Chapter 23 Integration and Hormonal Regulation of
Mammalian Metabolism
Multiple Choice Questions
1. The radioimmunossay (RIA) is based on competition of unlabeled and radiolabeled:
A) antibodies for binding to a hormone.
B) antibodies for binding to a receptor.
C) hormone for binding to a receptor.
D) hormone for binding to an antibody.
E) receptor for binding to a hormone.
2. One distinction between peptide and steroid hormones is that peptide hormones:
A) act through nonspecific receptors, whereas steroid hormones act through specific receptors.
B) are generally water-insoluble, whereas steroid hormones are water soluble.
C) are more stable than steroid hormones.
D) bind to cell surface receptors, whereas steroid hormones bind to nuclear receptors.
E) bind to their receptors with high affinity, whereas steroid hormones bind with low affinity.
3. Insulin is an example of a(n) ____________ hormone.
A) catecholamine
B) eicosanoid
C) paracrine
D) peptide
E) steroid
4. The maturation of insulin from its precursor (preproinsulin) involves:
A) acetylation.
B) oxidation.
C) phosphorylation.
D) proteolysis.
E) reduction.
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5. Epinephrine is an example of a(n) ____________ hormone.
A) catecholamine
B) eicosanoid
C) paracrine
D) peptide
E) steroid
6. An example of an eicosanoid hormone is:
A) epinephrine.
B) retinoic acid.
C) testosterone.
D) thromboxane.
E) thyroxine.
7. An example of a steroid hormone is:
A) epinephrine.
B) retinoic acid.
C) testosterone.
D) thromboxane.
E) thyroxine.
8. Some hormones are derived from amino acids; for example, catecholamines are derived from
while NO is derived from .
A) tyrosine; arginine
B) tryptophan; lysine
C) tyrosine; histidine
D) tryptophan; arginine
E) histidine; lysine
9. The tropic hormones (such as thyrotropin, somatotropin, and luteinizing hormone) are produced and
released by the:
A) anterior pituitary.
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B) hypothalamus.
C) ovaries.
D) pancreas.
E) posterior pituitary.
10. The normal sequence of action of these components of the hormonal hierarchy is:
A) adrenal cortex → hypothalamus → anterior pituitary.
B) anterior pituitary → adrenal cortex → hypothalamus.
C) anterior pituitary → hypothalamus → adrenal cortex.
D) hypothalamus → adrenal cortex → anterior pituitary.
E) hypothalamus → anterior pituitary → adrenal cortex.
11. In its role in the hormonal hierarchy, the hypothalamus produces and releases:
A) epinephrine.
B) insulin.
C) progesterone.
D) releasing factors.
E) thyroxine.
12. Which of the following statements about metabolism in the mammalian liver is false?
A) Most plasma lipoproteins are synthesized in the liver.
B) The enzymatic complement of liver tissue changes in response to changes in the diet.
C) The liver synthesizes most of the urea produced in the body.
D) The presence of glucose 6-phosphatase makes liver uniquely able to release glucose into the
bloodstream.
E) Under certain conditions, most of the functions of the liver can be performed by other organs.
13. Glucokinase:
A) acts in the conversion of liver glycogen to glucose 1-phosphate.
B) converts fructose-6-phosphate to glucose-6-phosphate
C) converts glucose 6-phosphate to fructose 6-phosphate.
D) is a hexokinase isozyme found in liver hepatocytes.
E) is found in all mammalian tissues.
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14. Which of the following is not a fate of amino acids in the liver?
A) Amino acids are incorporated into new proteins.
B) Nitrogen equivalents from amino acids are converted to urea.
C) Carbon equivalents from amino acids are converted to glucose.
D) Amino acids are stored for later use.
E) Amino acids serve as precursors to nucleotide biosynthesis.
15. Which of the following is not a fate of fatty acids in the liver?
A) Fatty acids are oxidized to generate ATP.
B) Fatty acids are converted to ketone bodies.
C) Fatty acids can be converted to cholesterol.
D) Fatty acids are stored for later use.
E) Fatty acids are converted to glucose.
16. A major difference between white adipose tissue and brown adipose tissue is that only:
A) white adipose tissue stores fatty acids as triacylglycerols.
B) brown adipose tissue degrades fatty acids via the citric acid cycle.
C) brown adipose tissue contains thermogenin.
D) white adipose tissue contains adipocytes.
E) white adipose tissue responds to hormone signals.
17. In skeletal muscle:
A) amino acids are an essential fuel.
B) at rest, fatty acids are the preferred fuel.
C) large quantities of triacylglycerol are stored as fuel.
D) phosphocreatine can substitute for ATP as the direct source of energy for muscle contraction.
E) stored muscle glycogen can be converted to glucose and released to replenish blood glucose.
18. In skeletal muscle, phosphocreatine functions as:
A) a reservoir of Pi for mitochondria.
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B) reservoir of high-energy of phosphate to replenish ATP.
C) reservoir of amino acids for protein synthesis.
D) an electron acceptor under anaerobic conditions.
E) None of the above
19. In anaerobic skeletal muscle, breakdown of glycogen yields ____ ATP per glucose equivalent.
A) 1
B) 2
C) 3
D) 4
E) 32
20. The Cori cycle is:
A) the conversion of lactate to pyruvate in skeletal muscle to drive glycogen synthesis.
B) the interconversion between glycogen and glucose l-phosphate.
C) the production of lactate from glucose in peripheral tissues with the resynthesis of glucose from
lactate in liver.
D) the synthesis of alanine from pyruvate in skeletal muscle and the synthesis of pyruvate from
alanine in liver.
