Carbohydrates and Their Classification

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Questions and Answers

What is the primary purpose of mobilizing muscle proteins during fasting?

To promote muscle growth

To increase fat storage

To stimulate insulin production

To produce glucose through gluconeogenesis (correct)

Which amino acid is particularly noted for its role in gluconeogenesis?

Serine

Glycine

Alanine (correct)

Glutamate

What is the molecular mass of insulin?

5000 Daltons (correct)

10000 Daltons

7500 Daltons

2500 Daltons

What is the relationship between proinsulin and diabetes?

Proinsulin indicates an inability of beta cells to secrete insulin. Signup and view all the answers

What happens to fatty acids during fasting?

They produce acetyl CoA for ketone production. Signup and view all the answers

What is the term for isomers that have the same order and types of bonds but different spatial arrangements?

Stereoisomers Signup and view all the answers

How many possible stereoisomers can be formed from a molecule with two asymmetric carbons?

4 Signup and view all the answers

In which series is a monosaccharide categorized if the hydroxyl group projects to the right?

D-series Signup and view all the answers

What type of isomers are non-superimposable mirror images of each other?

Enantiomers Signup and view all the answers

Which functional groups are predominantly found in carbohydrates?

Carbonyl and hydroxyl Signup and view all the answers

What is the primary source of energy for the brain and retinal cells in humans?

Carbohydrates Signup and view all the answers

Most sugars present in humans are categorized under which form?

D-form Signup and view all the answers

Which of the following statements about asymmetric carbons is true?

They are responsible for the chirality of molecules. Signup and view all the answers

What is the role of ketone bodies during starvation?

They serve as an energy source for vital organs. Signup and view all the answers

What is the typical serum ratio of C-peptide to insulin?

5:1 to 15:1 Signup and view all the answers

Which condition is characterized by increased levels of both insulin and C-peptide?

Insulinoma Signup and view all the answers

What regulates the conversion of non-carbohydrate substances to glucose in the liver?

Glucagon Signup and view all the answers

How does insulin affect protein synthesis?

It promotes synthesis of protein in most tissues. Signup and view all the answers

What is the impact of insulin treatment on C-peptide levels?

Decreased Signup and view all the answers

What is one of the interferences in measuring insulin levels?

Renal deficiency Signup and view all the answers

In which circumstance does the liver increase glycogenolysis?

During fasting Signup and view all the answers

Which symptom is categorized as adrenergic in the context of hypoglycemia?

Tremor Signup and view all the answers

What is one of the lab findings associated with hypoglycemia?

Decreased urine pH Signup and view all the answers

What describes the classification of post-prandial hypoglycemia?

It results from exaggerated insulin release. Signup and view all the answers

Which condition is NOT a potential cause of alimentary (reactive) hypoglycemia?

Electrolyte imbalance Signup and view all the answers

What must a patient meet to fulfill Whipple's Triad in diagnosing hypoglycemia?

Typical symptoms of hypoglycemia Signup and view all the answers

Which of the following is most likely true about neuroglycopenic symptoms?

They can include coma and seizures. Signup and view all the answers

Which factor can lead to hypoglycemia due to an imbalance in glucose utilization and production?

Insulin deficiency Signup and view all the answers

Which of the following could be a result of dehydration in the context of hypoglycemia?

Fluctuations in electrolyte balance Signup and view all the answers

What are the three classic manifestations of Diabetes Mellitus?

Polyuria, polydipsia, polyphagia Signup and view all the answers

Which statement correctly describes Type 1 Diabetes Mellitus?

It is due to an absolute deficiency of insulin. Signup and view all the answers

Which complication is associated with untreated Type 2 Diabetes Mellitus?

Nonketotic hyperosmolar coma Signup and view all the answers

What is one of the causes of Type 1 Diabetes Mellitus?

Viral infections and environmental factors Signup and view all the answers

In the context of insulin resistance, which category affects insulin’s ability to bind to receptors?

Receptor Signup and view all the answers

What best describes a common consequence of diabetic neuropathy?

Loss of sensation or pain in the extremities Signup and view all the answers

Which of the following conditions is NOT a common consequence of diabetes?

Thyroid dysfunction Signup and view all the answers

What is the potential outcome of untreated high glucose levels in someone with Type 2 Diabetes Mellitus?

