Transcript digest starch - Warren County Schools

ORGANIC
COMPOUNDS





Vocabulary
1/5 – monomer
1/6 – dehydration
reaction
1/9 – chitin
1/12 - nucleotide
I can……
1/5 – Explain why carbon is
unique.
1/6 – Explain why every
macromolecule is different.
1/8 – List parts of an amino acid.
1/12 – Name the 3 parts of a
nucleotide

Decide which macromolecule
each represent.
Organic Compounds
Organic Compounds: Compounds that contain
carbon and hydrogen bonding with other
atoms that build your cells and provide you
energy.
*Carbon is the backbone of life!!!
Organic Compounds

Contain the
element carbon
and hydrogen.
 Carbon is found in
things that are or
once were living.
 Carbon atoms share
electrons to form
covalent bonds.
CARBON
Why is carbon the backbone of life?
Why is it special?
1. Carbon has 4 electrons in its outer shell.
To satisfy the octet rule, it needs to share
4 other electrons.
2. This means that each carbon atom forms
4 covalent bonds with elements like H, O,
P, & N!!
What Builds This Object?
Find the Macromolecules!!!!
MACROMOLECULES
Another level in the hierarchy
of biological organization is
reached when small organic
molecules are joined
together
Macromolecules – Building of Cells
Carbohydrates
 Lipids
 Proteins
 Nucleic Acids


What Builds These Macromolecules?
Macromolecule
Large molecules that make up living things. They are
large chains of smaller molecules or compounds. It
means “giant molecule”.
Organic Compounds

Organic compounds are composed of
hundreds to thousands of individual
molecules.
– The single molecules in a polymer are
called monomers.
Macromolecules are BIG
molecules and are the building
blocks of cells. Macromolecules
are built by combining many single
units, or monomers, into larger
units, called polymers. All cells are
composed of the four general types
of macromolecules, although each
type can serve a cell in different
ways.
Most macromolecules are polymers,
built from monomers
 Three of the classes of life’s organic
molecules are polymers
– Carbohydrates
– Proteins
– Nucleic acids
– LIPIDS do not have monomers!!!
Monomers
All macro organic molecules are made up of
smaller subunits called monomers. This is just
the base unit that repeats over and again. The
monomers can be identical or different.
Polymers
Organic macromolecules are made up of
repeating monomers.These chains of monomers
are called polymers.
Organic Compounds

The long molecules formed by repeating
patterns of monomers are called
polymers.
Condensation(dehydration) Reaction
A condensation reaction is the removal of water to
connect monomers. The large chain is then bonded
to form a polymer.
Hydrolysis

Process of adding water to break apart
polymers.
What makes each compound
different?
ITS
FUNCTIONAL
GROUP!!!!!
Functional Groups

Functional group: an atom or group of
atoms within a molecule that will determine
how the compound will react.
THEY DETERMINE THE CHARACTERISTIC
OF THE MACROMOLECULE!!!!
 Functional groups are important for three
reason; they are
1. Determine compounds function
2. the sites of characteristic chemical reactions(polar
or nonpolar)
3. the basis for naming organic compounds
Functional Groups

Most of the useful behavior of organic
compounds comes from functional groups
attached to the carbons. A functional group is
a special cluster of atoms that performs a
useful function.
Hydroxyl group - alcohols
contain an -OH (hydroxyl) group
 Carbs
HH
-C-O-H
H-C-C-O-H

:
:
Functional
group
HH
Ethanol
(an alcohol)
Hydroxyl Group
OH
Functional Groups
Carbonyl Group
contain a carbonyl (C=O) group
 Carbon double bonded to oxygen
 Sugars or carbohydrates

O
O
C H
CH3 -C-H
Functional Acetaldehyde
group
(an aldehyde)
O
O
C
CH3 -C-CH3
Functional Acetone
group
(a ketone)
Carboxyl Group
contain a carboxyl (-COOH) group
 Acids because gives up H+
ions(vinegar)
 Amino Acids

