EO

Final Exam Review Notes - Chapters 24-27

General Final Exam Review

  • The final exam will cover chapters 24, 25, 26, and, to a lesser extent, 27.
  • Chapter 27: Focus on identifying structures with red underlines in the PowerPoint diagrams posted on Blackboard.
  • Questions from homework assignments related to reproductive systems may appear.
  • 80% of the questions will be from chapters 24, 25, and 26.
  • Bonus questions will be included, pertaining to questions you missed in exam four (study guide available on Blackboard), plus additional questions.
  • The remaining 20% will cover topics missed in previous lecture exams; refer to the study guides folder on Blackboard.

Chapter 24: Nutrients and Metabolism

Nutrients Overview

  • Nutrients: Substances needed for growth, health, cell function, and repair.
  • Two main groups:
    • Major Nutrients: Primarily organic compounds.
      • Carbohydrates
      • Proteins
      • Lipids
    • Other Nutrients: Needed in smaller amounts but still vital.
      • Vitamins: Act as coenzymes.
      • Minerals: Calcium, sodium, potassium (revisited in chapter 26).
      • Water: Considered a nutrient.

Major Nutrients

  • Characterization:
    • Significance
    • Regulation
    • Functions in the body
    • Metabolism

Vitamins

  • Functions: Mostly coenzymes; some act as antioxidants.
  • Structure: Organic compounds.
  • Solubility: Water-soluble vs. lipid-soluble.
  • Source: Made by the body or obtained from the diet.

Minerals

  • Seven minerals are needed in moderate amounts.
    • Examples: Calcium, sodium, chloride, potassium (especially important; revisited in chapter 26).
  • Functions of minerals.

Lipids

  • The liver plays a central role in their metabolism.

Metabolism

  • Anabolic vs. catabolic reactions or pathways.
  • Metabolic reactions encompass all chemical reactions in the body.
  • The body maintains a balance between anabolic and catabolic processes based on its needs.

Absorptive State

  • Metabolic state during and right after a meal.
  • Characterize the situation in terms of nutrient levels after absorption.
  • Understand how the body manages and processes nutrients, including hormonal responses to nutrient fluctuations.
  • Identify the main metabolic reactions taking place.

Post-Absorptive State

  • Metabolic state hours after a meal, with low nutrient levels in the blood.
  • Characterize the situation in terms of nutrient levels.
  • Understand hormonal secretion in response to low nutrient levels.
  • Determine the main metabolic reactions taking place.

Feeding Behavior

  • Controlled by the hypothalamus, the main visceral control center.
  • The hypothalamus processes signals from:
    • Sensory receptors
    • Nutrient content in the blood
    • Hormone signals
    • Temperature
    • Psychological mood
  • Hypothalamus response:
    • Activate hunger center: Chemicals cause appetite for specific nutrients.
    • Inhibit hunger center: Chemicals reduce appetite, creating a feeling of fullness.

Hormonal Conversations

  • Low carbohydrate level: Hypothalamus secretes neuropeptide Y, increasing appetite for carbs.
  • Low lipid level: Hypothalamus stimulates galanin secretion, increasing craving for fat.
  • Generally hungry: Orexins are secreted, increasing appetite.
  • Full: Hypothalamus responds to leptin (released from adipose tissue), inhibiting neuropeptide Y secretion.
  • Increased nutrient levels: Hypothalamus inhibits hunger center, leading to secretion of serotonin and GLP-1.

Other Factors Influencing Feeding Behavior

  • Signals from the digestive viscera (GI tract)
  • Temperature
  • Psychological mood (impacted by the limbic system)

Metabolic Rate and Body Temperature

  • Basal Metabolic Rate (BMR): Energy needed for essential functions.
  • Total Metabolic Rate (TMR): Energy needed for all functions.
  • Regulation of Body Temperature: Balanced between heat loss and heat-generating activities.
  • Heat Loss Mechanisms:
    • Radiation
    • Conduction
    • Convection
    • Evaporation

Carbohydrate Metabolism

  • Most readily usable fuel, with glucose being the most important.
  • All cells can use glucose.
  • Neurons and red blood cells solely depend on glucose.

Chemical Reactions

  • Cellular Respiration: Complete combustion of glucose to make ATP.
    • For each glucose molecule: 36-38 ATP molecules generated.
    • Involves three sequential pathways:
      • Glycolysis
      • Krebs cycle
      • Electron transport chain
  • Glycolysis occurs regardless of oxygen presence; Krebs cycle and electron transport chain occur in the mitochondria and depend on oxygen.

Metabolic Reactions Table (Carbohydrates)

  • Cellular Respiration:
    • Oxygen is used for the complete oxidation of glucose, breaking it down into six carbon dioxide molecules and water molecules.
    • Yield: 36-38 ATP molecules per glucose.
    • C6H{12}O6 + 6O2 othe 6CO2 + 6H2O + 36-38 ATP
    • Includes Glycolysis, Krebs Cycle, and Electron Transport Chain.
  • Glycolysis:
    • Convert glucose to pyruvic acid
    • C6H{12}O6 othe 2C3H4O3 + 2ATP + 2NADH
    • There is an intermediary step. After that, one carbon is detached or oxidized from the pyruvic acid, leaving a two-carbon molecule that, together with coenzyme A, makes acetyl-CoA.
  • Krebs cycle:
    • Cyclic pathway using Acetyl-CoA.
  • Electron transport chain
    • Electrons are transported from one molecule to another sequentially on the inner mitochondrial membrane
  • Glycogenesis: Making of glycogen from glucose
  • Glycogenolysis: Breakdown of glycogen to free glucose
  • Gluconeogenesis: Making glucose from non-carbohydrate sources

Glucose Level Regulation

  • During the absorptive state:
    • High glucose levels stimulate insulin secretion.
    • Insulin stimulates the liver to store excess glucose as glycogen (glycogenesis).
    • Insulin stimulates lipogenesis in adipose tissue, converting excess glucose into neutral fats.
  • during the post-absorptive state:
    • Low glucose levels stimulate glucagon secretion
    • Glucagon stimulates the liver to break down glycogen to free glucose (glycogenolysis).
    • Glucagon stimulates gluconeogenesis and lipolysis.

Protein Metabolism

  • Proteins are not for storage like glycogen or triglycerides.
  • Excess amino acids are processed in the liver.

Liver Reactions

*   Transamination: Transferring the amino group of the amino acid to another molecule.
*   Oxidative Deamination: Removing the amino group from the amino acids, turning it into a keto acid.

Protein Synthesis

  • Rule of all or none: All 20 amino acids must be present for protein synthesis to occur.
  • Essential amino acids: The body cannot make them, so they must be ingested.

Lipid Metabolism

Cholesterol Control

  • Liver is central to lipid metabolism.
  • Regulated by LDL (low-density lipoproteins) and HDL (high-density lipoproteins).
    • LDL: Carries cholesterol away from the liver to peripheral tissues.
    • HDL: Collects cholesterol from the periphery and returns it to the liver.
  • Maintain a balance: Avoid too little HDL or too much LDL to prevent cardiovascular issues.

Vitamins (Review)

  • Functions: Mostly coenzymes (helping enzymes); some as antioxidants.
  • Structure: Organic substances.
  • Solubility: Water-soluble (C, B) vs. lipid-soluble (A, D, E, K).
  • Made by the body: K and B complex by microbial flora, Vitamin D in the skin.