What about the Pancreas?

What about the pancreas?

The pancreas is a endocrine and exocrine glands.

The endocrine part of the pancreas is only a small portion of the gland and is made up of small bundles of cells called the “Islets of Langerhans”.  We have capillaries that run through each islet in order to transport pancreatic endocrine gland hormones to the rest of the body as needed.  Two cells- important ones to learn:

• Alpha Cells:  produce hormone glucagon that raises blood sugar levels
• Beta Cells: produce hormone insulin which lower blood glucose levels

The exocrine portion of the pancreas helps with the digestion process.

• Chyme (thick, acidic liquid) is released from the stomach – partially digested food- into the duodenum of the small intestine.
• The acini in the pancreas secretes pancreatic juice to complete the digestion of chyme in the duodenum
• Pancreatic juice is a mixture of water, salts, bicarbonate and digestive enyzmes
• The biocarbonate ions neutralize the acid in the chyme in order to protect the walls of the small intestine
• The pH level of the stomach is highly acidic in order to break down the food from a bolus into chyme but once the chyme enters the small intestine, the pancreatic juice is needed to create the ideal environment for the pancreatic enzymes to do their job in digestion.
  • pancreatic amylase:  breaks down carbohydrates – polysaccharides as starches and glycogen into smaller sugars:
    • Maltotriose, maltose and glucose.
    • Maltase is secreted by the small intestine then breaks maltose into monosaccharide glucose for the small intestine to absorb.
  • Trypsin, chymotrypsin and carboxypeptidase:  protein digesting enyzmes that breakdown proteins into amino acids
  • Pancreatic lipase: lipid digesting enzyme that breaks down large triglyceride molecules into fatty acids and monoglycerides
    • bile released by the gallbladder emulsifies the fat to increase the surface area of triglycerides for the pancreatic lipase enzyme to react with in the small intestine.
  • Ribonuclease and deoxyribonuclease:  enzymes that digest nucleic acids.
    • Ribo breaks down RNA molecules into sugar ribose and nitrogenous bases.
    • Deoxy. digests DNA molecules into sugar deoxyribose and nitrogenous bases.

-source: innerbody.com

The pancreas and the nervous system: 

The Sympathetic Nervous system: SNS

• The SNS neurons stimulate the alpha cells of the pancreas to release hormone glucagon into bloodstream
• Glucagon stimulates the liver to breakdown stored glycogen into smaller glucose molecules to use as energy
• The SNS nerves inhibit the beta cells and acini in order to reduce and prevent the secretion of insulin and pancreatic juice to provide more energy for other parts of the body that are needed to deal with the stressful situation (learn more about the adrenal glands- HPA Axis)

The Parasympathetic Nervous System: PNS

• Activated during rest and digestion
• PNS nerves stimulate the release of insulin and pancreatic juice by the pancreas
• Pancreatic juice helps with the digestion of food
• Insulin stores the glucose released from the digested food into the body’s cells (liver and fat cells)

The Endocrine System and Pancreas: Secretin and CCK

• In response to the acidic chyme from the stomach now into the duodenum, beginning of the small intestine, the cells of the duodenum lining produce secretin
• Secretin stimulates the pancreas to produce and secrete pancreatic juice (high amounts of bicarbonate ions)
• The bicarbonate ions reacts and neutralizes the HCL acid present in the chyme from the stomach (acidic environment) to bring the pH level up to around 7.
• The hormone CCK is produced by the duodenum cell wall lining when proteins and fats are present in the chyme.
• CCK moves into the bloodstream and binds to the receptor cells of the pancreas acini.
• CCK stimulates the acini cells in the pancreas to produce and secrete pancreatic juice – high levels of digestive enzymes that are needed to digest large protein and fat molecules that need more help breaking down than carbohydrates.

-www.innerbody.com