Download Mechanical and Chemical digestion

Digestive System
breakdown of food into
materials the body can use
http://highered. rmcgrawhill.com/sites/0072495855/student_view0/chapte26/animation__organs_of_digestion.html
3 major types of nutrients:
 Fats: Store energy for future use and build
cell membranes
 Proteins: Made of amino acids. Act as
enzymes and build tissues, hair, bones,
muscles.
 Carbohydrates: Used for quick energy for
the body Ex. Complex starch, simple sugar
Digestion... So materials can move
into the bloodstream!
 Mechanical... physical
crushing/smashing of food
into smaller pieces
 Chemical ... done by
enzymes (proteins) food is
changed into new materials
3
Mouth: *Begins digestion of carbs
 Mechanical & Chemical digestion
 Mech -ALL food crushed by teeth
 Chem - (amylase, an enzyme in saliva) breaks down
complex carbohydrates (starches) into simple sugars


Action of amylase
http://www.indiana.edu/~oso/animations/amylase.html
Esophagus
Tube from pharynx
 stomach
 Peristalsis (wavelike muscular
motion) pushes food through the
digestive tract. http://www.lionden.info/peristalsis.htm

2 valves or sphincters (rings of muscle) keep the bolus of food moving in
the correct direction on either side of the stomach!
Stomach-Muscular Sack
lined with mucus to protect it from acids!
 Mechanical and Chemical digestion
 Mechanical- muscular churning breaks food into
smaller pieces > soupy mixture called chyme
 Chemical- Gastric Juices made of

Pepsin and hydrochloric acid


http://yucky.discovery.com/flash/body/yuckystuff/gurgle/js.index.html
*Breakdown of proteins to amino
acids begins here and bacteria are killed!
Extra organs...
Pancreas, liver, & gallbladder
 Not part of the digestive
tract....food does not touch them ...
but they aid digestion!
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Small intestine
 MOST DIGESTION HAPPENS in the
Duodenum: the first 25cm of the Small Intestine
 ENZYMES ENTER…
 Pancreatic juice from pancreas - neutralizes
stomach acid and finishes the breakdown of
carbs, proteins, and fats.
 Bile starts the break down of fats. (This is made
by liver / stored in gall bladder)

Fats must be broken down by both because they are too large to
be absorbed through the villi. http://www.zerobio.com/secretin_flash.htm
Also in the Small Intestine…
 Fingerlike villi absorb nutrients into the
bloodstream. This occurs through Diffusion: The
movement of materials from high concentration
to low. Easy! Passive! No energy needed!
 Some of the nutrients go into cells and some
are stored in the liver.
A.
B.
C.
D.
E.
Small Intestine shape…
 Which of these is the correct form of the
small intestine?
Why does the small intestine have to have this shape?
 Form A- the microvilli increase the surface
area to slow the food passage and allow
nutrients to diffuse into the bloodstream.
 Form B- the food would pass through too
quickly and not enough nutrients would be
able to be absorbed to keep us alive.
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Large Intestine - Shorter but wider
 Water is reabsorbed into the
bloodstream by diffusion!
 Rectum – Solid waste compacted and stored
until it leaves through the anus...opening to the
outside of body
 Organize your organs

Where will I go song …

Lets digest something
http://www.medtropolis.com/VBody.asp
www.youtube.com/watch?v=OYWVbt6t2mw
http://kitses.com/animation/swfs/digestion.swf