O
: O:
:
Functional
group
CH3 -C-O-H
:
C O H
or CH3 COOH or CH3 CO2 H
Acetic acid
(a carboxylic acid )
Carboxyl Group
COOH
Functional Groups
Amino Group
Nitrogen bonded to two hydrogens and
carbon skeleton.
Proteins or amino acids
CH 3 N H
CH 3
:
H
:
:
CH 3 N H
CH 3 N CH 3
CH 3
Amine Group
N-H2
Functional Groups
Phosphate Group
Phosphorus atom bonded to four oxygen
atoms.
ATP energy and DNA
Methyl Group
Carbon bonded to three hydrogens
 Part of DNA – nucleic acid

4 Groups of Organic Compounds
1.
2.
3.
4.
Carbohydrates
Proteins
Lipids
Nucleic Acids
Carbohydrates  The ratio of the

Make up sugars and
starches
 Contain a hydroxyl
(OH) group
 Contain atoms of
carbon, hydrogen,
and oxygen.
 Monomer monosaccharides
atoms is 1 C : 2 H :
1O
 Provide energy to
the cells.
 Dissolve in water
(hydrophilic)
 Polymer polysaccharides
Carbohydrates
*Carbohydrates are composed of C, H, and O.
*Ratio: 1C:2H:1O
*Function:
1. Main source of SHORT term energy.
2. Plants and some animals use it for
structural purposes.
Types of Carbohydrates

Carbohydrates are classified according
to size.
• One sugar is a monosaccharide
(monomer).
• Two sugars make a disaccharide.
• Many sugar molecules linked together
form a polysaccharide (polymer).
Carbohydrates
Carbohydrates are made up of monomers called
monosaccharides.
Examples of monosaccharides:
1.glucose: plant produce during photosynthesis
2.Galactose: found in milk and diary
3.Fructose: sugar in many fruits
GLUCOSE!
Fructose
Monosaccharide
Milk Sugar
Fruit Sugar
Types of Carbs
Carbohydrates
Two monomers of monosaccharides together are
called disaccharides. Sucrose is a examples of a
disaccharide.
MALTOSE
Carbohydrates
Examples of polysacchrides:
1.glycogen:stored energy
2.Starch: plant stored energy
3.Cellulose: cell walls We can not digest cellulose for
energy. Our bodies use it for fiber. Herbivores have
enzymes and microorganisms to help digest the
cellulose. Cows have 4 stomachs.
4.Chitin: exoskeleton of insects and cell walls of
fungus
STARCH!!!
Polysaccharide
Starch is straight chain of glucose molecules with few side
branches.
Types of Carbs
Look at the difference between these two. Think about how
Plants use cellulose and animals use starch. They are shaped
this way because of their use. Cellulose – straight chains Starch
Branched.
Lipids

Class of
 Glycerol contains
macromolecules that
the hydroxyl (OH)
are hydrophobic
group.
 The three types of
 Fatty acids contain
lipids are fats, oils,
the carboxyl
and waxes.
(COOH) group.
 Contain carbon,
hydrogen, and
oxygen
 Typically contain two
monomers –
glycerol and fatty
acids
Lipids
DEFINE: Large groups of organic compounds
not soluble in water.
Functions:
1.Store energy for LONG term.
2.Waterproof covering
3.Protection
4.Steroids – hormones
5.Warmth
6.Cell membranes
Structure of lipid – Glycerol head
and fatty acid chain
4 main categories of Lipids
1.
2.
3.
4.
Fats & oils
phosolipids
Waxes
steroids
FAT!!!
No Monomer for LIPIDS!!!
Lipids
Saturated & Unsaturated Fats
Lipids
Saturated vs. Unsaturated
Saturated means that all the carbon bonds are taken.
They are solid at room temperature and bad for you.
Unsaturated means that there is at least one double
bond with the carbon. They are liquid at room temp.
and are better for you.
Lipids
All lipids are not soluble in water. That is why
they are placed together.
Saturated makes fats
Unsaturated makes oils
Which ones are
Saturated??
Steroid - Cholesterol
Phospholipid

