Pathophysiology: Alterations in Cell Functions

Overview

• Discuss the metabolic pathway and normal cellular function.
• Understand the importance of ATP production.
• Identify causes of cellular dysfunction.

Metabolic Pathway Review

• Blood Glucose Increase:
  • Eating increases blood glucose (transient hyperglycemia).
  • Stimulates insulin release from pancreatic beta cells.
• Role of Insulin:
  • Insulin enables glucose entry into cells.
  • Initiates glycolysis, forming pyruvate, NADH, and ATP.
• With Oxygen:
  • Pyruvate enters mitochondria, beginning the Krebs cycle.
  • Krebs cycle produces more NADH and ATP.
  • Electron transport chain activated by NADH, producing 34 ATP (total 38 ATP).

Cellular Dysfunction Causes

• Hypoxia:
  • Decrease in oxygen at cellular level.
  • Only glycolysis possible without oxygen (anaerobic).
  • Results in acidosis due to pyruvic acid accumulation.
• Nutritional Problems:
  • Glucose and vitamin deficiencies.
  • Glycogenesis and glycogenolysis.
  • Gluconeogenesis when glucose is unavailable.
• Electrolyte Imbalances:
  • Sodium-potassium pump affected without enough ATP.
  • Affects cell's resting membrane potential.
• Acid-Base Imbalances:
  • Normal body pH 7.35-7.45 (slightly alkalotic).
  • Acidosis occurs with pyruvic acid accumulation.

Metabolic Disorders

• Glycogen Storage Diseases:
  • Affect glycogenesis or glycogenolysis.
  • Example: McArdle's Disease (muscle glycogen breakdown issue).
• Type 1 Diabetes Mellitus:
  • No insulin production.
  • Chronic hyperglycemia, sustained gluconeogenesis.
  • Results in ketoacidosis.

Vitamin Deficiencies

• Common Deficiencies:
  • Alcoholism-related deficiencies (iron, thiamine, niacin).
  • Iron deficiency anemia: weakness, shortness of breath, fatigue.
• Thiamin (B1) Deficiency:
  • Causes neurological issues (beriberi, Wernicke-Korsakoff syndrome).
  • Symptoms: memory loss, ataxia, eye movement issues.
• Paresthesia:
  • Occurs with thiamine or B12 deficiency ("pins and needles" sensation).

Other Factors Affecting Vitamin Absorption

• Drugs:
  • Some prescription drugs (e.g., birth control) affect absorption.
• Diet & Substances:
  • Caffeine and certain poisons (e.g., cyanide) interfere with absorption.

Cyanide Poisoning

• Affects electron transport chain by inhibiting cytochrome oxidase.
• Reduces ATP production.
• Vague symptoms: headache to death.

Important Terms

• G-words to Know:
  • Glucose, Glycolysis, Glycogenesis, Glycogenolysis, Gluconeogenesis.

Conclusion

• Understanding metabolic pathways and disruptions is crucial.
• Cellular dysfunction affects overall body functions.
• Reach out to instructors for clarification on concepts.