B1 Exchanging Substances (page 21) Flashcards
In the Human Body, where do Gas Exchange Happen?
in the lungs.
What is the job of the lungs?
to transfer Oxygen to the blood and to remove waste carbon dioxide from it.
To do this, the lungs contain millions of little air sacs called Alveoli where gas exchange takes place.
Look at diagram of lungs on page 21
What is the Alveoli specialised to do?
The Alveoli are specialised to maximise the diffusion of O2 and CO2
Explain how Alveoli is adapted for it’s function?
They have:
An enormous surface area (about 75m² in humans).
A moist lining for dissolving gasses.
Very thin walls
A good Blood supply.
(look at diagram on page 21, as you may have to list or draw the lungs)
What is Villi?
The is inside of the small intestine is covered in millions and millions of these tiny little projections called Villi.
(Villi provide a really really big surface area).
What do Villi do?
They increase the surface area in a big way so that digested food is absorbed much more quickly into the blood.
What do Villi have?
they have a single layer of surface cells
a very good blood supply to assist quick absorption.
(please see diagram on page 21, as you may need to list the Villi in your exam).
The digested food moves into the blood by what?
by diffusion and by active transport (see page 19).
Give one way in which alveoli are adapted for gas exchange? (1 mark)
They have a large surface area
They have a moist lining for dissolving gasses.
They have very thin walls
They have a good blood supply. (1 mark)
Coeliac Disease causes inflammation of the small intestine, which can damage the Villi. Suggest why a person with Ceoliac Disease might have low levels of iron in their blood. (2 marks)
The damage to the villi is likely to reduce the surface area for absorption (1 mark).
Therefore less iron can be absorbed from the digested food in the small intestine into the blood (1 mark)
