CELL INJURY AND CELL DEATH

INTRODUCTION

Cell Injury is a result of the sequence of events that occur if the limits of the adaptive capability

of cells are exceeded or there is no adaptive response is possible, for specific stimuli or injurious agents.

There are several of factors or occurrences that cause cell injury such as ischemia, hypoxia, chemical injury

and infectious stimuli like bacteria and viruses.

Different changes inside the cell’s environment and organelles occur when it is injured and

different mechanisms of cell injury can be observed. Depletion in ATP, mitochondrial damage, influx of

Calcium, presence of free radicals and defects in the permeability of cells.

In order for cells to adapt to these stresses, cells developed different cellular adaptations. These

are the reversible changes in the number, size, phenotype, metabolic activity or functions of cells in

response to the changes in their environment. Hypertrophy, hyperplasia, atrophy and metaplasia are

some of the adaptations that are being utilized by the cells in the body as the need arises.

However, if the cells weren’t able to adapt to stress, it leads to cell death, to either necrosis or

apoptosis. Necrosis is the type of cell death that is associated with loss of membrane integrity and leakage

of cellular contents resulting to dissolution of cells. There are several types of necrosis: coagulative,

liquefactive, gangrene, caseous, fat and fibrinoid necrosis. As for apoptosis, or the process of programmed

cell death is a pathway of cell death that is induced by a tightly regulated suicide program in which cells

destined to die activate enzymes that degrade the cells' own nuclear DNA and nuclear and cytoplasmic

proteins.

This case study includes photographs and micrographs of different diseases. It aims to help the

students to explain descriptively the gross and histopathologic changes seen in clinical examples of cellular

adaptation and cell injury. Another objective of this activity is to link the microscopic findings of specific

examples of cellular adaptation and cell injury to its pathologic causes and clinical presentation.

CASE 1

Clinical History:

R.M., 48-year-old, male died of cerebral hemorrhage. He had a longstanding history of poorly controlled

hypertension (BP = 210/140).

Gross specimen:

Postmortem examination of his heart showed that it weighed 835 grams (Normal = 300-350 grams). The

heart was cut in cross-sectional "bread loaf" slices. In this image, the rounded left ventricle is on the right

and the triangular right ventricle is on the left. The wall of the left ventricle concentrically measured

approximately 2.5 cm in width (normal width, ~1 cm).

(Photograph of the heart specimen) Normal Histology Before you look at the case, you may wish to review the histology of the normal myocardium at several increasing powers of magnification. Observe the intracytoplasmic striations and central nuclei.

Histological Section of Patient's Heart

This is a transmural histological section of the patient's heart removed at autopsy (Virtual Slide 001). For orientation, the ventricular cavity is to the left (marked with a heart icon). An arrow indicates a papillary muscle. (The endocardium is not evident at this magnification.) To the right is the epicardium, with a star icon indicating the epicardial fat.

Look at this slide at higher magnification in the area marked by the box.

Compare the patient's myocardium (on the left) with the normal myocardium (on the right) observed at the same magnification.

Study Questions:

1. Describe the cytoplasmic and nuclear changes in the cells compared to normal. 2. What subcellular (organelle) component would be most likely to have been increased in the

cells? Case Study Questions:

1. What pathological diagnosis (of the heart tissue) would appear on the report? 2. Explain your answer above by defining the pathological diagnosis you had made 3. Is this morphological change indicative of cell death? If not, what cellular change is this? Explain

your answer 4. What specific clinical cause could explain the myocardial change in this patient? 5. What are the other etiologies that can produce similar histological changes in the heart?

Additional Questions on Cellular Change The following are photographs and micrographs of different organs that had undergone cellular adaptations, identify each adaptation, identify the possible etiology and describe your answers briefly.

1. Breast

2. Trachea

3. Kidney

(ANSWER SHEET)

STUDY QUESTIONS

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ADDITIONAL QUESTIONS ON CELLULAR CHANGE

PHOTO # Cell Adaptation/Change Description Etiology

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