Final answer:
Mechanical digestion in the stomach is a physical process that breaks down food into smaller pieces without changing its chemical composition. The stomach muscles churn and mix the food, aided by gastric juices. The end result is a semi-fluid mixture called chyme.
Step-by-step explanation:
Mechanical digestion in the stomach is a physical process that breaks down food into smaller pieces without changing its chemical composition. The stomach muscles churn and mix the food, further breaking it apart. This process is aided by gastric juices, including acid and digestive enzymes, which start the chemical digestion of proteins. The end result is a semi-fluid mixture called chyme.