b3 Flashcards
organisation and the digestive system
Name the five levels of organisation.
cells→tissues→organs→organ systems→organisms
What is a tissue?
group of cells with similar structures and functions
What is an organ?
group of tissues working together to perform a specific function
What is the function of the liver in digestion?
produces bile, which neutralises hydrochloric acid from the stomach and emulsifies fat to form small droplets with a large surface area
What is the function of saliva in digestion?
lubrication to help swallowing - contains amylase to break down starch
Name three enzymes produced in the pancreas?
amylase, protease, lipase
What are enzymes?
protein molecules that catalyse specific reactions in organisms
Why are enzymes described as specific?
each enzyme only catalyses a specific reaction, because the active site only fits together with certain substances (like a lock and key)
Describe the function of amylase.
to break down starch into glucose
Where is amylase produced?
salivary glands, pancreas, and small intestine
Describe the function of proteases.
to break down proteins into amino acids
Where are proteases produced?
stomach, pancreas, and small intestine
Describe the function of lipases.
to break down lipids into fatty acids and glycerol
Where are lipases produced?
pancreas and small intestine
What are two factors that affect the rate of activity of an enzyme?
temperature and pH
What does denatured mean?
shape of an enzyme’s active site is changed by high
temperatures or an extreme pH, so it can no longer bind
with the substrate
Describe the effect of temperature on enzyme activity.
as temperature increases, rate of reaction increases
until it reaches the optimum for enzyme activity –
above this temperature enzyme activity decreases and
eventually stops
Describe the effect of pH on enzyme activity.
different enzymes have a different optimum pH at which
their activity is greatest – a pH much lower or higher
than this enzyme activity decreases and stops
Why do different digestive enzymes have different optimum pHs?
different parts of the digestive system have very
different pHs – the stomach is strongly acidic, and the
pH in the small intestine is close to neutral
What is an organ system?
a group of organs working together to perform a specific function
