body systems
DESCRIPTION
Body Systems. The Digestive System. The Basics. 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. Types of Digestion. - PowerPoint PPT PresentationTRANSCRIPT
Body Systems
The Digestive System
The Basics
• 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
Types of Digestion• Two Types…• Mechanical: physical breakdown of food
– Chewing/mixing– Teeth/jaw & tongue
• Chemical: breaking down large particles into smaller particles using enzymes
Teeth – Cool Photo
• 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 sugarmolecules
Step 1: Mouth & Esophagus
Why is saliva important?
Aside - Carbohydrates• 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
Step 1: Mouth & Esophagus• 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
Step 2: The Stomach• 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!
Step 2: The Stomach• 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
Step 2: The Stomach• 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
Step 2: The Stomach
Step 3: Gastrointestinal Tract• 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
Step 3: Gastrointestinal Tract
Step 3: Gastrointestinal Tract• 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
Step 3: Gastrointestinal Tract• 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.
Bacteria … Can Be Good?
Step 4 – The End of the Road• 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!
Summary Video
Digestive System