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Questions and Answers

What happens to glucose in muscle cells after it is transported inside?

  • It is broken down into amino acids.
  • It is stored in the form of glycogen.
  • It is immediately phosphorylated and becomes a substrate for carbohydrate metabolic functions. (correct)
  • It is converted into fatty acids for energy.

What is the primary source of energy for muscle tissue during most of the day?

  • Amino acids
  • Glucose
  • Proteins
  • Fatty acids (correct)

What is the effect of insulin on the cell membrane of muscle cells?

  • It alters the shape of the cell membrane.
  • It increases the permeability of the cell membrane to glucose and other substances. (correct)
  • It has no effect on the cell membrane.
  • It decreases the permeability of the cell membrane to glucose.

What is the main purpose of this chapter?

<p>To discuss the physiological roles of insulin and glucagon (D)</p> Signup and view all the answers

What happens to the vesicles that carry glucose transport proteins when insulin is no longer available?

<p>They separate from the cell membrane and move back to the cell interior to be used again. (A)</p> Signup and view all the answers

What is the effect of insulin on the uptake of amino acids and ions in muscle cells?

<p>It increases the uptake of amino acids and ions. (A)</p> Signup and view all the answers

What is the approximate diameter of an islet of Langerhans?

<p>0.3 millimeter (D)</p> Signup and view all the answers

What is the primary function of the acini in the pancreas?

<p>To secrete digestive juices into the duodenum (D)</p> Signup and view all the answers

Why is insulin necessary for glucose uptake in muscle cells?

<p>Because muscle cells are only slightly permeable to glucose without insulin. (C)</p> Signup and view all the answers

What is the result of prolonged, untreated diabetes on protein metabolism?

<p>Decreased synthesis of proteins (A)</p> Signup and view all the answers

What is the effect of insulin on intracellular metabolic enzymes?

<p>It increases the activity of metabolic enzymes. (B)</p> Signup and view all the answers

What is the approximate number of islets of Langerhans in the human pancreas?

<p>1 to 2 million (B)</p> Signup and view all the answers

What happens to glucose uptake in muscle cells during two specific conditions?

<p>It increases during exercise and high-glucose meals. (A)</p> Signup and view all the answers

What is the primary function of insulin in the body?

<p>To regulate all of the above (D)</p> Signup and view all the answers

What is the name of the cells that secrete insulin and glucagon in the pancreas?

<p>All of the above (D)</p> Signup and view all the answers

What is the term for the condition caused by abnormalities of fat metabolism in patients with diabetes mellitus?

<p>Acidosis (B)</p> Signup and view all the answers

What is the primary function of glucagon in the body?

<p>To increase blood glucose concentration (D)</p> Signup and view all the answers

What is the first step in the cascade of events triggered by glucagon in the liver?

<p>Activation of adenylyl cyclase (B)</p> Signup and view all the answers

What is the byproduct of glycogen degradation triggered by glucagon?

<p>Glucose-1-phosphate (A)</p> Signup and view all the answers

What is the effect of increased blood glucose concentration on glucagon secretion?

<p>It decreases glucagon secretion (A)</p> Signup and view all the answers

What is the opposite effect of glucose on insulin and glucagon secretion?

<p>Glucose increases insulin secretion and decreases glucagon secretion (C)</p> Signup and view all the answers

What is the approximate blood glucose level at which glucagon secretion is stimulated?

<p>60 mg/100 ml of blood (D)</p> Signup and view all the answers

What is the end result of the cascade of events triggered by glucagon in the liver?

<p>Release of glucose from liver cells (D)</p> Signup and view all the answers

What is the primary factor controlling glucagon secretion?

<p>Blood glucose concentration (B)</p> Signup and view all the answers

What is the consequence of severe and prolonged insulin resistance?

<p>Pancreatic beta cell exhaustion (B)</p> Signup and view all the answers

What happens to the pancreas in some obese people with marked insulin resistance?

