The stomach in the digestive system acts as a muscular sac that temporarily stores food, mixes and churns it with gastric juices, and begins the breakdown of proteins using enzymes and acids. It converts food into a semi-liquid substance called chyme, which is then released in a controlled way into the small intestine for further digestion and absorption. Additionally, the stomach produces gastric acid that helps eliminate bacteria, secretes hormones involved in digestion and hunger signaling, and absorbs some substances like water and alcohol.
Key Functions of the Stomach in Digestion
- Storage: The stomach holds ingested food temporarily, allowing slow and regulated release into the small intestine.
- Mechanical Digestion: Muscular contractions churn food, breaking it into smaller pieces and mixing it with digestive juices.
- Chemical Digestion: Gastric juices containing hydrochloric acid and enzymes such as pepsin initiate protein digestion.
- Formation of Chyme: Food is transformed into chyme, a semi-liquid mixture suitable for further digestion.
- Absorption: Limited absorption occurs for water, alcohol, and certain drugs.
- Immune Role: The acidic environment destroys many harmful bacteria ingested with food.
- Hormone Production: Hormones like ghrelin (hunger hormone) and intrinsic factor (for vitamin B12 absorption) are produced.
The stomach acts as the crucial first site for chemical digestion of proteins and as a regulator for food passage into the small intestine, playing an essential role in the digestive process overall.