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Year 1: Alimentary System > 6. Pancreas > Flashcards

6. Pancreas Flashcards

1
Q

What does the developing pancreas start from?

A

It arises from the foregut-midgut junction forming a ventral pancreas and dorsal pancreas

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2
Q

What is the ventral bud a part of?

A

The hepatobilary bud

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3
Q

What happens when the duodenum swings round?

A

It rotates to form a C shape - ventral pancreas swings round to lie next to the dorsal pancreas and fuse together

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4
Q

Which bud becomes the main pancreatic duct?

A

The ventral bud

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5
Q

How is the pancreas described?

A

Head, neck, body, tail and uncinate (tail)

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6
Q

Where is the highest proportion of islets of Langerhans in the pancreas?

A

Tail section

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7
Q

Where does the pancreatic juice enter?

A

Duodenum via the pancreatic duct

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8
Q

Where does the pancreas sit in?

A

The C shape of the duodenum

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9
Q

How far the does pancreas extend across?

A

It reaches the spleen

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10
Q

What is posterior to the pancreas?

A

The IVC, aorta and left kidney

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11
Q

Where does pancreas get its blood supply from?

A

The coeliac and mesenteric arteries

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12
Q

Define endocrine

A

Endocrine is secretion of hormone into the blood. (autocrine/paracrine) ductless glands

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13
Q

Define exocrine

A

Exocrine is secretion into a duct - direct local effect

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14
Q

What is insulin

A

Anabolic hormone, promotes glucose transport into cells and storage as glycogen, reduces blood glucose level, promotes protein synthesis and lipogenesis

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15
Q

What is glucagon

A

Increases gluconeogenesis and glycogenolysis (increases blood glucose)

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16
Q

What is somatostatin

A

Suppresses the release of a lot different hormones. ‘endocrine cyanide’

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17
Q

What are the two functional parts of the pancreas?

A

Endocrine and exocrine

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18
Q

How much of the pancreas is made up of endocrine glands?

A

2%

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19
Q

How much of the pancreas is made up of exocrine glands?

A

98%

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20
Q

What is an example of an endocrine gland?

A

Islets of Langerhans

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21
Q

What does the exocrine glands secrete?

A

Secretes pancreatic juice into the duodenum via the pancreatic duct/common bile duct, It has digestive function

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22
Q

How do pancreatic diseases affect the 2 functional parts of the pancreas?

A

It effects both exocrine and endorine effect e.g cystic fibrosis

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23
Q

What structures exist from the ducts of the pancreas?

A

Acini and islets

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24
Q

Where does the endocrine tissue arise from?

A

It is derived from branching duct system, loses contact with ducts to form islets

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25
Q

Where does exocrine tissue originate from?

A

Ducts which have acini

26
Q

What are acini?

A

Grape like clusters of secretory unit

27
Q

What do acini secrete?

A

They secrete pro-enzymes stored in zymogen granules into ducts

28
Q

Describe the composition of alpha, beta and delta cells in the islets of Langerhans

A

15-20% are a-cells - glucagon
60-70% are b-cells - insulin
5-10% are d-cells - somatostatin

29
Q

Why are the islets highly vascularised?

A

To ensure that all the cells have close sites for secretion

30
Q

What lines a pancreatic duct?

A

Columnar epithelium

31
Q

What are the two components of pancreatic juice?

A

Low volume, viscous, enzyme rich - acinar cells

High volume, watery, HCO3- rich - duct cells

32
Q

What are centroacinar cells?

A

Join the duct and acinar cells

33
Q

What is function of the bicarbonate secretion?

A

1) neutralises acid chyme from stomach

2) washes low volume enzyme secretion out of pancreas into duodenum

34
Q

Why is the acid chyme neutralised?

A

To prevent damage to endothelium and raise pH for optimum range for pancreatic enzymes to work

35
Q

What is the concentration of bicarbonate in the secretion?

A

120 mM

36
Q

What happens when duodenal pH falls?

A

The rate of bicarbonate secretion increases. It plateaus at pH 3

37
Q

What helps the pancreas to neutralise the acid chyme?

A

Brunners gland in the duodenum (small intestine) and bile also contains bicarbonate

38
Q

How is bicarbonate secreted out of the pancreas?

A

1) H+ and HCO3- is produced - catalysed by carbonic anydrase
2) Na+ moves into the lumen via tight junctions by diffusion. H2O follows
3) The HCO3- is then exchanged with Cl- at the lumen, driven by electrochemical gradient
4) The H+ is then exchanged with Na+ at the basal lateral membrane, driven by electrochemical gradient
5) the Na+ gradient is maintained from the sodium potassium exchange pump - uses ATP
6) Any potassium brought in by the pump then diffuses back into the blood by K-channels
7) Cl- returns to the lumen via Cl-channels, this ensures that there will still be Cl- to exchange the HCO3- with

39
Q

What does cystic fibrosis effect?

A

The CFTR, which causes the chloride channel to not work

40
Q

What is synthesised and stored in zymogen granules?

A

pro-enzymes (lipases, proteases and amylases)

41
Q

How are proteases released from the zymogen granules?

A

inactive - protects the acini and ducts from self digestion

42
Q

What prevents trypsin activation?

A

trypsin inhibitor

43
Q

When do the enzymes become activated?

A

In the duodenum

44
Q

What can cause acute pancreatitis?

A

Blockage of the pancreatic duct - overload protection causing autodigestion

45
Q

What and where is trypsin activated?

A

Activated by enterokinase in the duodenum. trypsinogen to trypsin

46
Q

How does the pancreas adapt to diet?

A

It changes the proportion of different enzymes it secretes

47
Q

What is essential for normal digestion of meal? Lack of these can lead to malnutrition

A

Pancreatic enzymes and bile

48
Q

What does orlistat do?

A

It inhibits pancreatic lipases - causing steatorrhoea (fatty stool)

49
Q

How is orlistat used?

A

Anti-obesity drug - weight loss agent

50
Q

What is the role of the vagus nerve?

A

Parasympathetic stimulation. Cholinergic and communicates information from gut to brain and vice versa

51
Q

Which phase causes most of pancreatic secretion?

A

The intestinal phase causes 70-80% of pancreatic secretion. This is hormonally mediated

52
Q

What is the bicarbonate secretion controlled by?

A

Secretin (caMP)

53
Q

What is enzyme secretion controlled by?

A

Cholecystokinin CCK (Ca2+/PLC)

54
Q

What does CCK also stimulate?

A

Bile secretion

55
Q

What do lipases need to work?

A

Bile salts

56
Q

What releases secretin?

A

H+ binds to enteroendocrine cells in the duodenum which releases secretin into the blood.

57
Q

What effect does the HCO3- have on the duodenum?

A

It increases pH in the lumen switching off secretin secretion

58
Q

What releases CCK?

A

Peptides and fats bind to enteroendocrine cells which releases CCK into the blood

59
Q

What can stimulate the acinus?

A

Vagus - ACh

CCK in the blood

60
Q

How is CCK release switched off?

A

Absorption of fats and peptides removes the local luminal stimulus for CCK release

61
Q

What has a synergistic effect on the release of bicarbonate?

A

CCK + Secretin

Year 1: Alimentary System (15 decks)

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