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_Physiology Exam 6 > 3/30: Accessory GI Organs > Flashcards

3/30: Accessory GI Organs Flashcards

1
Q

Is the pancreas exocrine or endocrine?

A

More than 90% is exocrine

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2
Q

What do acinar cells synthesize and secrete?

A

Hydrolases for digestion

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3
Q

What do duct cells secrete?

A

Bicarbonate and water

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4
Q

What does the pancreas have luminal digestion of?

A

Carbohydrate, protein, fat

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5
Q

What does impaired digestion function of the pancreas cause?

A

Maldigestion and malabsorption

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6
Q

What does the pancreas neutralize?

A

Gastric H+: secretes HCO3- into duodenum up to 145 mEq/l

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7
Q

How are proteolytic enzymes synthesized, stored, and secreted as?

A

Inactive precursors

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8
Q

Where are proteolytic enzymes activated in/

A

Intestinal lumen
1. Enterokinase
2. Trypsin

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9
Q

What is trypsin inhibitor synthesized, stored, and secreted with/

A

Precursors

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10
Q

What is the function of acinar cells?

A

Digestive enzyme secretion

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11
Q

What are the two stimuli for acini cell enzyme secretion?

A
  1. CCK
  2. ACh/GRP (Vagovagal reflex)
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12
Q

What are CCKs function in the gallbladder?

A

Contraction

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13
Q

What do CCKs do in the pancreas?

A

Acinar secretion

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14
Q

What do CCKs do in the stomach?

A

Stimulates receptive relaxation
Reduce emptying
Reduce HCl secretion

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15
Q

What do CCK do in the sphincter of Oddi?

A

Relaxation

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16
Q

What cells secrete CCK?

A

I cells

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17
Q

What two substances stimulate I cells to secrete CCK?

A

Monitor peptide
CCK-RP

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18
Q

What does CCK-RP need to function?

A

Fatty acids
Amino acids

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19
Q

What are the two stimuli for ductal cell secretion of H2O and HCO3?

A
  1. Secretin (secretin receptor)
  2. ACh (M3 receptor)
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20
Q

What does secretin induce when bound?

A

cAMP
Phosphorylation of CFTR
Increase Cl conductance
Increase HCO3- secretion

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21
Q

What is HCO3 bicarbonate output used as an index of?

A

Secretin release

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22
Q

What pH is secretin released at?

A

pH <4.5

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23
Q

At what pH is secretin release maximal in segment of duodenum?

A

Below pH of 3

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24
Q

What does further release of secretin depend upon?

A

Area of small intestine affected

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25
Q

When is pH rarely <3.5 or 4?

A

During a meal

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26
Q

Compare the rate of pancreatic secretion of CCK and secretin

A

HCl-
- increases levels of Water and HCO3 because HCl stimulates secretin which stimulates ductal cells to secrete water and NaHCO3

Soap-
- fatty acids
Acids secrete secretin
Fats secrete CCK

Peptone-
- increases levels of enzymes because peptides stimulate CCK which stimulates acinar cells to secrete enzymes

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27
Q

What are cephalic and gastric phases mediated by?

A

Vagovagal reflex

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28
Q

What kind of secretion is vagovagal secretion?

A

Low volume, high enzyme (Ach/GRP)

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29
Q

What does acid in the intestine stimulate?

A

Secretin -> HCO3-/H2O

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30
Q

What do fats/proteins stimulate in the intestine?

A

CCK -> Enzymes
(indirectly via CCK-RP and monitor peptide)

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31
Q

What is secretion rate proportional to?

A

[secretin], [Ach], [CCK]

32
Q

What is bicarb and chloride concentration at low secretion rates?

A

Bicarbonate concentration is low
Chloride concentration is high

33
Q

What is bicarb and chloride concentration at high secretion rates?

A

Bicarbonate concentration is high
Chloride concentration is low

34
Q

What concentrations are always the same as the plasma?

A

Sodium and potassium concentrations

35
Q

What tonicity is pancreatic juice?

A

Isotonic

36
Q

What abnormal composition is caused by cystic fibrosis?

A

Abnormal swear composition
Decreased pulmonary and pancreatic secretion

37
Q

What is the inheritance trait of cystic fibrosis?

A

Mendelian autosomal recessive occurrence

38
Q

What does a defective CFTR cause?

