2.1 Digestion Flashcards
What is a cell?
The basic building block of a living organism
What is a tissue?
A group of cells with a similar structure and function working together. For example, muscular tissue contracts to bring about movement.
What is an organ?
A collection of tissues working together to perform a specific function. For example, the stomach contains glandular, muscular and epithelial tissues.
What is an organ system?
A group of organs working together to perform specific functions. For example, the digestive system contains organs such as the stomach, small intestine and large intestine.
What is the main function of the digestive system?
To digest food and absorb nutrients obtained from digestion
What is the role of the pancreas and salivary gland in the digestive system?
The pancreas and salivary gland are glands that produce digestive juices containing enzymes
What is the role of the stomach in the digestive system?
Produces hydrochloric acid - which kills any bacteria present and provides the optimum acidic pH for the protease enzyme to function
What is the role of the small intestine in the digestive system?
The small intestine is the site where soluble food molecules are absorbed into the bloodstream
What is the role of the liver in the digestive system?
Produces bile (stored in the gallbladder) which emulsifies lipids and allows the lipase enzyme to work more efficiently
What is the role of the large intestine in the digestive system?
Absorbs water from undigested food, producing faeces
What is the role of enzymes in the digestive system?
Enzymes act as biological catalysts which speed up the rate of biological reactions (the breakdown of food) without being used up
How does the shape of an enzyme affect its function?
Enzymes have a specific active site which is complementary to their substrate
What is metabolism?
The sum of all reactions in a cell or an organism
What types of metabolic reactions do enzymes catalyse?
● Building larger molecules from smaller molecules e.g. glucose to starch
● Changing one molecule to another e.g. glucose to fructose
● Breaking down larger molecules into smaller molecules e.g. carbohydrates to glucose
What is the lock and key hypothesis of enzyme function?
The shape of the enzyme active site and the substrate are complementary, so can bind together to form an enzyme-substrate complex.
How does temperature affect enzyme action?
Up to a certain point, increasing temperature increases enzyme action, as molecules have a higher kinetic energy.
Above a certain temperature, the shape of the active site is altered and the enzyme becomes denatured, so it can no longer catalyse the reaction. The optimum temperature is around 37 degrees celsius.
How does pH affect enzyme function?
The optimum pH for most enzymes is 7 (apart from proteases in the stomach). If the pH is too extreme, the shape of the active site may be altered and the enzyme may no longer work.
Where are carbohydrases, proteases, and lipases produced in the body?
● Carbohydrases: Amylase - salivary gland and pancreas; Maltase - small intestine
● Proteases: Pepsin - stomach; others - pancreas and small intestine
● Lipases: pancreas and small intestine
What is the role of carbohydrases in the digestive system?
● Carbohydrases break down carbohydrates into monosaccharides and disaccharides.
● Amylase breaks down starch into maltose, and maltase breaks down maltose into glucose.
What is the role of proteases in the digestive system?
Proteases break down proteins into amino acids
What is the role of lipases in the digestive system?
Lipases break down lipids into fatty acids and glycerol
How are the products of digestion used?
They are used to build bigger molecules such as carbohydrates and proteins. Glucose is used as a substrate in respiration.
Where is bile made and stored in the body?
Bile is made by the liver and stored in the gallbladder
What is the role of bile in the digestive system?
● Bile is an alkaline substance which neutralises the hydrochloric acid secreted by the stomach.
● Bile emulsifies lipids to form droplets - this increases the surface area for the lipase enzyme to work on.
