Physiology Of The Pancreas Flashcards
How long is the pancreas?
18cm
Describe the location of the pancreas
Found behind posterior peritoneum.
Lies in the curve of the duodenum.
The rest of the gland lies horizontal in the posterior abdominal wall
The pancreas has both an endocrine and exocrine function:
Explain and differentiate between the two:
Endocrine: Islets of Langerhans found dispersed in exocrine portion.
- A cells: Glucagon
- B cells: Insulin
Exocrine: Cells arranged in acini
- Secretion of pancreatic juice by hormone control
- Discharge of products via exocytosis into lumen of panc. ducts.
- Juice contains water, Na+, bicarbonate, K+, digestive enzyme amylase.
- This is an alkaline juice neutralizing stomach acid
Describe the connection between small pancreatic ducts, bile ducts and
Small ducts coalesce into single duct, duct of Wirsung.
• Duct of Wirsung joins common bile duct to form ampulla of Vater
- Opening into duodenum.
•Orifice of duodenum is encircled by sphincter of Oddi.
What is an accessory duct duct of Santorini?
Opens independently and more proximally in the duodenum.
Which enzyme digests starch?
Amylase
Name 3 enzymes that digest proteins:
Trypsin.
Chymotrypsin.
Carboxypeptidase
What kind of enzymes break down nuclei acid into nucleotides?
Nucleases.
What is the inactive form of trypsin that is released?
Trypsinogen.
What enzyme activates trypsin?
Enterokinase
Trypsin proceeds to activate 2 specific enzymes, name them:
Chymotrysinogen.
Carbxypeptidase.
Pancreatic secretions are under hormonal control.
Gastric secretions are classified into 3 phases, name them:
Cephalic
Gastric
Intestinal
Explain the cephalic phase of gastric secretions:
Cephalic phase: Conditioned and unconditioned reflexes
- Sight, smell and taste of food excites efferent Vargas fibers
- The juice secreted is viscid and has a high enzyme quality
- Small in volume though
Explain the Gastric phase of gastric secretions:
- Make mention of the 2 mechanisms involved:
Gastric phase: Triggered when food enters the stomach.
- Reflex response due to distention involving afferent and efferent Vargas fibers
- Gastrin is released from the Antral mucosa of the stomach
How is gastrin released?
Gastrin is released from the astral mucosa of the stomach.
Explain the Intestinal phase of gastric secretions:
- Name 2 hormones playing an important role.
Intestinal phase: Occurs as chime enters the duodenum.
- 2 Main hormones: Secretin cholecystokinin.
- Secrete water and electrolytes
- Released by the mucous of the duodenum and proximal jejunum.
- When chyme enters duodenum.
How is cholesterol in bile made soluble?
Cholesterol in bile combines with bile acids and lecithin.
How are gallstones formed?
Under abnormal conditions: Water soluble cholesterol Precipitates resulting in gallstones:
- Cholesterol and calcium ion precipitation
Name the 2 types of bile stones:
Pigment stones
Cholesterol stones
Which type of bile stones are more common?
Cholesterol stones
Which ethnicity has an increased tendency of gall stone formation?
Latinos
Name the most common cause for gallstones:
Abnormal gallbladder wall due to previous episodes of inflammation.
When is gallstone removal requested?
When there is rapid development of new stones in the gallbladder.
Name 6 causes of gallstone formation:
- Decrease in bile salts and lecithin
- Excess cholesterol
- Increase in bile concentration leading to excess calcium ions
- Disturbed cholesterol metabolism
- Damage/Infection in gallbladder epithelium
- Absorptive function of membrane mucous decreases.
- Excessive absorption of water or bile salts.
= inc in conc of cholesterol, bile pigment and calcium ions
- Obstruction to bile flow of the gallbladder.
Name 7 bile salt complications:
- Acute cholecystitis
- Inflammation of the gallbladder
- Caused by stones blocking the tube leading from the gallbladder to the small intestine. - Chronic cholecystitis
- Acute cholangitis
- Infection of the liver’s bile ducts ( when a stone blocks passage of bile)
- Fluid backs up, an infection can occur. - Acute biliary pancreatitis
- Gallbladder carcinoma
- Gallstones ileus
- Obstructive jaundice or cholestasis.
- Jaundice
- Symptoms due to a narrowed or blocked bile duct or pancreatic duct.
- Preventing the normal drainage of bile from the bloodstream into the intestines.
What is gallstones ileus?
Condition where gallstones obstruct the small or large bowel.
Can occur when inflamed Gallbladder becomes attached to the intestine.
- Gallstones erode their way through the gallbladder wall
- And into the intestine where they cause blockage
What is cholecystitis ?
This is the inflammation of the gallbladder.
Causes of this include:
- Choleliths, most commonly blocking the cystic duct
As a result: bile thickens, bile stasis and secondary infection by gut organisms may occur I.e. by Ecoli, bacteriodes species.
The gallbladders wall becomes inflamed and this may result in necrosis or rupture.
Inflammation may spread to outer covering, irritating surrounding structures I.e. diaphragm and bowel.
Name the main contributing factor to Gallbladder carcinoma formation?
Irritation of GB mucosa by stones
- Chronic inflammation occurs followed by repetitive epithelial repair
- Malignant transformation.
What is cholangitis?
Inflammation of the bile ducts
- May occur if bile ducts get blocked or
- Get infected by bacteria from small intestine
