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A Physiology > 6.4. Exocrine secretion of pancreas and its regulation. Bile production of the liver. Metabolism and secretion of bile pigments. > Flashcards

6.4. Exocrine secretion of pancreas and its regulation. Bile production of the liver. Metabolism and secretion of bile pigments. Flashcards

1
Q

I. Pancreatic secretion
1. What are the features of Pancreatic secretion?

A

98% of pancreatic cells are responsible for exocrine secretion into the intestine

2% of the cells are responsible for endocrine secretion into the blood

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2
Q

I. Pancreatic secretion
2. What is the amount of pancreatic juice secretion per day?

A

700-900 mL/day

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3
Q

I. Pancreatic secretion
3. What are features of pancreatic juice?

A
  • Isosmotic
  • Alkaline (bc it neutralizes the acidic content)
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4
Q

I. Pancreatic secretion
4. What are the 2 Functions of pancreatic juice secretion?

A
  1. Neutralize acidic content of stomach
    - Protection of intestinal mucosae (sensitive to low pH)
    - Digestive enzymes in the small intestine require neutral pH (~7) to work
  2. Pancreatic juice contributes to digestion of the meal
    - Has many digestive enzyme
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5
Q

I. Pancreatic secretion
5. What is Sequential secretion mechanism?

A
  • Not just acinar cells, but also duct cells produce fluid (actually more)
  • The acinar cells work similarly as in the salivary gland, but there are some differences: acinar cells here produce much more enzymes (digestive enzymes)
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6
Q

II. Make a schematic diagram of function of Acinar cells

A
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7
Q

III. Duct cells
1. What is the role of duct cells?

A

produce vast majority of fluid

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8
Q

III. Duct cells
2. What are 2 types of duct cells?

A

proximal + distal

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9
Q

III. Duct cells
3A. What is the role of proximal duct cells?

A
  • H2O secretion
  • Important to wash out protein that are exocytosed by the acinar cells
    => If CFTR is mutated -> H2O transport not present => Protein clogged in the system => Pancreatitis
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10
Q

III. Duct cells
3B. Make a schematic diagram of the function of proximal duct cells?

A
  • H2O secretion
  • Important to wash out protein that are exocytosed by the acinar cells
    => If CFTR is mutated -> H2O transport not present => Protein clogged in the system => Pancreatitis
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11
Q

III. Duct cells
4A. What is the role of distal duct cells?

A

If the distal duct cell have time. they will re-absorb some HCO3- ions

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12
Q

III. Duct cells
4B. Make a schematic diagram of the function of distal duct cells?

A
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13
Q

III. Duct cells
5. What happen When we have low rate of secretion?

A
  • When we have low rate of secretion, the HCO3—secretion is not so big
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14
Q

III. Duct cells
6. What happen if the secretion rate↑?

A
  • If the secretion rate↑, then distal duct cells have no time to exchange back HCO3-
    -> [HCO3-]↑ -> pH of pancreatic juice↑
    => In response to meal: PARA activity↑ + pancreatic juice↑ + GA secretion↑
    -> except more acid coming to stomach = need more HCO3- to neutralize
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15
Q

IV. Cystic fibrosis (CF)
1. What is Cystic fibrosis (CF)?

A

A genetic disease caused by mutation in CFTR (cystic fibrosis transmembrane conductance regulator)
=> impaired Cl- secretion

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16
Q

IV. Cystic fibrosis (CF)
2. What are the consequences of Cystic fibrosis (CF)?

A
  1. Pancreas (clogging of dig.enzymes -> autodigest tissue) – pancreatitis
  2. Lungs (H2O-secretion onto the airways requires Cl—transport) -> if mutation, dense mucus-rich layer = mucociliary clearance not possible
  3. Biliary system + intestines
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17
Q

V. Regulation of pancreatic juice formation
1. What are the 2 types of Regulation of pancreatic juice formation?

A
  1. Neural regulation
  2. Hormonal regulation
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18
Q

