How does the digestive system meets needs of body?
1. Ingestion: The process begins with ingestion, where we bring food into our mouth and chew it. This mechanical breakdown increases the surface area of food, making it more accessible for the digestive enzymes to act upon.
2. Digestion: Once in the mouth, salivary amylase, an enzyme produced by the salivary glands, begins the chemical digestion of carbohydrates. The food is then swallowed and travels down the esophagus to the stomach.
3. Stomach: In the stomach, gastric juices, including hydrochloric acid and pepsin, further break down food. Hydrochloric acid creates an acidic environment that kills bacteria and denatures proteins, making them susceptible to enzyme digestion. Pepsin, a protease, breaks down proteins into smaller peptides.
4. Small Intestine: The partially digested food from the stomach moves into the small intestine, where most of the absorption of nutrients occurs. The small intestine is lined with tiny finger-like projections called villi, which increase the surface area for absorption.
- Pancreatic Enzymes: The pancreas secretes digestive enzymes such as pancreatic amylase, lipase, and proteases into the small intestine. These enzymes break down carbohydrates, fats, and proteins into simpler molecules like monosaccharides, fatty acids, and amino acids.
- Bile: The liver produces bile, which helps in the digestion and absorption of fats. Bile emulsifies fats, breaking them down into smaller droplets that can interact with lipases and be absorbed.
5. Absorption: The products of digestion, such as simple sugars (like glucose), amino acids, and fatty acids, are absorbed through the walls of the small intestine. They pass through the villi into the bloodstream and are distributed throughout the body.
6. Large Intestine: The undigested materials, along with water and electrolytes, move into the large intestine. Here, beneficial bacteria aid in the further fermentation and breakdown of certain indigestible substances. Water is absorbed from the remaining waste material, solidifying it into feces.
7. Elimination: The final phase involves the elimination of undigested materials and waste products through defecation. This process allows the body to get rid of the substances it cannot utilize.
Overall, the digestive system efficiently breaks down food, extracts essential nutrients, and expels waste products, ensuring that the body's nutritional needs are met for growth, energy production, and proper functioning of various body systems.