Rohan007best
Badges: 12
Rep:
?
#1
Report Thread starter 5 months ago
#1
state 3 ways inwhich the structure of the lungs allow efficent gas exchange
0
reply
dinomedic
Badges: 18
Rep:
?
#2
Report 5 months ago
#2
(Original post by Rohan007best)
state 3 ways inwhich the structure of the lungs allow efficent gas exchange
walls of alveoli very thin only 1 cell thick- short diffusion distance
alveoli covered in surfactant- stops lungs collapsing
large number of small alveoli- creates large surface area to volume ratio for diffusion
0
reply
macpatgh-Sheldon
Badges: 20
Rep:
?
#3
Report 5 months ago
#3
(Original post by ewapieczykolan)
walls of alveoli very thin only 1 cell thick- short diffusion distance
alveoli covered in surfactant- stops lungs collapsing
large number of small alveoli- creates large surface area to volume ratio for diffusion
Hi good answer - 2 marks out of 3 [sorry!] - surfactant does stop lungs collapsing correct, but does not actually increase efficiency of gas exchange so would not be in mark scheme.

3rd mark is for:
EITHER:
rich blood supply to alveoli with intricately branched capillaries ----> large surface area

OR:
red cell diameter [7 micrometres] is very similar to internal diameter of capillaries -----> RBCs move slowly -----> time for gas exchange + reduced distance to diffuse

OR:
regular breathing brings in fresh O2 ----> conc-n gradient maintained -----> efficient diffusion

M
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Do you think receiving Teacher Assessed Grades will impact your future?

I'm worried it will negatively impact me getting into university/college (74)
38.34%
I'm worried that I’m not academically prepared for the next stage in my educational journey (19)
9.84%
I'm worried it will impact my future career (12)
6.22%
I'm worried that my grades will be seen as ‘lesser’ because I didn’t take exams (48)
24.87%
I don’t think that receiving these grades will impact my future (25)
12.95%
I think that receiving these grades will affect me in another way (let us know in the discussion!) (15)
7.77%

Watched Threads

View All
Latest
My Feed