Kakakaty
Badges: 9
Rep:
?
#1
Report Thread starter 1 year ago
#1
I have two questions to do with gas exchange in humans im just wondering if someone could help me figure out the answer?


Question 1) The air you breathe in contains about 20% oxygen and only about 0.04% carbon dioxide. The air your breathe out contains around 16% oxygen and 4% carbon dioxide. What happens in the lungs to bring about these changes? (I'm not sure what happens in the LUNGS, I know that cells use oxygen from the inhaled air to release energy and give out carbon dioxide as a byproduct but is that the answer)

Question 2) Sometimes people injured in an accident such as a car crash suffer from a pneumothorax. This is an injury where the chest wall is punctured allowing air to enter the pleural cavity. A patient was brought into A and E suffering from a pneumothorax on the left side of his chest. His left lungs had collapsed but he was able to breath normally with his right lung.

a) Explain why the pneumothorax caused the left lung to collapse [2 marks]

b) Explain why the right lung was not affected [2 marks]

c) If a patients lung is injured or infected a surgeon used to sometimes 'rest' it by performing an operation called an artificial pneumothorax. What do you think might be involved in this operation? [2 marks]

(I have no idea how to answer this one)
0
reply
Reality Check
Badges: 22
Rep:
?
#2
Report 1 year ago
#2
(Original post by Kakakaty)
I have two questions to do with gas exchange in humans im just wondering if someone could help me figure out the answer?


Question 1) The air you breathe in contains about 20% oxygen and only about 0.04% carbon dioxide. The air your breathe out contains around 16% oxygen and 4% carbon dioxide. What happens in the lungs to bring about these changes? (I'm not sure what happens in the LUNGS, I know that cells use oxygen from the inhaled air to release energy and give out carbon dioxide as a byproduct but is that the answer)

Question 2) Sometimes people injured in an accident such as a car crash suffer from a pneumothorax. This is an injury where the chest wall is punctured allowing air to enter the pleural cavity. A patient was brought into A and E suffering from a pneumothorax on the left side of his chest. His left lungs had collapsed but he was able to breath normally with his right lung.

a) Explain why the pneumothorax caused the left lung to collapse [2 marks]

b) Explain why the right lung was not affected [2 marks]

c) If a patients lung is injured or infected a surgeon used to sometimes 'rest' it by performing an operation called an artificial pneumothorax. What do you think might be involved in this operation? [2 marks]

(I have no idea how to answer this one)
No point answering them for you, but I can give you the clues to help you answer them for yourself

Q1 - this is about movement of these two gases within the alveolus. So how does CO2 move from the blood to the lungs to be expired and how does oxygen move out of the inspired air into the blood?

Q2a - look at a diagram of pleural pressures, transmural pressures and the role of the interpleural space and fluid. What keeps the lung inflated under normal conditions? Can you see why equalising the pressure between the lung and the atmosphere (which is what happens with a PT) results in the lung collapsing.

Q2b - again, have a look at the anatomy of the lungs with respect to the pleura.
0
reply
Kakakaty
Badges: 9
Rep:
?
#3
Report Thread starter 1 year ago
#3
(Original post by Reality Check)
No point answering them for you, but I can give you the clues to help you answer them for yourself

Q1 - this is about movement of these two gases within the alveolus. So how does CO2 move from the blood to the lungs to be expired and how does oxygen move out of the inspired air into the blood?

Q2a - look at a diagram of pleural pressures, transmural pressures and the role of the interpleural space and fluid. What keeps the lung inflated under normal conditions? Can you see why equalising the pressure between the lung and the atmosphere (which is what happens with a PT) results in the lung collapsing.

Q2b - again, have a look at the anatomy of the lungs with respect to the pleura.
For Q1 would it be something like - The oxygen we breathe in goes from the lungs through to the alveoli to the blood, the oxygen is then picked up by our red blood cells. This is then called oxygenated blood. The oxygenated blood is then pumped around the body to the cells in our tissues. The cells in our tissues then use the oxygen making our blood become deoxygenated, the cells in our tissue produce a waste gas called carbon dioxide. The carbon dioxide is then moved from our blood into our lungs. The increase in carbon dioxide is the waste product of gas exchange. ?
0
reply
Reality Check
Badges: 22
Rep:
?
#4
Report 1 year ago
#4
(Original post by Kakakaty)
For Q1 would it be something like - The oxygen we breathe in goes from the lungs through to the alveoli to the blood, the oxygen is then picked up by our red blood cells. This is then called oxygenated blood. The oxygenated blood is then pumped around the body to the cells in our tissues. The cells in our tissues then use the oxygen making our blood become deoxygenated, the cells in our tissue produce a waste gas called carbon dioxide. The carbon dioxide is then moved from our blood into our lungs. The increase in carbon dioxide is the waste product of gas exchange. ?
Good - getting there but not quite.

Why does the oxygen move from the inspired air in the lungs to the blood? What 'force' is driving it? Why doesn't it just stay in the lungs?

