Exam 1

Question 1

Pancreas- “Endocrine” function

Answer 1

(1%)
produce insulin and glucagon
released into blood stream
control glucose metabolism

Question 2

Pancreas- Exocrine”function

Answer 2

99%
produce secretions for digestion
released into duodenum
enzymes: lipases, proteases, amylases, etc.
HCO3-to buffer stomach acid, critical for enzyme activity, protect small intestine from acidity

Question 3

Zymogens

Answer 3

enzymes are first made in inactive forms.

•Activated by proteolysis after their release into the duodenum

Question 4

Liver and Gallbladder function

Answer 4

•Liver makes bile acids and bile salts
•Made from cholesterol
•Stored and concentrated in the gallbladder
•Emptied into the intestine when needed
•Acts as a detergent to break up fat “blobs”“
Emulsification”
•Forms “micelles”-small particles
•Needed for lipid absorption
•Also needed for absorption of fat-soluble vitamin

Question 5

Bile recycling

Answer 5

~90% of released bile is recycled

Question 6

microbiota function

Answer 6

Huge number of microbes live in GI tract, most in large intestine
10^14 total (vs. 10^13cells that are you)
>1000 species (dynamic)
E. coli is the most famous
•Benefits to us:
Niche-fillers
“Train”our immune systems
Make some vitamins we can then use (Vit K, biotin)
Digest unused energy sources we can then use
complex carbs converted into short chain fatty acids (2-6 C)
~10% of total calories come from this
Composition can affect risk of obesity

Question 7

Appendix function

Answer 7

“Vestigial”nature (left over from evolution) first proposed by Darwin 1871
•Contains “biofilms”of bacteria
•New theory: Reservoir of good intestinal bacteria that can repopulate your intestine after diarrhea or antibiotic treatment
•Appendectomy increases risk of C. difficile infection 400%

Question 8

Where are nutrients absorbed? - Stomach

Answer 8

Ethanol, water, iodide (I-)

Question 9

Where are nutrients absorbed? -SI

Answer 9

Sugars
Lipids (fatty acids, cholesterol)
Amino acids and small peptides
Fat-soluble vitamins (Vitamins A,D,E,K)
Water-soluble vitamins (B vitamins, C, folate)
Minerals (Ca, Cu, Fe, Se, Zn)

Question 10

Where are nutrients absorbed? LI

Answer 10

Water, electrolytes (K, Cl, Na)

Short chain fatty acids produced by microbes

Question 11

Why is the small intestine the major site of nutrient absorption?

Answer 11

Primary site of digestion
pancreatic enzyme secretions
brush border enzyme activity
•Site of lipid emulsification (micelles)
bile delivery to small intestine
•Enterocyte protein expression
location of transporter proteins that take up nutrients
•Structure large surface area, about 20 ft long but 2000-3000 sq ft in surface area

Question 12

Enterocytes:

Answer 12

the epithelial cells that line the luminal surface of the small intestine (also called mucosal cells or intestinal epithelial cells)

Question 13

After absorption, where to next?

Answer 13

Blood capillaries lead to portal vein and to the liver
Pathway of water-soluble nutrients, sugars, amino acids, water-soluble vitamins, minerals
•Lacteal leads to the lymph system
Pathway of fat-soluble nutrients
Lipids, cholesterol, fat-soluble vitamins
Drains into the circulation at the left subclavian vein

Question 14

Regulation of digestion

Answer 14

Digestion is highly regulated: control of peristalsis and motility
salivary, stomach, gall bladder, pancreatic secretions
appetite, energy balance
•Neuronal: nerves make contacts (innervate) throughout the GI tract“enteric nervous system”
stimulatory or inhibitory
e.g. norepinephrine signaling slows GI motility (stress response)
•Hormonal: over 100 regulatory peptides control digestion

Question 15

Gastroesophageal Reflux Disease (GERD)

Answer 15

• Stomach acid entering the esophagus
• Sensation of “Heartburn”
• Damages the esophagus (cancer risk)

Question 16

GERD causes

Answer 16

Increased pressure on LES (overeating, lying down while full)
Diet components that weaken the LES:
high fat foods, chocolate, nicotine, peppermint
[high protein diet increases LES contraction pressure]
Exacerbated by things that increase stomach acid
-Ca, coffee, tea
Symptoms aggravated by acidic, spicy food:
orange juice, tomatoes, onions, chili peppers

Question 17

Chronic Pancreatitis

Answer 17

•Decreased function of the pancreas
•Causes: 
chronic alcohol consumption
gallstones blocking pancreatic duct
•Blocks release of pancreatic enzymes
zymogen activation within organ
•Blocks release of HCO3-causes hyperacidity of small intestine inhibits brush border enzyme activity

Question 18

Inflammatory Bowel Disease (IBD)

Answer 18

e.g. Ulcerative colitis, Crohn’s disease
•Cause unknown -genetic link strong
•Inflammation of intestinal mucosa
•Disrupts absorption
loss of brush border enzyme activity
direct damage to enterocytes
increased rate of food movement
-diarrhea results from limits in water absorption
-steatorrhea-fat excretion in feces

Question 19

Infectious Diarrhea

Answer 19

“food poisoning”
Ingestion of toxin-producing bacteria or viruses
E. coliO157:H7 Salmonella Giardia Shigella(cholera)
Irritates the intestinal mucosaI
increases fecal transit rate
Decreased reabsorption of water and electrolytes
Severe diarrhea can lead to dehydration and electrolyte imbalances