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GI - Year 2 > Gastric Motility and Pancreatic Function > Flashcards

Gastric Motility and Pancreatic Function Flashcards

1
Q

Where do the peristaltic waves in the stomach occur?

A

From body to antrum

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2
Q

Describe contraction in the body of the stomach?

A

Weak contraction due to thin muscle - no mixing occurs

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3
Q

Describe contraction in the antrum of the stomach?

A

Powerful contraction due to thick muscle

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4
Q

What is the 2 main roles of the pyloric sphincter contraction in gastric motility?

A

Allows only small amounts of gastric content to enter duodenum
Keeps food content in stomach and forces antral contents back towards body to mix and break down

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5
Q

How is peristaltic rhythm generated? + length

A

Generated by pacemaker cells in the longitudinal muscle layer
~3/min

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6
Q

What are slow waves caused by?

A

Spontaneous depolarisation/repolarisation

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7
Q

What is the slow wave rhythm known as?

A

Basic electrical rhythm (BER)

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8
Q

How is slow waves conducted?

A

Through gap junctions along the longitudinal muscle layer

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9
Q

How does contraction work?

A

Slow wave depolarisation subthreshold which requires further depolarisation to induce APs which causes contraction

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10
Q

How is the strength of contraction determined?

A

By the number of APs/waves

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11
Q

How does distension of the stomach wall affect contraction?

A

Distension of the stomach wall causes a stretch –> detection of solid food in stomach which causes long/short reflexes –> an increased contraction

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12
Q

What affect does gastrin have on contraction?

A

Increases contraction

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13
Q

What affect does fat/acid/amino acid/hypertonicity in the duodenum?

A

Causes inhibition of motility

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14
Q

How is acid neutralised in the duodenum?

A

Bicarbonate secretion from Brunner’s Gland duct cells (submucosal glands)

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15
Q

What happens when acid is in the duodenum?

A 
Triggers long (vagal) and short (ENS) reflexes = HCO3 secretion
Release of secretin from S cells = HCO3 secretion from pancreas and liver
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16
Q

Why is acid neutralisation essential in the duodenum?

A

Duodenum doesn’t have the same protection as the stomach against HCl because the stomach has a thick mucus layer and the duodenum doesn’t

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17
Q

How is elevated pH maintained in the duodenum?

A

By only a small amount of food being allowed to pass into the duodenum

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18
Q

What affect does secretin have?

A

Inhibits gastrin release and inhibits acid production

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19
Q

Where is the head of the pancreas located?

A

In the curvature of the duodenum

20
Q

What is the endocrine portion of the pancreas?

A 
Pancreatic islets (islets of Langerhans)
Cells produce insulin, glucagon and somatostatin
21
Q

What is the exocrine portion?

A

Acinar cells = lobules

22
Q

How are lobules connected?

A

By intercalated ducts –> intralobular ducts –> interlobular ducts –> main pancreatic duct –> common bile duct –> hepatopancreatic ampulla (sphincter of Oddi) –> duodenum

23
Q

What is the endocrine portion responsible for?

A

The control of metabolism

24
Q

Is exocrine inside or outside the body?

A

Outside but inside the lumen of the gut

25
Q

What is the sphincter of Oddi responsible for?

A

Pancreatic juice and bile into duodenum

26
Q

What shape are acinar cells?

A

Triangular cells which join together to form a spherical structure

27
Q

What are the 2 ducts that join at the hepato-pancreatic ampulla?

A

Common bile duct

Pancreatic duct

28
Q

What is the exocrine portion responsible for?

A

Digestive function of pancreas

29
Q

What is the function of the exocrine pancreas?

A

Secretion of bicarbonate by duct cells

Secretion of digestive enzymes by acinar cells

30
Q

What do acinar cells contain?

A

Digestive enzymes stored as inactive zymogen granules

31
Q

What do zymogens do?

A

Prevents autodigestion of pancreas

32
Q

What does enterokinase do?

A

Converts trypsinogen to trypsin

33
Q

Where are enterokinases?

A

Bound to brush border of duodenal enterocytes

34
Q

What does trypsin do?

A

Converts all other zymogens to active forms

35
Q

What do proteases do?

A

Cleave peptide bonds

36
Q

What do nucleases do?

A

Hydrolyse DNA/RNA

37
Q

What do elastases do?

A

Digestion of collagen

38
Q

What do phospholipases do?

A

Turns phospholipids into fatty acids

39
Q

What do lipases do?

A

Turns triglycerides into fatty acids + glycerol

40
Q

What does a-amylase do?

A

Turns starch to maltose + glucose

41
Q

What is bicarbonate secretion stimulated by?

A

Secretin

42
Q

When is secretin released?

A

In response to acid in duodenum

43
Q

What is zymogen secretion stimulated by?

A

Cholecystokinin (CCK)

44
Q

When is CCK released?

A

In response to fat/amino acids in duodenum

45
Q

How is neural control triggered?

A

By arrival of organic nutrients in duodenum

GI - Year 2 (39 decks)

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