Biology 47 - Anatomy Lecture 15 Digestive System : Pancreas ...

Biology 47 - Anatomy
Lecture 15
Digestive System :
Pancreas :
• Assists in :
• Location : ~20 cm long
Encased in mesentery immediately below :
Extends from:
• Anatomical Regions:
a. Head : Broad portion residing within :
b. Body : Elongated portion inferior to :
c. Tail : Blunt end adjacent to :
Function : 99% of pancreas produce :
• Sodium Bicarbonate : Neutralizes :
• Enzymes :
Pancreatic Amylase :
Pancreatic Lipases :
Trypsin, & Chymotrypsin :
• Secretes into :
Pancreatic Secretory structures :
• Secretions enter Duodenum via :
2 Ducts :
1. Pancreatic Duct :
• Main delivery duct to :
Joins Common Bile duct from LIVER to form :
2. Accessory Duct :
Smaller, superior duct opening into :
Histology : Lobulated Gland
Glandular Epithelial Cells :
• 99 % :
1

Acinar Cells : Secrete :
• 1 % :
Islets of Langerhans: Groups of :
Beta Cells (60%): Insulin
Alpha Cells (25%): Glucagon
Delta Cells (15%): Somatostatin
Insulin & Glucagon regulate :
Liver : “Hepat” = Liver
Functions :
Largest :
A. Metabolic Regulation :
• Regulates :
ALL BLOOD leaving Digestive Tract travels directly to :
• Liver Cells : Hepatocytes
1. Monitor & adjust :
2. Remove & store :
3. Detoxify blood
B. Hematological Functions : Heme = “blood”
• Regulates Blood Composition
1. Kupffer Cells :
Remove old or damaged :
2. Produce :
C. Bile Synthesis & Secretion :
• Bile : Breakdown product of :
Function :
1. Neutralize Acid :
2. Emulsify Lipids ; Break lipids into :
Storage :
Anatomy : Large lobed structure (4)
• Lobes :
Large :
Small : Caudate & Quadrate lobe
2

Blood Circulation: High rate of Profusion
Input: 2 Blood Sources:
a. Hepatic Artery: Blood delivered from :
25% of total :
b. Hepatic Portal Vein: Blood delivered from the:
Nutrient Rich: Oxygen POOR blood from:
Blood to be PROCESSED by LIVER
Output: 1 Blood Outlet:
Histology :
Hepatocytes :
a. Hepatic Vein: Blood returned to :
Processed blood carried to heart to be :
• Hepatocytes arranged into Columns around a large :
Result :
“Spokes on a wheel”
Lobules: Functional hexangonal arrangement of :
(100,000 Lobules/ Liver)
Sinusoids : Extensions of blood vessels between :
Carries blood to be processed past :
(site of Kupffer cells)
Movement of Fluid through Liver :
• Blood enters via :
a.
b.
• BOTH vessels branch into smaller vessels
Supplying EACH :
• Blood enters lobules at the :
Blood travels down Sinusoids :
Regulating:
3

“Processed Blood”; Drains into :
• ALL Central veins unite to form the :
Delivers “processed” blood to the :
• Bile Canaliculi :
Canaliculi =
Narrow Intercellular Channels draining :
Bile flows away from Central Vein : Toward the :
Collected by :
Hepatic Triad : “Portal Triad”
• Arrangement of vessels at lobule periphery
Branch of :
Bile Drainage :
Hepatic Portal Vein
Hepatic Artery
Bile Duct
• Rt. Hepatic Ducts : Collects bile from bile ducts on :
• Lft. Hepatic Ducts : Collects bile from bile ducts on :
• Common Hepatic Duct : Union of :
4

• Cystic Duct : Duct to/from:
• Common Bile Duct : Union of :
Drains into :
Entrance of Common Bile Duct & Pancreatic Duct into :
Clinical Application : Liver Cirrhosis
• Scarring of liver: Formation of fibrous (scar) tissue associated with destruction of normal
liver architecture :
Study Questions :
1. What is the digestive functional significance of the pancreas? What composes the pancreatic juice? How is
the pancreatic juice released into the duodenum?
2. What is the functional significance of the Islets of Langerhans?
3. What are the 3 primary functions of the Liver?
4. Where does blood leaving the intestine travel? What is the functional significance of bile ? From what is bile
derived? What is the function of Kupffer cells
5. Describe the blood supply to the liver. What is the difference between the hepatic portal vein, the hepatic
artery and the hepatic vein? What degree of oxygenated blood is carried within each vessel ?
6. Describe the structure of the liver lobules : what cells comprise the lobule, how they are arranged, & the
sinusoid arrangement.
7. What is the function of the sinusoids and bile canaliculi? In which direction does fluid flow in each passage
way (toward the periphery of the lobule or toward the center)?
8. How is “processed blood” removed from the liver? To where does this blood travel?
9. How is “Unprocessed blood” delivered to the liver? What cells process this blood?
10. How are hepatocytes supplied with oxygen to maintain their active metabolism?
11. Describe the movement of bile from the hepatocytes to the hepatic ducts.
12. How is bile moved from the hepatic ducts to the gall bladder ? How is bile released into the duodenum from
the gall bladder?
5