V. Regulation of pancreatic juice formation
2A. Explain the parasympathetic regulation of pancreatic juice formation

A
  • ACh (Gq) – acinar cells -> enzyme secretion↑ (M3-R)
  • VIP (Gs) – vessels -> vasodilation -> volume of pancreatic juice↑
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19
Q

V. Regulation of pancreatic juice formation
2B. Explain the sympathetic regulation of pancreatic juice formation

A
  • NE (α1-AR) – vessels
    -> vasoconstriction
    -> pancreatic juice production↑
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20
Q

V. Regulation of pancreatic juice formation - hormonal regulation
3. What are the 2 hormones participating in hormonal regulation of pancreatic juice formation?

A
  1. Secretin
  2. CCK (cholecystokinin)
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21
Q

V. Regulation of pancreatic juice formation - hormonal regulation
4. What are the features of secretin?

A
  • Produced by S-cells in response to low pH in duodenum
  • Acts on duct cells (main site of HCO3-) => neutralize low pH
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22
Q

V. Regulation of pancreatic juice formation - hormonal regulation
5. What are the features of CCK (cholecystokinin)?

A
  • Produced by I-cells in response to protein degradation
  • ↑Pancreatic juice secretion (stimulates aff.arm of vagovagal reflexes to acinar + duct cells)
    => Secretin and CCK can enhance each other’s effect
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23
Q

V. Regulation of pancreatic juice formation - hormonal regulation
6. Explain the negative-feedback loop that responds to a fall in luminal pH in luminal pH in the duodenum
=> Make a schematic diagram if needed

A

Participation of secretion and HCO3- secretion in a classified negative-feedback loop that responds to a fall in luminal pH in luminal pH in the duodenum

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24
Q

VI. Bile
1. What are the features of biles

A
  • Is a secretory fluid that plays an important role in lipid (fat) digestion + absorption
  • Is also an excretory fluid, because that is how the body can remove certain substances (xenobiotics, drugs, cholesterol, bilirubin, heavy metals)
25
Q

VI. Bile
2. What are the features of bile production?

A
  • 200-1200 mL/day
  • Isosmotic, slightly alkaline (bc small intestine is sensitive to low pH -> needs to be neutralized)
26
Q

VI. Bile - Cell types in the liver
3. What is Hepatic triad?

A

Hepatic triad = bile duct (formed from bile canaliculi) hepatic artery, hepatic vein

27
Q

VI. Bile - Cell types in the liver
4. What are Hepatocytes?

A

modified epithelial cells (discontinuous endothelium prevents large macromolecules to pass)

28
Q

VI. Bile - Cell types in the liver
5. What are the features of paracellular and transcellular movements?

A
  • Paracellular movement = passive process
  • Transcellular movement = active/passive process
29
Q

VI. Bile
6. What is bile?

A

Bile is a mixture of hepatic bile and gallbladder bile.
=> Due to this, the dry weight composition can be different – BUT is all the time isosmotic

30
Q

VI. Bile
7A. What are the features of bile acids?

31
Q

VI. Bile
8. What are features of bile salts?

A

They are conjugated bile acids are present almost entirely as salts of various cations (mostly Na+)

32
Q

VII. Pathways for entry of solutes into bile
1. What are the Pathways for entry of solutes into bile?

A
  1. Active secretion (transcellular transport)
  2. Passive permeation (paracellular transport)
33
Q

VIII. Mechanism of bile salt secretion and bile flow
1. How are Bile acids, cholesterol and other constituents secreted?

A

Bile acids, cholesterol and other constituents are secreted into bile canaliculi from hepatocytes

34
Q

VIII. Mechanism of bile salt secretion and bile flow
2. What are the 2 types of Mechanism of bile salt secretion and bile flow?

