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GCSE OCR 21st Century B7 C7 P7 - W/C - Monday 20th June 2016

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Original post by rebbarn29
Can someone help me with tissue fluid and gas exchanges please


Admittedly, I have only just got to grasps with this. Tissue fluid forms when the plasma in the blood is forced out of the capillary (due to the high pressure of the artery from which the capillary starts) and this forms the tissue fluid which bathes the cells (e.g. muscle cells). This blood plasma contains oxygen and glucose as this is what are cells need to function. The oxygen and glucose then diffuse into the cells due to the concentration gradient (e.g. more oxygen and glucose in the tissue fluid than the cells, so it diffuses into the cells.

In the opposite direction, carbon dioxide and urea are forced out of the cells due to diffusion (there is a higher concentration of them in the cells so they are forced out into the tissue fluid where there is a lower concentration of them and even lower still in the blood plasma so they end up in the capillary). As this blood plasma moves towards the vein end the pressure drops and stops plasma being squeezed out. This is gaseous exchange and so the waste can be taken away (to be exhaled for the carbon dioxide and to the kidney for the urea where we urinate!) And oxygen and glucose are given to our working cells.

Hope this makes sense and if you have any more questions, feel free to ask!
Original post by realsmilee
Can someone explain how the heart has 4 chambers? :redface:


This image might help. Note: the four chambers are the two atria and the two ventricles.

Is this like diffusion in B4 where things move from a high concentration to a low concentration?

Original post by Speedbird129
Admittedly, I have only just got to grasps with this. Tissue fluid forms when the plasma in the blood is forced out of the capillary (due to the high pressure of the artery from which the capillary starts) and this forms the tissue fluid which bathes the cells (e.g. muscle cells). This blood plasma contains oxygen and glucose as this is what are cells need to function. The oxygen and glucose then diffuse into the cells due to the concentration gradient (e.g. more oxygen and glucose in the tissue fluid than the cells, so it diffuses into the cells.

In the opposite direction, carbon dioxide and urea are forced out of the cells due to diffusion (there is a higher concentration of them in the cells so they are forced out into the tissue fluid where there is a lower concentration of them and even lower still in the blood plasma so they end up in the capillary). As this blood plasma moves towards the vein end the pressure drops and stops plasma being squeezed out. This is gaseous exchange and so the waste can be taken away (to be exhaled for the carbon dioxide and to the kidney for the urea where we urinate!) And oxygen and glucose are given to our working cells.

Hope this makes sense and if you have any more questions, feel free to ask!
Original post by rebbarn29
Is this like diffusion in B4 where things move from a high concentration to a low concentration?


Yes, that is why the molecules move in the direction they do.
Original post by realsmilee
Can someone explain how the heart has 4 chambers? :redface:


The two atria where blood enters and the two ventricles where blood leaves, I think.
Original post by rebbarn29
Can someone help me with tissue fluid and gas exchanges please


Tissue fluid formation:
1. When blood flows into the capillary beds it is under high pressure.
2. Plasma is forced into tissues at high pressure.
3. Oxygen and glucose diffuse from the fluid into cells.
4. Urea and Carbon Dioxide diffuse out of cells into fluid.
5. Tissue fluid drains back to capillaries where blood pressure is lower.

Hope this helps :smile:
Original post by Pheebs_16
Tissue fluid formation:
1. When blood flows into the capillary beds it is under high pressure.
2. Plasma is forced into tissues at high pressure.
3. Oxygen and glucose diffuse from the fluid into cells.
4. Urea and Carbon Dioxide diffuse out of cells into fluid.
5. Tissue fluid drains back to capillaries where blood pressure is lower.

Hope this helps :smile:


Thanks. 👍


⚔🛡⚔~Nothing happens to anyone that he is not fitted by nature to bear - Maximus Decimus Meridius~⚔🛡⚔
All of this stuff is in the CGP revision guide. There are also very useful YouTube videos that covers every topic.


⚔🛡⚔~Nothing happens to anyone that he is not fitted by nature to bear - Maximus Decimus Meridius~⚔🛡⚔
I think the paper is going to be very similar to 2015 because they haven't released the paper online and only the teachers can view it.


⚔🛡⚔~Nothing happens to anyone that he is not fitted by nature to bear - Maximus Decimus Meridius~⚔🛡⚔
Thank you this is really good!!

Original post by Pheebs_16
Tissue fluid formation:
1. When blood flows into the capillary beds it is under high pressure.
2. Plasma is forced into tissues at high pressure.
3. Oxygen and glucose diffuse from the fluid into cells.
4. Urea and Carbon Dioxide diffuse out of cells into fluid.
5. Tissue fluid drains back to capillaries where blood pressure is lower.

Hope this helps :smile:
Does anyone know if we need to memories the BMI equation? it is not in the front of the paper
All the B7 papers are really similar. The 2015 paper is really really similar to the Specimen paper. 2 of the 6 markers are the same and they both have a labelling the heart question and many more similarities

Original post by MR.ANONYMOUS 786
I think the paper is going to be very similar to 2015 because they haven't released the paper online and only the teachers can view it.


⚔🛡⚔~Nothing happens to anyone that he is not fitted by nature to bear - Maximus Decimus Meridius~⚔🛡⚔
Original post by rebbarn29
Does anyone know if we need to memories the BMI equation? it is not in the front of the paper


Yes you do need to know it. Quite simple mass/height^2 and just remember the units for mass is kg and height is measured in metres.
Original post by Speedbird129
Yes you do need to know it. Quite simple mass/height^2 and just remember the units for mass is kg and height is measured in metres.


I don't think you do. They always provide the equation when it comes up.


⚔🛡⚔~Nothing happens to anyone that he is not fitted by nature to bear - Maximus Decimus Meridius~⚔🛡⚔
Original post by MR.ANONYMOUS 786
I don't think you do. They always provide the equation when it comes up.


⚔🛡⚔~Nothing happens to anyone that he is not fitted by nature to bear - Maximus Decimus Meridius~⚔🛡⚔


Yeah, but it is beneficial to learn it anyway.
Original post by Speedbird129
Yeah, but it is beneficial to learn it anyway.


Agreed.


⚔🛡⚔~Nothing happens to anyone that he is not fitted by nature to bear - Maximus Decimus Meridius~⚔🛡⚔
Any predictions?
This is really random.. :smile:

But why is a virus a vector?

I understand a plasmid is a vector because - they are small rings of DNA, easy to modify - and - they are small and can move in and out of bacterial cells easily.

But, why a virus?..
Genetic Modification, Genetic Testing, diabetes, Tissue Fluid, Components of the blood and something about closed/open loop systems

2015 6 markers; maintaining constant body temp, eutrophication and components and functions of the blood.

Original post by Alexandra00
Any predictions?
Original post by Alexandra00
Any predictions?


Maybe DNA technology? :dontknow:

Or something on the circulatory system?

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