00:01
Which of these is not true of the thymus? a, it's the organ where c -cell precursors mature.
00:07
B, it provides positive and negative selection for t -cells.
00:11
C, absence in the newborn will not affect b -cell -mediated immunity.
00:16
Or d, absence in the newborn will not cause t -cell -mediated immune disorders.
00:23
Okay, so with thymus, it is the site of maturation of t -cells.
00:28
So a is a true statement.
00:29
Its primary role is in maturation of the t cells.
00:34
So it's a small organ in the throat, and it does have two types of selection.
00:43
So negative selection is checking that the t cells don't attack the body's own proteins, because if they do, if they are self -reactive, obviously can't let those out into the bloodstream.
00:55
And then positive selection is checking, but it's, interacts with the mhc molecules on epithelial cells...