Digestive+System+hw-+kat

1. Name and describe the processes that occur during the digestive process. The organs of the digestive system are located within a tube called the **gastrointestinal tract (GI tract)**. During digestion, ingestion is the first process. During ingestion, everything you eat goes into your mouth and is broken down by the grinding of your teeth and saliva. Your saliva breaks down the molecules into sugars, amino acids, fatty acids, and glycerol that travel down your esophagus. the second process of digestion includes digestion. Digestion can be either mechanical or chemical. **Mechanical digestion** occurs when foods are divided into pieces that are acted on by the digestive enzymes, we actually help mechanical digestion by cutting up our foods before we eat them. An important part of the digestion system is the movement of food through the GI tract. It's very important for food to move from organ to the next to complete digestion. Absorption is another important part of the digestive system. It occurs as unit molecules produced by digestion cross the wall of the GI tract and enter the cells lining the tract. From there, all of the nutrients enter the blood to go to the cells. Elimination is the last process of the digestive system. This is when when the body removes indigestible wastes through the anus.
 * Digestive System Book Homework (p.144-155)**

2. What are the four layers of the GI tract? Associate an illness with each of the layers. (Describe the Illness) The four layers of the GI tract include the **mucosa**, the **submucosa**, the **muscularis**, and the **serosa.** - Illness: Diverticulitis--> occurs when pouches, part of mucosa push through other layers, become inflamed or infected. - Illness: Inflammatory Bowel Disease--> because of the blood vessels, its a site for inflammatory responses. (chronic diarrhea, abdominal pain, fever, and weight loss.) -Illness: Irritable Bowel Syndrome--> contractions of the wall cause abdominal pain, constipation, and/ or diarrhea. -Illness: Appendicitis--> an inflamed appendix.
 * Mucosa layer**--> This layer's main job is to produce mucus to protect the wall from the digestive enzymes inside the **lumen** (central space that contains water to digest food).
 * Submucosa layer**--> This layer contains blood vessels, lymphatic vessels, and nerves. All of these vessels carry nutrients absorbed from the mucosa. **Lymph nodules** (Peyer's patches): help protect us from disease.
 * Muscularis layer**--> This layer contains two layers of muscle. The inner layer encircles the tract, while the outer layer ies in the same direction as the tract. Both layers help the movement of the food during digestion from the esophagus to the anus.
 * Serosa**--> This layer secretes serous fluid.

3. Describe the mechanical digestion and the chemical digestion that occurs in the mouth. Mechanical digestion occurs when our teeth grind foods down into pieces small enough that the food is convenient enough to swallow. Chemical digestion is once the food has entered the digestive system, chemicals break down the foods.

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

5. What are the function of the stomach, and how is the wall of the stomach modified to perform these functions? The stomach has many functions including storing food, initiating digestion of proteins, and controlling the movement of chyme into the small intestine. The wall of the stomach consists of four layers, but two of them are used for specific functions. The muscularis layer contains three layers of muscle, a circular one, longitudinal one, and an obliquely one. The **oblique layer** allows the stomach to stretch and to mechanically break down food into smaller pieces that are combined with gastric juices. The mucosa of the stomach has deep folds that disappear as the stomach fills with about 1 liter of substances. There are millions of gastric pits, which lead into gastric glands, which produce gastric juices. The gastric juices contain the enzyme pepsin that digests proteins and HCl (hydrochloric acid).

6. What are the functions of the small intestine and how is the wall of the small intestine modified to perform these functions? The functions of the small intestine are to absorb molecules during the digestive system. The molecules include sugars, amino acids, fatty acids, and glycerol. The mucosa of the small intestine is modified for absorption.

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 pancreas, and the gall-bladder.

8. How does each accessory organ contribute to the digestion of food? The liver is the largest and a major metabolic gland in the body. It acts like a sewage treatment plant, it removes poisonous substances from the blood and detoxifies them, while blood courses through its lobules. The gallbladder contains bile, which has a yellowish green color because it also contains bilirubin from the breakdown of hemoglobin, another function of the liver. The pancreas produces pancreatic juice, which enters the duodenum (first 25 cm of the small intestine) via the pancreatic duct. Pancreatic juices contain sodium bicarbonate and digestive enzymes for all types of foods.

9. What are the different parts of the large intestine? The different parts of the large intestine are the cecum, the vermiform appendix, the colon, the rectum, and the anus.

10. What are the functions of the large intestine? The functions of the large intestine are absorbing water to keep our body hydrated, absorbing vitamins, and forming feces.