Deck 23: Hormonal Regulation and Integration of Mammalian Metabolism

Question 1

The normal sequence of action of these components of the hormonal hierarchy is:

A) adrenal cortex $\rightarrow$ hypothalamus $\rightarrow$ anterior pituitary.
B) anterior pituitary $\rightarrow$ adrenal cortex $\rightarrow$ hypothalamus.
C) anterior pituitary $\rightarrow$ hypothalamus $\rightarrow$ adrenal cortex.
D) hypothalamus $\rightarrow$ adrenal cortex $\rightarrow$ anterior pituitary.
E) hypothalamus $\rightarrow$ anterior pituitary $\rightarrow$ adrenal cortex.

Answer 1

hypothalamus $\rightarrow$ anterior pituitary $\rightarrow$ adrenal cortex.

Question 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.

Answer 2

D

Question 3

In skeletal muscle, phosphocreatine functions as:

A) a reservoir of P_i for mitochondria.
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 answers is correct.

Answer 3

B

Question 4

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.

Question 5

Which statement does NOT describe 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.

Question 6

Which statement 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.

Question 7

Insulin is an example of a(n) _____ hormone.

A) catecholamine
B) eicosanoid
C) paracrine
D) peptide
E) steroid

Question 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

Question 9

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.

Question 10

Epinephrine is an example of a(n) _____ hormone.

A) catecholamine
B) eicosanoid
C) paracrine
D) peptide
E) steroid

Question 11

Which statement does NOT describe 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.

Question 12

In anaerobic skeletal muscle, breakdown of glycogen yields _____ ATP per glucose equivalent.

A) 1
B) 2
C) 3
D) 4
E) 32

Question 13

The maturation of insulin from its precursor (preproinsulin) involves:

A) acetylation.
B) oxidation.
C) phosphorylation.
D) proteolysis.
E) reduction.

Question 14

An example of an eicosanoid hormone is:

A) epinephrine.
B) retinoic acid.
C) testosterone.
D) thromboxane.
E) thyroxine.

Question 15

The tropic hormones (such as thyrotropin, somatotropin, and luteinizing hormone) are produced and released by the:

A) anterior pituitary.
B) hypothalamus.
C) ovaries.
D) pancreas.
E) posterior pituitary.

Question 16

An example of a steroid hormone is:

A) epinephrine.
B) retinoic acid.
C) testosterone.
D) thromboxane.
E) thyroxine.

Question 17

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.

Question 18

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.

Question 19

The Cori cycle is the:

A) conversion of lactate to pyruvate in skeletal muscle to drive glycogen synthesis.
B) interconversion between glycogen and glucose l-phosphate.
C) production of lactate from glucose in peripheral tissues with the resynthesis of glucose from lactate in liver.
D) synthesis of alanine from pyruvate in skeletal muscle and the synthesis of pyruvate from alanine in liver.
E) synthesis of urea in liver and degradation of urea to carbon dioxide and ammonia by bacteria in the gut.

Question 20

In its role in the hormonal hierarchy, the hypothalamus produces and releases:

A) epinephrine.
B) insulin.
C) progesterone.
D) releasing factors.
E) thyroxine.

Question 21

When blood glucose is abnormally low, the pancreas releases:

A) epinephrine.
B) glucagon.
C) glucose.
D) insulin.
E) trypsin.

Question 22

Long-term maintenance of body weight is regulated by the hormone:

A) adiposin.
B) hypothalmin.
C) leptin.
D) obesin.
E) testosterone.

Question 23

Under conditions of prolonged starvation, which fuel is MOST catabolized by the brain in humans?

A) ketone bodies
B) glucose
C) amino acids
D) odd-chain fatty acids
E) glycerol

Question 24

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.

Question 25

Each enzyme listed below catalyzes a reaction in the skeletal muscles of an Olympic sprinter. However, the role of which one would be considered LEAST significant during the running of a 100m sprint?

A) adenylate kinase
B) creatine kinase
C) pyruvate dehydrogenase
D) lactate dehydrogenase
E) glycogen phosphorylase

Question 26

What two properties make triglycerides more efficient than glycogen for the storage of metabolic energy?

A) They are anhydrous and less reduced.
B) They are anhydrous and more reduced.
C) They are hydrated and less reduced.
D) They are hydrated and more reduced.

Question 27

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 $\beta$ 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.

Question 28

Which factor is NOT involved in triggering insulin from $\beta$ -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

Question 29

Which compound is NOT a peptide hormone?

