The next topic that we're going to talk
about in regards to cell injury and death
is how tissues and
cells fight back.
They adapt to injury.
They don't just get
hit and call it a day.
They do adapt.
Here's our road map.
We've previously talked
about an overview.
We've talked about things
that can cause injury
and how those insults actually
generate injury within
cells and tissue.
And now we're gonna talk
about how tissues and cells
adapt injury rather
than just die.
Remember our original kind of overview,
where you have on the left hand
side things living within
a normal homeostatic world
and normal levels of pH and
oxygen and nutrition etc.
And then injury happens,
and we get potentially
increased or decreased activity.
That's adaptation to maintain
cellular viability and to maintain
the integrity of the total
functioning of the organism.
So we're trying to maintain
An important point
that we will touch on
is that adaptation
can be maladaptive.
And just as an example,
let's say that we
and the heart has to pump
higher at greater velocities
with greater ATP use to
generate higher pressures.
When that happens, the individual
cells get bigger and bigger and bigger.
That's all they could do.
We cannot make more heart cells,
but those bigger and bigger cells
are not necessarily getting more
and more and more blood supply.
The blood supply stays the same.
So that adaptation,
at a certain point the cells get too big
and the diffusion distance from the
nearest capillary gets too short,
and you have cells that become
relatively ischemic or hypoxic.
And so that adaptation that initially
maintains normal profusion of the body
against higher pressure can
become maladaptive over time
and you can have heart failure.
All right, just a general,
high level concept.
But let's get down a little
bit more into the weeds.
We're gonna look at
several adaptive changes.
Atrophy- cells getting smaller,
tissues getting smaller.
We're gonna look at hypertrophy- cells
getting bigger, tissues getting bigger
of cell from one
mature adult form
to another one.
We'll talk about subcellular responses,
things going on within individual cells
and then we won't touch
on dysplasia today.
But keep in mind that adaptive
change might also involve things
becoming potentially malignant because of
the accumulation of additional mutations.