E) the synthesis of urea in liver and degradation of urea to carbon dioxide and ammonia by bacteria
in the gut.
21. Which one of the following statements is true?
A) The brain prefers glucose as an energy source, but can use ketone bodies.
B) Muscle cannot use fatty acids as an energy source.
C) In a well-fed human, about equal amounts of energy are stored as glycogen and as
triacylglycerol.
D) Fatty acids cannot be used as an energy source in humans because humans lack the enzymes of
the glyoxylate cycle.
E) Amino acids are a preferable energy source over fatty acids.
22. When blood glucose is abnormally high, the pancreas releases:
A) epinephrine.
B) glucagon.
C) glucose.
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D) insulin.
E) trypsin.
23. When blood glucose is abnormally low, the pancreas releases:
A) epinephrine.
B) glucagon.
C) glucose.
D) insulin.
E) trypsin.
24. An elevated insulin level in the blood:
A) inhibits glucose uptake by the liver.
B) inhibits glycogen synthesis in the liver and muscle.
C) results from a below-normal blood glucose level.
D) stimulates glycogen breakdown in liver.
E) stimulates synthesis of fatty acids and triacylglycerols in the liver.
25. Which of the following is not involved in triggering insulin from -cells release in response to
glucose?
A) Reduced efflux through ATP-gated K+-channels
B) Increased concentrations of ATP
C) cAMP-dependent phosphorylation of lipase
D) Phosphorylation of glucose to glucose-6-phosphate
E) Increased Ca2+ levels
26. The largest energy store in a well-nourished human is:
A) ATP in all tissues.
B) blood glucose.
C) liver glycogen.
D) muscle glycogen.
E) triacylglycerols in adipose tissue.
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27. Elevated epinephrine levels do not normally stimulate:
A) fatty acid mobilization in adipose tissue.
B) gluconeogenesis in liver.
C) glycogen breakdown in muscle.
D) glycogen synthesis in liver.
E) glycolysis in muscle.
28. Epinephrine triggers an increased rate of glycolysis in muscle by:
A) activation of hexokinase.
B) activation of phosphofructokinase-1.
C) conversion of glycogen phosphorylase a to glycogen phosphorylase b.
D) inhibition of the Cori cycle
E) the Pasteur effect.
29. Long-term maintenance of body weight is regulated by the hormone:
A) adiposin.
B) hypothalmin.
C) leptin.
D) obesin.
E) testosterone.
30. Which of the following effects is not mediated by the protein leptin?
A) Increased synthesis of uncoupler protein thermogenin
B) Decreased activity of the enzyme 5´-AMP-activated protein kinase (AMPK)
C) Increased activity of the sympathetic nervous system
D) Increased
-oxidation
E) Decreased desire to eat
31. The hormone leptin appetite; insulin appetite.
A) increases; increases
B) increases; decreases
C) decreases; increases
D) decreases; decreases
E) has no effect on; has no effect on
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32. The peptide hormone adiponectin, produced in adipose tissue, circulates in the blood and:
A) enhances fatty acid synthesis in liver cells.
B) increases the rate of
-oxidation of fatty acids in muscle cells.
C) inhibits glucose uptake and catabolism in muscle and liver cells.
D) reduces the transport of fatty acids into muscle cells.
E) stimulates gluconeogenesis in liver cells.
33. Which of the following is not a peptide hormone?
A) Grehlin
B) Insulin
C) Adiponectin
D) PPAR
E) PYY3-36
34. Which of the following hormones stimulates appetite?
A) Grehlin
B) Insulin
C) Adiponectin
D) Both A and B
E) Both A and C
35. Which of the following is not a mechanism for treating diabetes?
A) Increasing TAG by weight loss
B) Activating AMPK through exercise
C) Activating AMPK by taking metformins
D) Activating PPAR
through rosiglitazone
E) Stimulating insulin secretion by taking sulfonylureas
Short Answer Questions
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36. What is a major problem in isolating a new hormone once a bioassay has been developed?
37. Name five general classes of hormones and give an example of each.
38. Some hormones trigger very rapid responses, whereas for others the response takes much longer to
develop. What generalization about the mechanisms of action of these two types of hormones can
explain the differences in response times?
39. Provide some distinguishing characteristics between eicosanoids and hormones such as epinephrine.
40. Provide some distinguishing characteristics between peptide hormones and thyroid hormones.
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41. Which class of hormones acts via nuclear receptors? Give an example of this type of hormone and
briefly describe its mode of action.
42. How do hormonal cascades result in large amplification of the original signal?
43. Describe five possible fates for glucose 6-phosphate in the liver.
44. Describe five possible fates of amino acids arriving in the liver after intestinal uptake.
45. Describe five possible fates for fatty acids in the liver.
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46. Provide three distinguishing characteristics between white adipose tissue (WAT) and brown adipose
tissue (BAT).
47. Briefly explain the role of phosphocreatine in muscle.
48. Briefly explain the Cori cycle.
49. Compare in general terms the effects of epinephrine, glucagon, and insulin on glucose metabolism.
50. Explain the signaling pathway by which an increase in blood glucose causes the release of insulin
from pancreatic
-cells.
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51. Explain the response and the consequences of prolonged fasting on fuel metabolism by the liver.
52. What is leptin? How does it function in the long-term maintenance of body mass?
53. Describe the signaling cascade initiated by leptin binding to its receptor.
54. Briefly describe the effects of the hormone adiponectin.
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55. Briefly describe the “lipid burden” hypothesis that explains the development of type 2 diabetes.