Gas exchange in alveoli help

I've read that alveoli have moist walls so that oxygen can dissolve and therefore diffuse more efficiently. I understand that cell membranes need to have moisture obviously as they're not dry and shrivelled things but when learning about insect gas exchange I was taught that diffusion in the gaseous state is faster than liquid state? So why does the textbook now say that the oxygen (gas) diffuses more efficiently once it's dissolved (liquid)? Thanks in advance for any help you can offer :smile:

Reply 1

macpatgh-Sheldon

20

Hi with insects we are talking about diffusion WITHIN AIR thru their tracheae, BUT REMAINING IN AIR i.e. the oxygen is carried all the way to the respiring cells in the gaseous state.

In mammals, the oxygen NEEDS TO ENTER THE BLOOD and combine with haemoglobin and be taken to the respiring cells IN THE BLOOD i.e. IN THE LIQUID MEDIUM.

I hope this explains the difference in the respiratory mechanisms in these two vastly different animals: A] Insecta, which is an invertebrate animal very low down in the evolutionary tree [within Arthropoda = jointed legs - you will have noticed the "lumps" on the legs of insects [and actually also on those of spiders [Arachnida is also in Arthropoda]] and B] Mammalia, the most highly specialized phylum in the animal kingdom.

M

Reply 2

bluewhalestar

OP

6

Original post by macpatgh-Sheldon

Hi with insects we are talking about diffusion WITHIN AIR thru their tracheae, BUT REMAINING IN AIR i.e. the oxygen is carried all the way to the respiring cells in the gaseous state.

In mammals, the oxygen NEEDS TO ENTER THE BLOOD and combine with haemoglobin and be taken to the respiring cells IN THE BLOOD i.e. IN THE LIQUID MEDIUM.

I hope this explains the difference in the respiratory mechanisms in these two vastly different animals: A] Insecta, which is an invertebrate animal very low down in the evolutionary tree [within Arthropoda = jointed legs - you will have noticed the "lumps" on the legs of insects [and actually also on those of spiders [Arachnida is also in Arthropoda]] and B] Mammalia, the most highly specialized phylum in the animal kingdom.

M

Ahh I see now thank you! I didn't think about blood being a liquid medium so it makes sense now for the oxygen to dissolve and be in liquid state.

Reply 3

macpatgh-Sheldon

20

Original post by bluewhalestar

Ahh I see now thank you! I didn't think about blood being a liquid medium so it makes sense now for the oxygen to dissolve and be in liquid state.

My pleasure and oc you will know from your own body's working cos you need to ascend to the surface of the Pacific to take in your own oxygen tho your neighbours have gills so there is an even different mechanism possible, yeah? [sorry could not resist that one! :laugh: