The Digestive System

We all need energy to live We get it from different sources –Carbohydrates (sugars/starches) –Lipids (fats/oils) –Proteins (meat/lentils/beans) The Digestive system takes these sources and makes them useable to the body

Two Types… Mechanical: physical breakdown of food –Chewing/mixing –Teeth/jaw & tongue Chemical: breaking down large particles into smaller particles using enzymes

Food enters our body through our mouth We chew and grind it down It also mixes with saliva which comes from 3 different saliva glands They release the enzyme amylase Starch molecules into sugar molecules Why is saliva important?

Why are they important? What do they do? –They are the main fuel source for our body –The energy that gets used first –Recommended that 45-60% is carbohydrates Where do they come from? –Vegetables, grains, low-fat dairy, fruits

When ready to swallow food tongue pushes the food back Flap of skin called epiglottis moves across your windpipe Into the esophagus it goes It is pushed down your throat by the muscles that line the esophagus … this is peristalsis –Chewed food is known as bolus –Swallowing is known as delutition

Swallowing Video

A little history … Alexis St. Martin & Dr. William Beaumont Alexis had big wound in his left side Could not be repaired entirely What did they do? Dr. Beaumont put food on a string and dangled it into the stomach to see what happened – lol science history! As if you are letting me do this! Lol!

Food enters the stomach through a sphincter (esophageal) Muscular wall of the stomach mixes it around with the gastric juices What is that? –Water –Mucus –Hydrochloric Acid –Digestive Enzymes

The acid, enzymes and water liquefy the food and break it down chemically It passes into the small intestine through another sphincter (pyloric) Why do we need mucus in the stomach? –So acid does not burn a hole thru the stomach! –The acid in the stomach is hydrochloric acid Acid Video

The pancreas, a large gland in the back of the stomach, helps break down food, sends digestive enzymes into the small intestine Enzymes complete the breakdown of starches and proteins into small particles which are more easily absorbed by the body

The liver produces a substance called bile (which is stored in the gall bladder) The gall bladder sends bile into the small intestine, where it breaks up large amounts of lipids into small drops

When food is broken down into smaller particles, the small intestine absorbs these particles. The inner surface of the small intestine contains villi (small, finger like objects) – Villi increases the surface area of the intestine to help absorb nutrients. – Villi is covered with epithelial tissue & food molecules get absorbed by this tissue.

Food then passes from the small intestine to the large intestine Key part here is that water is absorbed in the large intestine When it hits the end of the road … washroom break!

Digestive System