Diffusion Of The Alveoli

Question 1

what are alveoli

Answer 1

exchange surfaces found in the lungs of mammals

Question 2

how are gases exchanged in the lungs

Answer 2

by diffusion

Question 3

what are the 3 factors that affect the rate of diffusion

Answer 3

• distance
• concentration difference (of gradient)
• surface area

Question 4

how does the distance of particles affect rate of diffusion

Answer 4

substances move more quickly when there is less distance to cover

Question 5

how does the concentration difference affect rate of diffusion

Answer 5

• substances diffuse faster if there is a big difference in concentration between area they are diffusing from and the area they are diffusing to
• if there are lots of particles on one side, there are more there to move across

Question 6

how does surface area affect rate of diffusion

Answer 6

the more surface there is available for molecules to move across, the faster they can get from one side to the other

Question 7

what is the job of the lungs

Answer 7

• transfer oxygen to the blood

- remove waste carbon dioxide from the blood

Question 8

what do lungs contain to carry out their function

Answer 8

millions of sacs called alveoli where gas exchange takes place

Question 9

where has the blood arriving to the alveoli just been and what does it contain as a result

Answer 9

• blood has been around the body

- so it contains lots of CO2 and not much O2

Question 10

what is the effect of not much O2 being in the blood arriving to the lungs but it having alot of CO2

Answer 10

it maximises the concentration gradient for the diffusion of both gases

Question 11

describe the process of gas exchange in the alveoli

Answer 11

• O2 diffuses out of air in alveoli and into the blood
• because O2 conc in alveoli is high
• and O2 conc in blood is low
• CO2 diffuses in opposite direction to be breathed out

Question 12

what are the characteristics of alveoli that specialise it for its function

Answer 12

• moist lining
• good blood supply
• very thin walls
• large surface area

Question 13

why do alveoli have a moist lining

Answer 13

for the dissolving of gases

Question 14

why do alveoli have a good blood supply

Answer 14

to maintain the concentration gradients of O2 and CO2 effectively

Question 15

why do alveoli have very thin walls

Answer 15

to minimise the distance that gases have to move

Question 16

what descrbes the relationship between rate of diffusion and the factors that affect it

Answer 16

Fick’s Law

Question 17

what is Fick’s Law

Answer 17

rate of diffusion is directly proportional to (the surface area x concentration difference) / thickness of membrane

Question 18

is the rate of diffusion is proportional to the factors ,this means that the rate of diffusion will double if…

Answer 18

• the surface area or concentration difference doubles

- or the thickness of the membrane halves