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Biology Paper 1 and 3 help HERE ONLY!!!

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Feva:
all that is mentioned in my textbook is :

EXTERNAL intercostal muscles contract to lift the ribcage up

EXTERNAL intercostal muscles relax so the ribcage goes back, if ur breathing hard the INTERNAL intercostal muscles contract to move the ribcage further back

Malak:

--- Quote from: monnie on June 07, 2009, 09:51:27 pm ---i dont know the difference between the internal and external intercoastal muscles
where are they situated and wt do they do and how do they work?


--- End quote ---
Umm..i dnt knw the exact difference..u can say they r like the antagonistic ones..Wen one contracts the other relaxes..
They are the part of Breathing system..n situated near the rib cage
Wen u breathe in the External intercostal muscle contracts and the internal intercoastal muscles relax...the ribs are pulled upwards and outwards and the diaphragm contracts and flattens..these movements makes the volue inside thorax increase which decreases the pressure inside it..therefore the air rushes inside the throax frm High pressure(outside) to low pressure(inside thorax)

Hope it helps

monnie:

--- Quote from: Feva on June 07, 2009, 09:58:38 pm ---all that is mentioned in my textbook is :

EXTERNAL intercostal muscles contract to lift the ribcage up

EXTERNAL intercostal muscles relax so the ribcage goes back, if ur breathing hard the INTERNAL intercostal muscles contract to move the ribcage further back

--- End quote ---
Thanks alot
+rep

angelic:

--- Quote from: monnie on June 07, 2009, 09:51:27 pm ---i dont know the difference between the internal and external intercoastal muscles
where are they situated and wt do they do and how do they work?


--- End quote ---
both intercostal muscles are attached to the ribs, they are antagonistic. when the external intercostal muscles contract, they move the rib cage upwards & outwards, & the diaphragm muscles contract increasing the volume of the thorax.
the opposite happens when we breath ou, during a forced exhalation the internal intercostal muscles contract & the diaphragm muscles relax, decreasing the volume of the thorax.

~M.J~:
I want help with insects, arthropods, crustacians... and all those in our syllabus
I had the notes but i just lost them yesterday
Pls can anyone post their characteristics and an easy way to learn them
or scan and give a copy of their notes

can  any1 do me this favour.... i will b v.gratefull to u

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