Found in cell
membranes
– Head is the
phosphate group.
• Hydrophilic
– Tails are the fatty
acids.
• Hydrophobic
Proteins
Composed of carbon, hydrogen,
nitrogen, and oxygen
 Contain amine (NH2) and carboxyl
(COOH) groups
 MONOMER – amino acids
 POLYMER – polypeptide or protein

Functions of Proteins







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
Some important functions of proteins are
listed below.
enzymes (chemical reactions)
hormones
storage (egg whites of birds, reptiles; seeds)
transport (hemoglobin)
contractile (muscle)
protective (antibodies)
membrane proteins (receptors, membrane
transport, antigens)
structural
toxins (botulism, diphtheria)
Proteins
Macromolecules that contain N, C, O and H.
Functions:
1.Rate of cell processes.
2.Cellular structures
3.Controls substances in and out of cell.
4.Fight disease.
1.
2.
3.
4.
5.
6.
7.
Examples of Proteins In Body
Hemoglobin in blood
Collagen
Enzymes
Insulin
Muscles
Antibodies
Cell Membrane
Foods with Protein
Eggs, milk, meat, beans, peanut
butter, yogurt, soybeans, cheese,
ETC
Proteins and Amino acid formation
Proteins are made up of monomers of amino
acids help together by peptide bonds.
3 parts of an amino acid:
1.Amino group
2.Carboxyl group
3.R group
Proteins(structure)
Long chains of amino acids are connected
by peptide bonds which are called polypeptides.
Proteins(examples of R-Groups)
There are 20 different amino acids found in
nature.Different proteins are determined by the
type of amino acids connected together. All
amino acids are the same except for the R-group.
The R-group gives the amino acids different
properties.
Amino Acids
Function of Proteins
R – Group
Nucleic acids
Macromolecules containing the elements H, N,
C, O and P.
Made up of monomers of nucleotides.
Nucleotides
3 parts of a nucleotide
1.Phosphate
2.Deoxyribose sugar
3.Nitrogen base
4 Nitrogen Bases
1.
2.
3.
4.
Adenine
Guanine
Cytosine
Thymine
Functions of a Nucleic Acids
1. Carry genetic material
2. Carries codes to make proteins
2 Examples of Nucleic Acids
1. RNA – ribonucleic acids
2. DNA – deoxyribosenucleic acid
Function of RNA
Function of RNA is to make proteins
from the code DNA carries.
1.
Organic
C ompound
C arbohydrate
C omposed of:
Examples
Function
C, H, O
Sugar
Starch
cellulose
Releases
energy for
cells
Organic
C ompound
Lipid
C omposed of:
Examples
Function
C, H, O
Fats
Oils
Waxes
Stores and
releases
MORE
energy for
cells
C ellmembranes are made oflipids
Nutrition & Digestion
Balanced Diet
Necessary to provide all elements and compound
to make new cells, provide energy, or essential
for life.
Elements become energy and new cells.
Metabolism – All the chemical reactions carried
on by the cell – protein synthesis, respiration,
DNA replication, etc.
Digestion

Food consists of what macromolecules?
– Carbohydrates, lipids, and proteins

Why is food chemically broken down?
– The macromolecules are too large to pass
through cell membranes
– The polymers must be broken down into
monomers, so that the organism can make
their own polymers
– ABSORPTION OCCURS IN SMLL
INTESTINES!!!!!
– LARGE INTESTINE REMOVES WASTES
Food Processing
Human digestive
system
Ingestion

