Final answer:
The main functions of the human digestive system are to digest food, absorb nutrients, and eliminate waste, primarily involving processes like digestion and peristalsis, with organs like the stomach and small intestine playing key roles.
Step-by-step explanation:
The human digestive system is responsible for three main functions: the digestion of food, the absorption of nutrients, and the elimination of solid food waste. Digestion is the mechanical and chemical breakdown of food into absorbable components, involving organs such as the mouth, esophagus, stomach, small intestine, and large intestine. Additionally, the liver, gallbladder, and pancreas produce substances that aid digestion.
Peristalsis is a critical process involving rhythmic contractions that move food through the digestive tract. The stomach is central in breaking down food with its acidic environment and enzymes, while the small intestine is the primary site for nutrient absorption into the bloodstream.