<p>It produces enough insulin to prevent severe abnormalities of glucose metabolism (A)</p> Signup and view all the answers

What is the primary goal of lifestyle modifications in treating type 2 diabetes?

<p>Increasing physical activity and caloric restriction (C)</p> Signup and view all the answers

What is the role of thiazolidinediones in treating type 2 diabetes?

<p>Increasing insulin sensitivity (B)</p> Signup and view all the answers

What is the consequence of moderate hyperglycemia in the early stages of type 2 diabetes?

<p>No significant abnormalities of glucose metabolism (C)</p> Signup and view all the answers

What is the treatment approach in the later stages of type 2 diabetes?

<p>Combination of lifestyle modifications and insulin administration (A)</p> Signup and view all the answers

What is the effect of insulin resistance on glucose metabolism?

<p>Impaired glucose regulation (A)</p> Signup and view all the answers

What is the role of sulfonylureas in treating type 2 diabetes?

<p>Causing additional release of insulin by the pancreas (A)</p> Signup and view all the answers

What is the approximate percentage decrease in blood calcium concentration that can lead to tetany?

<p>35% (A)</p> Signup and view all the answers

What is the effect of hypocalcemia on the heart in laboratory animals?

<p>Marked dilation of the heart (C)</p> Signup and view all the answers

What is the effect of hypercalcemia on the nervous system?

<p>Depression of nervous system activity (B)</p> Signup and view all the answers

What is the approximate blood calcium level above which calcium phosphate crystals are likely to precipitate throughout the body?

<p>17 mg/dl (B)</p> Signup and view all the answers

What is the normal rate of calcium intake in the diet?

<p>1000 mg/day (B)</p> Signup and view all the answers

What percentage of ingested calcium is usually absorbed from the intestines?

<p>35% (D)</p> Signup and view all the answers

What is the effect of hypercalcemia on the gastrointestinal tract?

<p>Decreased contractility of the muscle walls (A)</p> Signup and view all the answers

What is the term for the muscle spasms that occur in the hands and feet due to hypocalcemia?

<p>Carpopedal spasm (D)</p> Signup and view all the answers

What is the primary effect of insulin on glucose uptake in liver cells?

<p>Increase the activity of glucokinase (D)</p> Signup and view all the answers

What happens to glycogen in the liver when blood glucose levels fall between meals?

<p>It is broken down into glucose phosphate (B)</p> Signup and view all the answers

What is the role of glucose phosphatase in the liver?

<p>To remove the phosphate group from glucose phosphate (C)</p> Signup and view all the answers

What is the net effect of insulin on glycogen synthesis in the liver?

<p>It increases glycogen synthesis (C)</p> Signup and view all the answers

What is the result of decreased insulin secretion by the pancreas?

<p>Increased glucose release from the liver (A)</p> Signup and view all the answers

What is the maximum percentage of liver mass that can be composed of glycogen?

<p>5-6% (C)</p> Signup and view all the answers

What is the enzyme responsible for phosphorylating glucose in the liver?

<p>Glucokinase (D)</p> Signup and view all the answers

What is the primary function of the liver in regulating blood glucose levels?

<p>All of the above (D)</p> Signup and view all the answers

What happens to the storage of fatty acids in the liver when insulin is not available?

<p>It is almost blocked (D)</p> Signup and view all the answers

What is the primary energy substrate used by essentially all tissues of the body in the absence of insulin, except the brain?

<p>Free fatty acids (A)</p> Signup and view all the answers

What is the effect of insulin deficiency on the enzyme hormone-sensitive lipase in fat cells?

<p>It is strongly activated (B)</p> Signup and view all the answers

What is the consequence of insulin deficiency on the plasma concentration of free fatty acids?

<p>It increases rapidly (A)</p> Signup and view all the answers

What is the effect of insulin deficiency on the use of fat for energy?

<p>It is enhanced (D)</p> Signup and view all the answers

What happens to the availability of precursors required for gluconeogenesis in the absence of insulin?

