Pancreas and Liver Physiology Flashcards

GI Physiology

1
Q

What does a pancreatic islet contain?

A

Alpha cells
Beta cells and Exocrine acinus

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2
Q

What are the two endocrine functions of the pancreas?

A

Produces hormones e.g. insulin and glucagon
Hormones secreted directly into bloostream

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3
Q

What are the three exocrine functions of the pancreas?

A

Pancreatic juice
Site of action is the small intestine
Duct mediated secretion similar to salivary secretion

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4
Q

What is the microscopic structure of the pancreas similar to?

A

salivary glands - secretory

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5
Q

what do the pancreatic secretions move through, into what?

A

they move through intercalated ducts into one large duct - and then secretes into duodenum

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6
Q

in most species, where does the pancreatic duct secrete directly into?

A

directly into the duodenum

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7
Q

In goats and sheep, where does the pancreatic duct join the common bile duct?

A

joins BEFORE the entrance into the duodenum

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8
Q

what enters the duodenum from the pancreas?

A

A mixture of bile and pancreatic juice enters the duodenum

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9
Q

what does a lower concentration of HCO3- and Cl- determine about the secretion rate?

A

the lower the conc = the faster the secretion rate

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10
Q

what enzymes are found in the pancreatic juice?

A

lipase, amylase and proteases

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11
Q

what does lipase do?

A

it breaks down fat, glycerol and fatty acids

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12
Q

what does amylase do?

A

it breaks down starch, glucose and maltose

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13
Q

what do proteases do?

A

they break down peptides and amino acids

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14
Q

what form are all enzymes secreted in?

A

all secreted in their inactive form

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15
Q

what are inactive precursors?

A

the inactive forms of enzymes

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16
Q

what does trypsin do?

A

it activates all enzymes

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17
Q

what enzyme is an autocatalyst?

A

trypsin

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18
Q

what is autocatalysis?

A

the process where the reaction product is also the catalyst for the reaction

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19
Q

what does trypsin inhibitor do?

A

it can limit innapropriately activated trypsins

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20
Q

what is trypsin secreted as?

A

secreted as trypsinogen

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21
Q

where is trypsin formed and what forms it?

A

it is formed in the duodenum and it is formed by enteropeptidase

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22
Q

which cells secrete trypsin inhibitor?

A

gland cells

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23
Q

what is produced in large volumes?

A

pancreatic juice

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24
Q

describe the pH of pancreatic juice?

A

alkaline

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25
Q

why is pancreatic juice alkaline?

A

due to the HCO3- ions

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26
Q

Point of the pancreatic juice being alkaline?

A

it neutralises ingesta/chyme that is entering the duodenum from the stomach

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27
Q

Why is it good that the pancreatic juice is alkaline?

A

it prevents injury to mucosa
it provides the optimal pH for enzymatic activity

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28
Q

how many phases of juice secretion are there?

A

3 phrases

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29
Q

what are the three phases of pancreatic juice secretion?

A

cephalic phase
gastric phase
intestinal phase

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30
Q

what occurs during the cephalic phase of pancreatic juice secretion?

A

changes that occur before food enters the stomach - prehension, mastication and deglutition

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31
Q

what occurs during the gastric phase of pancreatic juice secretion?

A

changes in digestive tract motility initiated in the stomach - peristalsis and churning of food as a trigger

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32
Q

what does feeding result in for most species? what’s different for pigs and horses?

A

increases enzyme production in most species - increase in secretion of pancreatic juice HOWEVER pigs and horses there are also increases in water and ion secretion

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33
Q

what occurs during the intestinal phase of pancreatic juice secretion?

A

chyme entering the duodenum causes increases in pancreatic secretion - this is regulated by CCK and secretin

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34
Q

What feedback system is secretin involved in?

A

it is involved in the negative feedback system

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35
Q

when and where is secretin released from?

A

it is released from duodenum upon increased acidity

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36
Q

what is secretin?

A

it is a neuroendocrine peptide hormone

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37
Q

what does secretin have action on?

A

many organ systems

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38
Q

where is secretin secreted from?

