Review 3 functions of digestive system! 1. D 2. A 3. E Is this in your notes yet?
INTERCONNECTION Digestion Absorption Elimination of Waste
Digestion breakdown of food into molecular components small enough to cross the plasma membrane
Inside the mouth, shown magnified here, teeth, tongue, and saliva work together to physically and chemically break down food. Humans produce up to 3 pints (1.4 liters) of saliva daily, and chemical enzymes in the saliva play a major role in disintegrating starchy foods. http://science.nationalgeographic.com/science/photos/digesti ve-system/?source=A-to-Z#/human-mouth_1002_600x450.jpg Inside the Human Mouth Photograph by Lennart Nilsson
We know that M and C digestion begins in the mouth… What are the structures in the mouth? What do they do? Which structure starts C digestion? NOTES!
What’s happening with your saliva? Starch is a long glucose polymer Enzyme amylase, found in your saliva, breaks down starch into smaller glucose units NOTES!
Cracker Experiment Each person gets one cracker. Break off a small part of your cracker and place it on the front of your tongue. Leave it there for at least two minutes! What does it taste like (bitter, sweet, salty)? What is happening and why? Is there a connection between this experiment and the peristalsis experiment? Take notes in your notebook!
Brain Pop on the Digestive System http://www.brainpop.com/health/bodysystems/digestive system/preview.weml
Describe peristalsis and why you can eat upside down… Turn and talk to your table partner
Your stomach! Muscular sac where food mixes with gastric juice (also called stomach acid or Hydrochloric acid (HCl)). If HCl is so strong, why doesn’t your stomach burn from the inside out? HCl is produced in the stomach lining and activates the enzyme pepsin which starts protein digestion. Does peristalsis occur in the stomach too? Why or why not? Discuss with the people at the table in front or behind you. NOTES!
The Small Intestine What structures are associated with the small intestine? D L G P What functions of the digestive system do they support? NOTES!
This colored scanning micrograph shows a cast of blood vessels from the external wall of the small intestine. Measuring about 22 feet (6.7 meters) in length, the small intestine performs most of the major digestion and absorption of nutrients. The walls of the small intestine are lined with millions of projections called villi, which absorb and transmit nutrients into the bloodstream. http://science.nationalgeographic.com/science/photos/digestive- system/?source=A-to-Z#/small-intestine-vessels_1211_600x450.jpg
Villi in the small intestine Bumpy so well suited for absorption. Tiny finger shaped structures increase surface. They also absorb nutrient molecules and pass them to the blood vessels. NOTES!
Villi Volunteers (two different people!) Compare the two different pieces of fabric. The one with the finger like pieces is similar to the villi. Which fabric will absorb more water? What do you think? Each volunteer should submerge their piece of fabric into the water and hold it for five seconds. Bring the fabric out of the water and squeeze the water into a cylinder. Which piece of fabric absorbed more water?
How do nutrients get to the rest of the body? Nutrients pass from the cells of the villi into the body. Blood vessels are covered by a single layer of cells so nutrients pass through cells into the blood.
Absorption passage of molecules into body's interior & passage throughout the body
Liver and Gall Bladder Two more volunteers! Fill two jars half full of water. Add a few drops of oil to each jar. Add ¼ tsp baking soda to one jar. Stir contents of both jars. Which jar did the oil begin to break up? What does the baking soda represent?
Small Intestine Bile is a substance (not an enzyme) that breaks up fat particles into fat droplets and neutralize stomach acids. Liver produces bile.Gall Bladder stores bile. Pancreas produces enzymes to chemically breakdown fat droplets. NOTES!
Last but not least… The Large Intestine Colon Removes waste and reabsorbs water and salts Rectum Stores waste. Anus Excretes waste. NOTES!