Digestion ( 1 ) Flashcards

1
Q

What are the two types of digestion?

A
  • Physical Digestion

* Chemical Digestion

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2
Q

Why is physical digestion needed?

A
  • Food may be very large, it can be broken down into smaller pieces through structures such as the teeth, or getting churned by muscles in the stomach wall
  • This makes it possible to ingest the food.
  • Provides a larger surface area for chemical digestion
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3
Q

What is the purpose of chemical digestion?

A

Hydrolyses large, insoluble molecules into smaller soluble ones.

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4
Q

What is chemical digestion carried out by?

A

Enzymes

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5
Q

By which process do all enzymes carry out chemical digestion?

A

Hydrolysis

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6
Q

What is hydrolysis?

A

Hydrolysis is the splitting up of molecules by adding water to the chemical bonds so that hold them together

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7
Q

Why is more than one molecule required to hydrolyse a large molecule?

A

Enzymes are specific, a large molecule may consist of many different molecules

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8
Q

What are the main three enzymes involved in chemical digestion?

A
  • Carbohydrase - hydrolyses carbohydrates, to monosaccharides
  • Lipases - Hydrolyse lipids into glycerol and fatty acids
  • Proteases - Hydrolyse proteins to amino acids
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9
Q

What occurs during chemical digestion?

A
  • One enzyme hydrolyses a large molecule into sections

* These sections are then hydrolysed into smaller molecules by one or more additional enzymes

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10
Q

What are carbohydrates broken down into, and by what?

A
  • Carbohydrase breaks them down

* Broken down into disaccharides and then monosaccharides

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11
Q

What are fats broken down into, and by what?

A
  • Lipases break them down

* Broken down into fatty acids and monoglycerides

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12
Q

What are proteins broken down into, and by what?

A
  • Protease breaks them down

* Broken down into fatty acids and monoglycerides

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13
Q

Where is the enzyme amylase produced?

A
  • Mouth

* Pancreas

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14
Q

What does amylase do?

A

• Hydrolyses the alternate glycosidic bonds of the starch molecule to produce the disaccharide maltose.

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15
Q

What does maltose get hydrolysed into, and by what?

A
  • Maltose is hydrolysed into the monosaccharide alpha glucose by a second enzyme
  • Maltase breaks down maltose
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16
Q

What is maltase produced by?

A

lining of the ileum

17
Q

What does saliva contain?

A

Salivary Amylase

18
Q

What is the process of carbohydrate digestion in the mouth?

A
  • Saliva enters the mouth from the salivary glands, and is mixed with food during chewing
  • Saliva containing salivary amylase starts hydrolysing any starch in the food to maltose
  • Contains mineral salts that help maintain the pH at neutral levels, as it is the optimal pH for salivary amylase to function
19
Q

What is the optimal pH for salivary amylase?

A

Neutral

20
Q

How is the pH maintained in the mouth?

A

Saliva contains mineral salts that help maintain the pH at neutral levels

21
Q

What is the process of carbohydrate digestion in the stomach?

A
  • Food is swallowed and enters the stomach
  • Conditions are acidic in the stomach
  • Acid denatures the amylase and prevents further hydrolysation of the starch
  • After some time time the food food is passed into the small intestine
22
Q

What is the process of carbohydrate digestion in the small intestine?

A
  • In the small intestine, food mixes with the secretion from pancreas ( known as pancreatic juice )
  • Pancreatic juice contains pancreatic amylase, this continues the hydrolysis of any remaining starch to maltose
  • Alkaline salts are produced by both the pancreas and the intestinal wall to maintain pH at neutral so that the amylase can function
  • Muscles in the intestine wall push the food along the ileum
  • Epithelial lining produces maltase, maltase is not released into the lumen of the ileum but is part of the cell surface membrane of the epithelial cells that line the ileum
  • Referred to as a membrane bound disaccharide
  • Maltase hydrolyses the maltose from starch breakdown into alpha glucose
23
Q

What do the muscles in the intestine wall do?

A

Push food along the ileum

24
Q

Where is maltase produced in the intestine?

A
  • Epithelial lining produces maltase

* Maltase is not released into the lumen, but a part oif the cell surface membrane of epithelial cells

25
Q

How is the pH maintained in the ileum?

A

• Alkaline salts produced by both the pancreas and intestinal wall maintain pH at neutral so amylase can function

26
Q

What are the alkaline salts produced by?

A

Pancreas and intestinal wall

27
Q

What does the pancreatic juice contain?

A

Pancreatic amylase which continues hydrolysis of starch to maltose