<p>It decreases significantly (B)</p> Signup and view all the answers

What is the effect of insulin deficiency on the concentration of acetoacetic acid in the blood?

<p>It increases rapidly (C)</p> Signup and view all the answers

What is the consequence of removing the pancreas on the concentration of blood glucose and free fatty acids?

<p>Blood glucose and free fatty acids both increase (A)</p> Signup and view all the answers

What is the effect of prolonged secretion of glucagon, growth hormone, cortisol, and progesterone?

<p>Exhaustion of the beta cells of the islets of Langerhans (B)</p> Signup and view all the answers

What is the role of parasympathetic nerves in the pancreas?

<p>Increase insulin secretion during hyperglycemic conditions (D)</p> Signup and view all the answers

What is the primary signal that controls the switching mechanism between carbohydrate and lipid metabolism?

<p>Blood glucose concentration (B)</p> Signup and view all the answers

What is the effect of insulin on lipid metabolism?

<p>Increase glucose utilization and depress lipid metabolism (C)</p> Signup and view all the answers

What is the effect of lack of insulin on glucose utilization?

<p>Fat utilization mainly to the exclusion of glucose utilization (B)</p> Signup and view all the answers

What is the role of glucagon in the body?

<p>Increases glucose concentration in the blood (B)</p> Signup and view all the answers

What is the effect of sympathetic nerve stimulation on the pancreas?

<p>Decrease insulin secretion and increase glucagon secretion (B)</p> Signup and view all the answers

What is the role of specialized neurons in the hypothalamus and brain stem?

<p>Detect glucose concentration in the blood (B)</p> Signup and view all the answers

What is the primary mechanism by which excessive glucose in the urine causes dehydration?

<p>Osmotic diuresis (C)</p> Signup and view all the answers

What is the critical pH level below which acidotic coma and death can occur within hours?

<p>7.0 (A)</p> Signup and view all the answers

What is the consequence of excess fat utilization in the liver over a long time?

<p>Severe arteriosclerosis and vascular lesions (C)</p> Signup and view all the answers

What is the effect of untreated diabetes mellitus on protein metabolism?

<p>Increased protein utilization (B)</p> Signup and view all the answers

What is the primary cause of polyuria in diabetes?

<p>Osmotic diuresis (A)</p> Signup and view all the answers

What is the effect of severe diabetic acidosis on blood electrolytes?

<p>Variable changes in blood electrolytes (B)</p> Signup and view all the answers

What is the consequence of polyphagia in a person with severe untreated diabetes mellitus?

<p>Rapid weight loss (B)</p> Signup and view all the answers

What is the effect of dehydration on intracellular and extracellular fluids?

<p>Both intracellular and extracellular dehydration (A)</p> Signup and view all the answers

What is the primary function of the HbA1c test?

<p>To assess average blood glucose concentrations for the previous three months (C)</p> Signup and view all the answers

What is the normal range of blood glucose levels in a healthy individual after ingesting 1 gram of glucose per kilogram of body weight?

<p>120-140 mg/100 ml (B)</p> Signup and view all the answers

What is the significance of the glucose tolerance curve in diabetes?

<p>It shows a slow rise and fall of blood glucose levels (B)</p> Signup and view all the answers

What is the purpose of measuring hemoglobin A1c (HbA1c)?

<p>To monitor glycemic control in people with diabetes (C)</p> Signup and view all the answers

What happens to the glucose level in a person with diabetes after ingesting glucose?

<p>It rises slowly and remains elevated for 4-6 hours (B)</p> Signup and view all the answers

What is the significance of the lifespan of red blood cells in relation to HbA1c?

<p>It indicates the duration of hyperglycemia (C)</p> Signup and view all the answers

What is the difference between the glucose tolerance curve in a normal person and a person with diabetes?

<p>The curve is slower in a person with diabetes (C)</p> Signup and view all the answers

What is the role of the HbA1c test in diagnosing diabetes mellitus?

<p>It is used in conjunction with other tests (A)</p> Signup and view all the answers

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