Additional questions and answers
1. Xenical is a drug that inhibits pancreatic lipase. Explain how this drug might be effective in treating obesity.
2. People are give a glass of sugar water
to drink at time 0.
Blood is withdrawn at every half hour and glucose levels are measured.
Results are plotted below. Well, I haven't figured out the drawing programs
here. Levels of blood glucose in Person A rise quickly, then
decrease back to baseline quickly.
In Person B, the baseline is higher. Levels increase, but remain high and
decrease more slowly.
A. Why does it take about an hour to get maximal levels of blood glucose.
B. What causes the rapid fall in blood glucose in person A?
C. What causes the blood to fall to baseline in Person B?
D. Which one of these people has diabetes mellitus? A or B?
3. A certain drug is an alpha-1 receptor agonist (that is,
it stimulates the receptor) whichcan be used to prevent the localized edema that occurs in
the nasal passages during allergic responses.
A. This drug should increase/decrease/not affect the strength of heart contraction.
Explain briefly.
B. This drug should increase/decrease/not affect the flow of blood through the coronary
arteries. Explain briefly.
C. Describe the fluid changes that can cause edema, and how this drug prevents it.
4. Statins are drugs that inhibit HMG CoA reductase, the
rate-limiting enzyme involved in synthesis of cholesterol.
A. In which organ is this enzyme most likely to be found?
B. Explain what occurs in this organ (on a molecular level) when cholesterol synthesis is
inhibited.
C. Explain how this change makes these drugs useful in the prevention of atherosclerosis.
5. Choose the correct choice (a or b) and then explain the
effect on blood flow, using at least one of the equations discussed in class.
A. Cardiac muscle is weak......blood flow in capillaries a) speeds up or b) slows down?
B. Arterioles constrict............blood flow in capillaries a) speeds up or b) slows
down?
C. In part A, blood pressure is a) higher than or b) lower than normal?
In part B, blood pressure a) higher than or b) lower than normal?
6. The following types of drugs are used to lower blood
pressure. Explain how each works to decrease blood pressure:
A. inhibits sympathetic innervation of the kidney
B. inhibits Na+ transport in the ascending limb of the loop of Henle
7. True/False. Correct if false.
A. Nitric oxide and acetylcholine both can act as vasoconstrictors.
B. Dietary triglycerides are delivered to the tissues by VLDL's.
C. End Diastolic Volume is normally larger than End Systolic Volume.
D. Cholecystokinin (CCK) stimulates pancreas to release digestive enzymes.
E. Epinephrine and glucagon have opposite effects on blood glucose levels.
F. The liver breaks down hemoglobin, and stores all the iron that is released.
G. Pepsin is secreted from parietal cells.
Answers
1. Function of lipase is to breakdown triglycerides to monoglycerides and free fatty acids, which is necessary before they can be absorbed. If lipase is inhibited, no fat breakdown, no triglyceride absorption, fats exit in feces rather than going to adipose tissue for storage, less obesity.
2. A. The stomach is like a holding tank. It slowly
releases its contents to the small intestines, where absorption occurs as glucose combines
with carriers in epithelial cell membranes. It takes time for the ingested glucose
to reach the intestines.
B. Insulin stimulates uptake of glucose by liver, adipose, muscle, so less is left in the
blood.
C. Glucose in high concentration in blood produces high glucose concentration in the
glomerular filtrate, which saturates the carriers there, so excess glucose is lost in the
urine, lowering blood levels.
D. Person B
3. A. not affect. Epinephrine receptors on heart
muscle are beta-1, so shouldn't be affected.
B. Epinephrine receptors on coronary arteries are alpha and beta-2, so effect would depend
on dose. If there's sufficient alpha stimulation would decrease flow. Drug
wouldn't affect beta-2 receptors.
C. Fluid leaves capillaries when hydrostatic pressure outward from capillary is greater
than osmotic pressure pulling fluid inward. Hydrostatic presssure is dependent on
blood pressure. This drug will stimulate alpha receptors, causing vasoconstriction,
which would slow the flow of blood to nasal passages, decreasing the pressure pushing
fluid out, so preventing edema.
4. A. liver
B. decrease cholesterol in liver cells means less feedback inhibition of LDL receptor, so
more LDL receptors.
C. Increased LDL Receptor means more LDL taken out of blood. This delivers
cholesterol to liver where it can be added to bile and excreted from the body. Less
LDL in blood means less LDL available to enter arteriolar walls and contribute to
atherosclerosis.
5. A. b) slows down. Decreased strength of
contraction of heart means less pressure on the blood.
Flow = Pressure diff / Resistance, so decrease P ==> decrease F. OR you
could say:
BP = CO x R and CO = EDV-ESV. If decrease strength of contraction, then
increase ESV and Decrease CO so Decrease P and P=FxR, so flow decreases.
B. b)slows down
R is proportional to 1/r 4, so decrease radius ==> increase R. Flow = P/R, so the
increased R means decreased Flow.
C. In A, BP is lower; In B, BP is higher (pressure measured in arteries behind the constriction)
6. A. Sympathetic neurons innervate afferent arterioles to
cause vasoconstriction, and decrease blood flow to glomerulus. Without sympathetic
innervation, will be vasodilation of afferent arteriole, causing pressure to increase in
the glomerular capillaries, and increased GFR , increased urine formation, increased water
lost in urine, decreased blood volume, decreased cardiac output, decreased blood pressure.
B. Less Na+ transported from the nephron means more Na+ in the filtrate, increases osmotic
concentration so more water remains in filtrate, more water exits body, less water in
body, lower blood volume, lower blood pressure.
7. A. False. vasodilators.
B. False. ....by chylomicrons.
C. True
D. True
E. False. ...the same effects....
F. False. stores some of the iron...
G. False. Pepsin from chief cells.