Question 1

Mrs.Keller weighs 50 kg and is 1.5 m tall.This means she is considered:

Accepted Answer

The body mass index (BMI) is defined as weight/height².The value obtained (22.2 kg/m²) is in the "normal" range (between 20 and 25).

Question 2

Excess alcohol can impair fatty acid oxidation in the liver, thereby diverting fatty acids into triglyceride synthesis.The triglycerides are then exported as VLDL, or they stay in the liver, contributing to the development of fatty liver.This alcohol effect is mediated by:

Accepted Answer

Fatty acid oxidation requires NAD⁺.Alcohol oxidation depletes NAD⁺ and thereby deprives β-oxidation of one of its substrates.

Question 3

A 52-year-old man with chronic alcoholism has a plasma lipid profile with increased very-low-density lipoprotein (VLDL).The mechanism that best explains the increase of VLDL in the blood of patients with chronic alcoholism is:

Accepted Answer

β-Oxidation requires nicotinamide adenine dinucleotide (NAD⁺).Alcohol oxidation uses up NAD⁺ and raises the ratio of the reduced form of nicotinamide adenine dinucleotide (NADH) to NAD⁺.This impairs β-oxidation.Excess acyl-coenzyme A (CoA) is diverted into triglyceride synthesis.The triglyceride is exported in VLDL and/or it causes fatty liver.

Question 4

After their absorption in the intestine, most nutrients go to the liver first, before they reach the systemic circulation.Of the following nutrients, which one does not go to the liver before being distributed to the rest of the body?

Accepted Answer

Dietary lipids (including fat-soluble vitamins) are incorporated into chylomicrons, which are released into the lymph and reach the blood stream through the thoracic duct.

Question 5

Hemoglobin A₁C measurement can be used to monitor diabetic patients.The unique advantage of this test is that:

Accepted Answer

Hemoglobin A₁C is produced by the nonenzymatic glycosylation of hemoglobin.It accumulates slowly, in direct proportion to the blood glucose level, and over the whole life span of the hemoglobin molecules-up to 120 days.

Question 6

The insulin level is reduced in many (although not all) diabetic patients.Adipocyte metabolism in these hypoinsulinemic patients is altered in the following ways, in comparison with normal subjects:

Accepted Answer

Insulin induces the synthesis of the glycerolphosphate-acyl transferase.

Question 7

A 200-meter run is powered by the production of adenosine triphosphate (ATP) mainly from:

Accepted Answer

Creatine phosphate is used for the first seconds of vigorous physical exertion, and then anaerobic glycolysis from glycogen is most important for the next minute or so.Afterwards, oxidative phosphorylation is required for sustained activity.

Question 8

You have been on a strict Atkins diet for the past 2 weeks.Of your calories, 80% come from fat, 15% from protein, and 5% from carbohydrate.What is the major source of blood glucose under these conditions?

Accepted Answer

About 100 g of glucose is required per day.Because glycogen was used up long ago, only gluconeogenesis can supply the necessary amount, and only amino acids (both from the diet and from protein breakdown in the tissues) are sufficiently abundant as gluconeogenic substrates.

Question 9

The susceptibility to type 1 diabetes is affected by genes.Genes that are especially important for susceptibility to type 1 diabetes are those coding for:

Accepted Answer

Type 1 diabetes is an autoimmune disease.Susceptibility to most autoimmune diseases is affected by genetic variation of HLA.

Question 10

In Type I diabetes, high levels of ketone bodies are liable to result in acidosis because:

Accepted Answer

The ketone bodies are acidic products (acetoacetic acid and β-hydroxybutyric acid) that are formed from non-acidic storage fat during fasting and in diabetes mellitus.Stoichiometrically, the free acids are formed.Their deprotonation acidifies the medium.

Question 11

Infectious illnesses can precipitate ketoacidosis in patients with insulin-dependent diabetes.The reason for this is:

Accepted Answer

The "stress hormones" are functional insulin antagonists.Therefore, the insulin dose needs to be raised when an insulin-dependent diabetic patient becomes ill.

Question 12

Acute ethanol intake raises the NADH/NAD⁺ ratio in the liver.This can inhibit gluconeogenesis by influencing the reaction catalyzed by:

Accepted Answer

The lactate dehydrogenase reaction becomes virtually irreversible in the direction of lactate formation when the NADH/NAD⁺ ratio is high.Therefore, the gluconeogenic substrate pyruvate becomes depleted.

Question 13

You are treating a diabetic/hypertensive patient.When evaluating the effectiveness of the medical and dietary regimen, which of these results should give you reason for concern?

Accepted Answer

The high level of glycosylated hemoglobin (3% to 5% is normal) shows poor long-term control of hyperglycemia.

Question 14

One of the reasons for hyperglycemia in patients with diabetes mellitus is the effect of insulin on GLUT-4 transporters in:

Accepted Answer

Most other tissues have insulin-independent glucose carriers.

Question 15

When you wake up in the morning, 12 hours after supper, the main source of blood glucose is:

Accepted Answer

Liver glycogen lasts for 12 to 20 hours after the most recent meal.

Quiz 30: Integration of Metabolism