Biochemistry Of GI Tract And Pancreas

Question 1

Stomach and small intestine (SI) pH

Answer 1

. Stomach: 1 w/o food, 3 w/ food

. SI: 8 w/o food, 6 w/ food

Question 2

Components needed for rapid cell division in intestine

Answer 2

. Ingredients for de novo nucleotide synthesis
. AA like gln, asp, etc
. Folate and other vitamins
. Fuel for anabolic rxns

Question 3

Infant’s GI tract unique qualities

Answer 3

. Take in some proteins via pinocytosis

. Allows take in of maternal antibodies from breast milk, imparting immunological protection

Question 4

Changes in GI in elderly

Answer 4

. Lose taste acuity
. B12 absorption deficiency, treated w. Injections
. Lactose intolerance

Question 5

Goal of zymogens

Answer 5

Self protection because they must be cleaved in form active enzyme

Question 6

Transport in GI tract

Answer 6

. Na/K ATPase: hydrolysis of 1 ATP moves 3 Na out and 2 K in, important in intestinal cells to drive active transport of AA and monosaccharides
. Na-dependent glucose transport: secondary active transport, can occur against glucose gradient but needs Na gradient

Question 7

Cholera

Answer 7

. Caused by vibrio cholera
. Symptoms: severe diarrhea, dehydration, loss of electrolytes
. 130,00 people have it, 2,400 died
. Expensive antibiotics
. Cheap oral rehydration therapy: glucose solution, Na, Cl, K, and citrate

Question 8

CF transmembrane conductance protein

Answer 8

. Chloride channel protein
. In pancreas, lung, liver, sweat
. Channel normally closed, opens when cAMP inc.
. Heterozygous for mutation protected from cholera effects bc not all channels will open when cAMP inc. from cholera and they will not lose as much water

Question 9

GI in fed state

Answer 9

. Gln important fuel from dietary protein

. Intestinal cells can utilize various fuels

Question 10

GI in starved state

Answer 10

. No dietary nutrients
. GI depends on blood-born sources of fuel
. Enterocytes take in and oxidize glucose, but can use ketone bodies
. Gln still important but comes from skeletal muscle degradation that releases it from BCAA catabolism

Question 11

Advantages of enteric bacteria

Answer 11

. Provide source of some vitamins

. Action on bilirubin breakdown productsa makes urobilinogen and stercobilin

Question 12

Disadvantages of enteric bacteria

Answer 12

. Perforation can cause systemic infection
. Can generate substances that cause discomfort or harmful is reabsorbed
. Make urease that is enzyme that turns urea into NH3 and CO2
. Reabsorption of NH3 is toxic to nervous system

Question 13

Hyperammonemia in people with kidney failure

Answer 13

. Elevated plasma urea
. Some urea leaves blood and enters intestine
. Bacteria regenerate NH4 and CO2 and ammonia re-enters blood
. Toxic to brain is concentrations over 40 uM
. Treatment: administer antibiotics to kill bacteria

Question 14

Pancreas anatomy

Answer 14

. Large functional reserve
. 60-250g
. 5-6in long

Question 15

Exocrine functions of pancreas

Answer 15

. 1.5-3L secreted per day 
. Zymogens made 
. Protein-degrading: trypsin, chymotrypsin, aminopeptidases
. Fat-degrading: lipases, phospholipase
. Carb-degrading: amylase
. DNA and RNA degrading: nucleases

Question 16

Markers of pancreatic damage

Answer 16

Amylase

. Lipase

Question 17

Pancreatitis

Answer 17

. Acute: inappropriate activation of pancreatic enzymes
. Symptoms: abdominal pain radiating to back, chest, flanks, vomiting, tachycardia, hypotension
. Diagnosed by physical symptoms and inc. amylase and lipase, WBCs usually inc. too (chronic may not be high bc pancreas can’t make them anymore)
. Causes: alcohol, blocked bile duct, hypertriglyceridemia, drug side effects, CF, idiopathic

Question 18

Pancreatitis treatment

Answer 18

. Analgesics, IV fluids and nutrition, abstinence from taking food by mouth

Question 19

Pancreatitis epidemiology

Answer 19

. 80,000 cases of acute/year, 20% are severe
. African Americans 4x rate as whites
. Chronic pancreatitis more common in men than women