A) grehlin
B) insulin
C) adiponectin
D) PPAR $\gamma$
E) PYY_3-36

Question 30

Which hormone stimulates appetite?

A) grehlin
B) insulin
C) adiponectin
D) both grehlin and insulin
E) both grehlin and adiponectin

Question 31

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.

Question 32

Which statement 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.

Question 33

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.

Question 34

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.

Question 35

Which effect 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 $\beta$ oxidation
E) decreased desire to eat

Question 36

A hyperventilating patient is admitted to hospital after experiencing for some time excessive thirst, frequent urination, weight loss, and fatigue. Analysis of the blood reveals below normal pH and above normal glucose levels. What is the primary cause of this low blood pH?

A) ketoacidosis resulting from starvation
B) water loss due to frequent urination
C) excessive amounts of lactate produced by anaerobic metabolism
D) ketoacidosis resulting from untreated type I diabetes
E) excessive amounts of lactate produced by chronic alcohol use

Question 37

The three common $\alpha$ -keto acids involved in transamination reactions are:

A) glutamate, succinate, and acetate.
B) glutamate, aspartate, and alanine.
C) succinate, fumarate, and malate.
D) pyruvate, oxaloacetate, and $\alpha$ ketoglutarate.
E) citrate, 3-phosphoglycerate, and isocitrate.

Question 38

Which process 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 $\gamma$ through rosiglitazone
E) stimulating insulin secretion by taking sulfonylureas

Question 39

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

Question 40

When blood glucose is abnormally high, the pancreas releases:

A) epinephrine.
B) glucagon.
C) glucose.
D) insulin.
E) trypsin.

Question 41

Covalent modification via phosphorylation/dephosphorylation of specific key enzymes modifies their catalytic activity, and thus the flux through pathways. Which pathway below is NOT regulated by this strategy?

A) cholesterol synthesis in the liver
B) lipolysis in adipocytes
C) glycogen degradation in skeletal muscle
D) fatty acid synthesis in the liver
E) esterification to form triacylglycerols in the liver

Question 42

Which condition is associated with elevated insulin levels in the blood?

A) Acetyl-CoA levels rise and ketone body synthesis increases.
B) Oxaloacetate levels are high and citrate synthesis increases.
C) Gluconeogenesis is activated and glycolysis is inhibited.
D) The production of mevalonate decreases.
E) Liver glycogen phosphorylase is activated.

Question 43

Which consequence is MOST likely following the ingestion of ethanol after a heavy physical workout?

A) enhanced uptake of lactate by liver
B) gluconeogenesis will be inhibited in hepatocytes
C) glycogen synthesis will be stimulated in hepatocytes
D) secretion of glucagon will be inhibited
E) None of the answers is correct.

Question 44

Which statement is TRUE regarding the islet cells of the pancreas?

A) $\alpha$ cells secrete glucagon to stimulate glycogenolysis in skeletal muscle.
B) $\alpha$ cells secrete glucagon to stimulate glycolysis liver.
C) $\beta$ cells secrete glucagon to stimulate glycogenolysis in liver.
D) $\beta$ cells secrete insulin to stimulate glucose uptake by skeletal muscle, the liver, and adipose tissue.
E) $\alpha$ cells secrete insulin to stimulate glycolysis in skeletal muscle.

Question 45

Brown adipose tissue (BAT) is a specialized fatty tissue present in some hibernating and cold-adapted animals. The mitochondria of BAT contain an additional protein called thermogenin, which spans the inner mitochondrial membrane. What occurs when this protein is active?

A) a decrease in the overall consumption of oxygen
B) an increase in the storage of triglycerides in brown adipocytes
C) a significant increase in heat production
D) a decrease in the flux of $\beta$ oxidation in the matrix
E) no change in the amount of ATP produced per fatty acid catabolized

Question 46

Which statement is TRUE regarding the late stages of starvation?

A) The brain has decreased its need for glucose by switching to lactate as a major energy source.
B) High levels of acetyl-CoA derived from lipid catabolism lead to the production of acetoacetate.
C) Ketone bodies are produced from amino acids liberated from noncritical proteins.
D) Gluconeogenesis is extremely active in the liver because of the large amounts of lactate exported from the muscle.
E) Catabolism of triacylglycerols provides the major source of a gluconeogenic metabolite in the form of glycerol.

Question 47

Which hormone triggers the release of $\alpha$ -melanocyte-stimulating hormone from anorexigenic neurons?

A) leptin
B) insulin
C) ghrelin
D) both leptin and insulin
E) both leptin and ghrelin

Question 48

What would likely be the consequence of a biochemical defect in which glucagon was secreted in excess?

