Enzymes and digestion

 Major parts of the digestive system:

Mouth -

• Where mastication occurs

Oesophagus -

• Carries food from the mouth to the stomach
• Where paristalis occurs

Stomach -

• Muscular sac with an inner layer that produces enzymes
• Role is to store and digest food, especially proteins
• It has glands that produce enzymes which digest protein

Ileum -

• Long muscular tube
• Food is further digested in the ileum by enzymes that are produced by its walls and by glands that pour their secretions into it
• The inner walls of the ileum are folded into villi, which gives them a large surface are to volume ratio
• The surface area of these villi is further increased into tiny finger like projections, called microvilli on the epithelial cells of each villus
• This adapts the ileum for its purpose of absorbing the products of digestion into the blood stream

Large intestine -

• Absorbs water
• Most of the water absorbed is from the secretions of the many digestive glands

Rectum -

• Final section of the intestines
• Faeces are stored here before periodically removed via the anus in egestion

Salivary glands -

• Stimulated near the mouth
• Pass their secretions via a duct into the mouth
• These secretions contain the enzyme amalyse, which hydrolyses starch into maltose

Pancreas -

• Large gland situated below the stomach
• Produces a secretion called pancreatic juice
• This contains proteases to hydrolyse proteins, lipase to hydrolsye lipids and…