HUMAN NUTRITION

Detailed explanation-1: -The act of swallowing has voluntary and involuntary components. The preparatory/oral phase is voluntary, whereas the pharyngeal and esophageal phases are mediated by an involuntary reflex called the swallowing reflex.

Detailed explanation-2: -Another term for swallowing is deglutition. The pharyngeal-esophageal phase of swallowing is involuntary and is controlled by the swallowing center in the thalamus and lower pons. Fats significantly delay the emptying of the stomach through hormonal and neuronal signals.

Detailed explanation-3: -Esophageal Phase This is an autonomous process not under voluntary control, much like the pharyngeal phase. It occurs much slower than the pharyngeal phase, at a rate of about 3 to 4 cm/s. [12] This phase ends once the bolus passes through the lower esophageal sphincter (LES) and into the stomach.

Detailed explanation-4: -The first irreversible step in swallowing, the pharyngeal stage, occurs next and is categorized by a rapid phase of muscle contraction to propel the bolus through the upper esophageal sphincter and into the esophagus. This stage starts when the consumed bolus makes its way to the palatoglossal arch.