A
  1. Bile acid-dependent flow
  2. Bile acid-independent flow
35
Q

VIII. Mechanism of bile salt secretion and bile flow
3A. Describe Bile acid-dependent flow

A
  • Result of active transport of bile acids by the
    hepatocyte into bile canaliculi
  • Secretion of bile acids across the apical membrane of hepatocytes
    => Na+-gradient maintained by ATPase
36
Q

VIII. Mechanism of bile salt secretion and bile flow
3B. Make a schematic diagram of Bile acid-dependent flow

37
Q

VIII. Mechanism of bile salt secretion and bile flow
4A. Describe Bile acid-independent flow

A

Carbonic anhydrase synthesizes HCO3-, which gets secreted into the canaliculi via HCO3-/Cl—exchanger

38
Q

VIII. Mechanism of bile salt secretion and bile flow
4B. Make a schematic diagram of Bile acid-independent flow

39
Q

IX. Describe Metabolism and excretion of bile pigment (bilirubin)

40
Q

X. Bile modification in the ductules
1. Describe Bile modification in the ductules

41
Q

X. Bile modification in the ductules
2. Make a schematic diagram of Bile modification in the ductules

42
Q

XI. Regulation of bile secretion
1. What are the 2 types of Regulation of bile secretion?

A
  1. Primary regulation
  2. Secondary regulation
43
Q

XI. Regulation of bile secretion
2. Describe primary regulation of bile secretion?

A

Primary regulation: feedback mechanism where bile concentrations are sensed in hepatic portal system and upregulation/downregulation of the bile production, absorption and excretion is altered via genetic control. (↑bile acid secretion = more bile acid formed)

44
Q

XI. Regulation of bile secretion
3A. What are the 2 types of secondary regulation of bile secretion?

A
  1. Neural control
  2. Hormonal control
45
Q

XI. Regulation of bile secretion
3B. Explain neural control of secondary regulation of bile secretion?

A
  • PARA (via vagal N activation) -> ↑bile secretion
  • SYM -> ↓bile secretion (relaxation of SMCs of gallbladder)
46
Q

XI. Regulation of bile secretion
3C. Explain Hormonal control of secondary regulation of bile secretion?

A
  • Secretin -> duct cells (CFTR↑ -> HCO3–secretion↑)
  • CCK -> enhances effect of secretin
47
Q

XI. Regulation of bile secretion
4. The secretion of the bile duct epithelium is ___ with plasma

48
Q

XI. Regulation of bile secretion
5. The secretion of the bile duct epithelium is isotonic with plasma. However, the [HCO3-] is (1)____ and the [Cl-] is (2)____ than in plasma

A
  1. greater
  2. less
49
Q

XI. Regulation of bile secretion
6A. Fill in the gap

50
Q

XI. Regulation of bile secretion
6B. Fill in the gap

51
Q

XII. Concentration of bile during storage
1. Which organ is responsible for Concentration of bile during storage?

A

gallbladder

52
Q

XII. Concentration of bile during storage in the gallbladder
2. Describe water absorption from the gallbladder

53
Q

XII. Concentration of bile during storage in the gallbladder
3. We have 900mL hepatic bile
=> What happen to this number?

54
Q

XII. Concentration of bile during storage in the gallbladder
4. What are the important parameters in relation to bile acid?

55
Q

XIII. Neurohormonal control of gallbladder contraction
1. Describe Neurohormonal control of gallbladder contraction

56
Q

XIII. Neurohormonal control of gallbladder contraction
2. The role of NO in Neurohormonal control of gallbladder contraction

A

NO (cGMP/cAMP) + VIP (Gs) will relax SMCs of sphincter of Oddi

57
Q

XIII. Neurohormonal control of gallbladder contraction
3. The role of ACh in Neurohormonal control of gallbladder contraction

A

ACh (Gq -> M1,3,5)
=> SM contraction of gallbladder

58
Q

XIII. Neurohormonal control of gallbladder contraction
4. The role of CCK (I-cells) in Neurohormonal control of gallbladder contraction

A

CCK (I-cells) -> activated by breakdown of nutrients
- Acts as a hormone -> enhances effect of ACh
- Activates vagal afferent -> vagovagal reflex

A Physiology (88 decks)

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