Cell Injury and Adaptation: Introduction

by Richard Mitchell, MD

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    00:01 All right.

    00:03 The next topic that we're going to talk about in regards to cell injury and death is how tissues and cells fight back.

    00:10 They adapt to injury.

    00:12 They don't just get hit and call it a day.

    00:15 They do adapt.

    00:18 Here's our road map.

    00:19 We've previously talked about an overview.

    00:22 We've talked about things that can cause injury and how those insults actually generate injury within cells and tissue.

    00:32 And now we're gonna talk about how tissues and cells adapt injury rather than just die.

    00:38 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.

    00:52 And then injury happens, and we get potentially increased or decreased activity.

    00:59 That's adaptation to maintain cellular viability and to maintain the integrity of the total functioning of the organism.

    01:08 So we're trying to maintain normal homeostasis.

    01:11 An important point that we will touch on is that adaptation can be maladaptive.

    01:19 And just as an example, let's say that we have hypertension and the heart has to pump higher at greater velocities with greater ATP use to generate higher pressures.

    01:36 When that happens, the individual cells get bigger and bigger and bigger.

    01:40 That's all they could do.

    01:41 We cannot make more heart cells, but those bigger and bigger cells are not necessarily getting more and more and more blood supply.

    01:47 The blood supply stays the same.

    01:50 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.

    02:03 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.

    02:15 All right, just a general, high level concept.

    02:18 But let's get down a little bit more into the weeds.

    02:22 We're gonna look at several adaptive changes.

    02:26 Atrophy- cells getting smaller, tissues getting smaller.

    02:30 We're gonna look at hypertrophy- cells getting bigger, tissues getting bigger Hyperplasia- cell number increasing.

    02:39 Metaplasia- change of cell from one mature adult form to another one.

    02:46 We'll talk about subcellular responses, things going on within individual cells and then we won't touch on dysplasia today.

    02:55 But keep in mind that adaptive change might also involve things becoming potentially malignant because of the accumulation of additional mutations.

    03:06 First, atrophy.

    About the Lecture

    The lecture Cell Injury and Adaptation: Introduction by Richard Mitchell, MD is from the course Cellular Injury.

    Included Quiz Questions

    1. ...heart failure.
    2. ...increased heart contractility.
    3. ...increased blood supply to the myocytes.
    4. ...decreased size of the myocytes.
    5. ...preservation of peripheral perfusion.
    1. Hypertrophy
    2. Hyperplasia
    3. Dysplasia
    4. Atrophy
    5. Metaplasia

    Author of lecture Cell Injury and Adaptation: Introduction

     Richard Mitchell, MD

    Richard Mitchell, MD

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