First Steps of Digestion

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How Important Are Teeth?Teeth provide surface for mechanical digestion.• Molars—grinding • Incisor—biting • Canine—piercing • Bicuspid—grinding

Tongue• Keeps food in place• Push bolus back in mouth

Digestion In The Mouth:• Our teeth break down food into physically

smaller pieces that can be acted on by digestive enzymes.

• The first enzyme that the food encounters in our mouth is called salivary amylase.

Salivary Amylase:• Salivary amylase is released by our salivary

glands and is the most abundant enzyme in our saliva.

• Salivary amylase begins the digestion of carbohydrates.

Digestion of Starch:• Salivary amylase in the mouth begins the

digestion of starch.

Starch

Salivary Amylase

Disaccharides

Digestion of Starch:• The breakdown of starch continues in the small

intestine.

• Pancreatin (a mixture of several digestive enzymes produced by the pancreas) – Amylase– Lipase– Protease

• In the small intestine the disaccharides are further broken down into monosaccharaides.

Digestion of Starch:

Starch

Salivary Amylase

Disaccharides

Pancreatic Amylase

monosaccharaides

Digestion In The Mouth:• Your saliva also contains an enzyme called

Lysozyme.– Fights infection by breaking down the cell walls of

bacteria that may come in contact with food.

Pharynx and Epiglottis• Once food is chewed it moves to the back of

the throat- this area is called the pharynx.

Pharynx and Epiglottis• The epiglottis is a flap that

is made of elastic cartilage tissue.

• The epiglottis prevents food from going down your trachea.– Allows the passage of air to

the lungs.

Moving on…..• The food that has been mechanically digested by

the teeth and that has begun chemical digestion by salivary amylase is now called a bolus.

• The bolus enters the esophagus from the pharynx.