unit 3 nutritional process
TRANSCRIPT
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Unit 3 The Nutritional Process
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Index
1. Introduction
2. Digestive system
3. Respiratory system
4. Circulatory system
5. Excretory system
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1. Introduction
There are 4 system involved in nutrition:Digestive system:
- digestive tract
-associated glands
Respiratory system:
-respiratory paths
-lungs
Circulatory system:
-heart
-blood
-blood vessels
Excretory system:
-kidneys
-urinary tracts
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Products expelled Organ
Carbon dioxide Lungs
Urea, water and salts Kidneys
Faeces Intestin
Substances which enter the organism:
airwater
foods
Products expelled by the organism (waste products)
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2.2 The digestive process
There are three phases in food processing:
-Digestion(mouth, stomach and small intestine)separation of substances (nutrients)
that can be used from the food
-Absorption(small intestine) nutrients pass into the
bloodstream
-Expulsion of waste (large intestine)unusable substancesare expelled
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PERISTALTIC MOVEMENTS = Movement of food through the digestive tract. It consists
on the narrowing of the tube through the contraction of the muscles of the walls,what pushes the food.
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2.3 Digestion
A. Types of digestion
Mechanical digestioncutting, crushing food(physical changes)
Chemical digesionsubstances attack the food and
break it down into smaller chemical compounds (nutrients)
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B. Stages of digestion
In the mouthmastication and salivation take place
The salivary glands produce saliva, a liquid containing digestive enzymes (which act
chemically on the food)
Chemical digestion in the mouthamylase breaks down the starch into maltose
DIGESTION
starch maltoses
DIGESTION
Physical digestionChemical digestion
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In thestomach begins gastric digestion
(both physical and chemical digestion take place
simultaneously)
Movement of the walls of the stomach Food is mixed with the gastric juices,
which contain HCl and enzymes
http://www.youtube.com/watch?v=URHBBE3RKEs = gastric digestion
As a result of gastric digestion, a pulp known as chymeleaves the stomach via the pylorus
http://www.youtube.com/watch?v=URHBBE3RKEshttp://www.youtube.com/watch?v=URHBBE3RKEs -
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First section of the small intestine
(duodenum)
Chemical digestionthe chyme is mixed with
intestinal juices. They come from
the walls of the duodenum
the liverproduces bile
the pancreasproduces pancreatic juice
The result is called chyle
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2.4 Absorption (in the jejunum and illeon)
The digested food (nutrients) passes into the
bloodstream through the intestineswalls.
The walls of the intestine are filled with intestinal hairs (deep folds in the wall and many
blood vessels)this increases the efficiency of absorption considerably.
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Functions
water and some ions pass into the bloodstream (absorption of
water and ions)
faeces are released through the anus
2.5 Large intestine
Leftovers and water arrive to the large
intestine.
Page 65, activities 1 and 3
http://www.youtube.com/watch?v=IxNpXO8gGFM&feature=related = digestion and absorption
http://www.youtube.com/watch?v=IxNpXO8gGFM&feature=relatedhttp://www.youtube.com/watch?v=IxNpXO8gGFM&feature=related -
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3. Respiratory system