4.2.2.1 The Human Digestive System Flashcards
What is the role of the digestive system?
- breaks down food
- absorbs food
What are enzymes?
- biological catalysts produced by living things
- a substance that increases speed of a reaction without being changed or used up
What do the thousands of chemical reactions in a living thing need to be?
- carefully controlled
- to get right amount of substances
What are enzymes helpful for?
- reducing the need for high temperatures
- speed up useful chemical reactions
What is the nature of enzymes?
- large proteins
- chains of amino acids
- chains folded into unique shapes
What does every enzyme have?
- an active site
What is an active site?
- a unique shape that fits onto substrate involved in a reaction
- only catalyse one specific reaction
- if doesn’t match then reaction won’t be catalysed
What is the ‘lock and key’ diagram?
- simplified model of enzyme action
- reaction will only be catalysed if shape of substrate exactly matches active site
- active site changes a little for an induced fit
What does a higher temperature do to a reaction?
- increases rate at first
- if too hot some bonds that hold enzymes together break, which changes active site, making it denatured
What happens when the pH isn’t the right level?
- interferes with bonds, also making them denatured
What do all enzymes have that makes them work the best?
- optimum pH
- often neutral, pH 7
What are examples of large molecules?
- starch
- proteins
- fats
What are examples of small molecules that have been broken down from big molecules
- sugars (glucose, maltose)
- amino acids
- glycerol
-fatty acids
How are smaller molecules absorbed into the bloodstream?
- they are soluble so they can pass easily through walls
- diffusion
- active transport
What do carbohydrases convert carbohydrates into?
- simple sugars
What is amylase and what does it break down?
- carbohydrase
- starch
Where is amylase made?
- salivary glands
- pancreas
small intestine
What do proteases convert proteins into?
- amino acids
Where is protease made?
- stomach (known as pepsin there)
- pancreas
- small intestine
What does lipases convert lipids into?
- glycerol
- fatty acids
What are lipids?
- fats and oils
Where is a lipid made?
- pancreas
- small intestine
What does the body do with the products of digestion?
- make new carbohydrates, proteins and lipids
- some of glucose (carbohydrate) is used in respiration
Where is bile produced, stored and released?
- liver
- gall bladder
- small intestine
