Digestive System: Journey of Food

Macronutrients: These are the major components of food that our body digests and uses for energy, growth, and repair. They include:
- Carbohydrates (Carbs) - (digested in purple).
- Fats - (digested in yellow).
- Proteins - (digested in green).
Micronutrients: These are essential components like vitamins and minerals that are also important for body functions but are not digested in the same way as macronutrients.

The entire digestive system is essentially a long tube extending from the mouth to the anus, through which food passes and nutrients are absorbed. We will trace the path of food through this tube.

Beginning of Digestion: Digestion starts immediately in the mouth with the act of chewing.
Mechanical Digestion (Chewing): This process breaks down large pieces of food into smaller, more manageable pieces, increasing the surface area for enzymes to act upon.
Salivary Glands: These are accessory glands that secrete saliva into the oral cavity.
- Saliva Contents: Saliva contains important enzymes:
  - Amylase (Salivary Amylase): (colored purple, as it initiates carbohydrate digestion). This enzyme begins the breakdown of carbohydrates.
  - Lipase (Salivary Lipase): (colored yellow, as it initiates fat digestion). This enzyme begins the breakdown of fats.
Food Form: After chewing and mixing with saliva, food is swallowed as a soft mass called a bolus.

Function: The esophagus is a tube that transports the bolus from the mouth down to the stomach.
Peristalsis: Waves of muscle contractions (peristalsis) push the bolus along the esophagus.

Lower Esophageal Sphincter: This valve guards the entry of food into the stomach from the esophagus. If this valve becomes