Similarly, why does the CO2 move out of the blood into the alveolar air to be expired? Again, what 'force' is driving it?

This is the key to full marks on this question. No problems if you genuinely can't work it out, but I want to give you a chance to arrive at the answer yourself.
1
reply
Kakakaty
Badges: 9
Rep:
?
#5
Report Thread starter 1 year ago
#5
(Original post by Reality Check)
Good - getting there but not quite.

Why does the oxygen move from the inspired air in the lungs to the blood? What 'force' is driving it? Why doesn't it just stay in the lungs?

Similarly, why does the CO2 move out of the blood into the alveolar air to be expired? Again, what 'force' is driving it?

This is the key to full marks on this question. No problems if you genuinely can't work it out, but I want to give you a chance to arrive at the answer yourself.
errrr I really can't think of what it will be, I looked through my notes and can't find anything useful
0
reply
Reality Check
Badges: 22
Rep:
?
#6
Report 1 year ago
#6
(Original post by Kakakaty)
errrr I really can't think of what it will be, I looked through my notes and can't find anything useful
OK fair enough. The main thing is that you tried, rather than just expecting people to vomit up the answer for you. I wish more people could be like this

First thing to note is how the gases move, and this is through diffusion. For bonus marks, can you relate structure to function, i.e. how are the alveoli adapted to maximise gas exchange through efficient diffusion?

Secondly, and this is the the key to it is about concentration gradients. The concentration (more accurately 'partial pressure' because we're talking about gases) of oxygen in the inspired alveolar air is higher than that of the deoxygenated blood in the alveolar capillaries. Thus oxygen moves down its concentration gradient from the lungs to the blood (again, to be more accurate the oxygen is being loaded onto the deoxyhaemoglobin, though the principles are the same).

Equally, the concentration of CO2 in the alveolar capillary blood is higher than that of the alveolar air. Thus, CO2 again moves down its concentration gradient from the blood to the lungs.

With questions like these, always think of what is the force driving the movement. Often it's concentration, electrochemical or some sort of pressure differences (such as moving air into the lungs, and pumping blood around the body).
0
reply
Kakakaty
Badges: 9
Rep:
?
#7
Report Thread starter 1 year ago
#7
Ohhh, I remember learning about this now! So could I write something like = The oxygen we breathe in goes from the lungs through to the alveoli. The inspired alveolar air is a higher concentration than that of the deoxygenated blood in the alveolar capillaries. The oxygen then moves down its concentration gradient from the lungs to the blood, the oxygen is then picked up by our red blood cells. This is then called oxygenated blood. The oxygenated blood is then pumped around the body to the cells in our tissues. The cells in our tissues then use the oxygen making our blood become deoxygenated. This then creates a waste product called carbon dioxide. The concentration of CO2 in the alveolar-capillary blood is higher than that of the alveolar air. The CO2 moves down its concentration gradient from the blood to the lungs. The increase in carbon dioxide is the waste product of gas exchange. ?
0
reply
Reality Check
Badges: 22
Rep:
?
#8
Report 1 year ago
#8
(Original post by Kakakaty)
Ohhh, I remember learning about this now! So could I write something like = The oxygen we breathe in goes from the lungs through to the alveoli. The inspired alveolar air is a higher concentration than that of the deoxygenated blood in the alveolar capillaries. The oxygen then moves down its concentration gradient from the lungs to the blood, the oxygen is then picked up by our red blood cells. This is then called oxygenated blood. The oxygenated blood is then pumped around the body to the cells in our tissues. The cells in our tissues then use the oxygen making our blood become deoxygenated. This then creates a waste product called carbon dioxide. The concentration of CO2 in the alveolar-capillary blood is higher than that of the alveolar air. The CO2 moves down its concentration gradient from the blood to the lungs. The increase in carbon dioxide is the waste product of gas exchange. ?
You didn't quote me, so I didn't know you'd replied

That's much, much better. But you still need to mention diffusion. Give me a shout if you need any more help by quoting this post.
0
reply
Kakakaty
Badges: 9
Rep:
?
#9
Report Thread starter 1 year ago
#9
(Original post by Reality Check)
You didn't quote me, so I didn't know you'd replied

That's much, much better. But you still need to mention diffusion. Give me a shout if you need any more help by quoting this post.
Oh sorry I forgot to quote, for mentioning diffusion what sort of thing would I need to write? Could I put something like "This is called diffusion as the gas particles are moving from a high concentration to a low concentration" ?
0
reply
Reality Check
Badges: 22
Rep:
?
#10
Report 1 year ago
#10
(Original post by Kakakaty)
Oh sorry I forgot to quote, for mentioning diffusion what sort of thing would I need to write? Could I put something like "This is called diffusion as the gas particles are moving from a high concentration to a low concentration" ?
For diffusion you need to get across the idea of random movement of particles from an area of high concentration to low concentration. Again, for bonus marks you could relate structure to function and say how the respiratory membrane is adapted to maximise diffusion rate.