A

secrteed by the S cells of the duodenum

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39
Q

what does the release of secretin stimulate?

A

stimulates HCO3- secretion - neutralisation function

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40
Q

when does secretin production reduce?

A

once acid in the duodenum decreases

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41
Q

what does CCK stand for?

A

Cholecystokinin

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42
Q

what is CCK?

A

it is a peptide hormone secreted by the duodenum

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43
Q

when is CCK released?

A

when FAs and peptides/amino acids increase in duodenum

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44
Q

what does CCK stimulate?

A

it stimulates the pancreas to increase enzyme secretior and increases bile secretion

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45
Q

what effect does CCK have on enzymes?

A

it results in increased enzymes = increased ingesta degradation

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46
Q

overall, CCK results in?

A

increased products of digestion

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47
Q

what feedback system is CCK involved in?

A

positive feedback system

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48
Q

rate of secretion of pancreatic juice comparison between ruminants, horses and cats&dogs?

A

ruminants - constant rate of secretion and chyme transport
horses - increase in rate of rate of secretion within a few minutes of feeding starting –> low levels of enzymes due to microbial degradation
Cats&Dogs - great increase in amount of juice produced after feeding
little production when small intestine is empty

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49
Q

How many roles of the liver are there?

A

9

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50
Q

Role one of the liver:

A

The liver handles nutrients absorbed from the intestine and regulates their release into the blood

51
Q

Role two of the liver:

A

Inactivating substances (toxins and drugs)

52
Q

Role three of the liver?

A

Conversion of lipid soluble substances to water-soluble metabolites

53
Q

Role four of the liver:

A

excretion of substances

54
Q

role five of the liver?

A

production of plasma proteins

55
Q

role six of the liver?

A

production of blood coagulation factors

56
Q

role seven of the liver?

A

excretion of bile pigments

57
Q

role eight of the liver?

A

production of cholesterol

58
Q

role nine of the liver?

A

bile production BY hepatocytes

59
Q

what is bile made from?

A

made from cholesterol

60
Q

what type of processes are involved in bile production?

A

active processes - active transport

61
Q

what are bile salts transported into?

A

transported from the hepatocytes into bile canaliculi

62
Q

What is the journey for bile from bile canaliculi?

A

Bile canaliculi gradually feed into larger canals and then into the common bile duct

63
Q

What part of the bile salts is produced from cholesterol?

A

BILE ACIDS

64
Q

What are conjugated bile acids?

A

they are bile acids that are bound to amino acids

65
Q

what do conjugated bile acids do?

A

they attract sodium to become bile salts

66
Q

what do bile salts do?

A

they digest fat in the intestine

67
Q

what do the hepatocytes in bile secrete?

A

phospholipids and cholesterol

68
Q

function of phospholipids in liver?

A

aid with fat digestion

69
Q

function of cholesterol in liver?

A

waste product

70
Q

what is happening at the gall bladder?

A

site of storage for bile when no digestion is occurring

71
Q

what is extending from the common bile duct?

A

a side duct to the gall bladder

72
Q

contraction of gall bladder is controlled by what?

A

CCK

73
Q

What is the sphincter of Oddi?

A

band of smooth muscle cells between the bile duct and duodenum

74
Q

Solubility of bile salts? meaning…

A

they are not soluble meaning they are not absorbed by diffusion from the small intestine

75
Q

what is enterohepatic circulation?

A

when bile salt molecules are returned to the liver

76
Q

where do bile salts function and where do they get absorbed?

A

they function throughout the entire length of the small intestine before being absorbed at its end

77
Q

what type of organ is the pancreas?

A

a secretory organ

78
Q

pancreatic duct joins with bile duct and then into the duodenum?

A

sheep, rodents, humans etc.

79
Q

chyme pH?

A

really acidic

80
Q

point of bicarbonate?

A

instantly neutralises the acidic chyme

81
Q

what animals don’t have amylase in their saliva?

A

dogs

82
Q

ogen? e.g. pepsinogen

A

this enzyme is an inactive precursor

83
Q

which is the master regulator that activates all other enzymes?

