Digestion

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  • Created by: LMeadows
  • Created on: 08-04-14 14:37
Digestion
The hydrolysis of large, insoluble food molecules in to small, soluble molecules which can diffuse through the intestine lining and dissolve in the blood
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Absorption
Taking small molecules in to the body (i.e. via small intestine)
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Assimilation
Incorporating absorbed molecules in to body tissues
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Hydrolases
Enzymes that catalyse the breaking of bonds through the addition of a water molecule e.g. lipases, carbohydrases
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Excretion
Removal of waste products produced as a result of metabolic processes in an organism
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Egestion
Removal of waste products from body in form of faeces
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What do the salivary glands do and what enzymes are present ?
Near the mouth, pass secretions via duct to mouth. Secretions contain amylase (starch broken down in to maltose)
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What does the pancreas do and what enzymes are present ?
Large gland near stomach, secretes pancreatic juice containing proteases (protein ---> amino acids), lipase (lipids ---> fatty acids and glycerol), amylase (starch ---> maltose)
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What is the function of the colon ?
Absorbs water - food becomes drier and thicker, most reabsorbed comes from secretions of digestive glands so useful to reabsorb
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What is the function of the small intestine ?
A muscular tube where enzymes are produced by walls and glands to further digest food
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How is the structure of the small intestine adapted to its function ?
Inner wall contains villi and microvilli to increase surface area - adapted to absorb products in to blood stream
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How is the stomach adapted for digestion ?
Acidic (pH 2), hydrochloric acid digests food and the gland produces protease to break down proteins
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How does the stomach prevent self digestion ?
Mucus is produced to prevent digestion of stomach by enzymes
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How is the oesophagus adapted for transport ?
Thick muscular wall
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Explain the process of physical and chemical digestion in the mouth
Chewing - increases SA for enzyme action. Saliva from salivary glands contains amylase to break down starch by hydrolysis.
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Explain the process of physical and chemical digestion in the stomach
Squeezing and mixing. Gastric juice from gastric glands in stomach wall - contains mucus, hydrochloric acid (kill bacteria, pH 2 for protease enzyme)
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Explain the process of physical and chemical digestion in the duodenum (1st part of small intestine)
Peristalsis, Bile (secreted by liver cells and stored in gall bladder) - neutralises stomach acid and emulsifies fat to increase SA for lipase action, Pancreatic Juice contains lipase enzyme (pH 7-8 optimum) to hydrolyse fat to fatty acids+glycerol.
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Explain the process of physical and chemical digestion in the ileum
Absorption - small molecules enter blood, then carried to cells all over the body and assimilated in to body tissues or used in respiration
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Explain the process of physical and chemical digestion in the colon
Water absorbed from the mixture in to blood
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Peristalsis
Muscular contractions of gut wall, moves food along. Fibre provides bulk and gives muscles something to squeeze against (undigested fibre)
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Name all elements of physical digestion in the digestive system
Mastication/chewing by teeth in mouth, squeezing stomach wall - increases SA for enzymes to work
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Other cards in this set

Card 2

Front

Taking small molecules in to the body (i.e. via small intestine)

Back

Absorption

Card 3

Front

Incorporating absorbed molecules in to body tissues

Back

Preview of the back of card 3

Card 4

Front

Enzymes that catalyse the breaking of bonds through the addition of a water molecule e.g. lipases, carbohydrases

Back

Preview of the back of card 4

Card 5

Front

Removal of waste products produced as a result of metabolic processes in an organism

Back

Preview of the back of card 5
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