I bang on about structure relating to function a lot. That's because it's a central theme in biology.

Overall, you've got a good answer there
0
reply
Kakakaty
Badges: 9
Rep:
?
#11
Report Thread starter 1 year ago
#11
(Original post by Reality Check)
For diffusion you need to get across the idea of random movement of particles from an area of high concentration to low concentration. Again, for bonus marks you could relate structure to function and say how the respiratory membrane is adapted to maximise diffusion rate.

I bang on about structure relating to function a lot. That's because it's a central theme in biology.

Overall, you've got a good answer there
Thankyou so much for your help!
1
reply
Reality Check
Badges: 22
Rep:
?
#12
Report 1 year ago
#12
(Original post by Kakakaty)
Thankyou so much for your help!
You're welcome
0
reply
Bio 7
Badges: 21
Rep:
?
#13
Report 1 year ago
#13
(Original post by Kakakaty)
Thankyou so much for your help!
(Original post by Reality Check)
You're welcome
It was good to see someone get help and arrive to their final answer as a joint effort.

Good luck OP with future questions, it sounds like you’ll be fine come exam time with that kind of answer.
1
reply
Reality Check
Badges: 22
Rep:
?
#14
Report 1 year ago
#14
(Original post by Bio 7)
It was good to see someone get help and arrive to their final answer as a joint effort.

Good luck OP with future questions, it sounds like you’ll be fine come exam time with that kind of answer.
I absolutely :heart: threads like this. This is what TSR is about for me. That and being unnecessarily brusque in the other fora :laugh:
0
reply
Bio 7
Badges: 21
Rep:
?
#15
Report 1 year ago
#15
(Original post by Reality Check)
I absolutely :heart: threads like this. This is what TSR is about for me. That and being unnecessarily brusque in the other fora :laugh:
This is why I came to TSR, all my early visits were because I tried finding answers to maths questions. I joined to ask about the advanced higher biology projects.

Start uni though and then I get involved with a long homosexuality debate and I get dragged in and addicted.
0
reply
Kakakaty
Badges: 9
Rep:
?
#16
Report Thread starter 1 year ago
#16
(Original post by Reality Check)
No point answering them for you, but I can give you the clues to help you answer them for yourself

Q1 - this is about movement of these two gases within the alveolus. So how does CO2 move from the blood to the lungs to be expired and how does oxygen move out of the inspired air into the blood?

Q2a - look at a diagram of pleural pressures, transmural pressures and the role of the interpleural space and fluid. What keeps the lung inflated under normal conditions? Can you see why equalising the pressure between the lung and the atmosphere (which is what happens with a PT) results in the lung collapsing.

Q2b - again, have a look at the anatomy of the lungs with respect to the pleura.
Hi, just wondering I did Question 2) and looked at some diagrams of the pressures I got this answer. Would these be correct?

a) The patient suffering from a pneumothorax had it on the left side of their chest meaning the air was only able to enter the pleural cavity on the left side. The pleural cavity is the potential space between the visceral and parietal pleura. Negative pressure is created in the pleural space as the thoracic cage enlarges. The negative pressure is lost as fluid collects in the pleural space which makes the lung unable to expand fully.

b) The right lung was not affected as the air only entered the left pleural cavity. Each lung has its own pleural cavity which is separated by the mediastinum.

c) I think that the operation involves adding more air or nitrogen into the pleural cavity to force the lung to collapse so that it can repair itself.
0
reply
Reality Check
Badges: 22
Rep:
?
#17
Report 1 year ago
#17
(Original post by Kakakaty)
Hi, just wondering I did Question 2) and looked at some diagrams of the pressures I got this answer. Would these be correct?

a) The patient suffering from a pneumothorax had it on the left side of their chest meaning the air was only able to enter the pleural cavity on the left side. The pleural cavity is the potential space between the visceral and parietal pleura. Negative pressure is created in the pleural space as the thoracic cage enlarges. The negative pressure is lost as fluid collects in the pleural space which makes the lung unable to expand fully.

b) The right lung was not affected as the air only entered the left pleural cavity. Each lung has its own pleural cavity which is separated by the mediastinum.

c) I think that the operation involves adding more air or nitrogen into the pleural cavity to force the lung to collapse so that it can repair itself.
Just before I comment on these answers, what level is this? GCSE/A level? I should really have asked you this earlier
0
reply
Kakakaty
Badges: 9
Rep:
?
#18
Report Thread starter 1 year ago
#18
(Original post by Reality Check)
Just before I comment on these answers, what level is this? GCSE/A level? I should really have asked you this earlier
GCSE
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

Are you tempted to change your firm university choice on A-level results day?

Yes, I'll try and go to a uni higher up the league tables (61)
29.33%
Yes, there is a uni that I prefer and I'll fit in better (15)
7.21%
No I am happy with my choice (116)
55.77%
I'm using Clearing when I have my exam results (16)
7.69%

Watched Threads

View All
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