B5e: Digestion

Food provides the raw materials for growth as well as being the source of the energy we release through respiration. The different parts of the digestive system are each adapted for their own roles in digesting and absorbing food. 

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Describe the function of the salivary gland
produce saliva that moistens food and contains carbohydrase enzymes
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Describe the function of the stomach
produces hydrochloric acid and protease enzymes
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Describe the function of the liver
produces bile
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Describe the function of the gall bladder
stores bile
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Describe the function of the small intestine
produces carbohydrase, protease and lipase enzymes, and absorbs digested food
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Describe the function of the large intestine
absorbs water
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Describe the function of the pancreas
produces carbohydrase, protease and lipase enzymes
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What does physical digestion involve?
breaking food down into smaller pieces without making any chemical changes.
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In which two places does physical digestion take place? Explain.
The mouth: when food is chewed and the stomach: when food is squeezed and moved around
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What does chemical digestion involve?
breaking large food molecules into smaller molecules using chemical reactions. These smaller molecules can then be absorbed into the blood.
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Where does food enter and leave the blood?
Enters the blood in the small intestine and leaves the blood in body tissues.
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Why is physical digestion important?(2)
it lets the food pass through the digestive system more easily, and it provides a larger surface area for enzymes to work on.
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What are the three digestive enzymes?
Protease, Carbohydrase (e.g. Amylase) and Lipase.
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What does Protease break down? Into what?
Proteins into Amino Acids
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What does Carbohydrase (e.g. Amylase) break down? Into what?
Starch into sugars
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What does Lipase break down? Into what?
Fats into fatty acids and glycerol
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In which two places does carbohydrase (e.g. Amylase) catalyse the breakdown of starch?
in the mouth and small intestine
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In which two places does protease catalyse the breakdown of proteins?
in the stomach and small intestine
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In which place does lipase catalyse the breakdown of fats?
in the small intestine
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How does bile, from the gall bladder, improve fat digestion?
As food passes from the stomach into the small intestine, the pH must be raised. Bile - an alkaline substance - is released into the small intestine to achieve this. Bile also emulsifies (breaks down) fats in the small intestine.
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Why is bile important in the process of fat digestion?
because it provides a larger surface area in which the lipases can work.
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What is the pH level in the mouth and small intestine?
Alkaline/neutral
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What is the pH level in the stomach?
Acidic
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Why is important that the mouth and small intestine is maintained at a alkaline/neutral pH and the stomach maintained acidic pH? Give three examples.
Because the enzymes there work at different optimum pH levels. salivary amylase works best just below pH 7, stomach protease works best at around pH 1.6 and pancreatic lipase works best at around pH 8.
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What does stomach acid aid?
Protease function.
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What sort of carbohydrate is starch? Explain.
A complex one. Each molecule consists of very many glucose molecules joined together.
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How many stage process is the breakdown of starch? Describe these stages.
Two. it is first digested to form maltose and then the maltose is then digested to form glucose.
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The products of chemical digestion are absorbed into the body by what?
The small intestine.
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What do sugar and amino acids pass into? by what?
The bloodstream by diffusion.
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What do fatty acids and glycerol pass into? by what?
The lymph by diffusion.
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Where does the bloodstream and the lymph carry the products of chemical digestion to?
The bodies' tissues.
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What are the five adaptations the small intestine has for the effective absorption of small molecules for digestion?
It has thin lining, villi, a good blood supply and its very long and has a large suface area
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Talk about the villi - an adaption to efficient absorption in the small intestine.
Tiny finger-like projections called villi provide a large surface area for absorption to take place. They also have a rich supply of blood vessels to carry away absorbed molecules.
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Why do you want to break down the large insoluble molecules in food into small soluble molecules?
So you can absorb them into your blood plasma or lymph (a type of fluid that carries the products of fat digestion)
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Other cards in this set

Card 2

Front

Describe the function of the stomach

Back

produces hydrochloric acid and protease enzymes

Card 3

Front

Describe the function of the liver

Back

Preview of the front of card 3

Card 4

Front

Describe the function of the gall bladder

Back

Preview of the front of card 4

Card 5

Front

Describe the function of the small intestine

Back

Preview of the front of card 5
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