A) muscular fatigue due to lactic acidosis
B) inhibited glycolysis in the liver with depleted glycogen stores
C) lowered concentrations of ketone bodies circulating in the blood stream
D) depressed rate of urea excretion
E) excessive accumulation of triacylglycerols in adipocytes

Question 49

Which enzyme is likely to be activated by epinephrine?

A) hormone-sensitive lipase
B) acetyl-CoA carboxylase
C) glycogen synthase
D) HMG-CoA reductase
E) fructose 1,6-bisphosphatase in skeletal muscle

Question 50

In an attempt to control type 2 diabetes, some people follow a high-fat, low-carbohydrate diet. Which substance(s) would NOT have an increased concentration in the blood after two weeks on this diet?

A) fatty acids
B) glucagon
C) acetone
D) glucose
E) amino acids

Question 51

In a well-fed individual, which factor does NOT contribute to the synthesis of fatty acids and triacylglycerols in the liver?

A) dihydroxyacetone phosphate
B) carbon skeletons derived from amino acids
C) carnitine.
D) HCO₃^-
E) citrate

Question 52

In a cell, the relative concentrations of ATP and ADP in the matrix ultimately control the rate of:

A) glycolysis.
B) oxidative phosphorylation.
C) pyruvate oxidation.
D) both oxidative phosphorylation and pyruvate oxidation.
E) All of the answers are correct.

Question 53

Which protein is inhibited by insulin?

A) glucokinase
B) GLUT4
C) acetyl-CoA carboxylase
D) pyruvate dehydrogenase
E) glycogen phosphorylase

Question 54

Which enzyme does NOT catalyze a substrate level phosphorylation reaction?

A) ATP synthase
B) creatine kinase
C) pyruvate kinase
D) phosphoglycerate kinase
E) phosphoenoylpyruvate carboxykinase

Question 55

In uncontrolled insulin-dependent diabetes, which pathway or reaction is accelerated, possibly resulting in toxic effects by the end product(s)?

A) accelerated conversion of $\beta$ -hydroxy $\beta$ -methylglutaryl-CoA to acetoacetate
B) accelerated conversion of $\beta$ -hydroxy $\beta$ -methylglutaryl-CoA to mevalonate
C) acceleration of the citric acid cycle
D) accelerated removal of triglycerides from chylomicrons
E) acceleration of the pentose phosphate pathway in erythrocytes

Question 56

After a meal rich in carbohydrates, which condition would NOT be expected?

A) adenylate cyclase deactivation
B) increased activity of glucokinase
C) glycogen phosphorolysis
D) decreased secretion of glucagon
E) decreased production of $\beta$ hydroxybutryate

Question 57

Which enzyme is NOT activated by insulin?

A) acetyl-CoA carboxylase
B) glycogen synthase
C) HMG-CoA reductase
D) hormone sensitive lipase
E) kinase activity of PFK-2

Question 58

Which statement is TRUE regarding diabetes mellitus?

A) Diabetes mellitus is characterized by the abnormal depletion of blood glucose by the liver.
B) Diabetes mellitus is characterized by reduced levels of gluconeogenesis in the liver.
C) Diabetes mellitus is characterized by the destruction of glucagon-secreting cells of the pancreas.
D) Diabetes mellitus is characterized by the secretion of glucagon in the urine leading to "sweet urine."
E) Diabetes mellitus is characterized by ketonemia, metabolic acidosis, and ketouria.

Question 59

Which factor is NOT associated with exercise?

A) activation of AMP-activated protein kinase
B) decreased release of insulin from the pancreas
C) activation of acetyl-CoA carboxylase
D) activation of the kinase activity of PFK-2 in skeletal muscle
E) inhibition of glycogen synthase

Question 60

What would likely be the consequence of a biochemical defect in which insulin was secreted in excess?

A) muscular fatigue due to lactic acidosis
B) inhibited glycolysis in the liver resulting in enhanced glycogen stores
C) lowered concentrations of glucose circulating in the blood stream
D) depressed rate of fatty acid synthesis in the liver
E) enhanced rate of gluconeogenesis in hepatocytes

Question 61

What is a major problem in isolating a new hormone once a bioassay has been developed?

Question 62

Which hormone triggers the release of neuropeptide Y from orexigenic neurons?

A) leptin
B) insulin
C) ghrelin
D) both leptin and insulin
E) both leptin and ghrelin

Question 63

Which two hormones play a crucial role in regulating short-term eating behavior?

