DTS 505: Ch. 7

What provides the majority of blood glucose during the postabsorptive state?

Hepatic glycogenolysis

Which amino acid is considered purely ketogenic?

Leucine

After several weeks of starvation, what proportion of the energy needs of the brain is supplied by β-hydroxybutyrate and acetoacetate?

two-thirds

How does training enhance the utilization of fat as the primary energy substrate during submaximal exercise?

It enhances fatty acid oxidation inhibiting glucose uptake and glycolysis

How does creatine enhance muscle performance?

It improves contractile performance and brings about hypertrophy

As an "amphibolic" pathway, what is the TCA cycle capable of in addition to participating in oxidative catabolism?

It provides precursors for biosynthetic pathways

How long does it take for the postabsorptive state to evolve into the fasting state?

18-48 hours

What proportion of the glucose-6-phosphate used to synthesize liver glycogen is obtained from intestinally absorbed glucose?

2/3

At rest, the brain uses what percentage of available energy?

20-25%

Skeletal muscle accounts for what percentage of protein turnover?

25-35%

In an exercise such as an 800 m sprint, what proportion of energy is supplied by the anaerobic lactic acid system?

50%

A deficiency in carnitine acyltransferase I (CAT I) could lead to interference with which of the following processes?

ATP production

Which cells synthesize the protein hormone adiponectin?

Adipose cells

Which of the following stores large amounts of triacylglycerols?

Adipose tissue

Which of the following describes the lactic acid system?

Anaerobic glycolysis

Which of the following can adapt to using ketone bodies during prolonged energy deficit?

Brain

Which of the following amino acids are used primarily by muscle during protein turnover?

Branched-chain amino acids

Which of the following regulatory hormones stimulates gluconeogenesis and glycogenolysis in the liver similar to glucagon?

Cortisol

T or F: A fasted state is characterized by a marked increase in protein synthesis.

False

T or F: All tissues prefer glucose first, and then fatty acids, to meet their energy needs.

False

T or F: Brain and red blood cells adapt to using ketones during starvation.

False

T or F: Carbohydrate loading is a dietary and exercise strategy aimed at maximizing glycogenolysis in muscle and liver.

False

T or F: During very prolonged starvation nearing death, the body shifts from using protein for energy to using fat stores.

False

T or F: Most regulatory enzymes act in a bidirectional manner.

False

T or F: Muscle supplies its own glucose for energy needs by first using glycogen stores, and then converting amino acids to glucose.

False

T or F: The postabsorptive state evolves into the fasting state after 36-72 hours of no food intake.

False

Malonyl-CoA plays a regulatory role in which two processes?

Fatty acid synthesis and β-oxidation

In the postabsorptive and fasting states, what is the primary source of energy for the resting skeletal muscle?

Fatty acids

When glucose exceeds the glycogen storage capacity of the liver, what is the excess glucose converted to?

Fatty acids and tricylglycerols

Why is the brain unable to use fatty acids for energy?

Fatty acids cannot cross the Blood-brain barrier

Following a carbohydrate-rich meal, skeletal and cardiac muscles express which protein on their cell surfaces?

GLUT4

Which GLUT protein is the only one whose function is dependent on insulin?

GLUT4

An individual who has not eaten in five days will most likely have an elevated level of which hormone?

Glucagon

Amino acids from muscle breakdown provide the chief substrate for which metabolic process?

Gluconeogenesis

Only the glycerol portion of triacylglycerols can be converted into ____.

Glucose

What is the precursor for synthesis of the glycerol moiety of triacylglycerol in adipose tissue?

Glucose

How can muscle and adipose tissue obtain glycerol-3-phosphate?

Glycolysis

Which of the following conditions is attributed to a primary failure of the β-cells of the pancreas to secrete insulin?

Hyperglycemia

Where does most of the fatty acid synthesis occur in humans?

Liver

Which of the following uses little glucose-6-phosphate and stores much glycogen?

Liver

Which of the following strongly influences the timeframes assigned to each of the phases of an individual's fed-fast cycle?