Nonketotic hyperosmolar coma Signup and view all the answers

Study Notes

Carbohydrates

Primary source of energy for the brain, erythrocytes, and retinal cells.
Major food source and energy supply of the body, primarily stored as liver and muscle glycogen.
Provide structural integrity to the cell membrane.
Composed of carbon, hydrogen, and oxygen.
Contain carbonyl and hydroxyl functional groups.

Classification of Carbohydrates

Classified based on properties:
- Number of carbon atoms
- Location of the carbonyl group
- Stereoisomerism

Stereoisomers

Molecules with the same order and type of bonds but different spatial arrangements.
For each asymmetric carbon, 2^n possible isomers.

Monosaccharides

Assigned to the D or L series based on the configuration of the highest-numbered asymmetric carbon.
Hydroxyl group projects to the right: D-series.
Hydroxyl group projects to the left: L-series.

Enantiomers

Mirror images of each other that are not superimposable.
Most sugars in humans are in the D-form.

Insulin

Inhibits glucose production in insulin-sensitive tissues (liver, skeletal muscles, and adipose tissues).
Peptide hormone with a mass of approximately 5,000 Daltons.
Composed of 21 amino acids in the A chain and 30 amino acids in the B chain linked by disulfide bonds.

Proinsulin

Seen in Type 2 diabetes with decreased beta-cell insulin secretion, pre-Type 1 diabetes, insulinomas, and familial hyperinsulinemia.
Processed by cleavage to form C-peptide and insulin.
Ratio of C-peptide to insulin in serum is 5:1 to 15:1.

C-peptide

Marker for endogenous insulin production.
Measured with insulin and blood glucose to identify the cause of hypoglycemia.
Primarily degraded by the kidneys.

Insulin Secretion Stimulated by:

Stress
Severe infection
Dehydration or pregnancy
Pancreatectomy
Hemochromatosis
Insulin deficiency or abnormal insulin receptor.

Hypoglycemia

Characterized by low or decreased plasma glucose level.
Results from an imbalance between glucose utilization and production.
Symptoms are related to the CNS.

Whipple's Triad

Low blood glucose concentration.
Typical symptoms of hypoglycemia.
Relief of symptoms with glucose administration.

Diabetes Mellitus

Three classic manifestations:
- Polyuria (excessive urination).
- Polydipsia (excessive thirst).
- Polyphagia (excessive hunger).

### Type 1 Diabetes Mellitus (T1DM)

Caused by an absolute deficiency of insulin due to autoimmune attack of the beta-cells of the pancreas.
Causes hyperglycemia, ketoacidosis, and hypertriglyceridemia.

Causes of T1DM

Viral infection and environmental factors.
Genetic susceptibility (HLA DR3/DR4 on chromosome 6).

Type 2 Diabetes Mellitus (T2DM)

Characterized by insulin resistance, where tissues fail to respond normally to insulin.

Types of Insulin Resistance

Pre-receptor: Insulin is defective and has difficulty binding to receptors or insulin levels are low.
Receptor: Patient fails to respond to insulin due to deficient or defective receptors.
Post-receptor: Patient has normal insulin levels and receptors, but signal transduction is impaired or glucose transporters are unable to process glucose.

Effects of Insulin

Increases glycogenesis, lipogenesis, and glycolysis.
Decreases glycogenolysis.

Interferences in Measurement of Insulin, C-peptide, and Proinsulin

Alimentary (reactive) hypoglycemia.
Idiopathic (functional) postprandial hypoglycemia.

Symptoms of Hypoglycemia:

Adrenergic (mediated by epinephrine): Anxiety, weakness, palpitations, tremor, and sweating.
Neuroglycopenic: Headache, confusion, slurred speech, seizures, coma, and death.

Classification of Hypoglycemia

Post-prandial (Reactive): More common; Exaggerated insulin release and microvascular complications.
Non-traumatic amputation, adult blindness, diabetic neuropathy, atherosclerotic disease, heart attacks, and strokes.

Untreated Type 2 DM

Results in nonketotic hyperosmolar coma due to overproduction of glucose (>300 mg/dL) with severe dehydration, electrolyte imbalance, and increased BUN and creatinine.

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Description

This quiz explores the fundamentals of carbohydrates, their classification based on structure and function, and key concepts like stereoisomerism and monosaccharides. Test your knowledge on the role of carbohydrates in energy supply and cellular integrity.