Final answer:
In the human body, food undergoes four key processes: ingestion (taking in food), digestion (breaking down food mechanically and chemically), absorption (taking nutrients into the bloodstream), and excretion (expelling waste).
Step-by-step explanation:
Ingestion is the process of taking in food through the mouth. During ingestion, food is prepared for digestion through processes like chewing, which breaks large chunks into smaller, more manageable pieces.
Digestion involves both mechanical and chemical processes that break down food into its molecular components. Mechanical digestion is the physical breakdown of food, while chemical digestion uses enzymes to convert food into substances absorbable by the body.
Absorption is the next phase, where the nutrients from digested food are taken into the bloodstream. This mainly occurs in the small intestine, where the nutrients are transferred to cells throughout the body.
Excretion, or elimination, is the final stage where indigestible substances and waste materials are expelled from the body. This mainly takes place in the large intestine where water is absorbed and feces are formed for removal.