Metabolic rate

Which of the following regulatory hormones produced from phenylalanine and tyrosine functions as a neurotransmitter and stress hormone?

NOT Glucagon

Which substances become the main fuel for high-intensity exercise lasting more than one hour?

Plasma fatty acids

The metabolic fuel shifts associated with the starvation state are designed to spare which of the following substrates?

Protein

Which of the following relies solely on glucose for energy?

Red blood cells

In which state does a protein-sparing shift in metabolism from gluconeogenesis to lipolysis occur?

Starvation state

What is one of the problems associated with the use of dietary supplements used to enhance athletic performance?

There is little scientific evidence to prove that they are effective

The synthesis of which of the following would be disrupted in an individual with a deficiency of glycerol-3-phosphate?

Triacylglycerols

T or F: Acetyl-CoA is a significant metabolic junction for several pathways, including metabolism of carbohydrate, lipid, and cholesterol.

True

T or F: Glucagon and insulin control metabolic pathways that reflect a fasting and fed state, respectively; the primary signal to initiate this hormonal control is the glucose concentration in the bloodstream.

True

T or F: Glutamine transport is increased during the fasting state.

True

T or F: Glycogenolysis occurs exclusively in the liver.

True

T or F: Most of adiponectin's effects are targeted toward adipose tissue.

True

T or F: Skeletal muscle has a greater ability to store glycogen than cardiac muscle.

True

T or F: The Cori cycle would be active under anaerobic conditions, such as excessive muscle exertion.

True

What is the term used to represent maximum oxygen consumption relating to exercise capacity?

VO2 max

Which of the following TCA cycle compounds cannot be used as a gluconeogenic precursor?

acetyl CoA

Fatty acids with an even number of carbons are degraded exclusively into ____.

acetyl-CoA

In humans, fatty acids cannot be used to synthesize glucose because we lack the enzymes needed to convert ____.

acetyl-CoA to pyruvate

Which of the following amino acids is glucogenic in the postabsorptive state?

alanine

Which component of the diet provides the majority of energy for ATP production?

carbohydrate and lipid

Which 3-carbon intermediate of glycolysis is used as the substrate to synthesize glycerol for TAG formation in adipose tissue?

dihydroxyacetone phosphate

Which of the following describes a system involving messenger molecules that bind to target tissues, triggering a series of intracellular reactions leading to a metabolic response?

endocrine system

Which of the following regulatory hormones stimulates liver glycogenolysis and gluconeogenesis?

glucagon

What is pyruvate converted into when the cellular energy status favors anabolic reactions?

glucose

The excess of which of the following molecules are precursors for insulin's stimulation of fatty acid synthesis?

glucose and fructose

The lack of which muscle enzyme causes glucose to be trapped when phosphorylated in the muscle?

glucose-6-phosphate

What amino acid plays an important role in controlling toxicity from ammonia released during amino acid catabolism by the glutamate dehydrogenase reaction?

glutamine

Which of the following would the adipocytes of an individual with hypoglycemia have most difficulty producing?

glycerol-3-phosphate

Carbohydrate loading is a dietary and exercise strategy used to maximize ____.

glycogen storage in muscle and liver

Under the influence of insulin, which of the following is stimulated?

glycogenesis

Which of the following regulatory hormones stimulates lipolysis and increases triacylglycerol uptake from VLDL specifically in muscle?

growth hormone

What is the aim of supplementation with proteins and amino acids in conjunction with resistance training?

increasing muscle mass

Which hormone has the primary responsibility for directing energy metabolism in the fed state?

insulin

Which of the following regulatory hormones stimulates removal of glucose from the blood and anabolic reactions?

insulin

What is the preferred source of energy used by muscles to spare protein during prolonged starvation?

ketones

In which organ does urea synthesis occur?

liver

Which of the following relies on fatty acids/glucose as the major fuel?

muscle

Which of the following is a regulated enzyme in glycolysis?

phosphofructokinase

What are the two compounds that connect the metabolism of carbohydrates, lipids, and proteins?

pyruvate and actyl-CoA