.
46
Why does co2 get expired in the lungs during the intestinal phase?
This is a protective mechanism to avoid the digestion of the intestinal mucosa by HCl
47
Also during the intestinal phase, (blank) secretion also increases the pH of luminal contents which is more optimal for pancreatic enzymes (pH 8)
bicarb secretion
48
(blank) is released from I cells within the mucosa of the duodenum and upper jejunum. The stimulant that causes the release of CCK appears to be (blank and blank) (products of partial protein and long chain fatty acid digestion
CCK
| proteoses and peptones
49
(blank) is absorbed into the blood stream and travels to the pancreas where it stimulates the release of large amounts of digestive enzymes, similar to the effects of vagal stimulation and gastrin.
CCK
50
What wil ACh and CCk do to secretin release?
increase it!
51
During a normal meal pH does not drop below 4.5, why?
Pancreatic enzyme release gets increased by CCK and ACh working with secretin
52
What are the 2 major functions of bile?
to emulsify and transport fat into small intestine
| Allow for excretion of waste products from blood (bilirubin,cholesterol)
53
(blank) is A complex mixture of organic and inorganic components. Separately some of the components would precipitate out of solution in an aqueous medium.
bile
54
(blank) is a major organic constituents accounting for 50% of solid components. Several features are unique to account for their behavior in solution.
bile acids
55
In solution bile acid behavior depends upon their (blank). At (blank) concentrations there is little interaction among bile acids. At (blank) concs. bile acids aggregate into micelles.
concentration
low
higher
56
What is the point when bile acids turn into micelles?
The Critical Micellar Concentration.
57
(blank) is the primary bile acid from cholesterol
cholic acid
58
(blank) is the primary bile acid from choelsterol.
chenodeoxycholid acid
59
(blank) is one of the secondary bile acids, which are metabolic byproducts of intestinal bacteria.
Deoxycholic acid
60
(blank) is a secondary bile acid that acts as a detergent to solubilize fats for absorption. Bacterial action in the colon produces this.
lithocholic acid
61
Most bile acids exist as conjugates of (blank and blank).
taurine or glycine
62
Which are more soluble, conjugated or unconjugated biile acids?
conjugated
63
(blank) and bile salts are components of micelles and together, are better to solubilize other lipids (cholesterol) than bile salts alone.
phospholipid
64
What breaks up phospholipids?
bile salts (bile salts make phospholipids more soluble to become parts of micelles)
65
(blank) contributes to about 4% of solids in bile.
cholesterol
66
(blank) may be excreted and helps regulated body cholesterol levels.
Bile cholesterol
67
Where would you find cholesterol in a micelle?
on the inside (in hydrophobic portion)
68
(blank) contributes to about 2% of solids in bile.
bile pigements
69
Do bile pigments take part in micelle formation?
no
70
What is the most important bile pigment and what are bile pigments used for?
bilirubin
| color of feces/bile and utilized to assay function of liver
71
What are the inorganic ions of bile?
```
Na
K
Ca
Cl
HCO3
```
72
What are all the components of bile?
```
bile acids
phospholipids
cholesterol
bile pigements
inorganic ions
```
73
(blank) is isosmotic, because of the highly charged molecules bile acids attract a layer of cations that act as counter ions on the micelles and exert little osmotic activity.
Bile
74
The bile that is secreted passes into the small (blank) that lie between the hepatic cells and the hepatic plates.
bile canaliculi
75
Once bile flows into bile canaliculi, how does it flow from there?
canaliculi-->hepatic duct-> common bile duct-> either cystic duct or empty into duodenum
76
How does bile empty into the duodenum?
via the sphincter of Oddi
77
How often are bile acids and pigments secreted?
continually
78
How is the rate of secretion of bile altered?
the rate is dependent upon amount of bile delivered to the liver by the reuptake of bile. (hepatic circulation)
79
What are the three pathways involved in bile absorption?
I. passive diffusion
II. terminal ileum absorption (active carrier mediated)-> very efficient
III. Bacteria in terminal ileum and colon decongugate bile salts to bile acids (bile acids are able to reabsorbed)
80
How is bilirubin transported to liver?
albumin
81
Old RBC's are broken down into Hemoglobin. Hemoglobin is broken down in the reticuloendothelial system to hemin and globin. Hemin is then further broken down into (blank)
bilirubin
82
(blank) extract bilirubin.
hepatocytes
83
How do hepatocytes extract bilirubin?
via an active anion transport system, they conjugate bilirubin with glucuronic acid and then secrete it
84
Is bilirubin actively absorbed?
no
85
Some of the bilirubin is reduced by bacteria to (blank)
urobilinogen.
86
Some urobilinogen is excreted in feces as (Blank).
stercobilin
87
What are all the places urobilinogen can go?
excreted in feces
transported to liver
extracted, conjugated and secreted into bile
oxidized to form urobilin and excreted in urine
88
How are electrolytes secreted?
