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Digestion
Joanna
George-Johnson, Contributor
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| The
look on this Seaforth High School student's face tells he knows he is being watched.
- Photo by Oliver Wright | Digestion
is the breaking down of food into smaller components so it can be of use to the
organism. Digestion
occurs in two ways: 1)
Mechanical digestion and
2)
Chemical digestion Mechanical
digestion This
process is a physical breakdown of food. It happens first in the mouth by the
teeth where the food is crushed into smaller pieces. It also takes place in the
small intestines where bile breaks up fat globules into smaller droplets. Essentially,
mechanical digestion involves no enzymes. It provides a larger surface area for
the enzymes in chemical digestion to work on. Mechanical digestion NEVER leads
to a breakdown to the molecular level. Q
What are the four types of teeth you will mainly find in mammals, and state their
function. See
answers below:
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| The
structure of the tooth. | A
human adult has 32 teeth called permanent teeth. These start to grow when you
are about five-six years old. They replace your milk teeth. You
only have two sets of teeth in your life - take great care of them. The
general structure of the tooth consists of an exposed crown and a root, buried
in the gum and jaw. The crown is usually at least partly covered by an outer layer
of an especially hard substance, related to bone, called enamel. Beneath the enamel
is an intermediate layer of material called dentine, which is also similar to
bone and is not nearly as hard as enamel. It surrounds an inner pulp cavity which
serves as blood and nerve supply for the tooth. Blood
vessels and nerves reach the pulp cavity through a channel, the root canal that
penetrates the root. Problems
with Teeth Many
tiny organisms called bacteria tend to reside on our teeth. Our mouth is a great
habitat for these organisms. The reason is that our mouths are warm and dark,
have very little oxygen (these bacteria are anaerobic), and there is food for
the bacteria from sticky foods we eat remaining on our teeth. When the bacteria
feed, they excrete a very acidic substance. Thus, the billions of bacteria residing
on our teeth build up the acid in our mouths, which in turn weakens the enamel
of the teeth. What happens is that the tooth begins to decay and what is known
as dental caries develop. One could loose their tooth from this problem. Tooth
decay may be prevented by carrying out simple dental hygiene practices. This includes
brushing the teeth regularly, using a fluoride toothpaste, flossing and regular
use of mouthwash. | Types
of teeth | Function | Location | | Incisors | used
for cutting and biting off pieces of food | chisel-shaped
teeth in front of the mouth | | Canines | used
for biting and tearing off pieces of food | pointed
teeth to the side of the mouth | | Premolars | these
are the cheek teeth and are used for the crushing and chewing of food | found
to the back of mouth, with large rouged surfaces |
| Action | Effect | Brushing
Flossing | Removes
the plaque build-up from the teeth surface.
Removes the plaque build-up from
between the teeth and places that may be difficult for the brush to reach. | Fluoride
toothpaste | Toothpaste
does more than freshens breath. The fluoride in it toughens the enamel, making
it harder for the acid to decay the tooth. | | Mouthwash | Most
mouthwashes are alkaline in nature. Thus, use of this product will neutralise
the acid and, therefore, make it inert towards the enamel. |
Questions
1.
After careful study, draw a simple diagram of the cross section of a typical tooth
label and annotate the diagram. 2.
Churning is the process that takes place in the stomach where the food is mixed
and stirred to a soup- like consistency. State what type of digestion this is
and why. 3.
Design a product to help prevent tooth decay. 4.
Explain why the greatest damage of teeth happens at night? Joanna
George-Johnson teaches at Ardenne High School.
Email: Masterbio@gmail.com.
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