Mouth
– mechanical digestion
• teeth
– breaking up food
– chemical digestion
• saliva
– amylase
» enzyme digests starch
– mucin
» slippery protein (mucus)
» protects soft lining of digestive system
» lubricates food for easier swallowing
– buffers
» neutralizes acid to prevent tooth decay
– anti-bacterial chemicals
» kill bacteria that enter mouth with food
mouth
break up food
digest starch
kill germs
moisten food
Mouth
 Chemical
and
mechanical
digestion.
 Food is chewed
(masticated)
mechanically.
 A bolus (lump) is
formed with saliva
and the tongue.
Swallowing (& not choking)
 Epiglottis
– flap of cartilage
– closes trachea (windpipe) when swallowing
– food travels down esophagus
 Peristalsis
– involuntary muscle contractions to move food along
Pharynx
 The
back of the
throat.
 Larynxpassage for air,
closes when we
swallow.
 Is approximately
15cm long.
Peristalsis

series of involuntary
wave-like muscle
contractions which
move food along the
digestive tract
Stomach
 Food
is temporarily
stored here.
 Gastric juices are
secreted.
 Has layers of
muscle that line the
inside.
 Mechanically and
chemically breaks
down food.
Stomach
Functions
– food storage
• can stretch to fit ~2L food
– disinfect food
• HCl = pH 2
– kills bacteria
– chemical digestion
• pepsin
– enzyme breaks down proteins
But the stomach is made out of protein!
What stops the stomach from digesting itself?
mucus secreted by stomach cells protects stomach
lining
mouth
break up food
digest starch
kill germs
moisten food
stomach
kills germs
break up food
digest proteins
store food
sphincter
sphincter
Gastric Juices
 Secreted
by the
stomach.
 Acidic (pH 1.5-2.5)
(HCl).
 Pepsin- an enzyme that
breaks down large
proteins into amino
acids.
 Food is further broken
down into a thin liquid
called chyme.
Accessory Organs
Pancreas
Gall
Bladder
Spleen
Gall bladder

Pouch structure located near the liver
which concentrates and stores bile

Bile duct – a long tube that carries BILE.
The top half of the common bile duct is
associated with the liver, while the bottom
half of the common bile duct is associated
with the pancreas, through which it passes
on its way to the intestine.
BILE

Bile emulsifies lipids (physically breaks
apart FATS)

Bile is a bitter, greenish-yellow alkaline
fluid, stored in the gallbladder between
meals and upon eating is discharged into
the duodenum where it aids the process of
digestion.
Pancreas

An organ which secretes both digestive
enzymes (exocrine) and hormones (endocrine)

** Pancreatic juice digests all major nutrient
types.

Nearly all digestion occurs in the small intestine
& all digestion is completed in the SI.
Pancreas

Digestive enzymes
– digest proteins
• trypsin, chymotrypsin
– digest starch
• amylase

Buffers
– neutralizes
acid from
stomach
Liver

Function
– produces bile
• bile stored in gallbladder until needed
• breaks up fats
– act like detergents to breakup fats
bile contains colors
from old red blood
cells collected in
liver =
iron in RBC rusts &
makes feces brown
mouth
break up food
digest starch
kill germs
moisten food
liver
produces bile
- stored in gall bladder
break up fats
pancreas
produces enzymes to
digest proteins & starch
stomach
kills germs
break up food
digest proteins
store food
Small Intestine

Most chemical
digestion takes place
here.
 Simple sugars and
proteins are absorbed
into the inner lining.
 Fatty acids and
glycerol go to lymphatic
system.
 Lined with villi, which
increase surface area for
absorption, one cell
thick.
Small intestine

Function
– chemical digestion
• major organ of digestion & absorption
– absorption through lining
• over 6 meters!
• small intestine has huge surface area = 300m2
(~size of tennis court)

Structure
– 3 sections
• duodenum = most digestion
• jejunum = absorption of nutrients & water
• ileum = absorption of nutrients & water
Duodenum

1st section of small intestines
– acid food from stomach
– mixes with digestive juices from:
 pancreas
 liver
 gall bladder
mouth
break up food
digest starch
kill germs
moisten food
pancreas
produces enzymes to
digest proteins & starch
stomach
kills germs
break up food
digest proteins
store food
Absorption in the SI

Much absorption is thought to occur directly through the wall
without the need for special adaptations

Almost 90% of our daily fluid intake is absorbed in the small
intestine.