1) Bile acid dependent: Bile acids create osmotic gradient, water follows and passibely ions follow water
2) Bile acid independent: active transport of Na+ by heptocytes, in ducts bicarb is actively secreted and Na and Cl are absorbed. Bile becomes alkaline and Cl- decreases
89
How does the bile acid independent secretion of electrolytes stimulated?
by secretin
90
As bile acids are propelled towards the distal ileum, primary acids are converted to (bank)
secondary acids
91
(blank) acids are absorbed passively.
(blank) acids are absorbed by a sodium coupled active transport system. A minor fraction of bile acids are not absorbed but transported to (blanK)
hydrophobic
hydrophilic
colon
92
Where do absorbed bile acids end up?
| Why?
liver
| They can be actively extracted from the blood and resecreted
93
When we lose bile acids in the large intestine we make more from (blank)
cholesterol
94
What are the 2 main organic solutes of bile?
bile salts, phospholipids, and cholesterol
95
(blank) are actively secreted into bile through distinct bile salt-transport pumps.
bile salts
96
What are the four ways we can get gallstones?
1) Too much absorption of water from bile.
2) Too much cholesterol in bile, leading to precipitation.
3) Too much absorption of bile acids from bile.
4) Inflammation of the epithelium.
97
(blank) are found found extensively in the duodenum between the pylorus and papilla of Vater,
Brunner's glands
98
Brunner's gland will secrete mucous in response to what four things?
(i) tactile stimuli
(II) irritating stimuli
(iii) vagal stimulation
(iv) GI hormones - in particular secretin.
99
The function of the mucus secreted from the brunners glands is....????
to protect the intestinal wall from digestion by gastric juices,
lubricate
dilute noxious agents
100
What inhibits secretion of Brunner's glands?
sympathetic stimulation
101
If Brunner's glands is inhibited by sympathetic stimulation, what can this lead to?
unprotected duodenal bulb (may lead to peptic ulcer)
102
What do crypts of leiberkuhn of the small intestine secrete?
extacellular fluid (pH 7.5-8) which is reabosrbed by the villi.
103
What does the solution secreted by the crypts of leiberkuhn work as?
carrier for absorption of nutrients
104
What are the ions in the extracellular fluid solution secreted by the crypts of leiberkuhn?
Active secetion of Chloride
Active secretion of Bcarb
and Passive secretion of Na+
105
What does the Na+ of the solution secreted by the crypts of leiberkuhn create?
an osmotic potential which results in the movement of water into the crypt
106
(blank) line the mucosa of the large intestine
crypts of liberkhnn
107
Do the crypts of lieberkuhn have villi?
no
108
Mucus which contains large quantities of bicarbonate ions is secreted by (blank) cells in the crypts of lieberkuhn.
mucous
109
(blank) stimulation results in copious amounts of mucus secretion
parasympathetic
110
(blank) in the large intestine protects the lining from acid that is formed deep in feces. It also provides a medium for the formation and binding of fecal material.
mucus
111
What is the mechanism of the secretion of the crypts of lieberkuhns?
Na-CL cotransport at basal lateral side allows cl to move down gradient due to Na moving down its gradient. Cl secretion is regulated by cAMP.cAMP levels are controlled by VIP after meal
112
What is this:\Responsible for numerous pandemic infections of extreme diarrhea and dehydration across the globe, resulting in millions of deaths.
Vibrio cholerae.
113
What is this:
Onset of symptoms include abdominal pain followed by a sudden onset of massive diarrhea. This initial stool may be composed of over one liter of fluid, and several liters of fluid can be secreted within hours after. Vomiting is another common symptom of early cholera infection. As infection progresses, the stool becomes much more watery, and may have white flakes of mucus in it. These flakes are composed of slewn off gastrointestinal cells.
Vibrio cholerae.
114
What is this:
characterized by severe fluid loss, leading to extreme dehydration, fever, tachycardia, and dry skin and/or mucous membrane. During this time fluid released from the bowls or vomitus is rich in cholera toxin. If this late stage cholera is not treated, the mortality rate is approximately 50%. If cholera is detected and treated mortality rates decline drastically, to less than 2%.
Late stage cholera
115
neural endings and receptors that cause and increase in salivary secretion are predominantly located on the basal side of the cell membrane.
T or F?
T
116
Stimulation of the parasympathetic and sympathetic nerves can lead to an increase in salivary gland secretion. During periods when parasympathetic stimulation is high, sympathetic stimulation leads to a reduction in secretion mainly by constricting blood vessels that supply the respective glands.
T or F?
T
117
Parasympathetic stimulation causes the membrane potential in glandular secretory cells to become more positive resulting in saliva that is low in sodium. T or F?
False, actually when you have high amounts of secretion (which parasympathetic stimulation induces) you will have less time to reabsorb Na+ ions therefore you will have a more negative membrane potential and you will and saliva that is higher in sodium :)
118
Is heparin in the ECM?
nope
119
At low gastric secretion rates parietal cells produce a secretion that is high in NaCl ions, HCL and production increases as gastric secretion increase. T or F?
True
| Apparaently when you have low secretion you have high NaCl and as secretion increase you will get more HCL
120
What do parietal cells use to place H+ ions into the lumen of oxyntic glands during acid production?
a K+/H+ ATPase!
| Cl- hops a ride with H thus HCl is born
