Back to AI Flashcard MakerBiology /Biology IB HL - 6.1 Digestion Part 2
How does the bolus go down the oesophagus and not the trachea?
The epiglottis prevents the bolus from entering the trachea, while the uvula prevents the bolus from entering the nasal cavity
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Key Terms
Term
Definition
How does the bolus go down the oesophagus and not the trachea?
The epiglottis prevents the bolus from entering the trachea, while the uvula prevents the bolus from entering the nasal cavity
What is churning?
The stomach lining contains muscles which physically squeeze and mix the food with strong digestive juices ('churning’)
What happens to the food after prolonged churning?
Food is digested within the stomach for several hours and is turned into a creamy paste called chyme
Where does the chyme go?
Eventually the chyme enters the small intestine (duodenum) where absorption will occur
What is peristalsis?
Peristalsis is the principal mechanism of movement in the oesophagus, although it also occurs in both the stomach and gut
How does peristalsis work?
Continuous segments of longitudinal smooth-muscle rhythmically contract and relax
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| Term | Definition |
|---|---|
How does the bolus go down the oesophagus and not the trachea? | The epiglottis prevents the bolus from entering the trachea, while the uvula prevents the bolus from entering the nasal cavity |
What is churning? | The stomach lining contains muscles which physically squeeze and mix the food with strong digestive juices ('churning’) |
What happens to the food after prolonged churning? | Food is digested within the stomach for several hours and is turned into a creamy paste called chyme |
Where does the chyme go? | Eventually the chyme enters the small intestine (duodenum) where absorption will occur |
What is peristalsis? | Peristalsis is the principal mechanism of movement in the oesophagus, although it also occurs in both the stomach and gut |
How does peristalsis work? | Continuous segments of longitudinal smooth-muscle rhythmically contract and relax |
How (general) does food move? | Food is moved unidirectionally along the alimentary canal in a caudal direction (mouth to anus) |
What does segmentation involve? (how does it work) | Segmentation involves the contraction and relaxation of non-adjacent segments of circular smooth muscle in the intestines |
What is the purpose of segmentation? | Segmentation contractions move chyme in both directions, allowing for a greater mixing of food with digestive juices |
Is segmentation effective? | While segmentation helps to physically digest food particles, its bidirectional propulsion of chyme can slow overall movement |
What is chemical digestion? | In chemical digestion, food is broken down by the action of chemical agents (such as enzymes, acids and bile) |
What does the stomach contain? | The stomach contains gastric glands which release digestive acids to create a low pH environment (pH ~2) |
Why does the stomach have an acidic environment? | The acidic environment functions to denature proteins and other macromolecules, aiding in their overall digestion |
What lines the stomach and what is its purpose? | The stomach epithelium contains a mucous membrane which prevents the acids from damaging the gastric lining |
What pH compounds does the pancreas secrete and why? | The pancreas releases alkaline compounds (e.g. bicarbonate ions), which neutralise the acids as they enter the intestine |
Where is bile produced and stored? | The liver produces a fluid called bile which is stored and concentrated within the gall bladder prior to release into the intestine |
What does bile contain and what is its role? | Bile contains bile salts which interact with fat globules and divide them into smaller droplets (emulsification) |
What does the emulsification of fats cause? | The emulsification of fats increases the total surface area available for enzyme activity (lipase) |
What are enzymes? | Enzymes are biological catalysts which speed up the rate of a chemical reaction (i.e. digestion) by lowering activation energy |
Why are enzymes needed for digestion? | Enzymes allow digestive processes to therefore occur at body temperatures and at sufficient speeds for survival requirements |
Why is it important that enzymes are specific? | Enzymes are specific for a substrate and so can allow digestion of certain molecules to occur independently in distinct locations |
What secretes digestive enzymes? | Digestive enzymes are secreted predominantly by the pancreas, although other organs also contribute (salivary gland, stomach) |
What does the type of enzyme secreted and location depend on? | the type of enzyme secreted and location of secretion depends on the specific macromolecule required for hydrolysis |
Where does carbohydrate digestion first occur? | Carbohydrate digestion begins in the mouth with the release of amylase from the salivary glands (amylase = starch digestion) |
Where is amylase secreted from (apart from salivary glands)? | Amylase is also secreted by the pancreas in order to continue carbohydrate digestion within the small intestine |