Integration of Metabolism, Diabetes, Fasting, and Starvation

Question 1

The integration of energy metabolism across organ systems is controlled primarily by the actions of the pancreatic hormones

Answer 1

Insulin and Glucagon

Question 2

When food is available in abundance, responding changes in the circulating levels of these hormones allow the body to store energy in the forms of

Answer 2

Glycogen and FAs

Question 3

Represents the most common disruption that occurs in this complex system of hormones, enzymes, and metabolites in humans

Answer 3

Diabetes Mellitus

Question 4

There are two fundamental sorts of diabetes, type 1 is known as

Answer 4

Insulin-dependent diabetes (IDDM)

Question 5

Type 2 diabetes is classified as

Answer 5

Insulin-independent diabetes (NIDDM)

Question 6

A polypeptide hormone produced by the B-­ cells of the Islets of Langerhans, clusters of cells that comprise about 1% of the pancreas

Answer 6

Insulin

Question 7

Insulin is one of the most important hormones coordinating the utilization of

Answer 7

Fuel

Question 8

The metabolic effect of insulin are

Answer 8

Anabolic

Question 9

Composed of 51 amino acids arranged in two polypeptide chains, designated A and B (proteolytically processed from a single primary translation product)

Answer 9

Insulin

Question 10

These A and B polypeptide chains are linked together by two

Answer 10

Disulfide bridges

Question 11

The insulin molecule also contains an intra-­molecular disulfide bridge between amino acid residues

Answer 11

6 and 11

Question 12

The B-­cells of the pancreas release both the mature insulin and the processing by-­product

Answer 12

C-peptide

Question 13

Human insulin has the same potency as pig insulin, which is similar in structure to the human hormone and has been used in the past for treatment of

Answer 13

Diabetes

Question 14

Insulin secretion by the B-

cells of the Islets of Langerhans of the pancreas is closely coordinated with the release of

Answer 14

Glucagon by a-cells

Question 15

The most important glucose-­sensing cells in the body

Answer 15

Pancreatic Beta-cells

Question 16

Ingestion of glucose or a carbohydrate-­rich meal leads to a rise in blood glucose, which is a signal for increased

Answer 16

Insulin secretion

Question 17

Causes a transient rise in plasma amino acids levels, which in turn induces the immediate secretion of insulin

Answer 17

Ingestion of protein

Question 18

Insulin secretion is stimulated by the gastric peptides

-release following the ingestion of food

Answer 18

Secretin and Incretins

Question 19

Cause an anticipatory rise in insulin levels in the portal vein before there is an actual rise in blood glucose

Answer 19

Secretin and Incretins

Question 20

This may account for the fact that the same amount of glucose given orally induces a much greater secretion of insulin than if given intravenously

Answer 20

The anticipatory rise

Question 21

Decreased when there is a scarcity of dietary fuels, and also during periods of trauma

Answer 21

Synthesis and release of insulin

Question 22

Trauma effects on insulin secretion are mediated primarily by

Answer 22

Epinephrine

Question 23

Has a direct effect on energy metabolism, causing a rapid mobilization of energy-yielding fuels, including glucose from the liver and fatty acids from adipose tissue, via a receptor and signal transduction mechanism

Answer 23

Epinephrine

Question 24

Able to override the normal glucose-­stimulated release of insulin

Answer 24

Epinephrine

Question 25

Thus, in emergency situations, the sympathetic nervous system largely replaces plasma glucose concentration as the controlling influence over

Answer 25

Insulin secretion

Question 26

Glucose transport into most insulin responsive tissues, for example, skeletal muscle and adipocytes, increases in the presence of

Answer 26

Insulin

Question 27

Promotes the recruitment of glucose transporters from a pool in intracellular vesicles to the cell membrane

Answer 27

Insulin

Question 28

Depends on both the abundance of glucose transporters and their activation, probably by phosphorylation of transporters in the membrane

Answer 28

Glucose Transport

Question 29

Hepatocytes, erythrocytes, the nervous system, and the cornea have

Answer 29

Insulin-dependent glucose transport

Question 30

In the liver, brain, cornea, intestinal mucosa, renal tubes and the red blood cells, glucose transport is not sensitive to

