DIGESTIVE SYSTEM

The process of breaking down food into molecules the body can use is called digestion. Digestion occurs in the alimentary canal, or digestive tract. This organ begins at the mouth and winds through the body to the anus. Along the canal are the stomach and other organs that aid in digestion.

The first digestive organ that food passes through in your body is the mouth. In this phase the body physically breaks down the fluid into small particles. Sharp, flat front teeth cut into the food. Then the broad, flat surface of molars, or back teeth, grinds it up. The tong helps keep this food between the chewing surfaces of the upper and lower teeth by manipulating it against the hard palate, the bony; membrane covered roof of the mouth. The soft palate made of folded membranes and separated the mouth cavity from the nasal cavity.

Preparations for the chemical phase of digestion begin in the mouth too. The mouth starts to water-that is, the salivary glands increase their production of saliva, a mixture of water, mucus, and a digestive enzyme called salivary glands. The mucus softens the food and holds it together.

Once food has been thoroughly chewed, moistened, and rolled into a bolus, or ball, it is forced by the swallowing action of the tongue into the pharynx. The pharynx is the open area that begins at the back of the mouth and serves as the passageway for both air and food. During swallowing, the epiglottis prevents food from entering the trachea, or windpipe. Instead it passes into the esophagus, the muscular tube that connects the pharynx with the windpipe. The esophagus has two muscular layers- a circular layer that wraps around the esophagus and a longitudinal layer that runs the length of the tube. These two muscles contract to prove the bolus into the stomach. This is called peristalsis.

The stomach, an organ of both mechanical and chemical digestion, is located just below the diaphragm. When full, it is J shaped and when flat and folded is empty stomach and churn its contents.

The liver is a large shaped organ located to the right of the stomach. It secretes bile, which is not a digestive enzyme but an emulsifying agent that breaks fat globules into small droplets. It then goes to t the gall bladder.

The pancreas, small intestine, and large intestine are the other agents of digestion. All are very important. Digestion is extremely important in everyday life functioning.

Vocabulary

1) Digestion- the process of breaking down food into molecules the body can use.

2) Alimentary canal- The digestive tract.

3) Incisors- Sharp, flat, front teeth.

4) Molars- The back teeth that grind.

5) Hard palate- The bony membrane covered roof of the mouth

6) Soft palate-folded membranes that separate the mouth from the nasal cavity.

7) Saliva- A mixture of water, mucus, and a digestive enzyme called salivary amylase.

8) Bolus- When food is chewed into a ball

9) Pharynx- The open area that begins at the back of the mouth and is a passageway for both air and food.

10) Epiglottis- A flap of tissue that prevents food from entering the trachea.

11) Esophagus- The muscular tube that prevents the pharynx with the stomach.

12) Peristalsis- series of rhythmic muscular contractions and relaxation s.

13) Stomach- organ of both mechanical and chemical digestion.

14) Gastric pits- Open ends of gastric glands that produce the cells that release into the stomach.

15) Bile- Not a digestive enzyme, but an emulsifying agent that breaks down fat