[19941994]

(Original post by iesians)
i am expecting :-
a lot of muscle stuff ! (sliding filament theory slow and fast twitch stuff )
due to the upcoming olympic situation.
this leads to aerobic and anaerobic respiration in muscles as well. fate of lactate.
also performance enhancing drugs can be asked,
why are they allowed according to some, why arent they allowed ....
effect of too much exercise and efect of too little excercise.......
im expecting very little to come from the nervous system section :/

Ah i hope so, the stuff on muscles is a lot easier in my opinion :/


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[iesians]

disadvantages of GMO's ?

[kanchu]

Hi.. Can someone briefly explain all brain imaging technique please?


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[iesians]

(Original post by kanchu)
Hi.. Can someone briefly explain all brain imaging technique please?


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CT scan :- uses X rays to make up a 2 d image of the brain. the more dense areas of the brain absorb more x rays while less dense areas of brain absorb less x rays , this is detected by a detector on the other side which feeds the info in a computer which displays a 2 d image of brain. brain structure, local oedema, stroke, and aneurysm can be found from this.

MRI scans :- this uses radio waves to develop a 3d image of the brain. water in brain resonates at a particular frequency with the externally applied radio waves and so due to different dinsities and depths of brain a clear 3d image is formed form MRI scans. this scan can be used to study deep brain structure, any internal bleeding, formation of tumour etc

fMRI scans :- functional MRI is used to study activity in brain related to specific stimuli or tasks. active areas of brain have greater blood supply than other not so active areas. so oxygenated blood in here DOES NOT absorb radio signals and active areas appeae lighter on the scans. this can be used to study psychological attributes and abilities, including any psychiatric disorde. Also,the brain areas involved in different activities can be worked out too.

[iesians]

so according to CGP neurone cell membrane is permeable to K+ ions but not Na+ ions ...?!

[iesians]

OK so after hyperpolarisation, how is the resting potential obtained again ?

[kanchu]

(Original post by iesians)
CT scan :- uses X rays to make up a 2 d image of the brain. the more dense areas of the brain absorb more x rays while less dense areas of brain absorb less x rays , this is detected by a detector on the other side which feeds the info in a computer which displays a 2 d image of brain. brain structure, local oedema, stroke, and aneurysm can be found from this.

MRI scans :- this uses radio waves to develop a 3d image of the brain. water in brain resonates at a particular frequency with the externally applied radio waves and so due to different dinsities and depths of brain a clear 3d image is formed form MRI scans. this scan can be used to study deep brain structure, any internal bleeding, formation of tumour etc

fMRI scans :- functional MRI is used to study activity in brain related to specific stimuli or tasks. active areas of brain have greater blood supply than other not so active areas. so oxygenated blood in here DOES NOT absorb radio signals and active areas appeae lighter on the scans. this can be used to study psychological attributes and abilities, including any psychiatric disorde. Also,the brain areas involved in different activities can be worked out too.

Thank you!!


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[ConnorB]

(Original post by iesians)
OK so after hyperpolarisation, how is the resting potential obtained again ?

Na+ and K+ Pumps the Na+ ions out and the K+ ions back into the cell

3Na's are pumped out for every 2 K ions pumped back in. This is why the membrane is Polarised as there is a difference of voltage across it. When the Sodium potassium pump is resetting the ions channels it is called the refractory period where no action potential can be fired during this time

[kanchu]

(Original post by iesians)
OK so after hyperpolarisation, how is the resting potential obtained again ?

When the voltage dependent K+ channels close.. The K+ diffuses into the axon to obtain resting potential


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[iesians]

(Original post by ConnorB)
Na+ and K+ Pumps the Na+ ions out and the K+ ions back into the cell

3Na's are pumped out for every 2 K ions pumped back in. This is why the membrane is Polarised as there is a difference of voltage across it. When the Sodium potassium pump is resetting the ions channels it is called the refractory period where no action potential can be fired during this time

ok so hyperpolarisation means that inside of cell is more negative right ?
so it should be made more positive to bring it back to normal ?!
but you are saying the Na+ is moved outside ! wouldnt this make the inside even more negative ..?!

[moodychopin]

(Original post by iesians)
ok so hyperpolarisation means that inside of cell is more negative right ?
so it should be made more positive to bring it back to normal ?!
but you are saying the Na+ is moved outside ! wouldnt this make the inside even more negative ..?!

there are negative Chloride ions and proteins inside the membrane which means at rest it is always -70mV, more negative than the outside (:

[ConnorB]

(Original post by iesians)
ok so hyperpolarisation means that inside of cell is more negative right ?
so it should be made more positive to bring it back to normal ?!
but you are saying the Na+ is moved outside ! wouldnt this make the inside even more negative ..?!

You seem to be forgetting that there are K+ ions aswell?!

Read this http://faculty.washington.edu/chudler/ap.html

It will help loads

[bertiejess]

(Original post by iesians)
OK so after hyperpolarisation, how is the resting potential obtained again ?

K+ channels close and K+ ions diffuse back into the membrane from outside to restore resting potential

[iesians]

everybody thanks for the answers !

[iesians]

(Original post by ConnorB)
You seem to be forgetting that there are K+ ions aswell?!

Read this http://faculty.washington.edu/chudler/ap.html

It will help loads

AH ! thanks for the site !......xxx

[rudizzy123]

How do you measure heart rate from an electrocardiogram (ECG) ?

[ConnorB]

(Original post by rudizzy123)
How do you measure heart rate from an electrocardiogram (ECG) ?

You have the PQRS complex? electrocardiogram records the electrical activity of the heart, the heart muscle depolarises as it loses electrical activity when it contracts and repolarises when it relaxes.

The Electrocardiograph records changes by using electrodes placed on the chest

[PhantomPhreek]

(Original post by ConnorB)
Na+ and K+ Pumps the Na+ ions out and the K+ ions back into the cell

3Na's are pumped out for every 2 K ions pumped back in. This is why the membrane is Polarised as there is a difference of voltage across it. When the Sodium potassium pump is resetting the ions channels it is called the refractory period where no action potential can be fired during this time

That is seriously wrong, the ratio has nothing to do with the potential, it's the permeability of the membrane to the two different ions that determines the potential. The membrane is more permeable to K+ ions moving out than Na+ moving in, this determines the potential not the Sodium potassium pump.

[iesians]

finished the entire CGP guide just now !!
gonna do the question for pre release and then read the article once in the evening !
what are yall upto ?!

[iesians]

(Original post by rudizzy123)
How do you measure heart rate from an electrocardiogram (ECG) ?

work out the time from one p wave to the other p wave , change the time to seconds if necessary, divide 60 by this time , you get the heart rate per minute.