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Alimentary System > Gastric Motility and Pancreatic Function > Flashcards

Gastric Motility and Pancreatic Function Flashcards

1
Q

What is gastric motility?

A

Peristaltic waves from the body of the stomach to the antrum (contractions)

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2
Q

How does contractions strength vary across the stomach?

A

Is different in different areas

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3
Q

What is the contraction strength like in the body of the stomach?

A

Weak because it has a thin muscle

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4
Q

What is the contraction strength like in the antrum of the stomach?

A

Powerful because has a thick muscle

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5
Q

Where in the stomach does mixing occur?

A

Antrum

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6
Q

What happens when the pyloric sphincter is contracted?

A

Small quantitiy of gastric contents (chyme) enters the duodenum, further mixing occurs as antrul contents are forced back towards the body

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7
Q

What is gastric contents known as?

A

Chyme

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8
Q

What is the gastric peristaltic wave produced by?

A

Peristaltic rhythm

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9
Q

What is the peristaltic rhythm generated by?

A

Pacemaker cells in the longitudinal muscle layer

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10
Q

What is the rate of the peristaltic rhythm?

A

About 3/min

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11
Q

How does the signal from the peristaltic rhythm travel through the longitudinal muscle layer?

A

Gap junctions

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12
Q

What must be reached for the stomach to contract?

A

Action potential must reach threshold

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13
Q

What is the slow wave rhythm of the peristaltic rhythm known as?

A

Basic electrical rhythm (BER)

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14
Q

What is the action potential size proportional to?

A

Tension on the stomach wall

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15
Q

Explain the hormonal/neural control of contractions?

A

Gastrin increases contraction

Distension of stomach wall causes long/short reflexes which increases contraction

Fat/acid/amino acid/hypertonicity in duodenum inhibits motility (contraction)

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16
Q

How does gastrin impact contraction?

A

Increases

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17
Q

How does distension of stomach wall impact contraction?

A

Increases

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18
Q

How does the presence of fat, acid, amino acid, or hypertonicity in the duodenum impact contraction?

A

Decreases

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19
Q

What controls the force of contractions?

A

Frequency of action potentials

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20
Q

What secretes bicarbonate?

A

Brunner’s glands duct cells

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21
Q

In what layer are Brunner’s glands found?

A

Submucosal

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22
Q

What is neutralisation of acid in the duodenum done by?

A

Bicarbonate

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23
Q

What happens to the water and carbon dioxide produced during acid neutralisation?

A

Water flows down the gut and carbon dioxide diffuses away

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24
Q

Why is it important that the duodenum is not acidic?

A

It would denature enzymes from the pancreas and damage the duodenum epithelium which needs to absorb things such as iron

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25
Q

What does acid in the duodenum trigger?

A

Long (vagal) and short (ENS) reflexes causing HCO3 secretion

Release of secretin from S cells causing HCO3 secreiton

26
Q

What are long reflexes controlled by?

A

Vagas nerve

27
Q

What are short reflexes controlled by?

A

ENS reflexes

28
Q

What does secretin cause?

A

Bicarbonate to be secreted from the pancreas and liver which will end up in the duodenum as well as from Brunner’s glands in the duodenum

29
Q

How does acid neutralisation impact secretin release?

A

Inhibitis secretin release (negative feedback control)

30
Q

What are the 3 parts of the pancreas?

A

Head (located within curvature of duodenum)

Body

Tail (extends to spleen)

31
Q

What are the 2 classes of glands contained in the pancreas?

A

Endocrine

Exocrine

32
Q

Where do endocrine glands secrete into?

A

The blood

33
Q

Where do exocrine glands secrete into?

A

Surrounding tissues

34
Q

What is the endocrine portion of the pancreas?

A

Islets of Langerhans

35
Q

What do islets of Langerhans produce?

A

Insulin, glucogon and somatostatin

36
Q

What are the functions of insulin and glucagon?

A

Control [glucose]blood

37
Q

What is the function of somatostatin?

A

Control secretion of insulin and glucagon

38
Q

What are the exocrine portions of the pancreas?

A

Acinar cells found in lobules which are connected by intercalated ducts

39
Q

Explain the pathway exocrine hormones from the pancreas take?

A

Intralobular ducts -> interlobular ducts -> main pancreatic duct -> common bile duct -> hepatopancreatic ampulla -> duodenum

40
Q

What controls the hepatopancreatic ampullar?

A

Sphincter of Oddi

41
Q

What pancreatic duct is present other than the main one?

A

Accessory pancreatic duct that is closed unless the other duct becomes blocked, then it would open

42
Q

What does the sphincter of Oddi control?

A

Delivery of pancreatic juice and bile into the duodenum

43
Q

Which of the exocrine and endocrine pancreas is responsible for the digestive functions of the pancreas?

A

Exocrine

44
Q

Where are the exocrine hormones of the pancreas produced?

A

Acini

45
Q

What are functions of the exocrine pancreas?

A

Secretion of bicarbonate by duct cells

Secretion of digestive enzymes by acinar cells

46
Q

What is the classification of duct cells of the pancreas?

A

Cuboidal

47
Q

What is the shape of acinar?

A

Triangular to form bulb like structures

48
Q

What are digestive enzymes stored as in the acinar cells?

A

Zyogen granules

49
Q

Why are digestive enzymes stored in accini as zymogen granules?

A

Prevents autodigestion of the pancreas

50
Q

What converts all zymogens to their active form?

A

Trypsin

51
Q

What is the zymogen of trypsin?

A

Trypsinogen

52
Q

What converts trypsinogen into trypsin?

A

Enterokinase

53
Q

Where is enterokinase found?

A

Bound to brush border of duodenal enterocytes

54
Q

What are some categories of pancreatic enzymes?

A

Proteases

Nucleases

Elastases

Phospholipases

Lipases

a-Amylase

55
Q

What is the function of proteases?

A

Cleave peptide bonds

56
Q

What is the function of nucleases?

A

Hydrolyse DNA/RNA

57
Q

What is the function of elastases?

A

Collagen digestion

58
Q

What is the function of phospholipases?

A

Converts phospholipids to fatty acids

59
Q

What is the function of lipases?

A

Converts triacylglycerides to fatty acids and glycerol

60
Q

What is the function of a-Amylase?

A

Convert starch to maltose and glucose

61
Q

What is the mechanism for controlling bicarbonate secretion from the pancreas?

A

1) Secretin released in response to acid in duodenum
2) Bicarbonate secretion stimulated by secretin

62
Q

What is the mechanism for controlling zymogen secretion?`

A

1) Cholecystokinin (CCK) released in response to fat/amino acids in duodenum
2) Zymogen secretion stimulated by CCK
3) Also under neural control (vagal/local reflexes), triggered by arrival of organ nutrients in duodenum

Alimentary System (41 decks)

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