Gastric Motility and Pancreatic Function

Question 1

What is gastric motility?

Answer 1

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

Question 2

How does contractions strength vary across the stomach?

Answer 2

Is different in different areas

Question 3

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

Answer 3

Weak because it has a thin muscle

Question 4

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

Answer 4

Powerful because has a thick muscle

Question 5

Where in the stomach does mixing occur?

Answer 5

Antrum

Question 6

What happens when the pyloric sphincter is contracted?

Answer 6

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

Question 7

What is gastric contents known as?

Answer 7

Chyme

Question 8

What is the gastric peristaltic wave produced by?

Answer 8

Peristaltic rhythm

Question 9

What is the peristaltic rhythm generated by?

Answer 9

Pacemaker cells in the longitudinal muscle layer

Question 10

What is the rate of the peristaltic rhythm?

Answer 10

About 3/min

Question 11

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

Answer 11

Gap junctions

Question 12

What must be reached for the stomach to contract?

Answer 12

Action potential must reach threshold

Question 13

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

Answer 13

Basic electrical rhythm (BER)

Question 14

What is the action potential size proportional to?

Answer 14

Tension on the stomach wall

Question 15

Explain the hormonal/neural control of contractions?

Answer 15

Gastrin increases contraction

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

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

Question 16

How does gastrin impact contraction?

Answer 16

Increases

Question 17

How does distension of stomach wall impact contraction?

Answer 17

Increases

Question 18

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

Answer 18

Decreases

Question 19

What controls the force of contractions?

Answer 19

Frequency of action potentials

Question 20

What secretes bicarbonate?

Answer 20

Brunner’s glands duct cells

Question 21

In what layer are Brunner’s glands found?

Answer 21

Submucosal

Question 22

What is neutralisation of acid in the duodenum done by?

Answer 22

Bicarbonate

Question 23

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

Answer 23

Water flows down the gut and carbon dioxide diffuses away

Question 24

Why is it important that the duodenum is not acidic?

Answer 24

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

Question 25

What does acid in the duodenum trigger?

Answer 25

Long (vagal) and short (ENS) reflexes causing HCO₃ secretion Release of secretin from S cells causing HCO₃ secreiton

Question 26

What are long reflexes controlled by?

Answer 26

Vagas nerve

Question 27

What are short reflexes controlled by?

Answer 27

ENS reflexes

Question 28

What does secretin cause?

Answer 28

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

Question 29

How does acid neutralisation impact secretin release?

Answer 29

Inhibitis secretin release (negative feedback control)

Question 30

What are the 3 parts of the pancreas?

Answer 30

Head (located within curvature of duodenum) Body Tail (extends to spleen)

Question 31

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

Answer 31

Endocrine Exocrine

Question 32

Where do endocrine glands secrete into?

Answer 32

The blood

Question 33

Where do exocrine glands secrete into?

Answer 33

Surrounding tissues

Question 34

What is the endocrine portion of the pancreas?

Answer 34

Islets of Langerhans

Question 35

What do islets of Langerhans produce?

Answer 35

Insulin, glucogon and somatostatin

Question 36

What are the functions of insulin and glucagon?

Answer 36

Control [glucose]_blood

Question 37

What is the function of somatostatin?

Answer 37

Control secretion of insulin and glucagon

Question 38

What are the exocrine portions of the pancreas?

Answer 38

Acinar cells found in lobules which are connected by intercalated ducts

Question 39

Explain the pathway exocrine hormones from the pancreas take?

Answer 39

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

Question 40

What controls the hepatopancreatic ampullar?

Answer 40

Sphincter of Oddi

Question 41

What pancreatic duct is present other than the main one?

Answer 41

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

Question 42

What does the sphincter of Oddi control?

Answer 42

Delivery of pancreatic juice and bile into the duodenum

Question 43

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

Answer 43

Exocrine

Question 44

Where are the exocrine hormones of the pancreas produced?

Answer 44

Acini

Question 45

What are functions of the exocrine pancreas?

Answer 45

Secretion of bicarbonate by duct cells Secretion of digestive enzymes by acinar cells

Question 46

What is the classification of duct cells of the pancreas?

Answer 46

Cuboidal

Question 47

What is the shape of acinar?

Answer 47

Triangular to form bulb like structures

Question 48

What are digestive enzymes stored as in the acinar cells?

Answer 48

Zyogen granules

Question 49

Why are digestive enzymes stored in accini as zymogen granules?

Answer 49

Prevents autodigestion of the pancreas

Question 50

What converts all zymogens to their active form?

Answer 50

Trypsin

Question 51

What is the zymogen of trypsin?

Answer 51

Trypsinogen

Question 52

What converts trypsinogen into trypsin?

Answer 52

Enterokinase

Question 53

Where is enterokinase found?

Answer 53

Bound to brush border of duodenal enterocytes

Question 54

What are some categories of pancreatic enzymes?

Answer 54

Proteases Nucleases Elastases Phospholipases Lipases a-Amylase

Question 55

What is the function of proteases?

Answer 55

Cleave peptide bonds

Question 56

What is the function of nucleases?

Answer 56

Hydrolyse DNA/RNA

Question 57

What is the function of elastases?

Answer 57

Collagen digestion

Question 58

What is the function of phospholipases?

Answer 58

Converts phospholipids to fatty acids

Question 59

What is the function of lipases?

Answer 59

Converts triacylglycerides to fatty acids and glycerol

Question 60

What is the function of a-Amylase?

Answer 60

Convert starch to maltose and glucose

Question 61

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

Answer 61

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

Question 62

What is the mechanism for controlling zymogen secretion?`

Answer 62

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