Villi - increase the surface area of the small intestines, thus
providing better absorption of materials
Absorption by Small Intestines

Absorption through villi & microvilli
– finger-like projections
– increase surface area for absorption
VILLI
Large intestines
(colon)

Function
– re-absorb water
• use ~9 liters of water every
day in digestive juices
• > 90% of water reabsorbed
– not enough water absorbed
» diarrhea
– too much water absorbed
» constipation
Large Intestine
Solid materials pass
through the large
intestine.
 These are undigestible
solids (fibers).
 Water is absorbed.
 Vitamins K and B are
reabsorbed with the
water.
 Rectum- solid wastes
exit the body.

You’ve got company!

Living in the large intestine is a
community of helpful bacteria
– Escherichia coli (E. coli)
• produce vitamins
– vitamin K; B vitamins
• generate gases
– by-product of bacterial metabolism
– methane, hydrogen sulfide
Appendix
Vestigial organ
Rectum

Last section of colon
(large intestines)
– eliminate feces
• undigested materials
– extracellular waste
» mainly cellulose
from plants
» roughage or fiber
– masses of bacteria
Carb Digestion: Oral Cavity

At sight or smell of food, salivary
glands secrete saliva
– Glycoprotein protects & lubricates
lining of mouth
– Antibacterial agents
– Amylase to hydrolyze starch

Why do you chew your food?
– Easier to swallow
– Expose more surface area to
enzymes

Tongue pushes bolus to back of
oral cavity & into pharynx
Carbohydrates  )

.
 Monomer monosaccharides

Polymer polysaccharides
Carbohydrates
*Carbohydrates are composed of C, H, and O.
*Ratio: 1C:2H:1O
*Function:
1. Main source of SHORT term energy.
2. Plants and some animals use it for
structural purposes.
Types of Carbohydrates

Carbohydrates are classified according
to size.
• One sugar is a monosaccharide
(monomer).
• Two sugars make a disaccharide.
• Many sugar molecules linked together
form a polysaccharide (polymer).
Carbohydrates
Carbohydrates are made up of monomers called
monosaccharides.
Examples of monosaccharides:
1.glucose: plant produce during photosynthesis
2.Galactose: found in milk and diary
3.Fructose: sugar in many fruits
GLUCOSE!
Or
ganic
C ompound
C ar
bohydr
at
e
C omposed of:
E xampl
es
F unct
ion
C, H, O
Sugar
Starch
cellulose
Releases
energy for
cells
Breads, pasta, potatoes, corn,
sugars, lactose, etc.
Energy stored in bonds of carbs
Carbohydrates
Two monomers of monosaccharides together are
called disaccharides. Sucrose is a examples of a
disaccharide.
MALTOSE
Carbohydrates
Examples of polysacchrides:
1.glycogen:stored energy
2.Starch: plant stored energy
3.Cellulose: cell walls We can not digest cellulose for
energy. Our bodies use it for fiber. Herbivores have
enzymes and microorganisms to help digest the
cellulose. Cows have 4 stomachs.
4.Chitin: exoskeleton of insects and cell walls of
fungus
STARCH!!!
Carb Digestion
In stomach, the carb is mixed with HCl
acid to form chyme.
 Chyme leaves stomach and enter top
part of small intestines called the
duodenum.
 The polysaccharides are broken down
into monosaccharides and absorbed
into the SMALL INTESTINES wall.

Human Digestion: the tum tum

Why don’t we need to eat constantly?
– Besides breaking down food, the stomach stores food –
enough to satisfy our body for many hours

What prevents gastric juice from digesting away
the stomach lining?
– Pepsin, an enzyme which begins the chemical digestion
of protein, is secreted in the inactive form pepsinogen
• Protects the gastric gland cells
– Mucus helps protect the stomach lining from both pepsin
and acid
– However, the stomach lining must be replaced about
every 3 days
Carb Digestion
For carbs we do not have enzymes,
bacteria furthers the breakdown of
carbs so they can be absorbed.
 Fiber is need to needs to form wastes.
Helps to prevent constipation. We
cannot digest cellulose(plant sugar) so it
acts as fiber.

