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MBChB - Y2 - Systems - Gastrointestinal > Gastric Motility and Pancreatic Function > Flashcards

Gastric Motility and Pancreatic Function Flashcards

1
Q

What is the direction of peristaltic waves?

A

Body - antrum

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2
Q

Is there mixing in the body of the stomach?

A

Thin muscle - weak contraction - no mixing

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3
Q

Where is the powerful contraction in the stomach?

A

Antrum - thick muscle

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4
Q

What is the result of closure of the pyloric sphincter?

A

Only a small quantity of gastric content (chyme) enters the duodenum

Antral contents are forced back towards the body which results in further mixing

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5
Q

What generates the peristaltic rhythm?

A

Around 3 waves per min

•generated by pacemaker cells (in the longitudinal muscle layer)

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6
Q

What causes produces the slow waves?

A

Spontaneous depolarisation/repolarisation

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7
Q

What is the slow wave rhythm aslo known as?

A

Basic electrical rhythm

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8
Q

How are slow waves conducted?

A

Through gap junctions along the longitudinal muscle layer

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9
Q

How does the number of action potentials affect the strength of contraction?

A

More action potentials meakes a stronger contraction

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10
Q

What is the effect of gastrin on contractility?

A

Gastrin increases contractility

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11
Q

What is the effect of distension of the stomach on contractility?

A

Long/short reflexes - increased contractility

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12
Q

What is the effect of Fat/acid/amino acid/hypertonicity in duodenum on motility?

A

Inhibition of motility

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13
Q

What glands release bicarbonate in the duodenum?

A

Brunner’s glands (which are submucosal)

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14
Q

How does acid in the duodenum result in HCO3 secretion?

A

Long (vagal) & short (ENS) reflexes - HCO3 secretion (both act on brunner’s gland)

Release of secretin from S cells, resultant HCO3 secretion

  • Secretin - HCO3 secretion from pancreas & liver
  • Acid neutralisation - inhibits secretin release (negative feedback control) - When the duodenum receives sufficient bicarbonate, the acidity is reduced, so there is therefore less stimulus for the secretin production (negative feedback)
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15
Q

Where is the head of the pancreas located?

A

located within curvature of duodenum

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16
Q

What are the three parts of the pancreas?

A

Head, body and tail

17
Q

What is the endocrine portion of the pancreas?

A

Pancreatic islets (islets of langerhans)

Islet cells produce insulin, glucagon and somatostatin (controls secretion of insulin and glucagon)

18
Q

What is the exocrine portion of the pancreas?

A

Acinar cells and lobules

19
Q

What changes occur from the lubules to the duodenum?

A

Connected by intercalated ducts - intralobular ducts - interlobular ducts - main pancreatic duct - common pancreatic duct - hepatopancreatic ampulla (sphincter of oddi) - duodenum

20
Q

What is the exocrine portion of the pancreas responsible for?

A

Digestive function of the pancreas

21
Q

What are the products of duct cells and acinar cells?

A

Duct cells - bicarbonate

Acinar cells - digestive enzymes

22
Q

What is the purpose of the bicarbonate produced by the pancreas?

A

Bicarbonate keeps the pH high so that the digestive enzymes stay at their optimum pH, they would become denatured in the acidic conditions

23
Q

What is a zymogen?

A

An inactive form of an enzyme, they are found in acinar cells and are stored as granules

They prevent autodigestion of the pancreas

24
Q

How does trypsinogen get converted into trypsin?

A

•Enterokinase (bound to brush border of duodenal enterocytes) converts trypsinogen to trypsin

25
Q

What is the effect of trypsin?

A

Converts all other zymogens to active forms, it is a proteolytic enzyme

26
Q

What are the categories of pancreatic enzymes?

A
27
Q

What stimulates bicarbonate production of the pancreas?

A

Secretin, which is released in response to acid in the duodenum

28
Q

What causes the release of zymogens?

A

Cholecystokinin

29
Q

When is CCK released?

A
  • In response to fat/amino acids in duodenum
  • Also under neural control (vagal/local reflexes) - triggered by arrival of organic nutrients in duodenum
30
Q

Summary of Secretin and CCK function

A

MBChB - Y2 - Systems - Gastrointestinal (38 decks)

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