Back to AI Flashcard MakerAnatomy and Physiology /Biology IB HL - D2 Digestion Part 2
Biology IB HL - D2 Digestion Part 2
This deck covers key concepts related to digestion, focusing on the roles of secretin, CCK, and pancreatic juices, as well as the functions and conditions of the stomach and small intestine.
What is the role of secretin and CCK?
Secretin and cholecystokinin (CCK) stimulate the pancreas and liver to release digestive juices
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Key Terms
Term
Definition
What is the role of secretin and CCK?
Secretin and cholecystokinin (CCK) stimulate the pancreas and liver to release digestive juices
What is the role of pancreatic juices?
Pancreatic juices contain bicarbonate ions which neutralise stomach acids, while the liver produces bile to emulsify fats
What do the gastric glands secrete apart from hormones?
The gastric glands that line the stomach wall secrete an acidic solution that creates a low pH environment within the stomach
What is the normal pH of the stomach and why?
The normal pH of the stomach is roughly 1.5 – 2.0, which is the optimum pH for hydrolysis reactions by stomach enzymes
What are the 3 functions of the acid conditions of the stomach?
Assists in the digestion of food; Prevents pathogenic infection
How do the acidic conditions in the stomach help the digestion of food?
by dissolving chemical bonds within food molecules
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| Term | Definition |
|---|---|
What is the role of secretin and CCK? | Secretin and cholecystokinin (CCK) stimulate the pancreas and liver to release digestive juices |
What is the role of pancreatic juices? | Pancreatic juices contain bicarbonate ions which neutralise stomach acids, while the liver produces bile to emulsify fats |
What do the gastric glands secrete apart from hormones? | The gastric glands that line the stomach wall secrete an acidic solution that creates a low pH environment within the stomach |
What is the normal pH of the stomach and why? | The normal pH of the stomach is roughly 1.5 – 2.0, which is the optimum pH for hydrolysis reactions by stomach enzymes |
What are the 3 functions of the acid conditions of the stomach? | Assists in the digestion of food; Prevents pathogenic infection |
How do the acidic conditions in the stomach help the digestion of food? | by dissolving chemical bonds within food molecules |
How do the acidic conditions of the stomach help activate stomach proteases? | e.g. pepsin is activated when pepsinogen is proteolytically cleaved in acid conditions |
How do the acidic conditions of the stomach help prevent pathogenic infections? | stomach acids destroy microorganisms in ingested food |
What is the stomach wall lined by and why? | The stomach wall is lined by a layer of mucus, which protects the stomach lining from being damaged by the acid conditions |
What does the pancreas release in relation to pH? | The pancreas releases bicarbonate ions into the duodenum which neutralises the stomach pH (intestinal pH ~7.0 – 8.0) |
What may also neutralise stomach pH? | Certain foods (e.g. antacids) may also neutralise stomach acids, impairing digestion and increasing chances of infection |
What maintains low pH environment of stomach? | The low pH environment of the stomach is maintained by proton pumps in the parietal cells of the gastric pits |
How do proton pumps maintain acidic conditions in stomach? | These proton pumps secrete H+ ions (via active transport), which combine with Cl– ions to form hydrochloric acid |
What can decrease stomach acidity? | Certain medications and disease conditions can increase the secretion of H+ ions, lowering the pH in the stomach |
What are proton pump inhibitors? | Proton pump inhibitors (PPIs) are drugs which irreversibly bind to the proton pumps and prevent H+ ion secretion |
How do proton pump inhibitors affect pH? | This effectively raises the pH in the stomach to prevent gastric discomfort caused by high acidity (e.g. acid reflux) |
What is a side effect of PPI's? | Individuals taking PPIs may have increased susceptibility to gastric infections due to the reduction of acid secretion |
What is the role of the small intestine apart from absorbing nutrients? | The small intestine also releases digestive enzymes to ensure the complete hydrolysis of food molecules |
What is the structure of the small intestine? | The inner epithelial lining of the small intestine is highly folded into finger-like projections called villi (singular: villus) |
What is the (basic) function of the villi? | Many villi will protrude into the intestinal lumen, greatly increasing the available surface area for material absorption |