Life Science Organ Systems Digestion Notes Outline

Life Science Organ Systems Digestion Notes Outline Why It Matters ● The main purpose of the digestive system is to provide the body with nutrients, including ○ water ○ proteins ○ carbohydrates ○ lipids ○ vitamins ○ minerals ● The two main ways that the stomach breaks down proteins into amino acids are acidic stomach juice and enzymes ● Bile is secreted by the liver and helps separate fats so they can be broken down by enzymes and absorbed. ● Insulin is secreted by the pancreas and is involved in a disease called diabetes. What We Know ● Food first enters the body through the mouth where saliva begins to break down carbohydrates. ● The esophagus pushes food down into the stomach with muscular contractions. ● Bile is produced by the liver and is stored in the gall bladder. ● The pancreas helps digest carbohydrates, proteins, and fats as well as regulates blood sugar. ● The small intestine breaks down and absorbs proteins, carbohydrates, and fats. The large intestine absorbs moisture from what is left of the food. ● The final storage space before waste is removed is the rectum. ● Food stays in the stomach for 4-6 hours, the small intestine for 2-4 hours, and the large intestine for 24-48 hours ● The pharynx has openings that go into the lungs and to the esophagus/stomach. ● The epiglottis is the structure that covers the opening of the trachea and prevents food from entering the lungs. ● The body has a normal pH of 7.2. The stomach has a pH of 2.5 or 2. ● The stomach secretes mucous to protect the lining of the stomach and prevent ulcers. ● The pH of the small intestine is higher than the stomach. ● In addition to making bile, the liver: ○ Processes carbohydrates, fats, and proteins absorbed by the small intestine. ○ Breaks down hormones, drugs, and toxins ○ Makes the proteins in blood responsible for clotting ● The pancreas releases insulin when blood sugar is high and glucagon when blood sugar is low. ● The large intestine removes fluid and salt from solid waste and stores feces. ● The large intestine has many beneficial bacteria that aid in fermentation and produce vitamin K. How We Know ● A cow’s stomach has four (4) compartments. ● Enzymes in your saliva break down carbohydrates. ● Dr. Beaumont noted that proteins were especially degraded by acids in the stomach. ● The liver is a nutrient storage organ that releases stores as needed. ● The gall bladder is not necessary for life ● The pancreas secretes two hormones into blood ○ Insulin - triggers cells to absorb sugar from blood ○ Glucagon - triggers cells to release sugar into blood ● There are two ducts that connect the pancreas and the small intestine. ● The portal vein collects all of the blood leaving the small intestine and has high amounts of carbohydrates and amino acids. ● Fats from the small intestine are absorbed through lymphatic vessels. ● Blood leaving the large intestine has more water and salt than the blood entering the large intestine. ● Bacteria can break down certain foods that humans cannot. ● Vitamin K is needed for normal blood clotting. Common Hazards ● Ulcers ○ A lesion in the mucus lining of the stomach or duodenum is called a peptic ulcer. ○ Causes of ulcers include ■ a bacteria called Helicobacter pylori ■ long term use of NSAIDs ■ a disease called Zollinger-Ellison syndrome that causes tumors that release hormones that causes large amounts of acid to be produced. ● Food Poisoning ○ Symptoms of food poisoning are ■ nausea ■ vomiting ■ abdominal cramps ■ fever ■ diarrhea ○ Food poisoning can be avoided by ■ Washing your hands ■ Cleaning kitchen tools ■ Washing fruits and vegetables ■ Cooking food thoroughly ■ Refrigerating leftovers within 2 hours Fill in the blanks labeling the digestive system. (Source: NIH NIDDK)