HB+Digestive+System+(p.144-155)

=__**Digestive System Homework (text: p.144-155)**__=



//1. Name and describe the processes that occur during the digestive process.//

 * __Ingestion__: This step is when the human physically consumes the food.
 * __Digestion__: It can be either mechanical or chemical. Mechanical Digestion occurs when food breaks down into digestive enzymes, this occurs in both the stomach or mouth. Chemical Digestion starts in the mouth but is not completed until it reaches the small intestine. This thick fluid moving from the stomach to small intestine is called chyme.
 * __Movement__: The movement of the GI tract is important because it is important that the tract is clear and can perform its other functions.
 * __Absorption__: The molecules produced by digestion cross the GI tract and enter the cells lining it. At that point the nutrients enter into the blood flow.
 * __Elimination__: Some molecules can not be digested and are eliminated from the body. The removal of these unusable molecules occurs through the anus.

//2. What are the four layers of the GI tract? Associate an illness with each of the layers. (Describe the Illness)//

 * __Mucosa__: inner mucous membrane layer that is modified according to the digestive system.
 * __Submucosa__: broad band of loose connective tissue that contains nerves, blood, and lymphatic vessels
 * __Muscularis__: two layers of smooth muscle
 * __Serosa__: thin, outermost tissue that is the visceral peritoneum

//3. Describe the mechanical digestion and the chemical digestion that occurs in the mouth.//

 * __Mechanical__: The large pieces of food that are ingested have to be broken into smaller particles that can be acted upon by various enzymes. This is mechanical digestion, which begins in the mouth with chewing or mastication and continues with churning and mixing actions in the stomach. (1)
 * __Chemical__: The complex molecules of carbohydrates, proteins, and fats are transformed by chemical digestion into smaller molecules that can be absorbed and utilized by the cells. Chemical digestion, through a process called hydrolysis, uses water and digestive enzymes to break down the complex molecules. Digestive enzymes speed up the hydrolysis process, which is otherwise very slow. (1)

//4. What ordinarily prevents food from entering the nose or entering the trachea when you swallow?//

 * During swallowing, food normally enters the esophagus, a muscular tube that takes food to the stomach, because other possible avenues are blocked. The soft palate moves back to close off the nasal passages, and the trachea moves up under the epiglottis to cover the glottis. The glottis is the opening to the larynx, which is the voice box and thus your air passage. This air passage connects to the nose and mouth. The glottis closes when we consume something in order to block it from entering the larynx.

//5. What are the function of the stomach, and how is the wall of the stomach modified to perform these functions?//

 * The stomach stores food, initiates the digestion of protein, and controls the movement of chyme into the small intestine. The stomach wall has the usual four layers but two of them are modified for particular functions.

//6. What are the functions of the small intestine and how is the wall of the small intestine modified to perform these functions?//

 * From the stomach the next step of the digestive system is the small intestine. It receives the chyme removed from the stomach and processes what it can from what it retains from breaking down the food using enzymes. Whatever is left carries on to the next process of digestion. The wall of the small intestine has folds that bear finger-like projections called villi.

//7. What are the three main accessory organs that assist with the digestive process?//

 * The three main accessory organs that assist with the digestive process are the liver, the gallbladder and the pancreas.

//8. How does each accessory organ contribute to the digestion of food?//

 * __Pancreas:__ It creates pancreatic juice from its cells which help digest food. It also secretes hormone insulin into the blood.
 * __Liver:__ The liver performs as a toxin remover from the blood and stores vitamins and glucose as well as producing bile salts
 * __Gall blader__: The gall bladder stores bile salts and send them into the duodenum.

//9. What are the different parts of the large intestine?//

 * The Cucem, colon and rectum make up the large intestine.

//10. What are the functions of the large intestine?//
=SOURCES= http://training.seer.cancer.gov/module_anatomy/unit10_1_dige_functions.html (1)
 * The large intestine's primary function is to absorb water and vitamins from waste. It also produces feces.