• Has taste to help select food
• Rolls food into bolus, which makes it easier to swallow

Saliva:

• Secreted by salivary glands
• Contains muscin which softens food
• Contains salivary amylase

Starch->by salivary amylase->Maltose

Oesophagus

Struture:

• Long, narrow, muscular tube
• The oesophagus walls secretes a liquid called mucus which lubricates food so it moves easily along the gut

Function:

• Transport food from mouth to stomach

How does oseophagus transport food?

Peristalsis. A rhythmic wave-like contractions of the walls to move food along the gut.

Structure:

• Thick muscular and elastic bag
• Spincter muscles control the flow of food

What stomach contains?

Gastric juice:

• Hydrochloric acid ( pH=2 ) which activates pepsin and kill germs
• contains pepsin

Why does starch digestion stops in stomach?

Hydrochloric acid stops the action of salivary amylase

How does the stomach ensure even mixing of food with gastric juice?

Peristalsis. It can also occur in the stomach.

Chyme

The liquefied and partially digested food in the stomach.

Stomach

Function:

• Receive food from oesophagus
• Mix food with gastric juice
• Digest proteins to polypeptides
• Move chyme to small intestine

Stomach Ulcer is caused by:

• Excessive production of hydrochloric acid

Erode stomach walls-> Gastric ulcer

• Worry and stress

Increase the flow of gastric juice into the stomach