Physiology of the pancreas Flashcards
Where is the R lobe of the pancreas
mesoduodenum
where is the L lobe of the pancreas
leaf of greater omentum
where are the 2 pancreatic ducts in the dog
• Smallest, the pancreatic duct, opens with the bile
duct on the major duodenal papilla.
• Accessory pancreatic duct is larger and opens on the minor duodenal papilla.
exocrine glands
secrete substances on an epithelial surface via a duct.
endocrine glands
are ductless and secrete their substances (hormones) directly into the blood.
is the pancreas an endocrine, exocrine gland, or both
both
exocrine functions of the pancreas
critical for digestion
acini of pancreas secrete compounds (enzymes) to aid in further digestion of acidic chyme from stomach (HCl)
Centroacinar cells and duct cells secrete Bicarbonate
acini of the pancreas
secrete enzymes to help digest chyme
Centroacinar cells and duct cells
secrete Bicarbonate
release of enzymes from acini
Pancreatic enzymes are released from the acini in granules that are in the pre-enzymatic form (proenzyme).
• An enzyme released by the duodenum activates them – enterokinase, and the enzymes are ready to work.
• The released bicarbonate allows the pH to be maintained at an ideal level for the enzymes to function.
pancreatic amylase
reduces large polysaccharides to smaller units
• Breaks down starches to maltose, glucose, etc. Small intestinal enzymes can further reduce to glucose, which can be directly absorbed.
Trypsin, chymotrypsin
enzymes which reduce proteins to amino acid subunits, which can be absorbed.
pancreatic lipase
digests lipids→large triglycerides reduced to fatty acids and monoglycerides.
• Bile helps to emulsify the fats, allowing larger surface area for the enzymes to work with.
Ribonucleases and deoxyribonucleases
digest nucleic acids – reduces to the nitrogenous bases.
phases of pancreatic secretion
- Sight and smell of food leads to the a central vagal response called the cephalic phase.
- Distension of the stomach – gastric phase – stimulates pancreatic secretions.
- (These get the small intestine ‘ready’ for the oncoming food.)
- When food enters from the stomach, the duodenum distends and the intestinal phase begins.
cephalic phase of pancreatic secretion
Sight and smell of food leads to the a central vagal response called
gastric phase of pancreatic secretion
Distension of the stomach stimulates pancreatic secretions.
intestinal phase of pancreatic secretion
When food enters from the stomach, the duodenum distends and the intestinal phase begins.
pancreas functions
assists in digesting all major food compounds
buffers pH of small intestine where enzymes are most efficient 6.8
pancreatic intrinsic factor
required for b12 absorption
used in erythropoiesis, cellular metabolism, energy production, DNA creation and regulation, fatty acid synthesis, etc.
pancreatitis mechanism
increased fat ingestion
zymogens not normally activated until they reach small intestine
in pancreatitis, lysosomes and zymogens in pancreas cells can fuse, releasing digestive enzymes into the pancreas itself
damage of pancreas can be life threatening
islets of Langerhans (pancreatic islets)
make up 1-2% of pancreas but receive 10-15% of blood flow
4 cell types- alpha, beta (most numerous), D, F
what do alpha cells produce
glucogon
what do beta cells produce
insulin
what does insulin do?
prevent hyperglycemia
- promotes storage of all 3 nutrients (esp glucose)
- first, gets digested/absorbed nutrients out of blood, into cells
- then, promotes synthesis of storage form of each nutrient.
- so, dominates in “fed” state
What does glucagon do?
Raise BG, keep adequate glucose available in blood for cellular function.
promotes utilization of all 3 nutrients (esp. glucose):
• so, promotes catabolism of storage form of each major nutrient
• gets digested/absorbed nutrients out of cells, and into blood • so, dominates in “fasting” state
what is the brains preferred energy source?
glucose
