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Digestive System Study Cards
Free Biology Flashcards on Digestion
Learn the structure and function of each organ in the digestive system, the enzymes involved in breaking down food, and how nutrients are absorbed with these free Biology flashcards.
Question
What is digestion?
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Answer
The breakdown of large, insoluble food molecules into small, soluble molecules that can be absorbed into the bloodstream. Involves mechanical (physical) and chemical (enzymatic) digestion.
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Question
What are the main organs of the digestive system in order?
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Answer
Mouth → oesophagus → stomach → small intestine (duodenum, jejunum, ileum) → large intestine → rectum → anus.
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Question
What is the role of the mouth in digestion?
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Answer
Mechanical digestion by teeth (mastication) and chemical digestion by salivary amylase, which begins breaking down starch into maltose.
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Question
What is peristalsis?
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Answer
Wave-like muscular contractions of the gut wall that propel food along the digestive tract from the oesophagus to the rectum.
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Question
What is the role of the stomach?
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Answer
Churns food mechanically; secretes hydrochloric acid (kills bacteria, activates pepsinogen) and pepsin (protease that begins protein digestion). Produces chyme.
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Question
What does the pancreas produce for digestion?
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Answer
Pancreatic juice containing amylase (starch → maltose), lipase (fats → fatty acids + glycerol), and proteases including trypsin and chymotrypsin. Also secretes bicarbonate to neutralise stomach acid.
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Question
What is the role of bile?
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Answer
Bile (produced by the liver, stored in the gallbladder) emulsifies fats — breaking large fat droplets into smaller ones, increasing surface area for lipase to act on.
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Question
What is emulsification?
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Answer
The physical breakdown of fat globules into smaller droplets by bile salts. This is not chemical digestion — it increases surface area for lipase to work more efficiently.
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Question
What enzymes are found in the small intestine?
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Answer
Brush border enzymes: maltase (maltose → glucose), sucrase (sucrose → glucose + fructose), lactase (lactose → glucose + galactose), and peptidases (peptides → amino acids).
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Question
Where does most absorption occur and how is the small intestine adapted for it?
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Answer
The ileum. Adaptations: villi and microvilli (huge surface area), thin walls (short diffusion distance), rich blood supply (maintains concentration gradient), and lacteal vessels (absorb fats).
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