Human Digestion: large intestine


Colon absorbs water –approximately 90% of the
7 liters of fluid that enters the canal a day are
reclaimed (most in small intestine)
Remains of undigested food become more solid
as water is absorbed
– Feces
• Consists mainly of plant fibers and prokaryotes
• Diarrhea occurs when the colon is irritated and is less
effective at reclaiming water
• Constipation occurs when peristalsis moves the feces too
slowly
– Colon reabsorbs too much water and feces becomes too
compacted
» Diet low in plant fiber or lack of exercise
Human Digestion: small intestine

Capillaries that drain away from the villi
converge into larger blood vessels and
eventually into a main vessel that leads
directly to liver
Diabetes

Glucose cannot be absorbed into cells
because no insulin. Glucose builds up
in blood and no energy production.
Proteins
What is protein?

Protein is a complex structure containing carbon,
hydrogen, oxygen, and nitrogen, and in some
cases sulfur. These elements combine to form
amino acids.
Amino Acids
Two types:
1) Essential (9)
• Must be obtained from foods in the diet
2) Nonessential (11)
• May be formed in the body
What are some common foods that are
good sources of protein?

The Food Groups
– High
• Meat and meat substitutes (legumes)
• Milk
– Lower
• Starch
• Vegetable
• Fruit
• Fat
Figure 6.4
Protein Digestion
Chewed into piece in mouth.
 Digestion starts in stomach with
pepsin(enzyme)
 Continues into the small intestines with
enzyme proteases. Breakdown into
amino acids.
 Absorbed into small intestines wall.

Human Digestion: small intestine

Protein digestion
– Pancreas and duodenum secrete
hydrolytic enzymes that break
polymer into monomers (amino
acids)

Nucleic acid digestion
– Pancreas and duodenum secrete
hydrolytic enzymes which breakdown
DNA & RNA polymers into
• Nitrogenous bases, sugars, phosphates
Lipids

Class of
 ROLE: energy
macromolecules that  Cell membrane,
are hydrophobic
hormones, steroids,
 The three types of
lipids are fats, oils,
and waxes.
 Contain carbon,
hydrogen, and
oxygen
Lipids
DEFINE: Large groups of organic compounds
not soluble in water.
Functions:
1.Store energy for LONG term.
2.Waterproof covering
3.Protection
4.Steroids – hormones
5.Warmth
6.Cell membranes
4 main categories of Lipids
1.
2.
3.
4.
Fats & oils
phosolipids
Waxes
steroids
FAT!!!
No Monomer for LIPIDS!!!
Lipids
Lipids
Saturated vs. Unsaturated
Saturated means that all the carbon bonds are taken.
They are solid at room temperature and bad for you.
Unsaturated means that there is at least one double
bond with the carbon. They are liquid at room temp.
and are better for you.
Which ones are
Saturated??
Human Digestion: small intestine

Lipid digestion
– Lipids reach stomach almost
completely undigested
• Why?
– Fats are hydrophobic
– Bile salts from gallbladder coat tiny fat
droplets that keep them separated
from each other
• Why is the separation of fats into small
droplets beneficial for digestion?
– More surface area is exposed, which allows the
enzyme to breakdown the fats quickly
Lipid digestion
No lipid digestion except in small
intestines.
 Bile from liver digests it.
 Lipase enzyme that breaks down lipids.


