Chapter_15_Nutrition_and_Metabolism_rm_TDRM

Chapter 15: Nutrition and Metabolism

Section 15.1: The Basics of Nutrition

• Nutrition: An applied science studying food, water, and nutrients.

• Macronutrients: Needed by the body in large amounts.

  • Examples: Carbohydrates, lipids, proteins.

• Micronutrients: Needed in small amounts.

  • Examples: Vitamins, minerals.

Nutrition Guidelines

• Daily Values (DVs): Reference values by FDA for food labels including Reference Daily Intakes (RDIs) and Daily Reference Values (DRVs).

• Carbohydrates: Provide approx. 4 cal/g, ideal energy sources, and materials for cell/tissue synthesis.

  • Simple Carbohydrates: Monosaccharides, disaccharides (sugars).

  • Complex Carbohydrates: Polysaccharides (amylose and amylopectin).

Section 15.5: Lipids

• Lipids: Concentrated energy source, approx. 9 cal/g; transport fat-soluble vitamins.

• Essential Fatty Acids: Cannot be synthesized; must be obtained from diet (examples: linoleic and alpha-linolenic acid).

• Dietary Guidelines: Recommend <10% of calories from saturated fats.

Section 15.6: Proteins

• Proteins: Build tissues during growth, produce enzymes, hormones, and other nitrogen-containing compounds; also provide energy (4 cal/g).

• Recommended intake: 12% of total caloric intake.

• Complete Proteins: Contain all essential amino acids.

Micronutrients: Vitamins

• Vitamins: Organic micronutrients needed for good health, cannot be produced in sufficient amounts by body.

  • Water-soluble: Coenzymes (e.g., B vitamins, vitamin C).

  • Fat-soluble: Similar functions to hormones (vitamins A, D, E, K).

Micronutrients: Minerals

• Minerals: Utilized in the body as ions or compounds.

  • Major Minerals: >5 g in the body (e.g., calcium, sodium).

  • Trace Minerals: <5 g in the body (e.g., iron, iodine).

Metabolism Overview

• Metabolism: Sum of all reactions in an organism.

  • Catabolism: Breakdown of biomolecules.

  • Anabolism: Synthesis of biomolecules.

  • Metabolic Pathway: Sequence of reactions for product formation.

• Stages of Catabolism:

  1. Digestion: Break down complex molecules.

  2. Degradation: Convert smaller molecules to simpler units.

  3. Electron Transport Chain: Energy production.

Section 15.3: ATP: The Energy Currency

• ATP (Adenosine Triphosphate): Composed of adenine, ribose, and three phosphate groups.

• Hydrolysis of ATP: Transfers energy for biochemical reactions.

• Gibbs Free Energy (∆G): Energy change in reactions.

  • Negative ∆G indicates energy release; positive indicates energy absorption.

• ATP-ADP Cycle: ATP fulfills cellular work needs.

Mitochondria: Powerhouse of Cells

• Mitochondria: Site of energy production via catabolic pathways.

• Stages in Cellular Respiration: Glycolysis, Pyruvate oxidation, Citric Acid Cycle.

Glycogen Metabolism and Gluconeogenesis

• Glycogenesis: Glucose stored as glycogen in liver and muscle.

• Glycogenolysis: Breakdown of glycogen to glucose.

• Gluconeogenesis: Glucose synthesis from non-carbohydrates, primarily in the liver.

Hormonal Regulation of Glycogen

• Insulin: Trigger glucose absorption, glycogen, fatty acid, protein synthesis.

• Glucagon: Raises blood glucose levels by activating glycogenolysis.

• Epinephrine: Stimulates glycogen breakdown for energy during stress.

Lipid Metabolism

• Triglycerides: Major energy source from fatty acids during fasting.

• Fatty Acid Breakdown: Requires conversion to fatty acyl CoA.

• Ketone Bodies: Produced from excess acetyl CoA in low glucose conditions (e.g., starvation).

Diabetes and Ketoacidosis

• Diabetes: Elevated blood glucose due to insulin deficiency;

• Ketonemia & Ketonuria: High levels of ketones in blood and urine respectively.

• Ketoacidosis: Result of acidotic buildup from ketone bodies leading to severe complications.

Amino Acid Metabolism

• Amino Acid Pool: Source for protein synthesis, synthesis of nitrogen-containing compounds.

• Nonessential Amino Acids: Can be synthesized by the body.

• Metabolic Pathways: Degradation leads to nitrogen excretion, with varied fates of carbon skeletons.

Summary

• This chapter covers essential nutrients and their functions, metabolic processes including glycolysis, citric acid cycle, and overall cellular respiration, along with hormonal regulation mechanisms and the metabolism of carbohydrates, lipids, and proteins.