Gastrointestinal Physiology Quiz

Functions of the Gastrointestinal System

• The main function of the Gastrointestinal Tract (GIT) is to supply the body with water, nutrients, electrolytes, and vitamins.
• The GIT performs three main actions: digestion of food, absorption of digestive products, and regulation of various functions.

Physiology of the Mouth

Functions

• The mouth is responsible for mechanical and chemical digestion of food.
• Mechanical activity in the mouth involves mastication (chewing), which is performed by the anterior teeth (cutting action) and posterior teeth (grinding action).

Innervation of Muscles of Chewing

• The muscles of chewing are innervated by the 5th, 8th, and 12th cranial nerves.

Mechanism of Mastication (Chewing Reflex or Opening-Jaw Reflex)

• The presence of a bolus of food in the mouth compresses the teeth surface, causing reflex inhibition of the muscles of mastication.
• This inhibition causes the lower jaw to drop.
• The sudden drop in the lower jaw stimulates contraction of the jaw muscles, raising the lower jaw and closing the teeth.
• The teeth closure compresses the bolus again, allowing the jaw to drop, and the cycle repeats.