Hard Palate (Tongue) – The oral cavity initiates mechanical digestion. The hard palate, composed of the maxillary and palatine bones, serves as a rigid shield against which food is compressed. The tongue, a skeletal muscle strengthened by the hypoglossal nerve, manipulates food into a bolus.

Pancreas- The pancreas functions as both an exocrine and endocrine gland. As an exocrine gland, it produces pancreatic juice, which contains bicarbonate to neutralize acidic chyme entering from the stomach, and a variety of enzymes for the macronutrient breakdown. Its endocrine role, it produces hormones like insulin and glucagon to maintain glucosehomeostasis.

Stomach – The stomach is a J-shaped organ specialized for both mechanical and chemical processing.

Small Intestine- It is considered as the primary site of chemical digestion and nutrient absorption. It mainly functions as an absorption mechanism where the internal surface area is exponentially increased by circular folds, villi, and microvilli (the brush border).