1. Anatomy and Physiology Part 4: Pancreas and Pancreatic Control
Marieb’s Human
Anatomy and Physiology
Ninth Edition
Marieb w Hoehn
Chapter 23
Digestive System
Lectures 9 & 10
Part 4: Pancreas and Pancreatic Control
Slides 1-15; 80 min (with review of syllabus and Web sites) [Lecture 1]
Slides 16 – 38; 50 min [Lecture 2]
118 min (38 slides plus review of course Web sites and syllabus)

2. Pancreas Exocrine (digestive) and endocrine (metabolic) functions
Completes digestion of proteins that was started in the stomach

3. Blood Supply and Drainage of Pancreas
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

4. Pancreatic Juice
pancreatic amylase – splits glycogen into disaccharides
pancreatic lipases – break down triglycerides
pancreatic nucleases – digest nucleic acids
bicarbonate ions – make pancreatic juice alkaline (pH = 8) and neutralize acid coming from stomach
Pancreatic proteolytic enzymes…

5. Pancreatic Proteolytic Enzymes
Enteropeptidase (Enterokinase) (brush border of sm. intestine)
Know this chart
Trypsinogen
Trypsin
Chymotrypsinogen
Chymotrypsin
Pancreas
Procarboxypeptidase
Carboxypeptidase
Proelastase
Elastase
(Proenzymes, Zymogens)
(Active enzymes)
Dipeptides, tripeptides, amino acids
Proteins
Purpose of proteolytic enzymes is continued breakdown of proteins that began in the stomach

6. Regulation of Pancreatic Secretions
CCK and parasympathetic NS stimulate production and secretion of pancreatic enzymes and zymogens
acidic chyme stimulates release of secretin
secretin stimulates release of watery pancreatic juice with bicarbonate and phosphate (= buffers; to  pH)
The acini of the pancreas secrete enzymes/zymogens; the ducts secrete buffers (bicarbonate, phosphates)

7. Regulation of Pancreas/Intestinal Digestion
Key +
Stimulation
Acidic Chyme Enters Duodenum +
(brush border) + +
Enterokinase
Cholecystokinin (CCK)
Secretin +
Trypsinogen
Trypsin + + +
Gallbladder Contraction
Relaxation of hepatopancreatic sphincter
Chymotrypsinogen Procarboxypeptidase Proelastase
Trypsinogen Carboxypeptidase Elastase
Pancreas
Bile and Pancreatic ducts
(proenzymes, zymogens)
Proteins
Bile
Lipases
HCO3-, PO43-
(emulsification)
Nucleases (DNA, RNA)
Amylase (glycogen, starches)
Di- and tripeptides
Triglycerides Cholesterol Fat Soluble Vitamins
 pH to ≈ 8 (req. for enzyme action)
Nucleotides
Mono-, di-, trisaccharides
Action of brush border enzymes
Fatty acids, monoglycerides
Lacteals
Portal Vein
Amino acids
Conversion to chylomicrons
Subclavian vein
Monosaccharides

8. Review Stomach Cardiac, fundus, body, pylorus
Mixes food and begins digestion of protein
Limited absorption (alcohol)
Moves food into small intestine
Pyloric sphincter (entrance to small intestine)
Rugae and gastric pits
Gastric glands
Mucous cells (goblet) – secrete mucous
Chief cells (peptic) – secrete digestive enzymes, esp. pepsinogen
Parietal cells (oxyntic) – secrete HCl (Parietal, pH)
Infants only - Gastric lipase and rennin

9. Review Regulation of gastric activity
Cephalic phase (primarily neural)
Prior to food entry into stomach
Increased motility and production of gastric juice
Gastric phase
Neural: Food entering stomach / pH rising
Hormonal: gastrin release
Local: histamine release (stimulates parietal cells)
Intestinal phase
Neural: distension of duodenum (enterogastric reflex)
Hormonal: CCK, GIP, and secretin, gastrin
Reduction (slowing) of gastric emptying

10. Review Pancreas Both exocrine and endocrine functions
Main source of intestinal digestive enzymes
Pancreatic amylase (starches)
Pancreatic lipase (fats)
Nucleases
Proteolytic proenzymes / enzymes
Regulation of pancreatic activity
Acid chyme stimulates secretin
Secretin stimulates watery buffering secretion
Parasympathetic NS and CCK stimulate production and secretion of digestive enzymes