Pancreas – Digestive System Organs (Nursing)

00:01 A third important structure for the functioning of our small intestine is the pancreas.

00:08 The pancreas is located mostly retroperitoneal and is deep to the greater curvature of the stomach.

00:17 The head of the pancreas is encircled by the duodenum of the small intestine while the tail abut against the spleen.

00:30 The pancreas has two types of function both endocrine and exocrine.

00:36 Starting with exocrine, the pancreas is going to be responsible for the production of pancreatic juice.

00:43 This takes place in the acini which are clusters of secretory cells that produce zymogen granules containing pro enzymes or pre enzymes.

00:56 As well, we also have ducts which are going to secrete directly to the duodenum of the small intestines by way of the main pancreatic duct.

01:07 There are also smaller duct cells that are able to produce water and bicarbonate which will also go to the small intestine.

01:17 Recall that the pancreas also has endocrine function and is responsible for the secretion of insulin in response to high blood glucose levels and glucagon in response to low blood glucose levels.

01:32 This is going to be secreted by the pancreatic islet cells which are found in little Islands within the acinar cells of the pancreas.

01:44 The pancreatic juice is going to be about 1200 to 1500 milliliters produce per day.

01:52 This is a watery alkaline solution with about a pH of 8 that is necessary for the neutralization of that acidic chyme that is coming in from the stomach.

02:05 It contains electrolytes, but the primary electrolyte is going to be bicarbonate ion.

02:12 Also, our pancreatic juice is going to contain digestive enzymes that are able to break down each type of biomolecule.

02:21 So it's going to contain proteases that are going to be able to break down proteins amylases has that are able to break down carbohydrates, lipases that are able to break down lipids and nucleases that are able to break down nucleic acids.

02:41 The proteases that are secreted by the pancreas are secreted in an inactive form and they become activated, once they reach the duodenum.

02:53 The enteropeptidase enzyme which is an enzyme bound to the plasma membrane of the duodenal epithelial cells.

03:01 This enzyme is going to activate pancreatic protease trypsinogen so that it becomes active trypsin.

03:10 Once trypsin is activated it can then activate more trypsinogen pre carboxypeptidase to carboxypeptidase and chymotrypsinogen to active chymotrypsin.

03:28 This image depicts the activation of these different proteases from the enzymes that are released by the pancreas.

03:37 So recall, trypsinogen will be activated to form trypsin, chymotrypsinogen will be activated to form chymotrypsin, and pro carboxypeptidase will be activated to form carboxypeptidase.

03:53 All of this is going to take place by the enzymes that are secreted by both epithelial cells in the duodenum The bile duct and the pancreatic duct are going to unite together in the wall of the duodenum.

04:12 They fuse together in a bulb like structure that is referred to as the hepato pancreatic ampulla.

04:20 This ampulla then opens into the duodenum by way of this volcano shaped nipple known as the major duodenal papilla.

04:32 The hepato pancreatic sphincter is going to control the entry of bile and pancreatic juice into the duodenum.

04:40 And also there are some accessory pancreatic ducts which are smaller ducts that can bypass this hepatopancreatic duct and empty directly into the duodenum.

04:54 Bile and pancreatic juice secretions are both stimulated by neural and hormonal controls.

05:01 The hormones that are going to be responsible for controlling these include CCK or cholecystokinin as well as secretin.

05:12 Specifically looking at bile secretion we find that it is increased when in enterohepatic circulation returns large amounts of bile salts to the liver.

05:24 Also when secretin from intestinal cells that are exposed to hydrochloric acid and fatty chyme stimulates the gallbladder to release more bile and lastly, when the hepatic pancreatic sphincter is relaxed.

05:41 Normally the hepatopancreatic sphincter is closed.

05:44 But once digestion is active bile that is stored in the gallbladder is released to the intestine by the relaxation of the sphincter.