Pancreas Flashcards
Properties of chyme as it enters the duodenum/exits the stomach
Hypertonic (more solute than solvent)
Acidic
Only partially digested
What mechanisms are there to change the properties of chyme?
- water from ECF/circulation to make isotonic
- pancreatic secretions: enzymes + bicarbonate ions
- liver secretions: bile + bicarbonate ions
Why is chyme hypertonic as it enters the duodenum/leaves the stomach?
- food produces lots of solutes which are dissolved in gastric liquid
- stomach wall is mainly importable to water > water cannot dilute solutes in chyme
What controls pancreatic secretions entering the duodenum?
Sphincter of Oddi
Describe the structure of the pancreas involved in pancreatic secretions
- acinus > enzymes
- centroacinar > aqueous component
- duct > modifies aqueous secretions
What effect does the sympathetic and parasympathetic nerve system have on pancreatic secretions?
Sympathetic inhibits
Parasympathetic stimulates
What is the acinus in the pancreas stimulated by?
Vagus nerve
Cholecystokinin from I cells
What is released from the acinus of the pancreas?
- amylase/lipase (active)
- proteases (inactive) > trypsin, chymotrypsin, elastase, carboxypeptidase
Why are proteases released from the pancreas in their inactive form?
The pancreas is made of proteins so the proteases would breakdown the pancreas if released in their active form
Describe the production of enzymes in the acinus of the pancreas
- formed on rough ER
- move to Golgi complex
- packaged + condensed in vacuoles
- concentrated in zymogen granules
- released by CCK/vagus nerve
What do pancreatic enzymes in the blood signify?
Pancreatic damage
Function of pancreatic secretions
- secrete enzymes for digestion > break down partially digested food in chyme
- secrete bicarbonate to neutralise acidic chyme
Outline the secretion of secretin
From S cells
In response to detection of low pH
How is the hypertonicity of chyme resolved as it enters the duodenum?
- duodenum walls are permeable to water
- water moves into chyme from surround circulation
- dilutes solutes
- chyme is isotonic when it leaves the duodenum
How is the acidity of chyme resolved as it enters the duodenum?
Bicarbonate ions from the pancreas + bile
How is the partially digestive component of chyme resolved in the duodenum?
Enzymes secreted by the pancreas
- amylase/lipase
- protease: trypsin, chymotrypsin, elastase, carboxypeptidase
How many parts does the pancreas have?
Name them
5 parts
Tail
Body
Neck
Head
Unicate process
Is the pancreas retroperitoneal or intraperitoneal?
Head, neck + body are retroperitoneal
Tail is intraperitoneal due to its association with the spleen
Describe the relationship between the pancreas and the superior mesenteric artery
- SMA originates posterior to the neck of the pancreas
- comes anterior to unicate process
What is the unicate process of the pancreas?
** embryologicall when the two parts rotate
Check
What are zygomens?
Inactive enzymes
Where does the pancreatic duct enter the small intestine?
Midpoint of D2
At the ampulla of Vater
