W3006  Fall '98     Physiology       Problem Set #     Digestive system

1. Sometimes/Always/Never:  Chylomicrons are found in the blood.
2. Sometimes/Always/Never:  Digestive enzymes are secreted by the liver.

3. True/false: if false, correct it to make it true
A. The inner lining of the stomach is thrown into folds known as villi.
B. The parietal cells secrete both pepsinogen and HCl.
C. Chylomicrons, which have hydrophilic proteins on their surfaces, are absorbed directly into the capillaries.
D. Amino acids are absorbed by secondary active transport by the epithelial cells of the small intestine.
E. After emulsifying fat in the chyme, the bile is excreted with the feces.
F. A component of the bile is responsible for both the brown color of feces and the yellow color of urine.
G. Amylase breaks down starch into glucose.
H. Once bile has acted on triglycerides, they are ready for absorption through the intestinal epithelium.

4. Which is greater, X or Y, or both are equal?
A. X. Diameter of a very low density lipoprotein. Y. Diameter of a high density lipoprotein.
B. X. Osmotic pressure of interstitial fluid of healthy tissue. Y. Osmotic pressure in interstitial fluid when tissue is inflamed.
C. X. Stroke volume when End Diastolic Volume is 135 ml. Y. Stroke volume when End Diastolic Volume is 155 ml.
D. X. Velocity of blood flow through capillary. Y. Velocty of blood flow through arteriole.
E. X. Opening of external urethral sphincter when motor neuron is stimulated. Y. Opening of external urethral sphincter when motor neuron is inhibited.

5. Which of the following are functions of the liver? a. activates vitamin D b. produces clotting factors c. synthesis of bile d. synthesis of chylomicron remnants e. storage of glucose as glycogen f. synthesis of renin

6. The micturition (urination)  reflex is similar to the defecation reflex. You would expect the micturition reflex to a. begin when stretch receptors in the bladder are stimulated b. involve contraction of the bladder  c. involve contraction of the internal urinary  sphincter d. involve contraction of the external urinary sphincter e. be overridden in the adult by signals from the brain

7. After eating a meal, food stays in the stomach for a while before moving to the small intestines. During this time, the blood may become temporarily alkaline. Explain why.

8. Obstruction of the bile duct leads to an increase in tendency to bleed. Explain why. In addition to what you learned in class you'll need to use some (but not all) of the following information: Vitamins A,D,E,K are fat-soluble. Vitamin C and the B vitamins are water-soluble. Excess vitamin A is stored in the liver. Vitamins A,C,E are antioxidants. Vitamin C is a cofactor for an enzyme needed for collagen synthesis. Vitamin K is a cofactor for an enzyme needed for prothrombin synthesis.

9, The stomach is surgically removed from a person, and the remaining digestive tract sewn together. Briefly explain each of the following: Compared to a normal individual,

a. protein digestion is normal.
b. blood levels of vitamin B12 are much lower.
c. after a meal, hyperglycemia (high blood sugar) is more likely to develop.

10. During the early fall, brown bears up their caloric intake from a previous 5000 kcal/day to 20,000 kcal/day. They then begin a 3-5 month "denning" period, during which they stay in their dens without eating or drinking, maintaining their metabolic rate through metabolism of stored fats. Recent research shows that the lipoprotein lipase activity measured in blood vessels of adipose tissue is different during the eating and denning periods. During which period would you expect it to be higher? Explain why.