Let the fun begin
Yeah
22-3 Your Digestive System
-What organs make up your
digestive system??
-What is the path that food
Travels in your body??
Digestion
• Process of breaking down food into small
molecules that can be used for energy
• Not all food is used for energy.
Mechanical vs. Chemical Digestion
• Mechanical= food is broken down into smaller
pieces
– Done in the mouth and stomach
• Chemical = large molecules are broken down into
smaller molecules through changes by different
chemicals
– Molecules will be absorbed after this
– Found in mouth, stomach, + small intestine
• Both of these are used to release energy for the
body
• Major organs for this process are:
– Mouth
– Esophagus
– Stomach
– Small Intestine
– Large Intestine
– Rectum
– Anus
Your Mouth
• JOB- food is cut into smaller pieces
• mechanical and chemical digestion occurs
here.
Esophagus
• JOB- connect mouth and stomach
• Basically is a long tube (25 cm) that connects
the stomach to the mouth.
• Peristalsis– waves of contractions by smooth muscles, move
the food through the esophagus.
Stomach
• JOB= Food is turned into a soup (chyme)
• Mechanical (turns food)
• Chemical digestion (enzymes and acid) occurs
• Changes shape- when empty- is a long tube
(hotdog/sausage), when full- expands in size.
• Has Stomach Acid
– Is very acidic- pH = 9, is Hydrochloric acid-
– would eat away your stomach, but the
stomach has lining to not let happen
• Food stays here for about 4 hrs.
Small Intestine
• JOB = Food is absorbed here
• Is very long (4m to 7m)
• Pancreas, liver, and gallbladder release enzymes
into the small intestine
• Inside of the small intestine has many ridges
and folds= villi
– This allows the food to be absorbed by the
blood
Large Intestine
• Job= to absorb water from the chyme,
causing chyme to turn to a solid form
• Chyme may stay in the large intestine up to 3
days to get the job done
Rectum + Anus
• Rectum– Waste is stored here temporarily tell expelled
• Anus– Waste leaves the body here
Minor Organs
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•
•
•
•
•
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Appendix
Liver
Pancreas
Gall Bladder
Teeth
Salivary Glands
Tongue
• Teeth
– Cut/Tear food into smaller piece
• Salivary Glands
– Make and store saliva
• Tongue
– Moves the food around and helps a person talk
• Liver
– Makes bile
• Gall Bladder
– Stores Bile
– Found hidden in the liver
• Pancreas
– Releases juices into the small intestine to breakdown
and help food be absorbed
– Hidden behind your stomach
• Appendix
– Stores bacteria
– Located off the large intestine
What are Enzymes?
What is the role of Enzymes in our
body??
Can anyone name a few examples of
enzymes in the body.
Enzymes
• These are molecules that speed up
reactions in our body
• Can reduce amount of energy needed or
provide a place for the reaction to occur
• Enzymes also help build molecules (besides
just breaking them down)
– Used in blood clots
– Found in Muscle and nervous systems
• Humans couldn’t exist if they didn’t have
enzymes.
• Saliva– has amylase• this starts the break down carbohydrates
• Stomach– has pepsin• this starts the break down of proteins
Enzymes
-Insulin-Released by the pancreas,
-Allows glucose to be absorbed in the blood
• Bile
– Released by gallbladder
– helps breakdown fats
Food Absorption
• Peristalsis helps food continue to move
throughout the digestive tract
• Food molecules will start to move into the
bloodstream by diffusion, osmosis, and
active transportation
• Once in the bloodstream they will go
throughout the body- giving it energy
Good Bacteria in the Body
• Bacteria are heavily found in the large
intestine.
• They break down cellulose (carbohydrate
found in plants)
– releasing several vit. and minerals
• Bacteria and humans have a mutualism
relationship
The End