Transcript The Digestion System

The Digestion
System
Ch 38-2 Guide
Mechanical &
Chemical Breakdown
Of Food for energy
I 1) Mouth:
Mechanically
breaks up food
Chemically digests
 Carbohydrates
 Basic pH
 Enzyme amylase
from salivary
glands
Wets & forms
“bolus”
Esophagus
Bolus
movement to
stomach by
peristalsis
 (see video)

2. Stomach
Mechanically churns
Stores food
Chemically digests
 Acid pH
 Proteins
Enzyme Pepsin
Mucus Lining prevents
digestion of itself !
3. Small Intestine
Absorption
of food
Digestion of
 Lipids (fats)
 Carbohydrates
Uses Lipase &
Amylase from
the pancreas
4. Large Intestine
 Absorbs
water &
vitamins
 No Digestion
 Eliminates
wastes
Barium Enema: window to the intestines:
5. Salivary Glands:
 Makes
the
salivary juices
 Contains
amylase
enzymes
 Basic pH
 For the
digestion of
carbohydrates
6 Liver:. Makes bile & Stores sugar as glycogen
No food passes through the liver
No digestion takes place in the liver
Gall Bladder stores bile
7.Gall Bladder: Stores bile made by
the liver
 Bile
emulsifies
fats
 Makes them
water soluble
 In small
intestine
No food passes through the gall bladder
No digestion takes place in the gall bladder
Carter’s Little Liver Pills: cure=all
 Liver
also
cleanses the
blood
 Carter’s pills
claimed to cure
constipation,
headaches, skin
problems???
8.Pancreas makes digestive juices:
Enzymes & Acids or bases
No Digestion in the Pancreas !
No food passes through here
9. Appendix: vestigial organ
Types of Digestion:
Intracellular:
 Inside a cell
 Food vacuoles
 Small particles
 Examples:
Amoeba,
Paramecium
Extracellular:
 In a sack or
tube
 Larger food
 Then absorbed
into a cell
 Humans
Digestion Products:
Proteins



 Carbo-hydrates


Lipids




Amino acids subunits
Muscle,enzymes,Hb
Last use for food
Simple sugar (glucose)
Quick energy food
1st used
Fatty acids & glycerol
Long term food,
insulation,protection
2nd used for food
Digestion:
Is
 Breaking down food
 physically & chemically
For
 The purpose of distributing small
water soluble particles to the cells
for energy
Homeostasis
 Maintaining
balance
 “homo”=same
 “stasis”=state
 By constant
adjustments
 For survival
pH= Proper acid or base levels
 Basic
=>7
 Digestion of
carbohydrates
& lipids
 Acidic= < 7
 Digestion of
proteins in the
stomach
pH 2
7
8
10
12
Properties of Enzymes
 Proteins
 Catalysts
 Speed
reactions
 Work fast
 Denature at high
temp
Enzyme-Substrate complex
Active site =
where the
substrate
( reaction
molecule)
connects to
enzyme
Active Site
Substrate
Enzyme
Lock & Key Model
One
Substrate
enzyme
for every
substrate
unique fit
Enzyme
Enzymes are pH specific
 Different
enzymes
 Different body areas
 Different optimum pH
Stomach= acid pH
Uses PEPSIN
Mouth= basic pH
Uses AMYLASE
100
90
80
70
Blood
60
50
40
30
20
10
Stomach
Mouth
0
pH 2
pH 4
Ph 6
pH 8
Bile: Made in Liver Stored in
Gall Bladder
 Emulsifies
fats
 Makes them
water soluble
 In small
intestine
Villi: Small intestine absorb food
Many “finger-like” villi
maximize surface area
8.Peristalsis:
 Contractions
of the
Digestive
system
 Moves food
down
 Controlled by
the autonomic
nervous
system
Control of Digestion by the Nervous System