(urgent) RBc cells

[xim7007]

Explain why RBC looks darker at edges than in the middle? [2 marks]

[Vin]

Does this site help? :\

http://greenfield.fortunecity.com/rattler/46/blood2.htm

[Saladin]

Explain why RBC looks darker at edges than in the middle? [2 marks]

RBCs have higher concentration of haemoglobin at the edges so that there is faster transfer of gases between cells of the tissue and RBCs.

[Chingoo]

^Agreed.

For understanding purposes, you can take it this way.

   OOOO                             OOOO
 OOOOOO                         OOOOOO
OOOOOOO                       OOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOO                       OOOOOOO
 OOOOOO                         OOOOOO
   OOOO                             OOOO

Imagine the above is an RBC and O represents the haemoglobin molecules. Since haemoglobin gives the pink coloration to a RBC, and its present in larger amounts on the outer side, the outer side looks more reddish than the inner side, which is flattened.

[Heart Hacker]

and i thought it was beacuse of lighting 

less light reaches the centre because its hollow so it appears to be darker ...(thats what i thought)

[Chingoo]

less light reaches the centre because its hollow so it appears to be darker ...(thats what i thought)

Firstly, it's not hollow. It has plasma and haemoglobin too. Secondly, it's not 'darker', it's paler. If you look at what ~Vin~ posted, it is lighter from the inside and darker from the outside. Since the coloration is lesser in the centre, the amount of red light absorbed (in terms of physics, the part of light which is absorbed is the one which we see) is less than for the corners. Hence the trend in the light microscope.

[Heart Hacker]

aha...i got it Thanks