Nutrition: Vitamins
If one eats a balanced diet, one does
not need to take vitamins
– Most serve as coenzymes or are parts of
coenzymes
– Used over and over again in metabolic
processes
– Deficiencies and excessive use can cause
serious problems
– Water-soluble vitamins are not harmful
as excess can pass in urine and feces
– Excessive fat-soluble vitamins are
deposited in fat and can have toxic
effects
Nutrition: Minerals
Must obtain minerals through
dietary sources
 Ex: calcium needed for normal
functioning of nerves and muscles
 Ex: phosphorous is an ingredient
of ATP and nucleic acids

Human Digestion
Nutrition
Process by which organisms obtain and utilize their
food.
There are two parts to Nutrition:
1. Ingestion- process of taking food into the
digestive system so that it may be
hydrolized or digested.
2. Digestion- the breakdown of food (either
chemically or mechanically) in order to
utilize nutrients
Types of Nutrients

Micronutrients- vitamins, minerals, & water

Macronutrients- proteins, lipids,
carbohydrates, etc…
Human digestive
system
GI (gastrointestinal) tract = alimentary canal
Ingestion

Mouth
– mechanical digestion
• teeth
– breaking up food
– chemical digestion
• saliva
– amylase
» enzyme digests starch
– mucin
» slippery protein (mucus)
» protects soft lining of digestive system
» lubricates food for easier swallowing
– buffers
» neutralizes acid to prevent tooth decay
– anti-bacterial chemicals
» kill bacteria that enter mouth with food
mouth
break up food
digest starch
kill germs
moisten food
Mouth
 Chemical
and
mechanical
digestion.
 Food is chewed
(masticated)
mechanically.
 A bolus (lump) is
formed with saliva
and the tongue.
Swallowing (& not choking)
 Epiglottis
– flap of cartilage
– closes trachea (windpipe) when swallowing
– food travels down esophagus
 Peristalsis
– involuntary muscle contractions to move food along
Pharynx
 The
back of the
throat.
 Larynxpassage for air,
closes when we
swallow.
 Is approximately
15cm long.
Digestive Glands
 Groups
of
specialized
secretory
cells.
 Found in the
lining of the
alimentary
canal or
accessory
organs.
Peristalsis

series of involuntary
wave-like muscle
contractions which
move food along the
digestive tract
Stomach
 Food
is temporarily
stored here.
 Gastric juices are
secreted.
 Has layers of
muscle that line the
inside.
 Mechanically and
chemically breaks
down food.
Stomach
Functions
– food storage
• can stretch to fit ~2L food
– disinfect food
• HCl = pH 2
– kills bacteria
– chemical digestion
• pepsin
– enzyme breaks down proteins
But the stomach is made out of protein!
What stops the stomach from digesting itself?
mucus secreted by stomach cells protects stomach
lining
mouth
break up food
digest starch
kill germs
moisten food
stomach
kills germs
break up food
digest proteins
store food
sphincter
sphincter
Gastric Juices
 Secreted
by the
stomach.
 Acidic (pH 1.5-2.5)
(HCl).
 Pepsin- an enzyme that
breaks down large
proteins into amino
acids.
 Food is further broken
down into a thin liquid
called chyme.
Accessory Organs
Pancreas
Gall
Bladder
Spleen
Gall bladder

Pouch structure located near the liver
which concentrates and stores bile

Bile duct – a long tube that carries BILE.
The top half of the common bile duct is
associated with the liver, while the bottom
half of the common bile duct is associated
with the pancreas, through which it passes
on its way to the intestine.
BILE

Bile emulsifies lipids (physically breaks
apart FATS)

Bile is a bitter, greenish-yellow alkaline
fluid, stored in the gallbladder between
meals and upon eating is discharged into
the duodenum where it aids the process of
digestion.
Pancreas

An organ which secretes both digestive
enzymes (exocrine) and hormones (endocrine)

** Pancreatic juice digests all major nutrient
types.

Nearly all digestion occurs in the small intestine
& all digestion is completed in the SI.
Pancreas

Digestive enzymes
– digest proteins
• trypsin, chymotrypsin
– digest starch
• amylase

