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Patho 2 > 2 - Gastrointestinal 02 > Flashcards

2 - Gastrointestinal 02 Flashcards

(102 cards)

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1
Q

What causes acute pancreatitis?

A

Pancreatic secretions build up in the pancreas and overwhelm the effects of trypsin inhibitor

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2
Q

Where is pancreatic bicarb secreted?

A

Mainly in the epithelial cells in the ductules and ducts leading from the acini

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3
Q

What are the basic stimuli for pancreatic secretion?

A
  1. Acetylcholine
  2. Cholecystokinin (CCK)
  3. Secretin
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4
Q

Describe the cephalic phase of pancreatic secretion

A

acetylcholine released by the vagus causes moderate amounts of secretion (20%) into the acini

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5
Q

Describe the gastric phase of pancreatic secretion

A

nervous stimuli accounts for 5-10% of secretion

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6
Q

During what phase does pancreatic secretion become copious?

A

Intestinal Phase

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7
Q

________ stimulates copious secretion of bicarb ions, which neutralizes acidic stomach chyme in the intestines

A

secretin

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8
Q

Describe the intestinal phase of pancreatic secretion

A

Acid from the stomach releases secretin from the wall o fthe duodenum

Fats and amino acids from the duodenum release CCK

Secretin and CCK are absorbed in the blood

secretion causes copious secretion of pancreatic fluid and bicarb

CCK causes secretion of enzymes

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9
Q

How much bile does the liver secrete each day?

A

600-1000 ml/day

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10
Q

Bile serves two functions:

A
  • Fat digestion*: Bile acids emulsify large fat particles and aid in absorption of digested fat through the mucosal membrane
  • Excretion*: Bile serves as a means of excretion of bilirubin and excess cholesterol (among many other things)
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11
Q

What is the purpose of the gallbladder?

A

stores and concentrates bile

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12
Q

By far the most abundant substances secreted in the bile are:

A

bile salts

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13
Q

What substance stimulates gallbladder emptying?

A

CCK

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14
Q

gallbladder emptying requires relaxation of the _______

A

sphincter of oddi

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15
Q

The precursor of the bile salt is:

A

cholesterol

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16
Q

Without the presence of bile salts, what would happen?

A

40% of ingested fats would be lost into the feces

often leads to a metabolic deficit

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17
Q

What percentage of bile salts used in the intestines are reabsorbed into the blood?

A

95%!

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18
Q

Why does chronic inflammation of the gallbladder lead to gallstones?

A

Changes the absorptive characteristics of the GB mucosa

Allows excessive absorption of water and bile salts, but leaves behind cholesterol

Cholesterol gets more and more concentrated

Begins to precipitate and form crystal, which progress to gallstones

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19
Q

Secretion of mucus into the small intestine is acheived by _______ glands

A

Brunner’s Glands

located in the wall of the first few cm of the duodenum

Makes sense, because this is the area right before bicarb rich secretions from the pancreas and GB enter via the sphincter of oddi

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20
Q

Why do peptic ulcers often occur in the duodenum, as well as the stomach?

A

Brunner’s glands are inhibited by sympathetic stimulation, leaving the duodenal bulb unprotected

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21
Q

What are the crypts of liberkuhn?

A

small pits over the entire surface of the SI

Comprised of goblet cells and enterocytes

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22
Q

What are enterocytes?

A

Cells that secrete large quantities of water and electrolytes

reabsorb the water and electrolytes along with the end products of digestion

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23
Q

They crypts of Lieberkuhn produce marked secretion of watery fluid into the intestines. How do they do this?

A
  1. actively secrete Cl
  2. Actively secrete bicarb

Secretion of these causes an electrical drag of positively charged Na ions through the membrane into the secreted fluid

This mass movement causes osmotic movement of water into the gut

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24
Q

What is the life cycle of an intestinal epithelial cell?

