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Slide 1
ENERGY IN FOOD Enzymes and P H Digestive System 1
Slide 2
Organisms must obtain energy to carry out life processes Amount
of energy in food is measured in Calories Food also contains raw
materials (nutrients) used to build/repair body tissues 2
Slide 3
Nutrients supplied by food: 1. Water 2. Carbohydrates 3. Lipids
4. Proteins 5. Vitamins 6. Minerals 3
Slide 4
Breaks up food physically & chemically Stores food for a
short time Absorbs digested nutrients and passes them into
circulatory system Stores & eliminates undigested materials
from body 4
Slide 5
Types of digestion: 1. Mechanical physical breakdown of food by
non-chemical means 2. Chemical the use of enzymes & other
chemicals to break down food 5
Slide 6
Consumers must be able to break down food into molecules that
can be absorbed & used by cells In many multicellular
organisms, this is accomplished by a digestive system 6
Slide 7
Enzyme specialized proteins that act as biological catalysts
Catalyst substance that speeds up chemical reactions & remains
unchanged by the reaction All the activities of living things are
controlled by chemical reactions Without enzymes, these reactions
would not happen and the organism would die 7
Slide 8
Activation energy amount of energy needed to get a chemical
reaction started Chemical reaction the breaking down and/or forming
of new compounds 8
Slide 9
Are: a 3-dimentional protein Have: a specific area that
attaches to the chemical compound undergoing a change (active site)
Fit: like a puzzle piece to one type of compound (substrate) 9
Slide 10
Need: specific pH range Require: constant body temperature to
work correctly 10
Slide 11
When the enzyme bids with its specific substrate, changes occur
in the enzyme at the active site This change is called induced fit
and it enhances the ability of the enzyme to break down the
substrate 11
Slide 12
Denature a change in the shape of an enzyme; caused by change
in pH or fever If the enzyme is missing or denatured, the reaction
cannot happen Example: lactose intolerance 12
Slide 13
Competitive: Chemicals that resemble the enzymes normal
substrate Compete with substrate Allosteric Chemicals that bond to
a another part of the enzyme Changes shape of active site 13
Inhibitors keep something from working correctly
Slide 14
Pathway of the Digestion 14
Slide 15
Digestion begins in the mouth with: 1. Mechanical teeth and
tongue chop/mix food 2. Chemical salivary glands add enzyme amylase
to break down starches into simple sugars 15
Slide 16
Food moves into pharynx at back of throat; opening for 2 tubes
that lead to 2 systems 1. Esophagus digestive 2. Trachea
respiratory Epiglottis flap of tissue that covers opening not being
used 16
Slide 17
Peristalsis one way movement of materials through digestive
system; controlled by smooth muscle contraction Food moves down
esophagus into stomach: 1. Has a pH of 2 (hydrochloric acid) 2.
Secretes enzyme pepsin (acts on proteins) 3. Mechanical &
physical digestion 17
Slide 18
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Slide 19
AAfter ~2 hours, food leaves stomach and enters small
intestine: 1. 7 m long 2.5 cm diameter 2. Multiple enzymes secreted
to break down lipids and nucleic acids 3. Other enzymes used to
complete break down of carbs and proteins 4. Most absorption of
nutrients occurs 19
Slide 20
Anatomy inside of small intestine: Villi fingerlike projections
that absorb nutrients from small intestine 20
Slide 21
Accessory organs of small intestine: 1. Pancreas secretes
enzymes that work on carbs, protein and lipids; helps regulate
blood sugar; also secretes sodium bicarbonate that neutralizes
stomach acid 2. Liver produces bile to dissolve fats 3. Gall
bladder stores bile 21
Slide 22
Accessory organs of digestive system: 22
Slide 23
After 4-6 hours what is left of your food enters large
intestine: 1. ~1.5 m long 6 cm diameter 2. 3 sections cecum, colon
& rectum 3. Absorbs water and salts 4. Colonies of E.coli break
down rest of undigested material and produce Vitamin K (needed for
blood clotting) 5. Solid waste is stored in rectum & excreted
though anus 23