Presentation on theme: "The Digestive Process Caution: some pictures used in this presentation are actual photos of the human body."— Presentation transcript:
The Digestive Process Caution: some pictures used in this presentation are actual photos of the human body.
Functions of the Digestive System The digestive system has three main functions: – 1. Breaks down food into molecules the body can use. – 2. These molecules are absorbed into the blood and carried throughout the body. – 3. Wastes are eliminated from the body.
Mechanical and Chemical Digestion Mechanical: Teeth tear and slash the food into smaller pieces. Chemical: Enzymes “change” the pieces of food into nutrients your body can use. – Example: starch (like crackers) are changed into sugar molecules that fuel your body.
epiglottis There is a flap of tissue called the epiglottis that seals off your windpipe, preventing food from entering your lungs.
The Esophagus There are two tubes that divide off your throat. One opening leads to your windpipe and one leads to your stomach. The one that carries food to your stomach is the esophagus.
The esophagus is a muscular tube that connects the mouth to the stomach. It is lined with mucus, which is a thick, slippery substance produced by the body. It takes food about 10 seconds to travel down to the stomach. The smooth muscles that line the esophagus move the food with contractions called peristalsis.
The stomach is a J-shaped, muscular pouch. This organ uses both mechanical and chemical digestion to break down food. – Mechanical: three strong layers of smooth muscle contract to produce a churning motion. This action mixes the food with fluids. – Chemical: as the churning food makes contact with the digestive juice pepsin, which is made in the cells that line the stomach, some foods are broken down into smaller, different molecules. Digestive juice also contains hydrochloric acids. This creates an excellent environment for the pepsin to work in. The acid also kills many bacteria found in food. Food remains in the stomach until all the solid material has been broken down into liquid form.
Homework Read pages 516-521. Add to your notes when necessary. Complete the Math Analyzing Data on the top of page 520. Answer the questions in complete sentences. Review all key terms for this section.
Last Night’s Homework Answers: – 1. The values on the y-axis represent the percentage of egg white digested. – 2. I estimate that after about 14 hours half of the protein was digested. – 3. After 16 hours of digestion about 70% was completed. – 4. During the 12-16 th hours is when most of the digestion occurred.
Pop Quiz Take a piece of loose leaf and put your heading on it and number 1-5. Write the body part for each description below. – 1. this is a J-shaped muscular organ where both mechanical and chemical digestion occur. – 2. This is the area where your incisors are located. – 3. Peristalsis first occurs in this mucus lined tube. – 4. This flap of tissue seals off your windpipe when you swallow food. – 5. These body parts provide the first stage of mechanical digestion.
Answers to Pop Quiz 1. Stomach 2. Mouth 3. Esophagus 4. Epiglottis 5. Teeth
This is where the most all chemical digestion takes place. 6 meters in length 2-3 centimeters wide Almost all nutrients are absorbed by the villi that line the inside of the small intestine. The nutrients are then into blood vessels, where the nutrients are carried to all parts of the body.
The liver has several jobs in several body systems. In digestion its job is to make bile. Bile is a substance that breaks up fat particles. – Bile flows from the liver into the gallbladder, the organ that stores bile. – Bile is not an enzyme. It DOES NOT chemically digest foods. It mechanically does by physically breaking large fat particles into smaller fat droplets. These droplets can now be chemically broken down by enzymes produced in the pancreas.
Pancreas A triangular shaped organ that lies between the stomach and the first part of the small intestine. It too has many responsibilities in many systems. In digestion it produces enzymes that flow into the small intestine and help break down starches, proteins, and fats.
Nearly all nutrients have been absorbed as the material now reaches the large intestine. 1.5 meters long and 5 cm in diameter U-shaped Filled with “good” bacteria that makes a few vitamins, like vitamin K, for your body. As the remaining material moves through the large intestine, water is absorbed into the bloodstream. The remaining material is readied for elimination from the body.
Homework Read pages 524-527 Add to notes when necessary. Review for test (Nov 23) Tomorrow is a lab, you do NOT need your text book. All you need to bring is your notebook and something to write with.