The primary function of digestive juice is to chemically break down food into smaller, absorbable nutrient molecules.
Digestive juices are complex fluids secreted throughout the digestive system, from the salivary glands in the mouth to the glands in the stomach and small intestine. These juices contain enzymes, which are biological catalysts that speed up chemical reactions. The enzymes within digestive juices target specific types of food molecules, such as carbohydrates, proteins, and fats, and break them down into their constituent building blocks (e.g., sugars, amino acids, and fatty acids). This process is essential because the body can only absorb these smaller molecules into the bloodstream for distribution and use by cells.
Here's a breakdown of the function in different parts of the digestive system:
- Mouth: Salivary glands secrete saliva, which contains the enzyme amylase. Amylase begins the breakdown of complex carbohydrates (starches) into simpler sugars. Saliva also moistens food, making it easier to swallow.
- Stomach: Gastric juice, secreted by glands in the stomach lining, contains hydrochloric acid and the enzyme pepsin. Hydrochloric acid creates an acidic environment that activates pepsin. Pepsin breaks down proteins into smaller peptides.
- Small Intestine: Pancreatic juice, secreted by the pancreas, contains a variety of enzymes, including amylase (further carbohydrate digestion), lipase (fat digestion), and proteases like trypsin and chymotrypsin (protein digestion). Bile, produced by the liver and stored in the gallbladder, emulsifies fats, breaking them into smaller droplets, which increases the surface area for lipase to work on. Intestinal juice, secreted by the small intestine itself, contains enzymes that further break down carbohydrates, peptides, and nucleic acids.
In summary, digestive juices containing enzymes are vital for chemically digesting food, allowing the body to absorb nutrients necessary for energy, growth, and repair.
