Answer:
mouth
Explanation:
Mouth is the first part of the gastrointestinal tract, more precisely its upper part. This is the site where the digestion of the food begins.
Mechanical digestion of the food refers to chewing, which breaks down the food into pieces.
Chemical digestion refers to enzymatic breakdown of the food via secretion of salivary gland located in the mouth cavity. Beside saliva, salivary glands secrete enzyme such as amylases (breakdown of the carbohydrates) and lipases (the hydrolysis of lipids).
