Please enable JavaScript.
Coggle requires JavaScript to display documents.
Describe the body's response to injury (HYPERTROPHY (Enlargement of an…
Describe the body's response to injury
HYPERTROPHY
Enlargement of an organ or tissue
>
Increase in the
size
of its cells
In cells that
cannot divide
(cardiac muscle) Hypertrophy is the
only
adaptive response
Skeletal muscle undergoes hypertrophy stimulated by
increased muscle activity
on exercise
Cardiac muscle undergoes hypertrophy stimulated by
sustained outflow
Due to hypertension & aortic valve disease, R & L myocardium undergoes hypertrophy
HYPERPLASIA
Enlargement of an organ or tissue
>
Increase in the
cell turnover rate
Endometrium
undergoes hyperplasia due to
excess oestrogen
exposure causing abnormal uterine bleeding
Thyroid undergoes hyperplasia in
puberty & pregnancy
stimulated by
increased metabolic demand
ATROPHY
Wasting away of part of the body
Shrinkage
in cells
Immobilization patients, loss of function causes muscle atrophy & osteoporosis
Retreat
by the cell to a
smaller size
at which
survival is still possible
In bed-bound patients reduction in blood supply causes skin atrophy (
thinning
) leading to pressure sores
METAPLASIA
Reversible transformation
of a fully
differentiated cell
into another
Cells sensitive
to a particular stress are
replaced
by other cell types which are able to
withstand stress
Normal ciliated columnar epithelial cells of the trachea are replaced by the more ‘rugged’
stratified squamous
ones
Cells encounter physiologic stresses
But they undergo
adaptation
to allow them to
modulate
their structure & function to
escape injury
But If injury becomes
irreversible
, so the cell
cannot recover
it
dies
APOPTOSIS
Programmed cell death
induced by activation of enzymes capable of degrading the cells’ own nuclear DNA & proteins
NECROSIS
External factors
which result in the
premature death of cells
in living tissue by
autolysis