plotting ekg curve using a buffer

i have a matlab code that processes 8 images stored in a folder in C drive to find the percentage of red color in each image making use of counting pixels using a for loop. I have attached the matlab code and images.please make sure both matlab files and images are in same directory when running code. p is vector containing the percentage of red color in the images.

I need to plot a curve between p vector and time(in steps of let say 0.2 seconds) to see how percentage varies with time.The main problem is i need to have this curve updating itself like EKG signal. The buffer i wanna use is 5 time instants.That means after 5 time instants the curve between point 5 and point 6 will come into picture and the curve between point 1 and 2 will go out. Similarily when curve between point 6 and point 7 will come into picture and the curve between point 2 and 3 will go out(curve between point 1 and 2 has already gone out) .I hope i explained what kind of curve i need. Thanks