Gastric motility and Pancreatic function

Question 1

Which direction do peristaltic waves travel in the stomach?

Answer 1

From the body along the pyloric antrum

Question 2

Where does most of the grinding occur?

Answer 2

Pyloric antrum

Question 3

What is the role of the pyloric sphincter?

Answer 3

It stops chyme (gastric content) going through too fast (keeps duodenum not too acidic, and also helps stop dumping syndrome (osmotic effect into duodenum if too many small particles ie food), also acts as a wall to keep food in stomach and keep food churning around in the stomach

Question 4

Which nerve plexus sits between the circular and longitudinal layers of the stomach?

Answer 4

Myenteric plexus (muscle gut)

Question 5

WHat genarates the peristaltic rhythm? What type of wave/rhythm do they produce? How are the waves conducted? Is this wave reachimng threshold? WHat determines strength of contraction?

Answer 5

• Genarated by pacemaker cells (in longitudinal muscle layer)
• Slow waves produces rhythmic depol/repol ~ 3/min
• conducted through gap junctions in longitudinal muscle layer
• wave does not reach threshold - more depol required to reach threshold
• strength determined by frequency of waves

Question 6

What effects the contraction? 2 (increasing contraction, 1 inhibition of motility)

Answer 6

Increasing contraction:
-Gastrin
-presence of food (distension of stomach wall - long and short reflexes

Inhibiting motlity:
- presence of food in duodenum - fat/acid/amino acid/hypertonicity

Question 7

Where are the glands in the stomach (histiologically)?

Answer 7

Mucosal layer

Question 8

Where are glands found in th esubmucosa in the GI tract?

Answer 8

Oesophagus and duodenum

Question 9

What ar ehte submucosa glands in the duodenum called?

Answer 9

Brunner’s glands

Question 10

What is secreted by Brunners glands?>

Answer 10

Bicarbonate

Question 11

What triggers HCO3 release?

Answer 11

Acid in duodenum….
-Long (vagal) and short (ENS) reflexes and HCO3 secretion
-Secretin release from S cells -> HCO3 from pancreas and liver. Inhibited by acid neutralisation

Question 12

What type of control is the inhibition of secretion release?

Answer 12

Negative feedback

Question 13

WHat are the 3 parts of the panceras and where are they?

Answer 13

Head, body, tail

Head in C

Question 14

Where are hte endocrine portuion of the pancreas and what do they produc and secrete?

Answer 14

Insulin and glucagon.

In the islets of Langerhans

Question 15

What controls the release of glucagon/insulin?

Answer 15

Somatostatin - inhibitory

Question 16

Where are the exocrine portion of th epancreas? Which cells produce what?

Answer 16

In acinar bulb things aka LOBULES

Acinar cells = digestive enzymes
Duct cells = bicarbonate

Question 17

How are lobules combine to form the main pancreatic duct?

Answer 17

By tubes called Intercalated ducts - intralobuleducts - interlobule ducts

Question 18

What is the shincter of Oddi, waht is it ak?

Answer 18

The opening of the pancreatic duct into the duodenum

aka sphincter of ampulla or choledochal sphincter

Question 19

WHat happens if pancreatic duct gets blocked?

Answer 19

Can go through accessory pancreatic duct!

Question 20

What do duct cells release?

Answer 20

Bicarbonate (HCO3)

Question 21

What do acinar cells secrete?

Answer 21

Digestive enzymes in the inactive form of Zymogens

Question 22

Pancreatic duct cell shape? Intestinal cell shape?

Answer 22

Duct cells are more cuboidal, acinar cells are more columnar (beer can)

Question 23

What is autodigestion?

Answer 23

Digestion of the body by its own digestive enzymes

Question 24

How are our digestive enzymes stored?

Answer 24

As Zymogens (to become EN-ZYMes they need tripsinogen to be coverted to trypsin by ENterokinase and trypsin to take the -OGEN)

Question 25

Why do we store zymogens rather than enzymes?

Answer 25

To prevent autodigestion

Question 26

What is Enterokinase? WHere is it found? What doe sit do?

Answer 26

It is the enzyme (found in brush border of duodenal enterocytes) that converts trypsinogen to trypsin so that trypsin can go onto turn zymogens into digestive enzymes within the safety of the intestinal lumen.

Question 27

What is the role of Trypsin?

Answer 27

To turn the zymogens into their respective digestive enzymes in the intestinal lumen

Question 28

What secertes Trypsinogen?

Answer 28

The pancreas (alongside the Zymogens

Question 29

Pancreatic Enzyme -Proteases: how does it work where?

Answer 29

Acid hydrolysis - v efficient in the stomach
Hydrolysis everywhere else (inc. large intestine)

Cleave and break down proteins (peptide bonds)

eg pepsin

Question 30

Pancreatic Enzyme - Nucleases - do what?

Answer 30

They help break down (hydrolyse) DNA and RNA

Question 31

Pancreatic Enzyme - Elastases

Answer 31

Break downt he connective tissue eg collagen, elastin

Question 32

Pancreatic Enzyme - Phospholipases what do

Answer 32

Break down the cell wall (phsopholipids) into fatty acids

Question 33

Lipases - what do (Pancreatic enzyme)

Answer 33

Turn Triglycerides into fatty acids and glycerol

Question 34

Alpha amylase do what?

Answer 34

CHO (Startch) - glucose and maltose

Question 35

What is Bicarbonate secretion stimulated by? What is it released in ersponse to?

Answer 35

Stimulated by acid in the duodenum -> stimulates secretin release -> Secretin stimulates Brunners glands (in duodenal wall) -> produces bicarbonate -> neutralises acid -> decreases stimulus and inhibits secretion release (negative feedback)

Question 36

What is Zymogen secretion stimlus?

Answer 36

CCK - Cholecystokinin (secreted by small intestine in response to fatty acids and amino acids in the intestin)

Question 37

Wjat is CCK released in response to?

Answer 37

Intestinal Fatty and Amino Acids

Question 38

What is the neural control of the pancreatic function?

Answer 38

Vagal and local reflexes when there is organic nutrints in the duodenum (to secrete bicarbonate and pancreatic enzymes)