A) leptin and ghrelin
B) cortisol and leptin
C) ghrelin and PYY_3-36
D) insulin and glucagon
E) adiponectin and PYY_3-36

Question 64

Which statement does NOT describe a fate for fatty acids in the liver?

A) They are oxidized to yield acetyl-CoA and NADPH.
B) They are released into the bloodstream as a component of lipoproteins.
C) They are oxidized and converted into ketone bodies.
D) They are released as free fatty acids into the bloodstream.
E) They are oxidized and used in the synthesis of cholesterol.

Question 65

Which protein is likely to be activated by cortisol?

A) GLUT4 translocation to plasma membrane in myocytes
B) phoephoenolpyruvate carboxykinase
C) glycogen synthase in hepatocytes
D) All of the answers are correct.
E) None of the answers is correct.

Question 66

Which statement is FALSE regarding the protein ghrelin?

A) Levels of ghrelin are lowest in the blood just before a meal and lowest just after a meal.
B) Ghrelin is a peptide hormone produced by endocrine cells lining the gastrointestinal tract.
C) The receptors for ghrelin are found in the same location as the receptors for leptin.
D) Regulation of gastric ghrelin secretion may be influenced by specific microbes in the gut.
E) Ghrelin causes the release of orexigenic peptides from arcuate neurons in the pituitary gland.

Question 67

Provide some distinguishing characteristics between eicosanoids and hormones such as epinephrine.

Question 68

Which complication is likely as a result of a condition known as metabolic syndrome?

A) developing resistance to insulin
B) developing type 1 diabetes
C) developing cardiovascular disease
D) developing both cardiovascular disease and resistance to insulin
E) developing both type 1 diabetes and cardiovascular disease

Question 69

Which statement is TRUE regarding the protein leptin?

A) Leptin is a hormone made primarily by hepatocytes that functions to regulate energy balance by curtailing appetite.
B) Leptin makes hepatocytes and myocytes more sensitive to insulin.
C) Leptin is also involved in regulating the sympathetic nervous system, resulting in a decrease in blood pressure, heart rate, and thermogenesis.
D) The amount of leptin released by adipose tissue is independent of the number and size of adipocytes; rather, it is strictly correlated with ingestion of food.
E) Leptin causes the release of orexigenic peptides that act in the brain to inhibit appetite.

Question 70

Which statement describes one of the roles of mTORC1?

A) mTORC1 activates AMP-activated protein kinase (AMPK), resulting in energy production for cell growth.
B) mTORC1 activates translation of proteins involved in lipid synthesis and mitochondrial metabolism.
C) mTORC1 acts through AMPK to increase sensitivity of hepatocytes and myocytes to insulin.
D) mCTOR1 reduces the uptake of glucose by hepatocytes, ensuring the brain has an adequate glucose supply.
E) All of the answers are correct.

Question 71

Which signal is required for mTORC1 activation?

A) branched-chain amino acids
B) nutrient availability
C) energy resources
D) certain growth factors
E) All of the answers are correct.

Question 72

Name five general classes of hormones and give an example of each.

Question 73

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?

Question 74

What would likely be the consequence of a biochemical defect in which cortisol was secreted in excess?

A) muscular weakness
B) diabetes
C) osteoporosis
D) All of the answers are correct.
E) None of the answers is correct.

Question 75

Which hormone must bind to a nuclear receptor before it has an effect?

A) epinephrine
B) PGE₁
C) triiodothyronine
D) nitric oxide
E) GLUT4

Question 76

Provide some distinguishing characteristics between peptide hormones and thyroid hormones.

Question 77

Which condition is NOT typically associated with metabolic syndrome?

A) hypotension
B) elevated fasting plasma glucose
C) elevated serum levels of LDL
D) abdominal obesity
E) reduced serum levels of HDL

Question 78

Which hormone must bind to a plasma membrane receptor before it has an effect?

A) cortisol
B) retinoic acid
C) nitric oxide
D) norepinephrine
E) thyroxine

Question 79

Which hormone inhibits the release of neuropeptide Y (NPY) from orexigenic neurons?

A) leptin
B) ghrelin
C) glucagon-like peptide 1
D) both leptin and ghrelin
E) both leptin and glucagon-like peptide 1

Question 80

Which enzyme, found primarily in the liver, dictates that the gluconeogenic pathway of the Cori cycle occurs in the liver?

A) glucose 6-phosphatase
B) glucokinase
C) glucose 6-phosphate dehydrogenase
D) glyceraldehyde 3-phosphate dehydrogenase
E) phosphoglucomutase