A

5 days

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25
The most important regulator of SI secretion is:
local enteric nervous reflexes
26
How dose the mucosa of the LI differ from the SI?
Both have crypts of lieberkuhn but the LI contains no villi The epithelial cells only secrete mucus
27
What does elevated Parasympathetic stimulation of the LI cause?
Excess mucus secretion Ropy, mucoid diarrhea
28
What are polyscaccharides? How are they formed?
monosaccharides bound to one another by *condensation*: A H+ is removed from one monosaccharide and the OH- is removed from another to form water
29
What is hydrolysis?
The opposite of condensation returning the H and OH from H2O, thereby separating polysaccharides into monosaccharides
30
Almost the entire fat portion of the diet consiste of \_\_\_\_\_\_
triglycerides
31
What is the composition of a triglyceride?
Three fatty acid molecules condensed with a single glycerol
32
How is the digestion of carbs, fats, and proteins similar? How is it dissimilar?
All three are broken down by hydrolysis The only difference is the types of enzymes required to promote hydrolysis for each type
33
All of the digestive enzymes are \_\_\_\_\_\_\_
proteins
34
Where does carbohydrate digestion begin?
The mouth
35
Starches and maltose are broken down into \_\_\_\_\_\_\_ Lactose is broken down into \_\_\_\_\_\_\_ Sucrose is broken down into \_\_\_\_\_
Glucose Galactose and Glucose Fructose and Glucose
36
Proteins are amino acids bound by
peptide linkages
37
Why is cholesterol considered to be a fat if it contains no fatty acids?
Sterol compound, but it exhibits similar physical and chemical characteristics derived from fats and metabolized similarly
38
Most protein digestion results from:
pancreatic proteolytic enzymes: trypsin, chymotripsin, carboxypolypeptidase, elastase
39
Where are peptides finally broken down into amino acids?
inside the cytosol of the enterocyte
40
What is the first step in fat digestion?
Emulsification of fat by bile acids and lecithin
41
Why is it so critical that fats be emulsified?
Lipases are water soluble. They can only attach fat globules on their surface, so the surface area has to be high
42
What is the role of bile salts in fat digestion?
They aid in reabsorption by forming micelles They "ferry" nonsoluble fatty acids from to the brush border epithelial cells They are absorbed into the blood via the epithelium
43
No cholesterol is absorbed from the gut without the help of:
bile salt micelles
44
Why is the stomach such a poorly absorptive area?
lacks villus tight cell junctions
45
Only highly _____ soluble substances can be absorbed in small quantities from the stomach
lipid aspirin and alcohol
46
What are valvulae conniventes
Folds of Kerckring increase the surface area of the absportive mucosa by about three-fold
47
Describe how the intestinal mucosa surface area is increased
Folds of Kerckring (3x) Villi (10x) Brush border (microvilli) (20x) Combined, increase absoprtive area by 1000x
48
How is sodium reabsorbed from the gut
Actively pumped out of epithelial cells into the blood via ATPase pump, which reduces the sodium concentration inside the cell sodium moves down this steep gradient from the chyme into the epithelial cell
49
Aldosterone triggers intestinal sodium reabsorption primarily in the:
Large intestines
50
How is bicarb reabsorbed in the small intestines?
Sodium-hydrogen countertransport These H+ ions combine with HCO3 to form H2CO3 Converted into H2O and CO2 CO2 is blown off through the lungs
51
What role does the Large Intestine play in bicarb regulation?
Can secrete HCO3- in exchange for absorption of Cl- Provides the LI with bicarb to neutralize the acid products formed by bacteria
52
How does cholera cause life-threatening diarrhea?
Cholera toxin enters epithelial cells and stimualtes cAMP formation Opens tremendous numbers of Cl channels, allowing Cl to flow rapidly from inside the cell tot he intestines activates a sodium pump that pumps sodium ions into the crypts to keep a net charge Water pours into the gut
53
Besides sodium, what electrolytes are actively reabsorbed in the intestines?
calcium, iron, potassium, magnesium phosphate
54
How is glucose reabsorbed?
Transported by a sodium co-transport (SGLT1) into the epithelial cell diffues through GLUT2 into the blood
55
How much sodium and chloride are lost in the feces each day?
Almost none
56
What are alternative names for the proximal and distal colon
Correspond with their roles: absorbing colon storage colon
57
How does sodium transport in the LI differ from the SI?
LI has much tighter junctions, so there is less backleak the LI can absorb sodium ions more completely and against a stronger gradient, especially when aldosterone is present This means the LI is also ideal for reabsorbing water
58
How much fluid can the intestines absorb each day?
5-8 L the rest is excreted as feces
59
What is the composition of feces?
75% water 25% solid matter which is composed of: dead bacteria, fat, inorganic matter, protein, and roughage
60
What causes the brown color of feces?
stercobilin and urobilin, both derivatives of bilirubin
61
What causes the odor of feces?
bacterial actions produce: indole skatole mercaptans and hydrogen sulfide
62
\_\_\_\_\_\_\_, \_\_\_\_\_\_\_, and ________ increase the rate of gastric motility. How?
Gastrin Motilin Vagus PNS Lower the threshold potential
63
\_\_\_\_\_\_ and _____ decrease gastric motility. How?
SNS Secretin raise the threshold potential
64
What stimulates secretion of CCK? What does it do?
