INGESTION

PROCESS The digestive tract is normally 6.5 to 9 m long in adults. Physical digestion begins in the mouth. - Food is chewed and formed into a bolus by the tongue.

SALIVA Contains amylase enzymes -break down the starches (complex carbohydrates) to simpler carbohydrates Lubricates the food and dissolves food particles -Lubrification is necessary for swallowing and dissolving the food particles allows us to taste our food.

TEETH Also play a role in physical digestion Formed from 2 parts; the root and the crown

TEETH

ESOPHAGUS Tube that carries the food from the mouth to the stomach. Bolus stretches the walls of the esophagus activating peristalsis in the smooth muscles. These contractions are rhythmic in nature and involuntary.

Stomach and Digestion Site of food storage and initial protein digestion. Movement to and from the stomach is regulated by sphincters (cardiac and pyloric). The stomach is J shaped and can expand to store 1.5 L of food. Millions of cells line the interior of the stomach and secrete fluids that aid in digestion (gastric fluid or juice).

GASTRIC FLUID Approximately 500 mL is produced following a large meal. This fluid includes mucus, hydrochloric acid, pepsinogens and other substances. - Mucus - Hydrochloric acid - Pepsinogens

Pepsinogen and Pepsin

ULCERS The normal pH in a stomach is in between 2.0-3.0 but can approach 1.0 Ulcers occur when the protective mucous lining breaks down and the cell membrane is exposed to HCl and pepsin.

ULCERS Peptic ulcers occur when the cells of the stomach lining are irritated by acid which increase blood flow. Most ulcers are linked a bacterium called Heliobacter pylori. TREATMENT: In modern medicine, ulcers are treated with a device called an endoscope and lasers.

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