Notes

Mechanical digestion is the actual physical breaking apart of food by chewing with teeth or churning within internal organs.
Chemical digestion involves chemical reactions that separate large molecules into simpler, smaller molecules. This is usually achieved by a process called hydrolysis.
dentin-bone
connected tissue blood vessels - pulp
enamel - covered with it
Saliva is produced by three pairs of enzyme-rich glands. The largest salivary glands are the parotid glands. The smaller glands are the sublingual submaxillary glands.
Saliva moistens food and the enzymes in it chemically break food molecules apart.
The pharynx is a common tube that is used by both the digestive and respiratory systems. When food is swallowed, a flap of tissue called the epiglottis closes the entrance to the trachea so food is forced into the esophagus.
The esophagus is a muscular tube that leads to the stomach. It is lined with mucus-secreting cells called mucosa. Muscles surround the mucosa and push the food mass, called a bolus, through the esophagus in rhythmic waves.
This process of moving food through the digestive tract is known as peristalsis and occurs in the esophagus, stomach, and intestines.
The stomach is composed of three muscle layers that aid in the mechanical digestion of food.
Gastric juices break down the food. Gastric juices are formed from enzymes, water, and hydrochloric acid—three of the four substances secreted by the mucosa.