these.


PROCESS OF REPAIR

The process of repair in living tissue depends upon an inherent power
possessed by vital cells of reacting to the irritation caused by injury
or disease. The cells of the damaged tissues, under the influence of
this irritation, undergo certain proliferative changes, which are
designed to restore the normal structure and configuration of the part.
The process by which this restoration is effected is essentially the
same in all tissues, but the extent to which different tissues can carry
the recuperative process varies. Simple structures, such as skin,
cartilage, bone, periosteum, and tendon, for example, have a high power
of regeneration, and in them the reparative process may result in almost
perfect restitution to the normal. More complex structures, on the other
hand, such as secreting glands, muscle, and the tissues of the central
nervous system, are but imperfectly restored, simple cicatricial
connective tissue taking the place of what has been lost or destroyed.
Any given tissue can be replaced only by tissue of a similar kind, and
in a damaged part each element takes its share in the reparative process
by producing new material which approximates more or less closely to the
normal according to the recuperative capacity of the particular tissue.
The normal process of repair may be interfered with by various
extraneous agencies, the most important of which are infection by
disease-producing micro-organisms, the presence of foreign substances,
undue movement of the affected part, and improper applications and
dressings. The effect of these agencies is to delay repair or to prevent
the individual tissues carrying the process to the furthest degree of
which they are capable.