[b][color=#4400ff]Heterotrophic nutrination

[/color][/b][youtube]http://www.youtube.com/watch?v=A7jKCfx-0Mo&feature=player_embedded[/youtube]


[b]Digestion[/b]: is the conversion of large food molecule or polymers (porteins starch and fats) into smaller ones or monomers (amino acids, glucose, fatty acids and glycerol) in a process catalyzed by enzymes

[b]The enzyme[/b]
It is a proteinic substance has the properties of a catalyst & it has a specific ability to activate particular chemical reaction

[b][color=#880000]Types of mechanisms of enzyme action[/color][/b]

Breaking down -

Building up -

[b][color=#884400]Properties of enzymes[/color][/b]

They are specific in their function -
The enzyme is still as it is at the end of the reaction -
Some enzymes may have a reversible effect -
Enzyme only accelerate’ the rate of the reaction until it reaches a case of equilibrium -
Some enzymes are secreted ‘by the cells in an inactive state -
Enzyme can be used over and over again -
the enzyme is affected by the temperature and PH -

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[b][color=#440000]The steps of digestion[/color][/b]

[b][u]Digestion in mouth [color=#440044]buccal digestion[/color][/u][/b]

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[b]In the oesophagus[/b]

The oesophagus has glands to secrete mucus only to help in swallow food

[b][u][color=#440044]Digestion in the stomach gastric digestion

[/color][/u][/b][youtube]http://www.youtube.com/watch?v=Q-n_Q0qKXzg&feature=player_embedded[/youtube]


The stomach wall has 2 types of glandular cells that are
cells secretes HCl -
Cells secretes Pepsinogen enzyme -

[b]The functions of HCl[/b]

- ( It makes the stomach medium acidic ([b]1.5 : 2.5 PH[/b] -

It kills the microbes which enters into the stomach with the food -

it activates Pepsinogen into Pepsin -

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[b][color=#4400ff]Q. Why does not the stomach digest itself[/color][/b]

[b][u][color=#440044]Digestion in the small intestine[/color][/u][/b]

[b]A) The bile [u]it is not an enzyme[/u])[/b]
The bile emulsifies fats by decreasing its surface tension to increase the area which exposed to the digestive enzyme

[b][IMG]http://www.theegypedia.org/components/com_kunena/template/default/images/emoticons/cool.png[/IMG] The pancreatic juice[/b]

[b]NaHCO3[/b] -

Which neutralizes the acidic Chyme & creates an alkaline medium

[b]Pancreatic amylase[/b] which hydrolysis the remaining of starch into maltose -

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[b]Trypsinogen inactive[/b] -
it becomes active by the help of Enterokinase enzyme which is secreted from the ileum

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Trypsin hydrolysis the remaining of proteins & converts them into polypeptides

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[b]Lipases[/b] They hydrolysis emulsified fats into fatty acids & glycerol -

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[b][color=#440088]C) The intestinal juice[/color][/b]

[b]Peptidases[/b] They are a group of enzymes that hydrolysis polypeptides into amino acids -

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[b]Enzymes that hydrolysis disaccharides into monosaccharides[/b] -

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[b][color=#440088]Absorption of digested food[/color][/b]

[b]Absorption[/b] is the passage of digested food to the blood & lymph through the epithelial cells of the Ileum

[b]The absorbed food passes through 2 routes which are * [/b]

Lymphatic route -

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[b]The structure of the wall of the small intestine *[/b]

Blood route -

[b]Metabolism[/b]

It is the process in which the body benefits from the digested -
food which absorbed thorough the digestive system -
Metabolism = Anabolism + Catabolism -

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[b][color=#4400bb]Anabolism[/color][/b]
Anabolism is the conversion of small food molecule (monomers) into larger ones called polymers

The sugars change into starch, which stored in the form of glycogen in the liver or muscles -

Amino acids change into protein -

Fatty acids and glycerol change into fats that stored in the body specially the skin -

[youtube]http://www.youtube.com/watch?v=Z7xKYNz9AS0&feature=player_embedded[/youtube]



[b][color=#4400bb]Catabolism[/color][/b]

It is the oxidation process of the absorbed food specially sugar to release the energy that needed by the body to carry out all vital activities

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منقول للأمانة
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