Pancreas

Question 1

Properties of chyme as it enters the duodenum/exits the stomach

Answer 1

Hypertonic (more solute than solvent)
Acidic
Only partially digested

Question 2

What mechanisms are there to change the properties of chyme?

Answer 2

• water from ECF/circulation to make isotonic
• pancreatic secretions: enzymes + bicarbonate ions
• liver secretions: bile + bicarbonate ions

Question 3

Why is chyme hypertonic as it enters the duodenum/leaves the stomach?

Answer 3

• food produces lots of solutes which are dissolved in gastric liquid
• stomach wall is mainly importable to water > water cannot dilute solutes in chyme

Question 4

What controls pancreatic secretions entering the duodenum?

Answer 4

Sphincter of Oddi

Question 5

Describe the structure of the pancreas involved in pancreatic secretions

Answer 5

• acinus > enzymes
• centroacinar > aqueous component
• duct > modifies aqueous secretions

Question 6

What effect does the sympathetic and parasympathetic nerve system have on pancreatic secretions?

Answer 6

Sympathetic inhibits
Parasympathetic stimulates

Question 7

What is the acinus in the pancreas stimulated by?

Answer 7

Vagus nerve
Cholecystokinin from I cells

Question 8

What is released from the acinus of the pancreas?

Answer 8

• amylase/lipase (active)
• proteases (inactive) > trypsin, chymotrypsin, elastase, carboxypeptidase

Question 9

Why are proteases released from the pancreas in their inactive form?

Answer 9

The pancreas is made of proteins so the proteases would breakdown the pancreas if released in their active form

Question 10

Describe the production of enzymes in the acinus of the pancreas

Answer 10

• formed on rough ER
• move to Golgi complex
• packaged + condensed in vacuoles
• concentrated in zymogen granules
• released by CCK/vagus nerve

Question 11

What do pancreatic enzymes in the blood signify?

Answer 11

Pancreatic damage

Question 12

Function of pancreatic secretions

Answer 12

• secrete enzymes for digestion > break down partially digested food in chyme
• secrete bicarbonate to neutralise acidic chyme

Question 13

Outline the secretion of secretin

Answer 13

From S cells
In response to detection of low pH

Question 14

How is the hypertonicity of chyme resolved as it enters the duodenum?

Answer 14

• duodenum walls are permeable to water
• water moves into chyme from surround circulation
• dilutes solutes
• chyme is isotonic when it leaves the duodenum

Question 15

How is the acidity of chyme resolved as it enters the duodenum?

Answer 15

Bicarbonate ions from the pancreas + bile

Question 16

How is the partially digestive component of chyme resolved in the duodenum?

Answer 16

Enzymes secreted by the pancreas
- amylase/lipase
- protease: trypsin, chymotrypsin, elastase, carboxypeptidase

Question 17

How many parts does the pancreas have?
Name them

Answer 17

5 parts
Tail
Body
Neck
Head
Unicate process

Question 18

Is the pancreas retroperitoneal or intraperitoneal?

Answer 18

Head, neck + body are retroperitoneal
Tail is intraperitoneal due to its association with the spleen

Question 19

Describe the relationship between the pancreas and the superior mesenteric artery

Answer 19

• SMA originates posterior to the neck of the pancreas
• comes anterior to unicate process

Question 20

What is the unicate process of the pancreas?

Answer 20

** embryologicall when the two parts rotate
Check

Question 21

What are zygomens?

Answer 21

Inactive enzymes

Question 22

Where does the pancreatic duct enter the small intestine?

Answer 22

Midpoint of D2
At the ampulla of Vater