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Nutrition - the ability of an organism
to obtain and use food for
metabolism
Organisms can be:
1)
Autotrophic - make their own food
Example:
plants
2) Heterotrophic - can not make
their own food
Example:
Animals
Nutrients – materials an
organism needs for energy,
growth, repair, and maintenance.
Nutrients include:
1) carbohydrates
2) fats (lipids)
3) proteins
5) minerals
4) vitamins
6) water
The following three nutrients must be
broken down into their “building blocks”:
Carbohydrates - must be broken down
into sugars
Proteins - must be broken down
into amino acids
Lipids - must be broken down
into fatty acids and
glycerol molecules
1) The Mouth
• Where digestion
begins
• Site of both
mechanical
digestion and
chemical digestion
of food
1) Teeth and Tongue
- crush food; break
food into smaller
pieces (mechanical
digestion)
Mechanical breakdown
of food increases
surface area (makes
The tongue also
more area for
mixes saliva with
enzymes to work)
food
2) Salivary glands - produce saliva
a) Saliva
lubricates food
b) Saliva contains
the enzyme amylase
Amylase breaks down starch into
sugar molecules (chemical digestion)
Epiglottis and Esophagus
1) Epiglottis Small flap of tissue
that closes of the
trachea (windpipe)
when swallowing to
keep food out of the
lungs
• breathing momentarily stops when you
swallow
1) Esophagus muscular tube that
takes food from the
mouth to the stomach
Peristalsis a series of muscular
contractions that
push food forwards
Stomach
1) Stomach - Thick walled muscular
sac that stores and
digests food, turning it
into chyme (a soupy
liquid)
• site of both
chemical and
mechanical digestion
• contracts to mix food
(mechanical digestion)
• secretes hydrochloric
acid (HCl) and the
enzyme pepsin (chemical
digestion)
• pepsin breaks down
proteins into chains of
amino acids
• secretes mucus to
protect itself
Small Intestine
1) Small intestine the place where
nutrients are
absorbed, and where
most of the chemical
digestion occurs (by
enzymes)
• the longest part of the
digestive system (24 feet)
• nutrients get absorbed into the villi
of the small intestine
• contains small microscopic villi that
increase surface area (provides more
area for absorption)
The Villi of the Small
Intestines
• most of the chemical digestion occurs
in the small intestine
• enzymes for chemical digestion are
produced by the pancreas
Pancreas -
secretes digestive
enzymes which are
secreted into the
duodenum of the small
intestine
Pancreatic Enzymes
Include:
1) Intestinal protease -
breaks proteins down into amino acids
2) Intestinal lipase -
breaks fats down into fatty acids and
glycerol
3) Intestinal amylase -
breaks starch down into simple sugars
Liver - produces bile which breaks
down fat into smaller pieces
These are a few
of my LEAST
favorite things.
Gall bladder stores bile for delivery into the small
intestine (duodenum)
The liver and the pancreas
are accessory organs of the
digestive system; food does
not pass through them!
liver
pancreas
gall bladder
5) Large Intestine • absorbs the water in food
• absorbs vitamins that are produced
by intestinal bacteria
Rectum last part of the large
intestine that stores feces
to be removed through the
anus
V. DISEASES
• ULCERS- Lesions in the lining of the stomach
•
PancreaITIS- Inflammation of the pancreas
• AppendicITIS- Inflammation of the appendix
• Constipation- Too much water is being
reabsorbed by the large intestine
• Diarrhea- Too little water is being reabsorbed by the large intestine.
• Gallstones- Fat deposits inside the gallbladder can cause the
gallbladder ducts to be blocked.
pancreatitis
appendicitis
ulcers