Herbivores and Carnivores

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Herbivores and Carnivores

• By Claire J, Claire E, Robyn and Ian

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Carnivores Teeth

• The top and bottom canines thrust past each other
  as the jaw is closed, allowing the dog to pierce
  the body of its prey
• The premolars and molars and molars have sharp
  edges and are known as carnassial teeth.

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Chewing food

• Dogs dont chew their food, they keep it in their
  mouth long enough to chop it into small pieces to
  be swallowed.
• As meat doesnt contain starch, amylase doesnt
  need to be secreted and no chemical digestion
  happens in the mouth.
• Dogs stomachs contain even more acids than humans
  so they can eat rotten food without harm

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Digestion in dogs

• As in humans, pepsin in the stomach breaks down
  proteins
• Dogs food contains no cell walls so it is easy
  for proteases and lipases to digest their plasma
  membrane and cytoplasm

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Herbivores

• Cows are adapted to feed on a diet of green
  plants.
• The food that a cow eats is made up of cells
  surrounded by cellulose cell walls. No mammal is
  able to make an enzyme to digest cellulose.

• The energy value in plant food is in the
  cellulose molecules themselves.

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Cow teeth

• The cow has no canine teeth, just a gap called a
  Diastema. This enables the long flexible tongue
  to move grass around in the mouth so it can be
  thoroughly chewed from all angles.
• The chewing is done by premolars and molars. The
  molars have broad surfaces with ridges and cusps.
  The ridges on the upper jaw fit into the cusps of
  the lower jaw.
• Grass lying between these teeth is ground
  thoroughly as the cows jaws move from side to
  side while it chews.
• The cow does have incisors on its lower jaw,
  they are shaped like chisels and point forward.
  It uses these to tear off grass, along with using
  its tongue.

• Cows teeth grow continually as the roots of a
  cows teeth remain open, allowing blood to enter
  the teeth and supply the living cells with oxygen
  and nutrients.

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Cow stomach

• Only the abomasum is the equivalent of the
  stomach of a human or dog.
• This structure has evolved because it helps the
  cows get nutrients from plant material

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Chambers of the stomach

• Inside the largest chamber the rumen, there is a
  community of anaerobic micro organisms. They
  produce enzymes which break down cellulose to
  celloboise and glucose.
• Other enzymes convert these sugars to fatty acids
  releasing carbon dioxide and methane as they do
  so.

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• The carbon dioxide and methane go up the
  oesophagus and the fatty acids are absorbed
  through the walls of the rumen.
• Most tissues in cows are adapted to use fatty
  acids as their main respiratory substrate.
• Material from the rumen and reticulum pass back
  up the oesophagus into the mouth where they are
  chewed before being re swallowed.

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• Bacterial proteins are digested to amino acids in
  the abomasum and absorbed by the cow.
• Some of the amino acids make urea which is used
  so that an internal nitrogen cycle takes place
  via the salivary glands, saliva, stomach, blood
  and liver.
• Many cattle feeds contain urea to maximise the
  production of proteins in the rumen.