food and digestion Flashcards
(25 cards)
What are the main roles of the human digestive system?
Break down large macromolecules via hydrolysis and absorb small molecules.
Hydrolysis is the chemical breakdown of a compound due to reaction with water.
List the key components of the human digestive system.
- Mouth (ingestion & carbohydrate digestion)
- Oesophagus (peristalsis)
- Stomach (protein digestion, acidic pH)
- Duodenum (mixing with bile & pancreatic juice)
- Ileum (absorption via villi/microvilli)
- Large intestine (water absorption and faeces formation)
Each component plays a specific role in the digestion process.
What is the function of salivary amylase?
Starch → maltose in the mouth.
Salivary amylase initiates carbohydrate digestion.
What does pancreatic amylase do?
Starch → maltose in the duodenum.
Pancreatic amylase continues carbohydrate digestion after it leaves the stomach.
What is the role of maltase?
Maltose → glucose in the ileum lining.
Maltase completes the breakdown of carbohydrates.
What does pepsin do?
Proteins → peptides in the stomach.
Pepsin is active in the acidic environment of the stomach.
What is the function of trypsin?
Proteins → peptides in the pancreas.
Trypsin is activated in the duodenum and continues protein digestion.
What do peptidases do?
Peptides → amino acids in the ileum lining.
Peptidases finalize protein digestion.
What is the role of lingual lipase and gastric lipase?
Start lipid digestion in the mouth and stomach.
These lipases begin the breakdown of fats.
What does pancreatic lipase do?
Triglycerides → fatty acids + glycerol in the duodenum.
Pancreatic lipase is crucial for fat digestion.
What is bile’s role in digestion?
Produced in the liver, stored in the gallbladder, released into the duodenum, neutralizes acidic chyme, and emulsifies fats.
Bile’s emulsification increases surface area for lipase action.
What is enzyme specificity?
Enzymes display high specificity—each acts on a specific substrate.
This specificity is crucial for efficient biochemical reactions.
What are zymogens?
Inactive precursors of enzymes.
Zymogens are activated by specific conditions or other enzymes.
How is trypsinogen activated?
Converted to active trypsin by enteropeptidase in the duodenum.
This activation triggers a cascade for protease activation.
What structures maximize surface area in the small intestine?
Villi and microvilli.
These structures enhance nutrient absorption efficiency.
How do glucose and amino acids enter the bloodstream?
They enter blood capillaries.
This process occurs in the ileum.
How do fatty acids and glycerol enter the lymphatic system?
They enter lacteals as chylomicrons.
Chylomicrons transport lipids from the intestines.
What pH range is optimal for amylase activity?
~6.8 in the mouth.
Amylase functions best in slightly acidic conditions.
What is the optimal pH for pepsin activity?
~1.5–2 in the stomach.
Pepsin is adapted to the highly acidic environment of the stomach.
What is the optimal pH for proteases in the intestine?
~7.5–8.
This pH supports the activity of digestive enzymes in the small intestine.
What temperature is optimal for human enzymes?
~37 °C.
Deviations from this temperature can slow enzyme activity or cause denaturation.
What are the key types of digestive enzymes?
- Carbohydrases
- Proteases
- Lipases
Each type of enzyme is specialized for digesting different macromolecules.
What are the functions of bile?
- Neutralisation
- Emulsification
Bile is crucial for creating an optimal pH and increasing fat digestion efficiency.
What are the absorption methods in the digestive system?
- Use of capillaries
- Use of lacteals
Different absorption routes are used for different nutrients.