Buffers
– neutralizes
acid from
stomach
Liver

Function
– produces bile
• bile stored in gallbladder until needed
• breaks up fats
– act like detergents to breakup fats
bile contains colors
from old red blood
cells collected in
liver =
iron in RBC rusts &
makes feces brown
mouth
break up food
digest starch
kill germs
moisten food
liver
produces bile
- stored in gall bladder
break up fats
pancreas
produces enzymes to
digest proteins & starch
stomach
kills germs
break up food
digest proteins
store food
Small Intestine

Most chemical
digestion takes place
here.
 Simple sugars and
proteins are absorbed
into the inner lining.
 Fatty acids and
glycerol go to lymphatic
system.
 Lined with villi, which
increase surface area for
absorption, one cell
thick.
Small intestine

Function
– chemical digestion
• major organ of digestion & absorption
– absorption through lining
• over 6 meters!
• small intestine has huge surface area = 300m2
(~size of tennis court)

Structure
– 3 sections
• duodenum = most digestion
• jejunum = absorption of nutrients & water
• ileum = absorption of nutrients & water
Duodenum

1st section of small intestines
– acid food from stomach
– mixes with digestive juices from:
 pancreas
 liver
 gall bladder
mouth
break up food
digest starch
kill germs
moisten food
pancreas
produces enzymes to
digest proteins & starch
stomach
kills germs
break up food
digest proteins
store food
Absorption in the SI

Much absorption is thought to occur directly through the wall
without the need for special adaptations

Almost 90% of our daily fluid intake is absorbed in the small
intestine.

Villi - increase the surface area of the small intestines, thus
providing better absorption of materials
Absorption by Small Intestines

Absorption through villi & microvilli
– finger-like projections
– increase surface area for absorption
VILLI
Large intestines
(colon)

Function
– re-absorb water
• use ~9 liters of water every
day in digestive juices
• > 90% of water reabsorbed
– not enough water absorbed
» diarrhea
– too much water absorbed
» constipation
Large Intestine
Solid materials pass
through the large
intestine.
 These are undigestible
solids (fibers).
 Water is absorbed.
 Vitamins K and B are
reabsorbed with the
water.
 Rectum- solid wastes
exit the body.

You’ve got company!

Living in the large intestine is a
community of helpful bacteria
– Escherichia coli (E. coli)
• produce vitamins
– vitamin K; B vitamins
• generate gases
– by-product of bacterial metabolism
– methane, hydrogen sulfide
Appendix
Vestigial organ
Rectum

Last section of colon
(large intestines)
– eliminate feces
• undigested materials
– extracellular waste
» mainly cellulose
from plants
» roughage or fiber
– masses of bacteria
Digestive Homeostasis Disorders

ULCERS – erosion of the surface of the
alimentary canal generally associated
with some kind of irritant
Digestive Homeostasis Disorders
CONSTIPATION – a
condition in which the
large intestine is emptied
with difficulty.
 Too much water is
reabsorbed
 and the solid waste
hardens

Digestive Homeostasis Disorders
DIARRHEA – a gastrointestinal
disturbance characterized by
decreased water absorption and
increased peristaltic activity of
the large intestine.
 This results in increased,
multiple, watery feces.
 This condition may result in
severe dehydration, especially in
infants

Digestive Homeostasis Disorders
APPENDICITIS – an inflammation of
the appendix due to infection
 Common treatment is removal of the
appendix via surgery

Digestive Homeostasis Disorders
GALLSTONES – an accumulation of
hardened cholesterol and/or calcium
deposits in the gallbladder
 Can either be “passed” (OUCH!!) or
surgically removed

Digestive Homeostasis Disorders



ANOREXIA NERVOSA - a psychological
condition where an individual thinks they
appear overweight and refuses to eat.
Weighs 85% or less than what is
developmentally expected for age and
height
Young girls do not begin to menstruate at
the appropriate age.
Digestive Homeostasis Disorders

HEART BURN – ACID from the
stomach backs up into the esophagus.
Let’s go to the Video!
Digestive System Cadaver
Travel Through the Digestive
System