What is derma papilla, hair root or bulb, and hair shaft? After FUE during shedding which will fall, shaft along with bulb?

It is normal to lose transplanted hairs weeks after surgery.  It may take 6 to 12 months to see new hairs grow out.  The words you describe are just descriptions of the anatomy of a hair follicle.

Transplanted graft’s hair starts to shedding in the first week of surgery and may go on untill 4-6 th weeks after surgery. What does fall down or shedding is just hair shaft , not bulb or root that generate hair shaft and contains dermal papilla in it..İt is not surprising to lost approx.  %70-80 of all transplanted hair shafts in first month when you are washing, gently rubbing  or touching the head. İt is shock loss and not permanent. Even your native hair may affected with that post traumatic transient hair loss…New hair at transplant and donor area starts to grow at 3-4 th month after surgery .

at the post operative shed, the entire hair follicle will be shed; however, stem cells will remain behind to grow new hairs