Answer 30

Insulin

Question 31

Leads to significant changes in carbohydrate metabolism, including increased glycolysis, increased glycogen synthesis, and decreased gluconeogenesis

Answer 31

Intravenous administration of insulin

Question 32

Adipose tissue metabolism patterns respond within minutes to the administration of

Answer 32

Insulin

Question 33

This results in a marked increase in

Answer 33

FA synthesis

Question 34

Insulin decreases the level of circulating fatty acids by inhibiting the activity of

Answer 34

Hormone-sensitive lipase

Question 35

Insulin acts primarily by countering the stimulation of adenylyl cyclase by

Answer 35

Epinephrine and Glucagon

Question 36

Simultaneously, insulin increases the transport and metabolism of glucose, providing which three substrates for FA synthesis?

Answer 36

Acetyl CoA, Glycerol-3-phosphate, and NADPH

Question 37

Lastly, insulin stimulates the entry of amino acids into cells and contaminant

Answer 37

Protein Synthesis

Question 38

Like other peptide hormones, insulin binds to specific, high-­affinity receptors present in the cell membranes of specific tissues, including

Answer 38

Liver, muscle, and adipose

Question 39

Has very few insulin receptors, the functions of which are unclear

Answer 39

The brain

Question 40

For glucose metabolism, the signaling cascades caused by insulin influence which three enzymes?

Answer 40

Glucokinase, PFK-2/FBP-2, and Pyruvate kinase

Question 41

For glycogen metabolism, the signaling cascades caused by insulin influence which two enzymes?

Answer 41

Glycogen synthase and Glycogen phosphorylase

Question 42

For fatty acid metabolism, the signaling cascades caused by insulin influence which two enzymes?

Answer 42

Acetyl CoA carboxylase and Hormone sensitive lipase

Question 43

Enzyme expression is regulated at the level of mRNA synthesis while enzyme activity is regulated at the level of

Answer 43

Phosphorylation/dephosphorylation

Question 44

Eventually, the insulin:insulin receptor complex enters the cell by

Answer 44

Pinocytosis

Question 45

Ultimately degraded in the lysosomes and the receptor is recycled back to the membrane

Answer 45

Insulin

Question 46

A polypeptide hormone, secreted primarily by the a- | cells of the pancreatic islets

Answer 46

Glucagon

Question 47

Opposes many of the actions of insulin -The counter regulatory hormones

Answer 47

Glucagon, epi, cortisol, and GH

Question 48

Most importantly, acts to maintain blood glucose levels by activation of hepatic glycogenolysis and gluconeogenesis

Answer 48

Glucagon

Question 49

Composed of 29 amino acids arranged in a single polypeptide chain

Answer 49

Glucagon

Question 50

The a-­cell is responsive to a variety of stimuli that signal actual or potential

Answer 50

Hypoglycemia

Question 51

Specifically, glucagon secretion is increased by:

Answer 51

Low blood glucose, Amino acids, and Epi

Question 52

The primary stimulus for glucagon release

Answer 52

Low blood sugar

Question 53

During an overnight or prolonged fast, elevated glucagon levels prevent

Answer 53

Hypoglycemia

Question 54

Amino acids derived from a protein-­containing meal stimulate the release of both

Answer 54

Glucagon and insulin

Question 55

Elevated levels of circulating epinephrine produced by the adrenal medulla, and/or epinephrine produced by direct enervation of the pancreas, stimulate the release of

Answer 55

Glucagon

Question 56

Thus during periods of stress, trauma or vigorous exercise, newly elevated epinephrine levels can override the inhibitory effect on the a-­cell of circulating

Answer 56

Insulin and Glucose

Question 57

In these situations, regardless of the concentration of blood glucose—glucagon levels rise in anticipation of increased

Answer 57

Glucose utilization

Question 58

Glucagon secretion is markedly decreased by

Answer 58

Elevated Blood Sugar

Question 59

The intravenous administration of glucagon leads to an immediate rise in

Answer 59

Blood sugar

Question 60

This results from alterations in carbohydrate metabolism that lead to an increase in

