Lecture 1 Gastrointestinal Tract

FNH 350 – Fundamentals of Nutrition

Today’s Lecture

Significance of Macronutrients:

  • Importance in nutrition and health.

Integrative Metabolism:

  • Understanding how nutrients interact in metabolic pathways.

Syllabus Overview:

  • Learning objectives, course material, class format, and evaluation scheme.

Significance of Macronutrients

Importance of Macronutrients in Diet:

  • Source of energy for bodily functions.

  • Building blocks for growth and maintenance of tissues.

  • Serve hormone-like functions in the body.

Macronutrients BreakdownRoles in Human Nutrition:

  • Carbohydrates, lipids, and proteins are essential for energy, growth, and regulation of metabolism.

Caloric Intake:

  • Macronutrients contribute significantly to daily caloric intake:

    • Carbohydrates: 45-65% of energy %E

    • Proteins: 10-35% of energy %E

    • Lipids: 20-35% of energy %E

Metabolism

  • Key Concept for Understanding Nutrient-Disease Relationships:

    • Important in conditions like cardiovascular disease, cancer, obesity, diabetes, and mental health.

Nutritional Determinants:

  • Saturated fatty acids significantly contribute to coronary heart disease progression.

Course Content Overview

  • Covered topics include:

    • Carbohydrates, Lipids, Proteins, Fiber, (Alcohol)

    • Their digestion, absorption, metabolism, and health implications of excess/inadequacy.

    • Integrative Metabolism and Energy Metabolism.

Learning Outcomes

  • Describe the structure of macronutrients and fiber.

  • List functions and food sources of macronutrients.

  • Explain digestion and absorption processes.

  • Understand transportation and metabolism of macronutrients.

  • Describe methods determining human protein and energy needs.

  • Explain factors affecting protein and energy requirements.

  • Understand metabolic effects of excess/inadequate nutrient intake.

  • Analyze effects of feeding and fasting on metabolism.

Importance of Nutrition in Public Health

  • Course aims to enable discussions about:

    • Relationships between dietary practices and public health issues (e.g., obesity, fatty acids consumption, alcohol effects on health).

Learning Objectives for Part II

  • List participating and accessory organs in digestion.

  • Describe structure and function of organs.

  • Explain breakdown and transport of food.

  • Identify absorption sites for various nutrients.

  • Describe mechanisms for nutrient absorption.

Organs of the Gastrointestinal Tract

  • Upper Digestive Tract:

    • Pharynx, Esophagus, Stomach.

  • Lower Digestive Tract:

    • Small Intestine, Large Intestine.

  • Accessory Organs:

    • Liver, Gallbladder, Pancreas.

Oral Cavity and Salivary Glands

  • Salivary Amylase:

    • Main enzyme that aids in starch hydrolysis.

Esophagus

  • Length: 10 inches (25 cm).

  • Function: Moves bolus from oral cavity to stomach via swallowing and peristalsis.

Stomach

  • Capacity: 50 mL (resting) to 1.0 - 1.5 L (fed).

  • Regions: Cardia, Fundus, Body, Antrum.

  • Key Digestive Functions: Gastric juices (includes HCl) aid in digestion.

Small Intestine

  • Main Site for Nutrient Digestion and Absorption:

    • Composed of Duodenum, Jejunum, Ileum.

Accessory Organs of Digestion

  • Pancreas:

    • Major contributor to nutrient digestion.

    • Secretes enzymes that digest carbohydrates, proteins, and fats.

  • Liver/Gallbladder:

    • Produces/store bile to emulsify fats.

Large Intestine

  • Function: Absorbs water and consolidates waste into feces.

Absorption Mechanisms

  • Transport of nutrients occurs through diffusion, facilitated diffusion, active transport, and pinocytosis.