A

Sweat Cl- reabsorption
Pancreatic duct cell function
Pulmonary mucus clearance

39
Q

What are disorders of exocrine pancreatic function?

A

Cystic fibrosis
Pancreatitis
Duct obstruction

40
Q

What are types of pancreatitis?

A

Acute and chronic

41
Q

What causes pain and inflammation in pancreatitis?

A

Trypsin activation

42
Q

What does chronic pacreatitis destroy?

A

Acini

43
Q

What do consequences of pancreatitis reflect?

A

Decreased digestive enzyme production

44
Q

What are types of duct obstruction?

A

Gallstones
Tumors

45
Q

What happens if there are no pancreatic enzymes?

A

60% fat not absorbed (steatorrhea)
30-40% protein and carbs not absorbed

46
Q

What is the functional unit of the liver?

A

Liver lobule

47
Q

What are hepatic functions?

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 cell regenerations
48
Q

Describe the resistance of vessels to blood flow in liver

A

Very low

49
Q

What does cirrhosis do?

A

Increases resistance, produces portal hypertension

50
Q

What can increased vascular resistance cause?

A

Ascites

51
Q

What are bile salts (acids) and lecithin required for?

A

Digestion (emulsification) and absorption (micelles) of dietary fat

52
Q

What is the role of bile with excretion?

A

Excretion of lipophilic metabolites (bilirubin), excess cholesterol, other waste products, drugs, and toxins

53
Q

What do hepatocytes secrete?

A

Bile salts, cholesterol, lecithin, bilirubin, many other lipophilic substances

54
Q

What do duct epithelial cells modify?

A

Primary secretion, add HCO3

55
Q

Where is bile stored and concentrated?

A

Gallbladder

56
Q

What reabsorbs some components of bile?

A

Enterohepatic circulation

57
Q

What synthesizes and secretes bile?

A

Liver hepatocytes

58
Q

What are organic compounds that hepatocytes secrete?

A

Bile salts (produced from cholesterol)
Cholsterol
Organic substances

59
Q

What do bile duct cells secrete?

A

Water, Na and HCO3

60
Q

Describe the transport of bile

A
  1. Small intestine for fat digestion
  2. Gall bladder for storage
61
Q

What happens to someone whos had a cholecystoectomy?

A
  • no problems with fat digestion
  • bile flow directly into duodenum
62
Q

What does secretin stimulate in the gallbladder?

A

Liver ductal secretion

63
Q

What does vagal stimulation cause?

A

Weak contraction of gallbladder

64
Q

What does cholecystokinin via blood stream cause?

A
  1. Gallbladder contraction
  2. Relaxation of sphincter of Oddi
65
Q

How are substances secreted into bile by?

A

Hepatocytes

66
Q

Where are substances that are secreted into bile delivered to?

A

Lumen of ileum, then reabsorbed

67
Q

Where and how are bile salts transported?

A

To hepatocytes via sinusoids

68
Q

What transporter helps with active absorption of bile salts?

A

Apical sodium-dependent bile salt transporter (ASBT)

69
Q

What are BARI (bile acid reabsorption inhibitors)?

A

Drugs that inhibit bile recylcing

70
Q

What is BARI used for?

A

To lower LDL levels in blood

71
Q

How is LDL taken up from blood?

A

Via hepatocytes as source of cholesterol for bile salts

72
Q

What are the two types of drugs that inhibit bile recycling?

A
  1. BIle acid sequestrants
  2. ASBT inhibitors
73
Q

What do bile acid dequestrants bind to?

A

Bile salts in intestinal lumen and block transport

74
Q

What are benefits of bile acid sequestrants?

A
  • drugs work in intestinal lumen (do not need to be absorbed)
  • reduce harmful side effects
75
Q

What do ASBT inhibitors do?

A

Promising new drugs to reduce cholesterol levels in ECF

76
Q

What is low ASBT activity awssociated with?

A
  • Crohn’s dsease
  • congenital primary bile acid malabsorption
  • idiopathic chronic diarrhea
  • Irritable bowel syndrome
77
Q

What are disorders of biliary secretion?

A
  • hepatocyte dysfunction impairs bilirubin, bile salt secretion:
    drugs (acetaminophen), viral hepatitis, toxins
    fibrosis, cirrhosis
  • duct obstruction
    Gallstones, tumors
  • intestinal mucosal defects impair bile salt reabsorption

_Physiology Exam 6 (6 decks)

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