the digestive system chapter 22-3. science words/objectives digestion mechanical digestion chemical...
TRANSCRIPT
The Digestive System
Chapter 22-3
Science Words/Objectives
• Digestion
• Mechanical digestion
• Chemical digestion
• Saliva
• Peristalsis
• Chyme
• Villi
Objectives
• Distinguish between mechanical and chemical digestion
• Mane the organs of the digestive system and describe what takes place in each
• Explain how homeostasis is maintained in digestion
Processing food
• Digestion- the process that breaks down food into small molecules so they can move into the blood.
Introduction to Digestion
Digestive system
• Mouth
• Esophagus
• Stomach
• Small intestine
• Large intestine
• Rectum
• anus
• Does not pass thru the liver, pancreas, gallbladder- they produce or store enzymes and chemicals that help break down food as it passes through the digestive tract
Parts of digestive system,
Enzymes
• Are molecules that speed up the rate of chemical reactions in your body.
• Enzymes in the mouth, stomach, small intestine,.
• Breaks down proteins and fats
Where and How digestion occurs
• Mechanical digestion-takes place when food is chewed and mixed in the mouth and churned in the stomach.
• Chemical digestion-breaks down large molecules to small molecules. Mouth, stomach and small intestine
Forms of Digestion
Mouth
• Mechanical digestion starts with your teeth.
• Chemical digestion starts with your saliva.
• Saliva-produced by 3 glands, is water, mucus, and salivary amylase(enzyme)
• Moved by tongue- swallowed into esophagus.
The Mouth
Esophagus
• Muscular tube 25 cm long, 4-10 seconds to go through it
• No digestion takes place
• Smooth muscles move food by squeezing.
• Peristalsis- waves or contractions
The Esophagus
Stomach
• Is a muscular Bag.
• As food enters it expands and the folds smooth out
• Mechanical and chemical digestion
• Changes into a thin watery liquid called chyme, which goes into the small intestine
The Stomach
Small Intestine
• 4-7 meters in length• Enters the duodenum
where most of all digestion takes place.
• Liver produces bile to help break down food
• Pancreas produces enzymes to break down fats and proteins
Small IntestineGall Bladder and
Pancreas
Small intestine
• The small intestine has ridges and folds, the folds are covered with tiny fingerlike projections called villi.
• Villi make the surface of the intestine greater so that there are more places for food to be absorbed.
Large Intestine
• Main job is to absorb liquid from chyme- undigested materials become more solid.
Large intestine
The Role of Bacteria
• Bacteria feed on cellulose and produce several vitamins that you need
Digestion and Nutrients
Digestion and Nutrients
Homeostasis
• The regulation of steady, life maintaining conditions inside an organism or cell, despite changes in its environment.
• Water is removed and returned to the body
References
• Glencoe Life Science
• UnitedStreaming.com
• Adam.com