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Physiology > GI 4 > Flashcards

GI 4 Flashcards

1
Q

More than —% of pancreas is exocrine:
– Acinar cells synthesize
and secrete
– Duct cells secrete

A

90
hydrolases for digestion
bicarbonate and water

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2
Q

Luminal digestion of (3)

– Impaired function causes (2)

A

carbohydrate, protein, fat.

maldigestion and malabsorption.

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3
Q

Neutralizes gastric H+:
secretes HCO3- into
duodenum up to

A

145 mEq/L

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4
Q 
Proteolytic enzymes 
synthesized, stored and 
secreted as inactive 
precursors.
- Activated in intestinal 
lumen (2)
A
  1. Enterokinase

2. Trypsin

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5
Q

—- synthesized, stored and

secreted with precursors.

A

Trypsin inhibitor

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6
Q

Regulation of Acinar Cell Secretion

Function =

A

Digestive Enzyme Secretion

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7
Q 
Two Stimuli for Acini Cell 
Enzyme Secretion (2)
A
  1. CCK

2. ACh/GRP (vagovagal reflex)

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8
Q

Two Stimuli for Ductal Cell

Secretion of H2O and HCO3- (2)

A
  1. *Secretin (Secretin receptor).

2. Ach (M3 receptor).

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9
Q

Secretin (4)

A 
 cAMP
 Phosphorylation of 
CFTR
 increase Cl- conductance
 increase HCO3- secretion
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10
Q

Secretin released when pH

A

< 4.5.

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11
Q

Below pH = 3,

A 
secretin 
release is maximal in segment 
of duodenum. Further release 
of secretin depends upon area 
of small intestine affected.  
(Maximal bicarbonate 
response is 30 mEq/hr)
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12
Q

During meal pH rarely

A

< 3.5 or 4.0.

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13
Q

Phases of Pancreatic Secretion (3)

A

 Cephalic (20%)
 Gastric (5-10%)
 Intestinal (70-80%)

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14
Q

 Cephalic (20%)
 Gastric (5-10%)
Both phases mediated by

A

vagovagal
reflex - low volume, high enzyme
secretion (Ach/GRP)

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15
Q

(2) both potentiate the effects of secretin on water and

bicarbonate secretion.

A

CCK and Ach

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16
Q

Secretion Rate α

A

[Secretin] + [Ach] + [CCK]

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17
Q

Low secretion rates - (2)

A

 bicarbonate concentration is low

 chloride concentration is high

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18
Q

High secretion rates - (2)

A

 bicarbonate concentration is high

 chloride concentration is low

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19
Q

Sodium and potassium concentrations

always same as —

A

plasma

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20
Q

Pancreatic juice is —

A

isotonic

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21
Q

Cystic Fibrosis (3)

A 
 Abnormal sweat composition.
 Decreased pulmonary and pancreatic 
secretion.
 Mendelian autosomal recessive 
occurrence.
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22
Q

Defective CFTR: (3)

A

– Sweat Cl- reabsorption;
– Pancreatic duct cell function;
– Pulmonary mucus clearance.

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23
Q

Disorders of Exocrine Pancreatic

Function (3)

A

 Cystic Fibrosis
 Pancreatitis
 Duct Obstruction

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24
Q

Pancreatitis (4)

A 
– Acute and chronic
– Trypsin activation causes pain, 
inflammation
– Chronic disease destroys acini
– Consequences reflect decreased 
digestive enzyme production
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25
Q

Duct Obstruction (2)

A

– Gallstones

– Tumors

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26
Q

Without pancreatic

enzymes - (2)

A 
 60% fat not absorbed 
(steatorrhea)
 30-40% protein and 
carbohydrates not 
absorbed
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27
Q

Functional Unit of liver =

A

Liver

Lobule

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28
Q 
skipped
Hepatic Function (7)
A

Cleansing and storage of blood
Metabolism of nutrients
Synthesis of proteins (coagulation factors,
plasma proteins, angiotensinogen)
Metabolism of hormones, chemicals
Storage of energy, vitamins, iron
Excretion of lipid-soluble waste products
Marked capacity for cellular regeneration

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29
Q

Secretion of bile –

A

600-1000 ml/day

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30
Q

Liver Has High Blood and Lymph Flow

 Total blood input approaches

A

1,350 ml/min (27% of resting

cardiac output).

31
Q

Liver Has High Blood and Lymph Flow
 Resistance of vessels to blood
flow very —

A

low

32
Q

Cirrhosis increases resistance,

produces

A

portal hypertension.

33
Q

Hepatic lymph accounts for –%

of total body production.

A

50

34
Q

Increased vascular resistance can

cause —.

A

ascites

35
Q

Role of Bile (2)

A 
1. Bile salts (acids) and 
lecithin required for 
digestion (emulsification) 
and absorption (micelles) of 
dietary fat.
2. Excretion of lipophilic 
metabolites (bilirubin), 
excess cholesterol, other 
waste products, drugs, and 
toxins.
36
Q

Hepatocytes secrete (5)

A 
bile salts, 
cholesterol, 
lecithin, 
bilirubin, 
many other lipophilic substances.
37
Q

Duct epithelial cells modify —, add —

A

primary secretion

HCO3-

38
Q

Storage and concentration in —.

A

gallbladder

39
Q

— circulation reabsorbs some

components.