Answer 60

Glycogenolysis and gluconeogenesis

Question 61

Promotes the oxidation of fatty acids in a number of tissues, as a preferred energy source

Answer 61

Glucagon

Question 62

Stimulates the formation of ketone bodies from acetyl CoA

Answer 62

Glucagon

Question 63

Glucagon also stimulates

Answer 63

Hormone sensitive lipase

Question 64

Glucagon increases the uptake of amino acids by the liver resulting in the increased availability of a variety of carbon skeletons for

Answer 64

Gluconeogenesis

Question 65

Results in a decrease in the plasma levels of amino acids

Answer 65

Glucagon

Question 66

Glucagon binds to high affinity receptors on the cell membrane of target cells such as the

Answer 66

Hepatocyte or adipocyte

Question 67

There are no glucagon receptors in

Answer 67

Muscle tissue

Question 68

Glucagon binding results in activation of adenylyl cyclase in the plasma membrane. This causes a rise in

Answer 68

cAMP

Question 69

This increase in cAMP in turn activates

Answer 69

cAMP-dependent protein kinase

Question 70

This cascade of activities results in the phosphorylation-­mediated activation or inhibition of key regulatory enzymes involved in

Answer 70

Carbohydrate and lipid metabolism

Question 71

Classified as roughly the 2-4 hour period following ingestion of a balanced meal

Answer 71

Absorptive state

Question 72

During this interval there occurs a transient increase in plasma glucose, amino acids, and triacylglycerol, the latter primarily as components of

Answer 72

Chylomicrons

Question 73

The elevated insulin:glucagon ratio, and the ready availability of circulating substrates, makes the 2-­4 hours following ingestion of a meal an

Answer 73

Anabolic Period

Question 74

May result from an inability to obtain food, the desire to lose weight rapidly, or to clinical situations in which an individual cannot eat because of trauma

Answer 74

Starvation

Question 75

Not one disease, but rather is a heterogeneous group of syndromes characterized by an elevation of fasting blood glucose caused by a relative or absolute deficiency in insulin

Answer 75

Diabetes

Question 76

An excess of glucagon aggravates metabolic alterations caused by inadequate release of

Answer 76

Insulin

Question 77

Constitute 10% to 20% of the many million diabetics in the United States

Answer 77

Insulin-dependent diabetes mellitus (IDDM)

Question 78

Individuals with IDDM require insulin to avoid life-threatening

Answer 78

Ketoacidosis

Question 79

IDDM is characterized by an absolute deficiency of insulin caused by massive autoimmune attack on the

Answer 79

Pancreatic Beta-cells

Question 80

The islets of Langerhans then become infiltrated with activated

Answer 80

T-lymphocytes

Question 81

The islets of Langerhans become infiltrated with activated T-­lymphocytes, leading to a condition called

Answer 81

Insulitis

Question 82

IDDM symptoms typically appear -when 80-90% of B-cells have been destroyed

Answer 82

Abruptly

Question 83

At this point the pancreas can no longer respond adequately to ingestion of glucose, and patients reqire

Answer 83

Insulin therapy

Question 84

The most common form of the disease, afflicting approximately 80% of the diabetic population in the United States

Answer 84

Non-insulin-dependent Diabetes Mellitus (NIDDM)

Question 85

Diagnosis is based most commonly on the presence of fasting hyperglycemia—that is, blood glucose concentration of greater than 140 mg/dL persisting several hours after a meal

Answer 85

NIDDM

Question 86

Having said that, it is also correct that some individuals with NIDDM do have noticeable symptoms of

Answer 86

Polyuria and polydipsia

Question 87

The disease does not involve viruses or autoimmune antibodies, but rather “insulin resistance” in peripheral tissues

Answer 87

NIDDM

Question 88

The metabolic alterations observed in NIDDM are milder than those described for the insulin-­dependent form of the disease and are thought to be due to a combination of which two factors?

Answer 88

Dysfunctional B-cells and Insulin resistance