products of fat digestion in the duodenum inhibits food intake reduces gastric motility decreases gastric emptying
65
What is the effect of hyperglycemia on gastric emptying? Hypoglycemia?
Decreases Increases
66
Parietal cells secrete what? (3)
HCl intrinsic factor gastroferrin
67
Chief cells secrete what?
pepsinogen acidic lipase
68
In the pyloric glands, G cells secrete \_\_\_\_\_\_ Enterochromaffin-like cells secrete \_\_\_\_\_\_ and D cells secrete \_\_\_\_\_\_
gastrin histamine somatostatin
69
What are the three main actions of gastric HCl?
1. dissolve food 2. act as a bactericide 3. convert pepsinogen to pepsin
70
A high rate of gastric secretion results in _______ in the venous blood
"alkaline tide" may result in alkaline urine as well
71
What hormones inhibit gastric acid secretion?
Somatostatin secretin CCK GLP1 ANP Prostaglandins
72
What stimulates acid secretion?
vagus nerve --\> Ach--\>Gastrin --\>Histamine--\> Parietal cells make acid ALSO: caffeine calcium ghrelin
73
What is special about gastric lipase?
Unlike pancreatic and intestinal lipases, it can be active in an acidic environment
74
\_\_\_\_\_\_\_\_\_ and ________ protect the mucosal barrier by stimulating secretion of mucus and bicarb and inhibiting acid secretion
prostaglandins nitric oxide
75
The cephalic phase of gastric secretion is mediated by the ______ nerve via the _____ plexus
vagus myenteric
76
Hyperglycemia inhibits _______ and increases _______ in the stomach
motility secertion
77
What are the two main stimuli of the gastric phase?
1. distention of the stomach (vagus and enteric local reflex) 2. prescen of digested protein (stimulates gastrin)
78
Trace the small intestines
duodenum treitz ligament jejunum ileum ileocecal valve
79
The digestion and absorption of fat occurs in four phases:
1. emulsification and lipolysis 2. micelle formation 3. fat absorption 4. resynthesis of triglycerides and phospholipids
80
Calcium is primarily reabsorbed in the:
ileum
81
Why are bile salts important in the regulation of calcium uptake
Bile salts enhance calcium absorption by facilitating the absorption of Vitamin D, which is fat soluble Anything that decreases fat absorption will decreases Ca levels
82
Following a massive hemorrhage, the intestinal cells will start reabsorbing more iron after about three days. Why?
Intestinal stem cells in the crypts of Lieberkuhn sense the need they take three days to develop and migrate to the tips of the villi, where they absorb iron
83
Ileogastric reflex inhibits _____ when \_\_\_\_\_\_
gastric motility ileum is distended
84
Intestinointestinal Reflex inhibits _______ when \_\_\_\_\_\_
intestinal motility one part of the intestines is overdistended or irritated
85
Gastroileal reflex stimulates ______ when \_\_\_\_\_
ileal motility and relaxation of ileocecal sphincter gastric motility and secretion is increased
86
Trace the large intestines
cecum ascending transverse descending sigmoid rectosigmoid sphincter internal anal sphincter external anal sphincter
87
What are paneth cells?
small intestinal cells near the crypts produces defensins and other antimicrobial peptides and lysosomes
88
What are peyer patches?
lymph nodules in the SI containing collections of lymphocytes, plasma cells, and macrophages Play a major role in antigen processing and immune defense
89
What is special about intestinal macrophages?
When they phagocytize pathogenic bacteria, they don't produce any harmful cytokines
90
What is the largest solid organ in the body?
Liver
91
What are kupffer cells?
liver macrophages largest population of tissue macrophages in the body central to innate immunity and healing after liver injury Also produce bilirubin
92
List the cells in the liver involved in immunity
Kupffer (macrophages) Stellate Natural Killer Cells
93
What is a choleretic agent?
Substance that stimulates the liver to secrete bile
94
List 4 choleretics
1. high concentration of bile salts 2. secretin 3. CCK 4. Vagal Stimulation
95
What happens to heme and globin once they are separated?
Globin is further broken down in AAs which are recycled to make proteins Heme is converted biliverdin and iron Iron attaches to transferrin and is stored in the liver or used by the bone marrow to make new RBCs Biliverdin is converted to bilirubin and released into the plasma, where it binds to albumin Bound to albumin it is called "unconjugated bilirubin"
96
What happens to unconjugated bilirubin?
In the plasma, serves as an antioxidant and provides cytoprotection Once it gets to the liver, converted to water-soluble conjugated bilirubin Excreted in the bile
97
What happens to conjugated bilirubin after it's been secreted in bile?
Once it makes its way from the duodenum to the distal ileum, it is deconjugated by bacteria and converted to urobilinogen Urobilinogen is reabsorbed in the intestines and transported to the kidney Excreted as urobilin Gives urine its yellow color
98
How are amino acids converted to carbohydrates?
Deamination Removal of Ammonia
99
Why is elevated LDH indicative of hemolysis?
LDH is largely found inside RBCs
100
Why are elevated ALT and AST indications of liver damage?
Both are enzymes in hepatocytes that are critical in deamination If they are present in the blood stream, it means liver cells are breaking down and these enzymes are escaping
101
How long does the liver store Vitamin A?
Several years!
102
Why is the exocrine pancreas called "exocrine"
it's secreting substances into the inner lumen of the intestines, which is actually the outside of the body

Patho 2 (24 decks)

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