L. Pancreas (Accessory)
1. Position
Posterior, inferior to stomach
2. Pancreatic duct
Pancreas to duodenum
3. Islets
Endocrine cells
4. Pancreatic Juice
a. Acinar Cells [99%]– Exocrine cells
b. Bicarbonate (pH 8)
c. Pancreatic Amylase (Carbohydrate Enzymes)
d. Protein Enzymes
1. Trypsin
2. Chymotrypsin
3. Carboxypolypeptidase
e Lipase
f. Controls of Release
The following increase pancreatic juice release:
1. Secretin
2. Cholecystokinin
3. Neurally (Vagus nerve)
M. Liver(Hepato-) (Accessory)
1. 4 Lobes; Right & Left Lobes are large-separated by Falciform Ligament
2. Hepatocyte
3. Common Bile Duct– Hepatic ducts and gall bladder ducts join and empty into duodenum
4. Blood supply
Quite large
5. Bile Production [600-1000 ml/day]
a. Liver Cells
b. Gall Bladder –Stores bile
c. Bile composition
1. Water
2. Bilirubin
Break down product of hemoglobin
3. Bile salts –Emulsification
Breaks fat into smaller particles
d. Enterohepatic circulation
Bile salts released into duodenum are reabsorbed in ileum and returned to liver
e. Rate of secretion
The following increase bile secretion:
1. Increased Enterohepatic circulation, increased hepatic blood flow
2. Vagus nerve
3. Secretin
4. Cholecystokinin
6. Other Liver functions
a. Metabolic Regulation – Blood filtering, monitoring
b. Blood Regulation – Clotting factors, blood protein production
c. Phagocytose old WBC, RBC
d. Detoxification, Storage of poison
e. Stores Glucose (glycogen), Fat, Protein, Cu,
Fe, Vitamins
N. Small Intestine[3-5 hours]
1. Duodenum (1′), Jejunum (8′), Ileum (12′)
2. Microstructure
a. Villi and Microvilli
b. Blood vessels & Lacteals
3. Intestinal Secretions/Juice (2-3 l/d)
– Duodenal (Brunner’s) glands
Protective mucus
– Intestinal glands make isotonic juice containing enzymes
4. Motility
a. Segmentation
Mixing
b. Peristalsis
Wave like weak contractions for movement of chyme
5. Absorption
a. Definition
Nutrients pass from GI tract into bloodstream or lymph vessel, 90% absorption occurs in small intestine
b. Villi & microvilli
Increase surface area for absorption!
c. Active transport, diffusion, facilitated diffusion, cotransport
d. Carbohydrate
– Glucose
e. Proteins
f. Lipids
1. Emulsification
2. Lipase
3. Micelles [fat + bile salt]
4. Chylomicrons [more breakdown within epithelial cells, bile recirculated]
5. Lacteals
Lymphatics
g. Vitamins
Vitamins ADEK absorbed along with fat, Vitamins BC absorbed along with water
h. Water & Electrolytes (ions in solution)
1. 200-400 ml water/hour by osmosis (9 liters/day)
2. Sodium
3. Calcium; Vit. D dependent
O. Large Intestine[3-5 hrs; 5′]
1. Cecum
a. Ileocecal sphincter (valve)
b. Appendix
2. Colon
a. Ascending
b. Transverse
c. Descending
d. Sigmoid
3. Rectum
4. Anus
5. No Villi
6. Goblet Cells
Make mucus
7. Taeniae coli
Flat muscular bands
8. Haustra
Pouches formed by contraction of Taeniae coli muscles
9. Motility
a. Peristalsis
b. Haustral churning
c. Mass peristalsis [3-4x/d]
Drives contents into rectum
d. Gastroileal reflex [activates mass peristalsis]
e. Defecation reflex
Relaxation of internal anal sphincter
f. Anal sphincters
Internal & external
10. Function
a. Some absorption (water)
b. Lubrication
c. Form & Store feces
d. Vitamin K & some B’s & absorption
e. Bacterial fermentation