NS 1410-001 EXAM 3 REVIEW

Metabolism Overview

• Definition: The sum of all chemical and physical processes by which the body breaks down and builds up molecules.

• Types of Metabolism:

  • Anabolism: Synthesis of larger molecules from smaller ones.

  • Catabolism: Degradation of larger molecules to smaller ones.

Key Processes

• Hydrolysis vs. Condensation:

  • Hydrolysis: A catabolic process that breaks down complex compounds with the addition of water.

  • Condensation: An anabolic process joining smaller compounds while releasing water.

• Oxidation vs. Reduction:

  • Oxidation: Removal of electrons by oxygen.

  • Reduction: Gaining electrons, making the molecule more negative.

ATP (Adenosine Triphosphate)

• Definition: High energy compound consisting of adenine, ribose, and three phosphate groups.

• Characteristics:

  • High energy phosphate bonds, when broken, release energy.

  • Considered the energy currency of cells.

  • Small amounts stored in every cell.

• ATP Production: Primarily occurs in mitochondria.

Phosphorylation

• Definition: Addition of one or more phosphate groups to a chemical compound, e.g., ATP to ADP (by removing one phosphate group).

Metabolic Pathways

• Glycolysis:

  • Converts glucose to pyruvate.

  • Anaerobic process occurring in cytosol, generating 2 molecules of pyruvate and a net of 2 ATP.

• Cori Cycle:

  • Anaerobic conversion of pyruvate to lactate in muscles; lactate is converted back to glucose upon oxygen availability.

• Gluconeogenesis:

  • Synthesizes glucose from non-carbohydrate sources, maintaining blood glucose levels during fasting and exercise.

• TCA Cycle (Tricarboxylic Acid Cycle):

  • Series of eight reactions in mitochondria metabolizing acetyl CoA, producing CO2, GTP, NADH, and FADH2.

• Electron Transport Chain:

  • Series of reactions transporting electrons from NADH or FADH2, leading to ATP production.

Lipid Metabolism

• Lipolysis:

  • Catabolism of triglycerides into free fatty acids and glycerol.

  • Glycerol becomes pyruvate and then acetyl CoA for TCA cycle entry.

• Beta-Oxidation:

  • Oxidation of free fatty acids producing water, CO2, and ATP.

• Lipogenesis:

  • Synthesis of free fatty acids from non-lipid sources (ketogenic amino acids or ethanol).

• Ketone Synthesis:

  • Conversion of fatty acids to ketone bodies in the liver during low carbohydrate availability.

• Protein Deamination:

  • Removal of the amine group resulting in ammonia and carbon skeleton (keto acid).

Anaerobic vs. Aerobic Pathways

• Anaerobic: Glycolysis, Cori Cycle.

• Aerobic: TCA Cycle, Electron Transport Chain, Beta Oxidation.

Nutrient Metabolism Outputs

• Outputs of metabolism include: ATP, proteins, lipids, nucleic acids, CO2, and water.

Hormonal Regulation

• Anabolic Hormone: Insulin (during fed state).

• Catabolic Hormones: Glucagon (fasted), epinephrine (exercise), cortisol (stress).

Macronutrient Pathways

• Carbohydrates: Glycolysis leading to ATP production starting from glucose.

• Fats: Beta-oxidation starting from triglycerides leading to ATP production.

• Proteins: Oxidative deamination starting from amino acids producing ammonia and keto acids.

Energy Storage Characteristics

• Energy is used during fasting, sleep, and exercise.

• Stored as glucose in limited amounts in liver and muscle; triglycerides stored unlimitedly.

Metabolic States

• Fed State: Anabolic state; bloodstream rich in glucose, fatty acids, and amino acids.

• Short-Term Fasting: Catabolic; liver glycogen is broken down for glucose; cells utilize fatty acids and ketones.

• Starvation: Catabolic; primary fuel shifts to fatty acids; brain and red blood cells utilize ketones.

Alcohol Intake

• Moderate Alcohol Intake: 2 drinks for men, 1 drink for women (defined quantities).

• Binge Drinking: 5+ drinks for men, 4+ drinks for women in a single occasion.

• Alcohol Metabolism Rate: 0.5 oz per hour by the liver.

Benefits and Risks of Alcohol

• Positive Effects: Moderate alcohol may lower risks for cardiovascular disease, enhances sociability, reduces stress, increases HDL.

• Negative Effects: Risks include breast cancer, hypertension, increased caloric intake, dehydration, and cirrhosis.

Vitamins & Minerals

• Water-soluble Vitamins: Absorbed directly into the bloodstream, excreted in urine (e.g., B-complex, Vitamin C).

• Fat-soluble Vitamins: Absorbed through lymphatic system, can accumulate in liver/adipose tissue (e.g., Vitamins A, D, E, K).

Enrichment Acts

• Enrichment Act 1941: Required enrichment of refined grains with B vitamins and iron.

• Enrichment Act 1996: Mandated folic acid enrichment for bread and cereals.

Food Sources of Vitamins and Minerals

• Table of sources for vitamins including Thiamin (B1), Riboflavin (B2), Niacin (B3), and others.

Deficiency Diseases

• Thiamin: Beriberi leading to cardiac issues and neuropathies.

• Riboflavin: Ariboflavinosis with sore throat and skin issues.

• Niacin: Pellagra with dermatitis, diarrhea, and depression.

• Vitamin B6: Microcytic anemia and neurological problems.

Toxicity Symptoms

• Thiamin: None.

• Niacin: Flushing and potential liver damage from supplements.

• B6: Nerve damage and skin lesions from overconsumption.

Interesting Facts

• Riboflavin: Light sensitive.

• Niacin: Used medically to manage high cholesterol.