A

trypsin - release as trypsinogen

84
Q

importance of inhibitors?

A

if none, there might be not enough food components for trypsin to break up so instead it gets ‘bored’ and starts breaking down small intestines

85
Q

alkaline carbonates function?

A

break down connective tissue in ‘meaty’ meals

86
Q

how many phases of pancreatic juice secretion are there?

A

3

87
Q

when we are eating, tasting, smelling the food what messages are sent to brain by what nerve?

A

by vagus nerve

88
Q

in which stage of pancreatic juice secretion do enzyme rich secretions occur?

A

gastric phase

89
Q

what does chyme entering the duodenum result in?

A

an increase in pancreatic secretions

90
Q

when is secretin released

A

when pH drops below 4.5

91
Q

where is secretin secreted?

A

mucosa in duodenum

92
Q

2 hormones that stimulate intrinsic phase?

A

secretin and CCK

93
Q

CCK is going to be released as long as…

A

we’re receiving products from the stomach

94
Q

apetite suppressant?

A

CCK - males are less susceptible to CCK

95
Q

Ruminants - how much pancreatic juice made in 24 hours?

A

4-5L

96
Q

horses - level of pancreatic enzymes in juice?

A

low levels

97
Q

how much pancreatic juice does a horse produce in 24 hours?

A

30-35L

98
Q

how much pancreatic juice will a 20kg dog produce?

A

2-3 ml/min

99
Q

why does liver convert lipid soluble substances to water soluble substances?

A

so that they can be excreted

100
Q

portal triad, what is it made up of?

A

arterioles of hepatic artery, portal venule and bile duct

101
Q

bile canulili?

A

form between tight junctions of cells

102
Q

caniliculi?

A

increases surface area

103
Q

two most common bile acids

A

coalic acid, keodnocoalic acid

104
Q

what makes bile acids attracted to sodium in order to become bile salts?

A

when the bile acids bind to amino acids

105
Q

other lipids found in bile?

A

phospholipid
cholesterolb

106
Q

bile is 95%?

A

water

107
Q

bile leaving bile duct controlled by?

A

sphincter of Oddi

108
Q

5% of bile salts?

A

excreted in faeces

109
Q

return to liver?

A

hepatic… circulation route

110
Q

regulation of bile secretion stimulated by?

A

by increased parasympathetic activity mediated via vagal nerves and secretin

111
Q

what is the most important factor determning the volume of bile?

A

the amount of bile salts in the bile canaliculi

112
Q

what happens when the conc of bile salts in the portal blood rises?

A

the amount of bile released from the hepatocytes increases

113
Q

between meals, where is bile stored?

A

in gall bladder

114
Q

when is bile production the greatest?

A

when bile salts recirculate after a meal

115
Q

when does blood concentration of bile salts and therefore excretion of bile salts remain low?

A

in between meals

116
Q

how does secretin regulate bile secretion?

A

release stimulated by acidic duodenal content
causes increase of HCO3- from pancreas
Causes increase of bile production

117
Q

when will the sphincter of Oddi be closed and the gall bladder relaxed?

A

when there is no food in the small intestine

118
Q

what happens to bile in the gall bladder?

A

bile gets concentrated in the gall bladder - ions get actively transported out of the bile - water follows by osmosis as a water potential gradient is formed

119
Q

which species do not have a gall bladder?

A

horses, trickle feeders, constantly eating

120
Q

after a meal, what happens to the gall bladder and sphincter of Oddi?

A

the gall bladder contracts and the sphincter of Oddi opens

121
Q

after a meal, what happens in response to CCK?

A

fat and peptides in the duodenum cause CCK release
ensuring pancreatic and hepatic secretions coincide

122
Q

what happens when fat digestion is complete?

A

the stimulus for CCK release is removed and bile is stored in the gall bladder

123
Q

describe fat digestion in dogs and cats?

A

fat digestion is intermittent therefore bile is not present in the intestine all the time - very useful to have a gall bladder

124
Q

describe the gall bladder of a ruminant?

A

gallbladder has a short retention time - poorly developed concentrating mechanism