A

Enterohepatic

40
Q

Hepatocytes secrete
organic component of
bile into bile ducts (3)

A
  • Bile Salts (produced
    from cholesterol)
  • Cholesterol
  • Organic substances
41
Q

Bile Duct cells secrete (3)

A

water, Na+ and HCO3-

42
Q

Bile Transported (2)

  1. Small intestine for
  2. Gall Bladder for
A

fat digestion

storage

43
Q

Bile secreted — by liver

A

continually

44
Q

Most stored in

A 
Gall Bladder 
(max. volume = 30-60 ml)
45
Q

12 hours of liver bile secretion

or — ml bile (concentrated)

A

450

46
Q

(2) reabsorbed from bile while in
Gall Bladder (5-20x more
concentrated)

A

Electrolytes and water

47
Q

Cholecystectomy (2)

A

 No problems with fat digestion

 Bile flow directly into duodenum

48
Q

Enterohepatic Circulation Conserves Bile Salts
Substance secreted into
bile by

A

hepatocytes.

49
Q

Enterohepatic Circulation Conserves Bile Salts
Delivered to lumen of
—, then reabsorbed.

A

ileum

50
Q

Enterohepatic Circulation Conserves Bile Salts
Transported to
hepatocytes via —

A

sinusoids

51
Q

Enterohepatic Circulation Conserves Bile Salts
—% of bile salts
recirculated

A

94

52
Q

Enterohepatic Circulation Conserves Bile Salts
Bile salts circulate –x
before lost in feces.

A

17x

53
Q

Active absorption: (2)

A

Apical sodium-dependent bile salt
transporter (ASBT)
ASBT also present in renal PT

54
Q

BARI (Bile Acid Reabsorption Inhibitors) (4)

A

Drugs that inhibit Bile Recycling
Used to lower LDL levels in blood
Hepatocyte production of bile increases
6-10x if bile salt recycling reduced.
LDL taken up from blood via hepatocytes
as source of cholesterol for bile salts

55
Q

Types:

1. Bile acid sequestrants

A

Bind to bile salts in intestinal lumen and

block transport

56
Q

Benefits: (2)

A

Drugs work in intestinal lumen (do not
need to be absorbed)
Reduce harmful side effects

57
Q

Low ASBT Activity Associated with: (4)

A

Crohn’s disease
Congenital 1° bile acid malabsorption
Idiopathic chronic diarrhea
Irritable Bowel Syndrome

58
Q

Hepatocyte dysfunction impairs (2) secretion:

A

bilirubin, bile salt

59
Q

Hepatocyte dysfunction impairs bilirubin, bile

salt secretion: (2)

A

– Drugs (acetaminophen), viral hepatitis, toxins;

– Fibrosis, cirrhosis.

60
Q

Duct obstruction: (2)

A

– Gallstones, tumors.

61
Q

Intestinal mucosal defects impair`

A

bile salt

reabsorption.

62
Q

Stimuli for Gut Hormone Secretion

Gastrin (stomach) (3)

A

 amino acids and peptides
 distention
 (H+ inhibits)

63
Q

Stimuli for Gut Hormone Secretion

Ghrelin (stomach) (2)

A

 absence of nutrients

 (inhibited by stretch)

64
Q

Stimuli for Gut Hormone Secretion

Secretin (Small Intestine) (1)

A

 H+

65
Q

Stimuli for Gut Hormone Secretion

CCK (Small Intestine) (3)

A

 amino acids and peptides
 fatty acids
 Indirectly via secretion of CCK-
RP and Monitor peptide

66
Q

Stimuli for Gut Hormone Secretion

GIP, GLP-1 (Small intestine) (1)

A

 Glucose

67
Q

Stimuli for Gut Hormone Secretion

Motilin (Small Intestine) (2)

A

 stimulus unknown
 some studies suggest that an
alkaline pH in the duodenum
stimulates its release.

68
Q

Endocrine Regulation: Specific Actions of Each Hormone

Gastrin (4)

A

↑ Histamine Release (ECL cell)
↑ H+ Secretion (Parietal Cell)
↑ Gastric emptying
Trophic affects on Mucosa

69
Q

Endocrine Regulation: Specific Actions of Each Hormone

Ghrelin (1)

A

↑ Hunger

70
Q

Endocrine Regulation: Specific Actions of Each Hormone

Motilin (2)

A

↑ Gastric Motility (MMC/Fasting)

↑ Intestinal Motility (MMC/Fasting)

71
Q

Endocrine Regulation: Specific Actions of Each Hormone

GIP, GLP-1 (3)

A

↑ Insulin response to glucose
↓ Gastric Acid Secretion
↓ Gastric emptying

72
Q

Endocrine Regulation: Specific Actions of Each Hormone

Secretin (4)

A

 ↑ Panc & Biliary HCO3- secretion
 Trophic affects on Exo. Pancreas
 ↓ Gastric Acid Secretion
 ↓ Gastric emptying

73
Q

skipped
Endocrine Regulation: Specific Actions of Each Hormone
CCK (7)

A 
 ↑ Pancreatic enzyme secretion
 ↑ Gall Bladder Contraction
 Trophic affects on Exo. Pancreas
 ↓ Gastric emptying
 ↓ Gastric Acid Secretion
 Relaxation of Sphincter of Oddi
 Gastric receptive relaxation

Physiology (53 decks)

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