[Image of the Stomach]
Functions of the Stomach:
1. Food Reservoir: The stomach acts as a reservoir for swallowed food. It can expand to hold a considerable amount of ingested material, allowing for gradual digestion and preventing overstretching of the esophagus.
2. Mechanical Digestion: The stomach muscles contract and relax, mechanically breaking down the food into smaller pieces. This process, known as churning, helps increase the surface area of the food, making it more accessible for digestive enzymes.
3. Chemical Digestion: The stomach secretes gastric juices, which contain hydrochloric acid (HCl) and the enzyme pepsin. HCl creates an acidic environment that kills bacteria and facilitates the activation of pepsin. Pepsin begins the digestion of proteins by breaking them down into smaller peptides.
4. Absorption: The stomach absorbs certain substances, such as water, alcohol, and drugs, directly into the bloodstream. However, the majority of nutrient absorption occurs in the small intestine.
5. Regulation of Gastric Emptying: The stomach regulates the passage of food into the small intestine. It releases partially digested food, known as chyme, through a muscular valve called the pyloric sphincter. Factors like stomach distension, pH, and hormonal signals control the rate of gastric emptying.
6. Protection: The acidic environment, low pH, and antibacterial substances in the stomach help protect against harmful microorganisms present in ingested food.
It's important to note that the stomach is just one part of the digestive system, and the digestion process continues in the small intestine, where most nutrient absorption takes place.
Remember, this simplified explanation provides a general overview of the stomach's structure and functions. For more detailed information, it's best to consult a medical professional or study anatomy and physiology resources.