Digestive System Overview

Digestive System

Overview

• The digestive system is a complex process by which the body breaks down and absorbs nutrients from food
• Involves mechanical and chemical digestion, as well as absorption and elimination of waste products

Organs of the Digestive System

• Mouth:
  • Mechanical digestion: teeth chew food into smaller pieces
  • Chemical digestion: salivary enzymes break down carbohydrates
• Esophagus:
  • Muscular tube that transports food to the stomach
• Stomach:
  • Mechanical digestion: stomach muscles churn and mix food
  • Chemical digestion: gastric enzymes break down proteins and fats
• Small Intestine:
  • Most of nutrient absorption takes place here
  • Walls are lined with finger-like projections called villi, increasing surface area
• Large Intestine:
  • Also known as the colon
  • Absorbs water and electrolytes, and stores and eliminates waste
• Liver:
  • Produces bile, which aids in fat digestion and absorption
  • Plays a role in detoxification and metabolism
• Pancreas:
  • Produces digestive enzymes that break down carbohydrates, proteins, and fats
  • Regulates blood sugar levels through insulin and glucagon production

Digestive Enzymes

• Amylase: breaks down carbohydrates into simple sugars
• Lipase: breaks down fats into fatty acids and glycerol
• Protease: breaks down proteins into amino acids

Digestive Process

• Ingestion: food enters the mouth
• Mechanical digestion: food is broken down into smaller pieces through chewing and churning
• Chemical digestion: enzymes break down food into smaller molecules
• Absorption: nutrients are absorbed into the bloodstream through the walls of the small intestine
• Elimination: waste products are eliminated from the body through the anus

Digestive System

Overview

• The digestive system is a complex process that breaks down and absorbs nutrients from food
• Involves mechanical and chemical digestion, as well as absorption and elimination of waste products

Organs of the Digestive System

Mouth

• Performs mechanical digestion through teeth chewing food into smaller pieces
• Performs chemical digestion through salivary enzymes breaking down carbohydrates

Esophagus

• A muscular tube that transports food to the stomach

Stomach

• Performs mechanical digestion through stomach muscles churning and mixing food
• Performs chemical digestion through gastric enzymes breaking down proteins and fats

Small Intestine

• Most of nutrient absorption takes place here
• Walls are lined with finger-like projections called villi, increasing surface area

Large Intestine

• Also known as the colon
• Absorbs water and electrolytes, and stores and eliminates waste

Liver

• Produces bile, which aids in fat digestion and absorption
• Plays a role in detoxification and metabolism

Pancreas

• Produces digestive enzymes that break down carbohydrates, proteins, and fats
• Regulates blood sugar levels through insulin and glucagon production

Digestive Enzymes

• Amylase breaks down carbohydrates into simple sugars
• Lipase breaks down fats into fatty acids and glycerol
• Protease breaks down proteins into amino acids

Digestive Process

• Ingestion: food enters the mouth
• Mechanical digestion: food is broken down into smaller pieces through chewing and churning
• Chemical digestion: enzymes break down food into smaller molecules
• Absorption: nutrients are absorbed into the bloodstream through the walls of the small intestine
• Elimination: waste products are eliminated from the body through the anus

Macronutrients

• Provide energy and support growth and maintenance of the body
• Three main categories: carbohydrates, proteins, and fats

Carbohydrates

• Provide energy for the body (4 kcal/gram)
• Main sources: grains, fruits, vegetables, and dairy products
• Include simple carbohydrates (sugars) and complex carbohydrates (polysaccharides)
• Simple carbohydrates: glucose, fructose, galactose
• Complex carbohydrates: starches, cellulose, glycogen

Proteins

• Provide energy and building blocks for growth and repair (4 kcal/gram)
• Main sources: animal products, legumes, nuts, and seeds
• Functions: building and repairing tissues, producing enzymes and hormones, maintaining fluid balance and pH

Fats

• Provide energy and support brain function (9 kcal/gram)
• Main sources: animal products, oils, nuts, and seeds
• Include saturated fats, unsaturated fats, omega-3 and omega-6 fatty acids
• Saturated fats: typically solid at room temperature, found in animal products and some plant-based sources
• Unsaturated fats: typically liquid at room temperature, found in plant-based sources

Importance of Macronutrient Balance

• A balanced diet should provide adequate amounts of each macronutrient for optimal health and function
• Imbalances or deficiencies can lead to various health problems, such as energy imbalances, protein deficiencies, and fat imbalances
• Energy imbalances: fatigue, lethargy, or weight gain/loss
• Protein deficiencies: muscle wasting, impaired immune function
• Fat imbalances: cardiovascular disease, impaired brain function